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Chemical Oceanographic Research: 

Present Status and Future Direction 



Arlington, Virginia 

Approved for public release; distribution unlimited. 


Chemical Oceanographic Research: 

Present Status and Future Direction 

Deliberations of a workshop held at Naval Postgraduate 
School, Monterey, California, December 11-15, 1972 

Dr. Neil R. Andersen, Convener, Ocean Science and Technology 
Division, Office of Naval Research, Arlington, Va. 


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Oceanography can be portrayed as a description of the sea as an 
environment, and as the study of all processes taking place within this 
environment and at its boundaries. Oceanography thus utilizes a variety 
of scientific disciplines, and its division into separate fields of study, 
such as chemistry and biology, is somewhat artificial. Nevertheless, 
a growing awareness of specific chemical problems and recent trends 
in studying the chemistry of the marine environment provides a basis 
for identifying chemical oceanography as a discrete programmatic 
area. This recognition is underscored by the fact that all branches of 
oceanography in some way depend on chemical information and tech- 

Traditionally, chemical oceanography has been almost completely 
descriptive, with emphasis on analytical chemistry. In the majority of 
cases, these studies have been solely directed at identifying water 
masses to gain insight into their movement and mixing, and at assisting 
biological investigations, such as productivity studies. More recently, 
however, the chemical oceanographer has been seeking to elucidate the 
entire spectrum of physical and chemical processes responsible not only 
for the composition of the ocean itself but also for the reactions occurring 
at the various interfaces (i.e. air-sea, sediment- and land-sea, and sus- 
pended material-sea). These considerations embrace the occurrence 
and distribution of the elements in the ocean and the types of reactions 
that occur between the various chemical species in solution, as well 
as the rates and mechanisms of supply and removal of each oceanic 
component (i.e., the routes and reservoirs). 

To explain the results of chemical studies, it is often necessary to 
consider circulation and mixing patterns and also interactions between 
the various phases present. Thus, chemical investigations of basic pro- 
cesses in the ocean environment can yield a better understanding of 
the chemical processes, and the results can elucidate physical processes 
of the ocean, such as water mass movement and mixing. As in the past, 
chemical oceanographic research will provide support and assistance 
in the understanding and solution of problems that mainly concern 
disciplines other than physical oceanography, such as marine biology 
and geology. Moreover, conducting a research program in a manner 
that addresses fundamental processes in the marine environment will 
reduce the constant redirection and disruption of well-planned research 
eflForts arising from the pressures of newly recognized or socially active 


problems (e.g. pollution) that will continually arise. In general, the 
results of basic research will have direct applicability to such problems. 

The major operating area of the Navy is the open ocean. However, 
ports and harbors with a wide range of marine environmental character- 
istics are also used extensively. To operate effectively, the Navy must 
possess a substantial knowledge of this marine environment; with this 
knowledge the degree of operational effectiveness obtained can be 
directly related to the understanding of all the factors that make the 
oceans and their properties what they are. It is for this reason that the 
Office of Naval Research supports a diverse research program in the 
ocean sciences. Inasmuch as chemical oceanography occupies a central 
role in the understanding of the multifaceted marine environment, 
chemical oceanographic research forms a part of this Ocean Sciences 
Program. The research provides insight into the processes and mech- 
anisms that determine the chemical character of the sea. Therefore, it 
is directly applicable to solving specific problems of Navy relevance, 
such as the corrosion and deterioration of materials in the marine en- 
vironment; the monitoring, assessment, and possible control of pollutants 
in the sea; the interchange of materials across the air-sea and sea-bottom 
boundaries; the effect of chemical processes on the properties of sound 
transmission, absorption, and scattering in the marine environment; and 
the use of tracers for the identification of water masses in studying ocean 
circulation and mixing mechanisms. All these problem areas share a 
common basis in chemistry. 

Unfortunately, most of the basic marine chemical processes, their 
controls, mechanisms, alterations by outside influences (e.g. pressure), 
and their effects upon man's utilization of the ocean, are not well under- 
stood. The number of organic compounds in the sea far exceeds that 
of all inorganic species combined, yet little is known of their involve- 
ment in trace-element chemistries. Few laboratories pursue the qualita- 
tive or quantitative assays of organics in the marine environment. We 
now possess only an extremely crude understanding of the chemical 
basis and effects of sound attenuation in the ocean. We know virtually 
nothing of the basic mechanisms and interrelationships of the chemical 
and bacteriological processes resulting in the corrosion of material in 
the marine environment, or the effects of antifouling material (e.g., 
copper) on a semienclosed body of water supporting heavy ship traffic. 
These are but a few examples. The objective of the research supported 
by the Navy in chemical oceanography is to understand the controls 
and mechanisms maintaining the chemical characteristics of the ocean 
environments and to elucidate the properties of marine equilibria. That 
understanding will then be applied to solving problems of naval relevance. 

The attainment of the aforementioned goal is synonomous with 
determinations of the present status and future direction of the field of 


chemical oceanography. To determine where chemical oceanography 
stands at the present time and what are the pressing problems that 
should be attacked during the next several years (i.e., the direction of 
the field), a group, comprising promient American chemical oceanog- 
raphers, assembled at the Naval Postgraduate School, in Monterey, 
California, December 11-15, 1972. Four days of deliberations and 
discussions were conducted in three major areas of concern: (A) Pro- 
cesses and Mechanisms Governing the Inorganic Composition of Sea- 
water, (B) Chemical Fluxes Through the Marine Environment, Including 
Air-Sea and Sediment-Sea Exchanges, and (C) Impact of Life Processes 
on the Chemistry of the Ocean. The specific objectives of this confer- 
ence were ( 1 ) to promote the exchange of information, especially among 
ONR-supported scientists; (2) to promote any cooperative research; 
and (3) to assess the future areas of investigation in chemical oceanog- 
raphy and thereby make recommendations for the future direction of 
research in this field generally, and thereby the ONR Program, specifi- 
cally. The first two of these objectives were accomplished during the 
gathering. The third objective, the results of the considered opinions 
of the participants of the meeting, are contained in the subsequent 
text. This discussion not only provides insight into the extent of con- 
temporary understanding of the chemistry of the ocean, but also ad- 
dresses specific problem areas requiring research to enhance this under- 

Neil R. Andersen 
Workshop Convener 
Washington, D.C. 
February, 1973 


Preface Hi 

Executive Summary 1 

Session A 
Processes and Mechanisms Governing 
the Inorganic Composition of Seawater 

Dr. Frank J. Millero, Discussion Leader 



The Chemical Composition of Seawater 7 

The Physical and Chemical Properties of Seawater 12 

Chemical Interactions Among the Major Components 13 

Measurement and Prediction of the 

Properties of Solutes in Seawater 15 


Homogeneous Reactions 17 

Heterogeneous Reactions 18 

Air-Sea Interface 21 

Analytical Studies 21 






Session B 

Chemical Fluxes Through the Marine Environment, 

Including Air-Sea and Sediment-Sea Exchanges 

Dr. Edward D. Goldberg, Discussion Leader 




Present Conditions in the Ocean 33 

Chemical and Radioactive Properties 35 






Session C 

Impact of Life Processes 

on tlie Chemistry of the Ocean 

Dr. Francis A. Richards, Discussion Leader 




Contemporary State of Knowledge 49 

Processes, Rates, and Mechanisms 50 

ModeUng 52 

Future Efforts 52 



Nutrients and Dissolved Gases 57 


Synthetic Organic Materials 59 


Occurrence, Formation, and Degradation 61 

Hydrocarbon Gases 61 


Redox Potential 62 

pH 63 

Alkalinity 65 







The following discussions consider in varying detail the present 
status of knowledge in chemical oceanography and the various problem 
areas that merit research support during the next several years. The 
purpose of these comments is to summarize the collective recommenda- 
tions of the workshop participants, and not to preempt background 
material in the succeeding sections. 

Because residence times of the chemical constituents of seawater 
are much shorter than the age of the oceans, chemical processes removing 
these constituents must occur continuously. Although there are many 
possible reactions, the sites where most reactions occur are essentially 
unknown. Two locations for many of the reactions, the continental 
margins and the photic zone, are probably highly important and have 
been little studied as areas where the mechanisms that control the 
major constituents of seawater operate. These areas should be studied 
in detail, using new field techniques such as in-situ sensors. Their 
highly reactive amorphous phases should be characterized and experi- 
ments should be designed to elucidate their thermodynamics and kinetics. 
Both field and laboratory experiments should be carried out on the 
possible effects of organisms on major and trace-element constituents, 
as well as on the conventional nutrients and organic phases, and these 
experiments should be coupled with physical oceanographic and geo- 
chemical work on the same areas. 

In addition to investigations at the geographical locations indicated 
above, identification of other sites where chemical processes are active 
is needed. For example, chemical reactions (e.g., adsorption), including 
their kinetics, need to be studied throughout the range of saUnities 
encountered where river water mixes with seawater, taking into account 
seasonal changes. Specific consideration should be given to chemical 
speciation and the association of these species with inorganic and 
organic ligands. 

More research needs to be conducted on the pressure-volume-tem- 
perature (P-V-T) relationships of seawater to provide a more reliable 
equation of state and to improve our understanding of the effect of 
pressure on chemical equilibria. Differences in data on the physical 
properties of seawater should be reconciled. Associated with this area 
of research, more work is needed on the kinetics and equilibria responsi- 
ble for the properties of sound (e.g., absorption) in the marine environ- 
ment. Research is also needed on the generation of gas bubbles (e.g., 


©2, H2S, and CH4), their characterization and chemical composition in 
seawater, the diagenetic processes resulting in the formation of gases 
in the sediments, and their flux into the overlying water. 

Variations in space and time of suspended matter in the ocean require 
further research as do processes occurring at the ocean bottom and the 
influence of sediments on the chemistry of the water column. Specifically, 
mechanisms and rates of in situ production and consumption of sus- 
pended material need to be determined both in the water column and at 
the bottom. The occurrence of trace elements in calcareous and silicious 
tests needs further elucidation, as do the rates of reaction (e.g., solution) 
of such tests. Similar studies on the hydrated metal oxides and particu- 
late organic carbon are needed. The composition and flux of organic 
carbon and the preferential formation of minerals (e.g., high magnesium 
calcite over aragonite) are important research areas. 

A host of organic compounds is dissolved in the sea, yet their com- 
position, distribution, and ecological importance are unknown. An 
inventory of organic chemicals in the marine environment needs to be 
established, and their origin, age, composition, and fate need to be 
determined. Processes, mechanisms, and rates — both in rapid-turnover 
areas as well as low-productivity locations — need to be studied. For 
example, what is the role of organic matter in sedimentation, diagenesis, 
and air-sea interaction? What is the nature of the interaction between 
organic matter and the inorganic components of the ocean? 

Many aspects of the influence of the ecosystem on chemical distribu- 
tions are unknown, specifically with respect to heavy metals. Knowledge 
of the distributions, forms, and fate of these chemicals is presently in- 
adequate to define their role in stimulation and control of the biosphere. 
Little is known of the synergism and antagonism of heavy metals in 
this system. The low levels of chemical constituents that control biologi- 
cal systems and the competitive nature of membrane transport sites 
require that low concentrations, both of nutrients and of antimeta- 
bolites (such as arsenate and trace metals), be considered simultaneously. 
Backleakage of nutrients and of organic metabolites significantly alters 
water chemistry; the rates of backleakage are important terms in the 
flux relations in any models constructed. Realtime rates of nutrient uptake 
are needed and the regulatory processes that control and determine the 
characteristics of nutrient fields need further investigation, especially 
for incorporation into models. 

The marine environment is a dynamic system. Our degree of under- 
standing of this system will be directly related to our understanding 
of chemical fluxes within it. Important questions concern how much 
material is being added to the present-day ocean from each of the various 
sources and how much is being removed to each of the various sinks. 
Do addition and removal rates change as functions of time? Information 

on the injections of major and minor elements into the oceans, their 
speciation, and regional mesoscale air-sea transport studies of reactive 
and unreactive gases (e.g., the transfer coefficients), can be used to 
calculate time-dependent fluxes. This information can then serve as the 
basis for constructing three-dimensional models describing oceanic 
processes that in turn provide the foundation for predictions of oceanic 
conditions, predictions that, for operational needs such as those of the 
Navy, can be considered the ultimate goal of oceanographic research. 

Two specific recommendations for future research were made: (1) 
the study of plutonium chemistry of the ocean, and (2) chemical processes 
occurring under and near ice. Plutonium is a toxic, radioactive, man- 
made element whose behavior in the marine environment is inadequately 
known. Only a few determinations have been made of its concentra- 
tions in seawater, in marine organisms, and sediments. The use of 
plutonium is expected to expand rapidly. Two of its nuclides, Pu-239 
and Pu-238 are being used as fuels, and accidents have already released 
both of them into the environment. The chemical behavior of plutonium 
in the ocean cannot be extrapolated from what has been observed on 
land, making it essential that the marine chemistry of this element be 

The second specific research recommendation was to study the factors 
governing the composition of seawater below the polar ice cover. 
Neither the effects of freezing of seawater on the chemistry of the 
water-ice interface nor ice-related chemical processes are generally 
well understood. The intermittently ice-covered polar seas may be 
areas of strong air-sea gas exchange. The freezing process and biota 
unique to the ice-seawater system may impart chemical properties to 
this seawater that may be distinct from those of open-ocean regions. 

The research recommended, discussed during the workshop, and 
summarized here was selected on the basis of immediate requirements 
in the field of chemical oceanography. However, as was pointed out in 
the Preface, the recommendations will also form the basis of a research 
program to be appUed to solving diverse operational problems with 
which the Navy is faced. For example, in some regions the scattering 
of sound by biological populations in the upper layers can place practical 
Hmits on the operation of low-frequency (2-20 kHz) sonar. In recent 
years it has become clear that scattering strength varies over the oceans 
in accordance with some pattern. The pattern is apparently associated 
with variations in populations of marine organisms whose density and 
distributions closely depend on other Unks in the food chain, on mixing, 
thermal gradients, light, chemical nutrients, etc. A data base of volume 
reverberation measurements has been accumulated for the development 
of a prototype model for forecasting volume reverberation. Zones of 

scattering strength stand out as identifiable regions of the ocean. Signifi- 
cant correlations between zooplankton distribution and volume rever- 
beration are encouraging, but our understanding must be improved. 
More effort is needed in investigating the dynamic character of the 
interactions between biological populations of "natural hydrographic 
regions" and the chemical variability of their waters. Results of research 
in chemical oceanography, as recommended in this document, can have 
numerous applications in gaining this understanding of the chemical 
factors responsible for the seasonal and long-term changes in marine 
ecosystems and bioacoustical provinces of the ocean, and in providing 
a prediction capability. This is but one example of the many applications 
of results from basic research in chemical oceanography to the solving 
of operationally Navy-relevant problems. 

The amount of published information in the field of chemical oceanog- 
raphy, like that in many other fields of science, has doubled every few 
years recently. Moreover, much information germane to problems of 
chemical oceanography is generated by parties in diverse fields, remote 
from the problems faced in chemical oceanography, and is published in 
journals or kept in files not readily accessible to oceanographers, except 
by occasional, coincidental contacts or discoveries. No concerted effort 
has been made to search out appropriate information, evaluate it, and 
present it to the oceanographic community. The lack of such an effort 
has an unknown, but possibly significant, impending effect on progress 
in chemical oceanography. Under the traditional system of financing 
oceanographic research, principally with the aim of collecting more 
data, the inefficiency of information gathering, synthesis, and transmittal 
to younger and future scientists is growing. 

This situation should be remedied. It should be financially and sci- 
entifically sound to periodically free selected, experienced individuals 
from the burden of having to collect new data and sponsor them, for 
perhaps a year, for the purpose of collecting, synthesizing, and pre- 
senting scattered information in their field of expertise. Another possible 
solution is to have some junior investigators at each research institution 
for the purpose of gathering and assimilating information in support 
of existing programs. 

Session A 

Processes and Mechanisms Governing 
The Inorganic Composition of Seawater 

Dr. Frank J. Millero, Discussion Leader 


The ocean is commonly considered a steady state system, at least 
with regard to the major dissolved constituents over long periods of 
geological time. Furthermore, it appears that throughout most of the 
ocean the ratios Na/Cl, K/Cl, SO4/CI, Mg/Cl and Br/Cl are constant 
within analytical precision (Lyman and Fleming, 1940; Culkin, 1965; 
Culkin and Cox, 1966; Riley and Tongudai, 1967; Riley and Chester, 
1971). There is conflicting evidence regarding the variability of Sr/Cl, 
HCO3/CI, B(OH)3/Cl and F/Cl. The variations of Ca/Cl with depth 
have been well defined. Fluctuations arising from river runoff and 
freezing are locally significant, and may, such as in the Arctic, include 
vast geographical areas (see p. 35). The minor elements are potentially 
more variable in concentration and reactive in the marine environment; 
however, in most cases reliable analytical data and physical chemical 
understanding of these variations are lacking. The present status of our 
knowledge of the chemical composition of seawater and of chemical 
speciation, as well as needed research, were reviewed previously by 
Pytkowicz and Kester (1971). 

The processes that control the major composition of seawater must be 
removal reactions, because the residence times of these elements are 
shorter than the age of the ocean. Although the equihbria models of 
Sillen (1961; 1965a,b; 1967a,b), Holland (1965), and MacKenzie and 
Garrels (1966a,b) have yielded reasonable suggestions as to how sea- 
water attained its present major composition and how this composition 
is maintained, many questions exist concerning the mechanisms and 
processes that regulate the concentrations of all the major and minor 
constituents. Many questions pointed out by Broecker (197 1), Chave and 
Smith (1972), and others concerning the effect of the circulation of 
the world's oceans and the effect of biochemical processes on the com- 
position of seawater remain unanswered. For example, Pytkowicz 

has shown that equilibrium models of the ocean may often not apply, 
in that for the carbon dioxide system, kinetic controls by organisms 
are more likely than controls by chemical equilibria. To test whether 
the ocean is in a steady state, or, if not, how the system is approaching 
equilibrium, it is necessary to identify the chemical reactions that 
regulate the concentration of each element and to determine the physical 
chemistry of each reaction. 

Correct specific or generalized concentration-control reactions for 
the major constituents of seawater probably can be written. Our knowl- 
edge of the thermodynamics, the kinetics, and the environmental influ- 
ences on these reactions varies considerably. Some of our ignorance is 
a result of the natural (biological or chemical) production of thermo- 
dynamically unstable phases or of extremely slow reactions. 

We cannot state with certainty the concentrations of the minor con- 
stituents of seawater, let alone define the chemical and physical reactions 
that control the concentrations. 

To understand the processes and mechanisms governing the inorganic 
composition, three major questions must be answered. What is the 
medium of seawater? What kinds of chemical reactions control the 
composition of seawater? Where do these chemical reactions occur? 

In the following discussion we have attempted to focus on six major 
topics that should lead to a better understanding of the processes and 
mechanisms controlling the inorganic composition of seawater. These 
are (1) seawater as a medium; (2) minor elements; (3) the role of estuaries 
in modifying the composition of seawater; (4) particulate matter; (5) 
the role of bottom deposits in modifying the composition of seawater; 
and (6) numerical models in chemical oceanography. 

Some important areas where information concerning the processes 
and mechanisms governing the inorganic composition of seawater is 
needed include the following (National Academy of Sciences, 1971a): 

• Pollution of the environment. Since the ocean is the final reservoir 
for pollutants, we must have a better knowledge concerning the fate 
of present and potential pollutants. The introduction of radioactive 
wastes (such as plutonium) to the marine environment may present us 
with many new problems. 

• Chemical products from the sea. Although it is not possible at 
present to recover economically trace constituents from seawater, 
further work may yield better methods than those presently being used. 

• DesaHnation. With the increasing need for water, new techniques 
may become available. 

By studying the chemical processes that control the composition of 
seawater under natural conditions (a dynamic chemical system) and 
obtaining an understanding of the inputs and outputs (the fluxes), much 
better estimates can be made for changes that will occur in the oceans. 

Since the future of the earth is intimately related to the future of the 
oceans, it is important to understand the composition of seawater and 
how this composition affects the processes occurring in the oceans. 


Some of the major questions facing chemical oceanography are: 
How did seawater reach its present composition? How does this com- 
position affect processes that control the composition of minor com- 
ponents? Part of the answers are related to the questions, what is the 
medium of seawater? What are the chemical forms of the major com- 
ponents? What fluctuations occur? How are the physical and chemical 
properties of seawater related to the chemical composition? How does 
the medium of seawater influence various chemical processes occurring 
in the oceans? Although the answers to some of these questions have 
been found, many questions still remain and must be answered. In the 
following section some of the areas that have been studied, and some 
that need to be studied further are discussed briefly. This discussion 
will be divided into four major topics: the chemical composition of 
seawater, the physical and chemical properties of seawater, chemical 
interactions among the major components, and measurement and 
prediction of solutes in the medium of seawater. 

The Chemical Composition of Seawater 

Although we know the concentrations of the major components 
(Lyman and Fleming, 1940; Culkin, 1965; Riley and Chester, 1965; 
Pytkowicz and Kester, 1969 and 1971) (Table 1), little is known about 
the mechanisms regulating these concentrations in the oceans and 
where this regulation occurs. 

From Table 2, it can be seen that thermodynamic and kinetic data 
on the concentration-controlling reactions for the major dissolved con- 
stituents of seawater are limited. Furthermore, organic processes are 
known to influence some of these reactions. To understand the mechan- 
isms controlling the concentration of more than 99% of the dissolved 
matter in seawater, it is necessary to study many of the reactions in 
Table 2. This can be done through \ 

1 . Careful studies of pure systems in the laboratory 

2. Careful studies of "carefully impure" systems in the laboratory 

3. Careful studies of real oceanic situations with as many variables 
as possible controlled 

4. Chemical and structural analysis of materials (notably alumino- 
silicates) supplied to the oceans from the land 

Table 1 
The Most Abundant Ions in Seawater* 


gm/Cl (%)t 

1 Kgm of Seawatert 



















































*Values of g/kgm of seawater/chlorinity seawater; taken 

from Millero (1973a,b). 
tFor 357^„ salinity or 19.374°/^ chiorinity seawater; taken 

from Millero (1973a,b). 

5. Chemical and structural analysis of intermediate natural materials 
in the iron-sulfur and similar systems 

6. Use of information and materials in 4 and 5 and experiments in 

Since the oceans have nearly a constant composition of constituents, 
reactions must be occurring nearly equally everywhere (unlikely) or 
at rates slower than mixing rates (hkely). When we ask the question, 
"Where do these reactions take place?" we come up with several an- 
swers, and each answer raises a question. Consider the reactions listed 
in Table 2. 

Reaction 1. About 10^^ moles of CaCOs are precipitated in the 
oceans yearly. The majority of this precipitation in near-surface pelagic 
areas as a result of biological activity; lesser amounts are biologically 
precipitated on continental shelves and on coral reefs. Although the 
near-surface layers of the ocean are invariably super-saturated with 
CaCOa, there is little evidence for chemical precipitation of this com- 
pound. This problem is discussed by Chave and Seuss (1970) and 
Pytkowicz (1965). Another problem concerned with Reaction I is that 


Table 2 

Chemical Reactions Controlling the Concentration 

of Major Constituents in Seawater 









Dissolved — Solid Reactions: 

1. Ca+2 + 2HCO:f ^ CaCO. + CO. + H.O 




2. Ca+- + SOj2 + 2H:.0 ^ CaSOr2H.O 



None (?) 

3. Fe*- + HS- + (H.O) ^ FeSnH.O + H + 




4. FeSnH.O + H.S ^ FeS. + (H-O) 




5. Na* + CI- ^ NaCl 




6. K^ 

Mg+'J + Al-Silicate (amorphous?) + SiO. 

+ HCOr 

+ H+ ^ Mg+'J Al-Silicate (amorphous or 

crystalHne) + CO. + H.O 



None (?) 

7. Same as 6 with initial crystalline Al-Silicate 




8. Exchange reaction Me-Clay + Me + + ^ 

Me-Clay + Me + 




9. 2Mg+2 + 3H4Si04 + 40H ^ 

Mg.Si,,08+6H + 




10. H^Si04^Si02+2H.O 




1 1. H4Si04 ^ SiO-nH.O + (H.O) 




12. Reactions with basalts on the sea floor 




only 10'^ moles of calcium are deHvered to the ocean each year by 
rivers. Thus, more than 90% of the carbonate precipitated each year 
must redissolve if the ocean is to maintain a constant composition 
(Chave and Smith, 1972). It is not at all clear where this resolution 

Reaction 2. Seawater is about one-fifth saturated with respect to 
gypsum. Thus, for this reaction effectively to remove SOj- from sea- 
water, significant evaporation must occur. There appear to be too few 
marginal hypersaUne seas in the modern oceans to affect significantly 
the SOr^ concentration in the ocean. Perhaps in the past this mechanism 
was more effective. 

Reactions 3 and 4. Anoxic conditions are necessary for the reduction 
of sulfate to sulfide and for the precipitation of metal sulfides. Although 
Bemer (1971) presents some thermodynamic data on the metastable 
ferrous sulfides, there is still much to be learned. Precipitation of hydrous 


sulfides is known to occur in the Black Sea, estuaries, fjords, and other 
restricted environments, but these areas are probably too small to affect 
the SO4 - concentration of seawater. Because of the restricted areas in 
which Reactions 2-4 can occur in the ocean, it is likely that SO^^ is 
increasing in concentration in seawater. 

Reaction 5. A higher degree of evaporation is required to precipitate 
halite than gypsum. Thus, the question asked under Reaction 2 is even 
more significant. In that no other mechanism for chemical removal of 
sodium and chloride is known (except possibly Reaction 12), we must 
conclude that these elements are increasing in concentration in seawater. 

Reactions 6 and 7. Reactions of some aluminum silicates have the 
potential of removing SiOi, HCO:!^ and cations from seawater or near- 
surface interstitial waters. Although aluminum silicates are present in 
all oceanic environments, there is little evidence that reactions are 
occurring. Because the exact nature of the aluminum siHcates entering 
the sea from rivers is unknown, predictions of the kinetics or the loca- 
tion of these reactions are impossible. 

Reaction 8. Exchange reactions of metals on clays have been thor- 
oughly studied. They do not appear to be of sufficient magnitude to 
regulate the concentration of ions such as K+ and Mg^^ in seawater. 

Reaction 9. The precipitation of sepiolite should occur in seawater 
or in near-surface interstitial waters. There is little evidence that it 
does. The regulation of Mg+" in seawater by any combination of Reac- 
tions 6-9 is still a puzzle (Drever, in press). 

Reaction 10. Anhydrous silica (quartz, trydimite, or chrystobalite) 
does not appear to react with seawater although it is commonly under- 
saturated with respect to these phases. Some deep Pacific waters are 
supersaturated with respect to quartz, yet no reactions appear to be 
occurring there (Wollast, in press). 

Reaction II. Biogenic opal (SiOi-nHsO) is precipitated in enormous 
quantities in surface waters of the ocean as diatom and radiolarian 
tests. All seawater and near-surface interstitial water is undersaturated 
with this phase, and at most only a few percent of this opal reaches the 
sea floor. It is not known where or how this resolution occurs. Wollast 
(in press), and Hurd (1972a,b) have suggested some mechanisms. 

Reaction 12. The hydration of basaltic glass on the sea floor and 
subsequent reaction of the hydration products with seawater may re- 
move cations from seawater. Little is known about these reactions. 

Many questions regarding mechanisms and locations for the regula- 
tion of major constituent concentrations in seawater are mentioned 
above. Although reactions that are probably vahd can be written, the 
locations of these reactions in the ocean system are essentially unknown. 
A summary of our ignorance on these matters is given in Table 3. 


Table 3 
Location of Chemical Reactions in the Ocean 


Air-Sea Interface 

Photic Zone 

Continental Boundaries 

Bulk Ocean 


Lost as aerosols. 


Precipitation impor- 



but rapidly 

very important. 

tant. Solution in low 



returned to the 


pH environments 

Solution may 

Solution may 

ocean by rivers. 



be important. 

be important. 


As above 

No reactions 

Only possible sink 
for oxidized sulfur. 
Importance probably 

No reactions 

No reactions 

(S- = ) 

No reaction 

Possibly important 

Only probably sink 

No reaction 

Possible sink in 

due to photo- 

for reduced sulfur. 


synthetic sulfur 

Importance probably 

waters. Impor- 



tance unknown. 

Lost as aerosols. 

No reactions 

Only possible sink 

No reaction 

No reaction 

but rapidly 

for CI. Importance 

returned to the 

probably small. 

ocean by rivers. 

As above 

No reaction 

Only significant sink 
for Na. Importance 
probably small. 

No reaction 

Possible uptake 
by hydrated 
basalt. Impor- 
tance unknown. 

As above 

Possible reactions 

Possible reactions with 

Possible reactions 

Possible reactions 

with Al-silicates. 

Al-silicates. Some pre- 

with Al-silicates. 

with Al-silicates. 


cipitation as Mg- 




calcites. Importance 



As above 

As above 

Possible reactions 
with Al-silicates. 
Importance unknown. 

As above 

As above 


Nearly all HCOr 

Involved in all 

As with photic zone 

As with photic 

As with photic 

must return to 

carbonate and Al- 



the atmosphere 

silicate reactions. 

as COj through 


this interface. 




Biogenic precipita- 


Solution of bio- 

Small percentage 

tion very signifi- 

reactions may be 

genic opal slower 

of biogenic opal 

cant. Resolution 


than photic zone 

reaches the sea 

may be significant 

because of lower 

floor. Al-silicate 

because of higher 

temperatures and 


temperature and 

pH, and higher 


pH, and low Si. 

Si. Importance 

Important. Impor- 

unknown. Al- 

tance of Al- 

silicate reactions 

silicate reactions 

probably not 



1 1 

Although Table 3 can be basically summarized as "significance 
unknown," two locations for many of the reactions are suggested which 
have been little studied from the point of view of controlling mechanisms 
of major seawater constituents. These are the continental margins and 
the photic zone. We should (1) carefully investigate these areas using 
new field techniques such as in-situ sensors, (2) characterize the highly 
reactive, amorphous phases, and design experiments to study their 
thermodynamics and kinetics, and (3) consider and experiment in the 
field and the laboratory on the possible effects of organisms on major 
constituents, as well as conventional nutrients and organic phases. 

The Physical and Chemical Properties of Seawater 

The bulk thermodynamic and transport properties of seawater (such 
as P-V-T data, viscosity, conductivity, specific heat, enthalpy, freezing 
point, sound absorption, etc.) are useful to describe physical oceano- 
graphic processes such as adiabatic mixing and deep sea stability. 
Although numerous measurements (Pytkowicz and Kester, 1971; 
Millero, 1973a,b) have been made on the physical properties of sea- 
water, there still is a need to reconcile the differences that exist between 
various investigators. For example the P-V-T properties (the equation 
of state) and the sound absorption of seawater need further work. There 
is a need for a reliable equation of state for seawater for deep-sea stability 
calculations. One method of deriving a reliable equation of state for 
seawater is to calculate compressibilities from sound velocity and specific 
heat measurements by an iterative technique (Crease, 1962). Since one 
can measure sound velocities with great precision, and the difference 
between adiabatic and isothermal compressibilities is small, the com- 
pressibilities derived from sound velocities are more precise than those 
determined by direct methods (Fine, Wang and Millero, 1973). Unfor- 
tunately, the velocity of sound measurements made by Wilson (1960) 
and Del Grosso and Mader (1972) are not in good agreement at high 
pressures and low temperatures (the oceanographic range of importance 
for deep-sea stability calculations). These discrepancies must be rec- 
onciled before we can derive a reliable equation of state. Direct mea- 
surements on the P-V-T properties of seawater with accuracies ap- 
proaching those of sound velocity measurements (Millero, Knox, and 
Emmet, 1972; Emmet and Millero, 1973) would also yield useful data. 
It is important that all the P-V-T properties (as well as the other physical- 
chemical properties) of seawater be directly related to pure water. The 
reason is twofold: first, pure water is the working standard for the 
P-V-T properties of liquids, and if corrections are needed in the future 
they can be made; second, and probably more important, by examining 


the difference between the P-V-T properties of seawater and pure water, 
one can magnify the effect of sea salts, which is what one is normally 
interested in when studying the oceans. 

The most useful form of an equation of state would be one formulated 
in terms of the contributions of each significant solute. This would 
make the equation of state applicable in regions where special condi- 
tions prevail, such as in the Red Sea, or in low sahnity regions near 
rivers or ice. Such an equation would reduce to that of pure water for 
zero salinity, and would account for the contribution of each significant 

Recent work on sound absorption in the ocean has opened up several 
questions concerning pressure-dependent chemical equilibria and 
chemical relaxation processes in the ocean. It is clear that the Schulkin 
and March equation (1962), originally developed to account for sound 
absorption due to the relaxation of magnesium sulfate in the ocean 
cannot explain the following anomahes: 

• The low-frequency relaxation of 1 kHz deduced by Thorp (1965) 
from his analysis of long-range, deep sound channel acoustic propaga- 
tion. The absorption below 1 kHz is greater by a factor of ten than 

• The decrease with pressure of sound absorption in the 30-150 
kHz region observed by Bezdek (1972, 1973). The pressure effect is 
greater by a factor of two than predicted. 

• The asymmetry in absorption-per-wave-length plots in real sea- 
water in the 30-300 kHz region obtained recently by Bezdek (1973) 
in the ocean and also in the original work by Wilson (1951) in the labora- 
tory. This implies another relaxation between 1 kHz and the MgS04 
absorption at 60 kHz. 

The kinetics and equilibria responsible for these effects need to be 
identified by careful laboratory measurements of sound absorption 
from 500 Hz to 300 kHz due to the various solutes in seawater whose 
concentrations are above 1 ppm. The synthetic seawater used by early 
investigators omitted boric acid which, according to temperature jump 
work by Fisher, Yeager, MiceU, and Brussel (1972), could be the cause 
of the 1-kHz relaxation. The asymmetry in the high-frequency plot may 
be due to magnesium bicarbonate which Garland and Atkinson (1973) 
predict, on a theoretical basis, to have a relaxation frequency in the 
10-kHz region. 

Chemical Interactions Among the Major Components 

Knowledge of ionic interactions in multicomponent electrolyte solu- 
tions Hke seawater and body fluids is necessary (Millero, 1971a, 1973a) 


for an understanding of the physical and chemical properties of the medi- 
um. These interactions also are important because they affect many of 
the chemical processes that occur in seawater. For example, short-range 
interactions in seawater have been shown to affect the pH of the oceans 
(Weyl, 1961), the solubility of minerals in the oceans (Garrels, Thomp- 
son, and Siever, 1961), and the ultrasonic absorption of the oceans 
(Liebermann, 1949; Fisher, 1967). 

Classically the ionic interactions in seawater have been treated by 
using Bjemim's (1926), ion-pairing model as exemplified by the work 
of Garrels and Thompson (1962), Kester and Pytkowicz (1968, 1969, 
1970), Atkinson, Dayhoff, and Ebdon, 1972 and Hawley, 1973. This 
approach formulates the electrostatic cation-anion interactions in terms 
of equilibrium constants that can be determined at the temperatures, 
pressures (Lafon, 1969; Kester and Pytkowicz, 1970; Millero, 1971b; 
Millero and Berner, 1972), and chemical environments characteristic 
of the oceans (Kester and Pytkowicz, 1968, 1969, 1970). The results 
of these methods have been successful in accounting for the activity 
coefficients of many solutes in the seawater medium (Kester and Py- 
tkowicz, 1968, 1969, 1970), for the solubility of some minerals in the 
ocean (Garrels, Thompson, and Siever, 1961), and for the ultrasonic 
absorption of seawater (Fisher, 1967). Recently, the ion-pairing model 
has also been useful in explaining the Raman spectra of multicomponent 
sulfate solutions (Daly et al., 1972). An alternative approach that has 
been developed recently (Millero, 1971a, 1973a,b) considers ionic inter- 
actions in more general and less mechanistic terms. The model simply 
states that any physical property of seawater {Psw) is equal to the 
property for pure water (Ph^o) plus a contribution from the weighted 
ion-water interactions of the major components and one from the weight- 
ed ion-ion interactions of the major components: 

Psw = P//20 + ion-water interactions + ion-ion interactions. (1) 

The first two terms can be estimated from infinite dilution data in 
single-salt solutions (binary mixtures of salt + H2O). The third term 
can be divided into a theoretical Debye-Hiickel Limiting Law term and 
a term arising from deviations from the Limiting Law of the weighted 
major ionic components. This general approach of examining the physi- 
cal-chemical properties of seawater serves two purposes. First, it pro- 
vides the theoretical concentration dependence of the physical-chemical 
properties and second, it emphasizes the importance of ion-water and 
ion-ion interactions of major components of seawater. 

Preliminary applications of these methods to the thermodynamic and 
transport properties of seawater have been successful (Millero et al., 
1973, and Millero, 1973a,b). All of this preliminary work has been 


carried out using data for single-electrolyte solutions. Further refine- 
ments must await more reliable single-electrolyte data as well as data 
for the excess thermodynamic and transport functions. 

Measurement and Prediction of the Properties of Solutes in Seawater 

One of the most important problems in examining chemical reactions 
in seawater is the estimation or prediction of the thermodynamic and 
kinetic properties of solutes (ionic and non-ionic). The thermodynamic 
equilibrium of a chemical process A + B — > C can be characterized by 
an equilibrium constant 

K- ac _ [C] yC 

SLA^B [A][B] 7A7B' ^"-^ 

where a;, [i] and yi are the activity, concentration, and activity coeffi- 
cients of species i. The effect of pressure on K is given by 

dUn K\ AV 

dP )^ RT' ^^^ 


AV = V(C)-V(A)-V(B). (4) 

V(i) is the partial molal volume of species i. 
The effect of temperature on K is given by 

Bin K\ AH 


AH = H(C)-H(A)-H(B). (6) 

H(i) is the partial molal enthalpy of species i. 

The determination of the equilibrium constant, its pressure dependence 
(Millero, 1971b; and Millero and Berner, 1972), and its temperature 
dependence can be made by (1) direct measurements in seawater (Kester 
and Pytkowicz, 1968, 1969, 1970), and (2) estimation from known 
properties of pure water and simple solutions (Millero, 1971a,b). To 
provide information in the absence of direct measurements, it is impor- 
tant to develop methods to estimate the activity coefficients, the partial 
molal volumes, and partial molal enthalpies of solutes in seawater. 


Direct measurements of some selected systems (e.g., the ion com- 
piexing of metal ions) must also be made because they serve as a check 
for the various estimates. Several methods have been developed to 
predict activity coefficients, partial molal volumes, and enthalpies of 
solutes in seawater. Some of these are semiempirical (based on direct 
measurements in seawater), while others are theoretical (based on 
measurements in pure water). Further work is needed to determine 
which method is more useful. Since there are considerable thermo- 
dynamic and kinetic data available in pure water, estimates based on 
pure-water data could prove to be the easiest and fastest to make. 


Chemical processes involving minor constituents in the ocean may 
be either homogeneous (within the solution phase) or heterogeneous 
reactions (at a solution-solid phase or solution-gas interface). Knowledge 
of the homogeneous reactions, such as chemical complexation and redox 
transformation, is important in assessing and predicting the chemical 
reactivity of minor elements in seawater. Understanding heterogeneous 
reactions, such as adsorption, ion exchange, precipitation, and dissolu- 
tion, is necessary for considering the flux of materials through the 
ocean. Evaluations of these fluxes were considered in detail in Session 
C; the concern here is to identify the processes and to indicate those 
that should be emphasized in future research. 

A characterization of chemical reactions implies the quantification 
of both their equihbrium and kinetic aspects. However, to apply this 
information in the marine environment, we must identify the sites at 
which active chemical processes occur. Analytical studies and in-situ 
experimentation in the ocean will reveal the locations of active chemical 

Knowledge of inorganic chemical processes involving minor con- 
stituents is important for a variety of reasons. For one, these reactions 
determine the nonbiological cychng of trace elements in the marine 
environment. The impact of man's activities on the ocean is largely 
determined by the fate of chemical substances added to the sea. Con- 
versely, the effect of the environment on man's activity within the 
ocean depends on some of these processes. Minor elements can serve 
as sensitive indicators of biochemical and geochemical processes in 
seawater and sediments, and some of these constituents may be related 
to biological productivity. Some of the reactions involving minor com- 
ponents are significant in the formation of economically important 
substances such as ferro-manganese and phosphate deposits. 


Homogeneous Reactions 

A complete understanding of the distribution of trace elements in 
the oceans requires a knowledge of the forms— free and combined — in 
which these elements occur in seawater. The speciation of trace ele- 
ments in seawater is poorly known, and trace elements are often char- 
acterized as either "soluble" or "particulate." 

Present knowledge of trace-element speciation is based on a variety 
of experimental techniques. The distribution of trace metals between 
free and complexed forms has been calculated from thermodynamic 
data (Goldberg, 1965; Stumm and Morgan, 1970). These calculations 
serve to identify the most important complexes, but their accuracy is 
often poor because of lack of knowledge of the activity coefficients 
of individual ions in seawater, and because of errors in the thermo- 
dynamic association constants themselves. Polarographic techniques 
such as anodic stripping voltrammetry have shown that only small 
fractions of zinc, cadmium, copper, and lead are present as free ions 
at the normal pH of seawater (Zirino, et al., 1972; Zirino and Healy, 
1972). This suggests that these metals are complexed with pH-dependent 
species such as bicarbonate, carbonate, and hydroxide. Separation 
techniques such as solvent extraction (Slowey and Hood, 1971) have 
shown that trace metals in seawater exist in both free and complexed 
forms. Association constants for iron-hydroxide complexes in seawater 
have been determined by potentiometric methods (Kester and Byrne, 

Solving problems such as the behavior of radioactive tracers in 
seawater requires a better knowledge of the chemical speciation of 
these tracers. The use of radioactive tracers usually requires the as- 
sumption that the radioactive and stable isotopes of the tracer behave 
similarly. However, it is known that artificially produced zinc-65 does 
not behave in the same manner as does the naturally occurring zinc 
in seawater (Piro, Bernhard, and Verzi, 1972). This difference in be- 
havior is because artificially introduced zinc-65 occurs in different 
forms than natural zinc. Similar differences in behavior may occur 
with other isotopes. This consideration is important in undertaking 
research involving radioactive isotopes such as that discussed in Session 
C and for tracer equilibration in analysis. 

The speciation of trace elements in the sea must be studied using 
both field and laboratory techniques. Laboratory studies of the associa- 
tion of trace elements with naturally occurring inorganic and organic 
ligands in seawater will yield a knowledge of equihbrium speciation. 
Naturally occurring trace elements may be present in compounds that 


are not in equilibrium with the seawater medium in which they are dis- 
solved. For this reason, it is important that the chemical forms of natu- 
rally occurring trace elements be identified and their concentrations 

Laboratory studies and model calculations of trace-element associa- 
tions should include the major inorganic ligands in seawater: chloride, 
sulfate, bicarbonate, carbonate, hydroxide, fluoride, and borate. The 
measurement of association between trace elements and organic com- 
pounds is important, but these studies require a knowledge of the most 
important naturally occurring organic ligands, which is not available 
at present. 

The kinetics and mechanisms of the reactions of trace metals with 
both inorganic and organic ligands is important for a complete under- 
standing of trace-element chemistry. Some knowledge is available on 
the inorganic systems, but it must be extended to include the effects of 
the seawater medium, temperature, and pressure. The study of the 
organic systems must await a more detailed knowledge of important 
potential ligands in the organic composition of seawater (see pp. 61- 

Laboratory studies of trace element speciation should be made in 
solutions that approximate the composition of seawater as closely as 
possible and must include the effects of temperature, pressure, redox 
potential, and hydrogen ion concentration. 

Heterogeneous Reactions 

Several types of heterogeneous reactions can be identified as being 
significant in the marine environment. The adsorption of substances such 
as dissolved metals and phosphate on suspended matter is beUeved to 
be important in the removal of some minor elements from seawater. 
Ion exchanges with adsorbed materials as it is subjected to compositional 
gradients in coastal and estuarine regions, or to pH gradients within 
the ocean, may produce variations in the concentrations of the minor 
constituents. The precipitation and dissolution of solid phases in sea- 
water alter the distribution and sedimentation of some of the minor 
elements. The formation and entrapment of gas bubbles not only produce 
variations in dissolved gas concentrations, but also alter the acoustical 
properties of the environment, and may provide sites for chemical 
reactions that would not otherwise occur. 

Adsorption — Existing knowledge of adsorption reactions in seawater 
has been acquired by observing the removal of specific minor elements 
such as zinc and phosphate from a solution by a particulate solid phase 
such as a clay mineral or natural sediment. This process depends on 


several variables; the chemical form of the element in solution, the 
characteristics of the solid phase, and competing reactions for the 
adsorption sites. An adsorption process may be distinguished as a 
nonspecific physical type or as a stronger chemical interaction termed 
chemisorption. The type of process will determine the subsequent 
mobility of the minor element and the significance of competing reactions. 

Adsorption as a chemical process in the marine environment has not 
received the intensive and definitive investigation it merits. Even through 
it is widely acknowledged as a significant process, we do not know its 
quantitative role in geochemical cycles nor the specific locations in 
the marine environment where it is most important. Studies in regions 
where rivers mix with seawater indicate that the greatest chemical 
transformations occur at salinities of several parts per thousand rather 
than gradually throughout the mixing range of salinities. Further knowl- 
edge of this process is im.portant to evaluate the fate of both pollutants 
and natural injections brought to the ocean by rivers. 

Several approaches can be suggested as possible ways to gain more 
information on adsorption reactions. Basic knowledge can be obtained 
through laboratory investigations of specific minor elements and specific 
solid phases. Consideration should be given to the effects of the medium 
on adsorption processes by duplicating as closely as possible the main 
constituents of natural waters. For example, the presence of carbonate 
ions may be important in the adsorption of those trace metals that form 
carbonate complexes. The use of added minor element tracers is ham- 
pered by the potential problems arising from the presence of nonequilib- 
rium forms of the el'ement in natural systems. Variables in the solution 
phase that should be considered for coastal adsorption reactions are 
temperature, pH, ionic composition, and the potentially synergistic 
efi'ects of adsorbable minor constituents. The solid phase should be 
characterized in terms of its surface area, availability, and strength of 
adsorption sites. Laboratory investigations of this type for selected 
systems such as geochemically active metals (e.g., Al, Mn, Fe, Cu, Zn), 
toxic technological metals (e.g., Cd, Hg, Pb), radioactive elements 
(e.g., Cr, Co, Sr, Cs, Ra, Th, and especially Pu), and biologically im- 
portant constituents (e.g., P, As, Se, Mo, I) will provide the information 
required to assess some aspects of their behavior at continental bound- 
aries of the ocean. These assessments would be substantiated or refined 
by observations in the marine environment. 

In addition to the factors affecting adsorption processes in coastal 
environments, the effects of pressure on the exchange of minor con- 
stituents in the deep sea should be considered. This effect may be 
significant for adsorption reactions on biogenic particles or within a 
nepheloid layer. The study of adsorption processes should recognize 
not only the equilibrium distribution of the minor element between the 


solution and solid phases, but also the time scale or kinetics by which 
the exchange occurs. 

In this consideration, an ion exchange has been identified as a process 
separate from adsorption; however, in practice these two are closely 
related, and the considerations of adsorption apply to a large extent to 
ion-exchange processes. 

Precipitation and dissolution — The distribution of trace elements is 
affected by their incorporation into solid phases such as calcium car- 
bonate (Thompson and Bowen, 1969), opal (Chester, 1965), and various 
metal hydroxides (Cronan and Tooms, 1969). The movement of these 
solids through the oceans and their alteration, deposition, and/or solu- 
tion provide mechanisms for the transport of trace elements. 

The incorporation of trace elements into calcium carbonate and opal 
is probably biologically controlled, and the transport of trace elements 
in these solid phases can be studied through analytical determinations 
of their concentrations in calcareous and siliceous tests, coupled with 
a knowledge of the rates of precipitation and solution of calcium car- 
bonate and opal in the ocean. Our knowledge of trace-element concentra- 
tions in calcareous and siliceous tests and of the rates of solution of these 
tests is negligible. For instance, the chemical and biological factors 
influencing the oceanic distribution of barium must be known in studies 
involving the radioactive tracer radium-226, but the concentration of 
barium in calcareous and siliceous tests is not well known. 

The properties, rates of reactions, and distribution of metal hydroxides, 
such as iron and aluminum, in seawater and in interstitial waters, are 
poorly known. These compounds deserve further study because of their 
importance in the formation of ferro-manganese nodules (Mero, 1965) 
and in the alteration of clays (Sillen, 1961). 

Gas bubbles — Gas, bubbles in the ocean have been considered in 
connection with their eff'ect on the injection of air into seawater (Bieri, 
1971; Craig and Weiss, 1971) and on gas exchange (Kanwisher, 1963; 
Atkinson, 1972). In shallow water, gas bubbles may be produced by 
biological processes such as oxygen production from photosynthesis 
and hydrogen sulfide and methane generation from anaerobic decompo- 
sition of organic matter. Extension of these studies, which have been 
carried out largely through analyses of noble gas saturation anomalies, 
will most likely continue to reveal unique information on the role of 
gas bubbles in the ocean. 

It is generally assumed that bubble formation by /// situ production 
is inhibited by hydrostatic pressure; however, it is still necessary to 
consider conditions that can stabilize small gas bubbles under relatively 


high hydrostatic pressures. These might include interfacial tension of 
small bubbles on solid surfaces, or surface active films under high 
compression at the bubble-solution interface. 

Progress has been made in characterizing the size distribution of bubble 
populations in the surface layers of the ocean (Medwin, 1970). This 
effort should continue to be pursued, along with chemical characteriza- 
tion of the bubbles. Classical studies of the stability and dissolution of 
bubbles in seawater (Wyman et al., 1952; Liebermann, 1957) should 
be extended, where possible, to smaller bubbles and to include con- 
sideration of their behavior in the presence of surface active substances 
and solid surfaces. 

Air-Sea Interface 

In recent years there has been intensive consideration of chemical 
processes that occur at the air-sea interface. Some of these processes 
can be related to bubbles and the mechanisms by which they burst 
through the interface, producing chemical fractionation in the droplets 
injected into the atmosphere (Bloch and Luecke, 1972; and Maclntyre, 
1972). However, there also appear to be other unique chemical char- 
acteristics of the air-sea interface that affect the minor elements of 
seawater. Duce et al. (1972) demonstrated the near-surface enrichment 
of such components as iron, lead, copper, and fatty acids. The specific 
processes involved in this enrichment have not been clearly estabhshed, 
although it is assumed that minor element association with surface 
active organic material is a significant factor. These mechanisms should 
be determined and the chemical stability of surface active materials 
on the sea surface must be examined. Factors to be considered are the 
breakdown of surface active materials by wave action, or chemically, 
photochemically, or by biochemical oxidation. 

Examination of near-surface gradients of phosphate (Goering and 
Wallen, 1967) and of others that undoubtedly occur for other minor 
constituents may provide significant clues about the processes occurring 
near the air-sea interface. 

Analytical Studies 

Historically, the direction of effort to investigate an important chemical 
process has been dependent to a great extent on the availability of a 
useful analytical method. The solution of analytical problems continues 
to be of crucial importance (Carpenter, 1972) in the study of trace- 
element chemistry of the marine environment. It is necessary to have 


techniques available not only to study the distribution of total concentra- 
tions of trace elements in seawater but also to distinguish between 
weakly associated and complexed forms or other important physico- 
chemical states (i.e., speciation). 

Although the appearance of a powerful new technique may permit 
the investigation of a minor element not previously considered, a major 
effort should continue to be undertaken in the refinement of techniques 
presently being applied to the study of any of the minor elements. These 
efforts help locate active sites of chemical processes in the ocean en- 

At the present time, it is difficult to decide when variations in mea- 
sured metal concentrations among various investigators are real differ- 
ences or artifacts caused by different, arbitrarily chosen, sampling and 
pretreatment methods. A serious effort to continue to develop techniques 
for the construction and operation of noncontaminating sampling devices 
is needed. Existing commercial and laboratory-built samplers should be 
checked for adsorption and exchange reactions involving the minor 
element to be determined from the sample. 

The problems of sample storage and shipment also remain unsolved. 
Most investigators have arbitrarily chosen a certain container material 
and subject the sample to some treatment such as acidification, freezing, 
freeze-drying or the addition of preservatives such as mercuric chloride. 
This has been operationally necessary to obtain any data at all, but the 
consequences of such treatment on any given minor element are not 
necessarily known. Also, existing methods for determining minor 
elements all suffer to some extent from the lack of intercalibration 
and standardization. The results of the Geochemical Ocean Sections 
(GEOSECS) intercalibration attempts (Brewer and Spencer, 1970) 
show that a perfectly reasonable and timely project in chemical oceanog- 
raphy is the caHbration of methods. The question of how to store and ship 
standards is unsolved. Research should be undertaken on the develop- 
ment of sets of solids, soluble powders, standard solutions, and seawater 
samples with sufficient integrity to permit intercalibration for perhaps 
several years. 

Our ability to make direct measurements of trace-element concentra- 
tions in the oceanic environment is in many cases inadequate. A con- 
certed effort should be made to refine and extend the use of presently 
available methods such as atomic absorption, polarography, and specific- 
ion electrodes. At the same time, strenuous efforts should be made to 
apply other spectroscopic techniques such as UV-visible spectroscopy 
to direct and in situ measurements. 

The valuable information from the in situ equilibrium measurements 
of Ben-Yaakov and Kaplan (1971), Petersen (1966), and Berger (1967) 


point up the need for more measurements of this type. More equihbrium 
methods — both heterogeneous and homogeneous — should be developed 
and applied, and the development of in situ kinetic methods should be 

One of the great unknowns in trace-metal speciation studies is the 
role of organic ligands. The characterization of classes of compounds 
and individual organic species is a well-developed field of chemistry. 
However, the enormous variety and overall low concentration of organic 
species in the ocean make in-situ measurements improbable. Previous 
comments on sampling and standardization obviously apply here. Once 
these steps are taken, the enormously powerful battery of new techniques 
used by organic and biochemists can be applied — Fourier Transform 
infrared and nuclear magnetic resonance spectroscopy, computer- 
assisted gas chromatography, mass spectrometry, gel permeation, and 
high-pressure liquid chromatography. 

Finally, chemical oceanographers must be encouraged to adopt and 
adapt the highly developed analytical methods used in other areas of 
science. Examples are the sensitive analytical methods developed for 
lunar rock analysis and the recent advances in cUnical analytical chem- 



Streams bring a burden of dissolved and particulate substances to 
the sea, and in the region of encounter between fresh water and seawater 
a variety of processes occur to alter locally the composition of seawater. 
The natural phenomena occurring in this region provide the context 
for understanding the effect of man-induced changes in the quality and 
quantity of materials supplied to the estuarine zone. The coastal zone, 
therefore, provides an environment for modifying the composition of 
seawater that may be as important as the open-ocean environment. 
Some fundamental problems in this area are 

1 . The flux of dissolved elements to the ocean from streams is known 
fairly well on a worldwide average basis for the major components. 
However, seasonal changes in the chemical composition of streams as 
they enter the ocean are not well understood, and a few reliable data 
on trace constituents are available. 

2. The quahty and quantity of sediment loads brought to estuarine 
environments by rivers require attention. For example, the total quantity 
of sediment delivered by the Susquehanna River as the result of hurricane 
Agnes in 1972 equaled the total sediment load transported in the past 
50 to 100 years. This large supply of fresh water and sediment seriously 


altered both the chemical properties of the estuarine water and the 
physical and chemical properties of the sediment in Chesapeake Bay. 
Similar areas of interest occur throughout the United States and the 
world, each with their own erosional and hydrological characteristics. 

3. A major study of the dissolved and particulate trace-element 
burden of streams is required. There is good evidence that organic 
particles, especially, act as a major carrier of trace metals to the sea 
where subsequent estuarine processes may release the metals to sea- 
water. On the basis of sediment and water studies it is clear that as 
much as 80% of the content of some trace elements and organic particles 
are released to the estuarine water. The release mechanism is not known. 
It may in part be released by ion exchange, in part by biological degrada- 
tion of the organic carrier of the metals, processes that also occur in 
the open ocean. 

4. The fate of metals and silica in estuarine waters must be assessed 
to understand not only the pathway of these elements brought to the 
estuary by streams, but also the modifying role of open-ocean seawater 
when it encounters the coastal zone. We know that in areas where the 
supply of organic matter from the continent is great and biological produc- 
tivity in the adjacent marine environment is high, organic matter accumu- 
lates rapidly in the sediment, and sulfate reduction occurs. Silica is 
deposited rapidly by diatom productivity in the same areas. The high 
sulfide-ion concentration results in the sequestering, as sulfide, of many 
trace metals released in the sediment from in-situ organic degradation. 
The result of this process is to extract many metals from seawater, 
reducing their concentrations in open seawater. This is especially true 
for mercury, lead, gold, and silver. Iron and manganese (and possibly 
other metals) may be exceptions to this because of the higher solubilities 
of the sulfides of the doubly charged ions of these two elements. Hence, 
a flux of iron and manganese out of an estuary is possible. These pro- 
cesses are now mainly understood intuitively on the basis of the com- 
position of sediments and thermodynamic arguments. Experimental 
and direct observational confirmations are required. 

One aspect of trace-element studies in estuaries, including both 
radioactive and stable nuclides, involves the transfer of minor elements 
from polluted rivers and estuaries to the sediments. One can observe 
the disappearance of lead, cadmium, and similar metals from the water 
column near shore at a rate faster than can be accounted for by dilu- 
tion. Analysis of sediment cores reveals that the sediments are a sink 
for these pollutants. However, the processes of transfer are difficult 
to define. The chemical forms of the accumulated metals in the sediments 
may not be related to those in the water column because of the rapid 
transport and mixing of the sedimentary material. The sampHng problem 


is serious but might be resolved in shallow water areas through the use 
of research submersibles. Near-bottom sensors and samplers might be 
set in place and the accumulation of sedimentary material be observed 
without washing out or exchanging with nearby sediments. If truly 
representative samples could be obtained, and if the rate of sedimenta- 
tion could be inferred from the collected material, the pathways of the 
pollutants might be elucidated. 


A first-order feature of the density field in the ocean is the shallow 
pycnocline. This boundary coincides approximately with the bottom of 
the photic zone and forms a barrier to mixing between the upper few 
hundred meters and the deep sea. The water above the boundary is 
the immediate recipient of all the continentally derived dissolved and 
particulate material. Particles introduced or formed in this layer can 
sink through the mixing barrier (a one-way process) into the deep water, 
thereby depleting the surface water of their constituents. 

At the present time the particulate flux in the ocean is similar in many 
respects to the "ether" of 19th century physics in that its nature is more 
described by the eflFects attributed to it than by experimental observation. 
These observational data on dissolved trace constituents are explained 
in terms of scavenging. 

One of the central problems of marine geochemistry is to resolve by 
direct measurement the source and composition of the particles con- 
stituting the nepheloid layers as functions of space and time. The main 
study areas can be categorized as follows: 

• Physics — Size frequency distribution 

— Density contrast with water 

— SettUng rates (Stokesian or not) 

— Effect of turbulence and shear. 

These factors determine the vertical flux of material and its concentra- 
tion in the water column and how much water has to be collected to 
obtain a statistically significant sample. It is necessary to calculate 
reasonable sedimentation rates from measured fluxes to determine the 
available surface area for reaction and the transit time through the 
water column. 

• Chemistry — Identification of organic and inorganic phases and 

their temporal and spatial variations 
— Radioisotope analyses to determine injection and 
settling rates directly (Pb-210, Fe-55, Si-32, C-14, 
Ra-226, Pu-238 and 239) 


— Scavenging and dissolution processes (require paral- 
lel measurements in the water column and accounting 
for lateral motions that may amount to thousands of 

These studies would give source functions for the in situ production 
and consumption of dissolved materials. They are particularly important 
for the radioactive constituents, especially the plutonium isotopes dis- 
cussed in Session C. They would also indicate to what extent the various 
species dissolve on the bottom or during sinking. 

Analyses of particulate matter collected from the water column should 

1 . Physical composition and morphology by x-ray diffraction, scanning 
electron microscopy, electron probe, and biological species identifica- 
tion (size, frequency, and distribution) 

2. Chemical: Elemental composition of the organic fraction; C:N:P 
ratios; characterization of protein, lipid, and carbohydrate components; 
composition of inorganic fraction by neutron activation, x-ray fluores- 
cence, atomic absorption, mass spectrometry, and leaching experiments 

3. Radiochemical analyses: Silicon-32, carbon- 14, and radium-226 
to be determined on all samples, Lead-210 and thorium isotopes on 
the upper portion of bottom samples and iron-55 and other artificially 
produced isotopes on shallow samples 

4. Stable isotope measurements. 



In addition to the controls of clay and calcium carbonate on the overall 
chemical state of seawater, there are specific modifications in the con- 
centration of trace and minor components in the water column resulting 
from processes occurring at the ocean bottom. None of these processes 
is as yet sufficiently understood, especially with regard to their relative 
importance in modifying the composition of seawater. The specific 
areas needing more research include 

1. The flux of elements in and out of the water by reactions with 
igneous rocks on the ocean floor 

2. Transport to the deep ocean of elements brought in by hot fluid 
transport from depth 

3. The eff"ect of minerals in sediments which sequester elements 
from seawater and interstitial waters. In particular, the flux of radium-226 
and radon-220 to the deep ocean from bottom sediment will be controlled 
by the presence or absence of radium traps such as barite and phillipsite 
in the sediment. These two nuclides are of interest in ocean circulation 


studies. Similar constraints can be anticipated for other elements. The 
mode of manganese and iron oxide deposition on the ocean floor and 
its role in modifying ocean chemistry are still not well known. 

4. The movement of bottom sediments by bottom currents or down- 
slope movements may result in the solution of some components such 
as biogenic silica and calcium carbonate but may also transport them 
into deep pockets where they are protected from solution. The injection 
of silicon-32 with stable silicon into bottom water originating in the 
Antarctic region by the solution of biogenic silica during current 
transport is of interest in deciphering water paths and the material 
balance for both sihcon-32 and stable silica. The association of barium 
with biogenic silica deposits in the Antarctic region is of importance 
in understanding the geochemical cycle of this element. Sedimentation 
rates in the deep sea should be measured using isotopes with diiferent 
half-lives to estimate the flux of material into bottom waters. 

5. The environment of the midocean ridge areas is diff"erent from 
that of the abyssal plains in a number of ways that can influence the 
composition of the sediments of this region. The association of high 
concentrations of calcium carbonate, barium, organic matter, and some 
metals with the high ridge areas has been described. The reasons for 
each of these elements being found in the same general location may 
not be the same. Biologic, sedimentologic, and volcanic causes may 
combine in one location to give the end result of enrichment of chemicals 
along the ridge area. To understand the environment of the ridge area, 
it is important to unravel these processes. The use of research sub- 
mersibles is admirably suited to such studies of the ridge. Further 
consideration of fluxes at the sediment-sea interface are contained in 
pp. 62 to 84 of this document. 


One major area that has been neglected in chemical oceanography 
is the incorporation of major and minor element distributions into 
ocean circulation models. An important ingredient of such models is 
an understanding of the chemical and physical processes that alter the 
concentrations of elements within the water column. A water mass is 
an open system that exchanges material by advective and diffusive 
processes, and interacts with the descending particulate flux. Simple 
mass balance models are often adequate for such concepts as apparent 
oxygen utilization (AOU). However, such concepts oversimplify the 
complex nature of the actual processes occurring in the oceans. The 
first aspect of the modeling process should emphasize the incorporation 
of transport and particulate interaction terms into the simple mass 


The second important aspect of model calculations is the "feedback" 
of the chemical distributions as a check on the physical models. Even 
the simplest chemical systems such as dissolved oxygen and nutrients 
are characterized by much more complicated and variable distributions 
than those observed for temperature, salinity, and density. Incorporation 
of such components into the simple physical transport models provides 
a more stringent constraint for the model itself. 

A third important aspect of the appUcation of chemical variations 
to physical models is the increasingly important use of natural and 
artificial radioisotopes for to incorporate real time into the cirulation 
models. The major radioisotopes presently useful for general circulation 
models are carbon- 14, radium-226, and potentially silicon-32. These pro- 
vide time scales of the order of 8000 years, 2000 years and 700 years for 
mixing and circulation studies. Each is involved in chemical and particu- 
late interaction processes in the sea. Both stable carbon and radiocarbon 
are supplied to the deep sea by the oxidation of organic material and 
the dissolution of calcium carbonate contained in the particulate flux. 
The actual application of the radiocarbon "clock" to mixing and circula- 
tion processes demands a most careful and detailed study of variations 
in total dissolved inorganic carbon, dissolved oxygen, alkalinity, and 
the stable carbon isotope carbon- 13, together with the measurement 
of specific activity variations of radiocarbon in the sea. Similar con- 
siderations apply to radium-226, which is involved in the particulate 
interaction problem and is introduced into the sea by diffusion from 
bottom sediments, and to silicon-32, which is involved in the stable 
silicon cycle in the sea. 

As important class of constituents for model studies is the group of 
"stable-conservative" tracers, which difi'er in their relationships to 
salinity throughout the sea but are not altered by in-sitii chemical pro- 
cesses. These constituents, which include some dissolved gases, the 
stable isotopic water molecules HDO and H2 0'^, and certain trace 
elements, receive their initial variability at th sea surface through 
air-sea interaction processes. Some of these tracers, such as hehum- 
3 and helium-4, are injected into the sea at the bottom and in certain 
specific areas such as the crests of ocean rises. These provide especially 
valuable localized tracers for regional circulation and mixing studies 
in deep and bottom water. 

At the present time, several types of analytical and numerical models 
of varying complexity have been applied to the distribution of chemical 
and isotopic species. One-dimensional diffusion and advection models 
with in-situ production and consumption terms have been used for the 
carbon- 12, carbon- 13, carbon- 14, oxygen and nutrient systems in the 
Pacific with encouraging results. Simple vertical diflFusion models 
with constant and variable diffusivities have been applied to Radon 


222 and radium-228 in both the surface layers and the bottom water. 
These results are useful for studying the air-sea and bottom-sea inter- 
change of material. Several trace elements, notably copper, scandium, 
antimony, and nickel, have been studied sufficiently to show that vertical 
models should be useful in understanding their chemistry in the sea. 

A second type of model currently being used for chemical constituents 
is a two-dimensional, horizontal diffusion and advection model. These 
models are based on "Strommelian" geostrophy with vertical advection 
balancing the horizontal inflow of water from western boundary currents 
which feed the interior regions of the world oceans. Conceptually, they 
are a natural extension of the simple "box models" that have been used 
successfully to understand the general nature of the vertical distribution 
of radioisotopes. 

Physical oceanographers are extending these simple models account 
for such effects as topography and nonlinear terms in the equations 
of motion. A similar approach can be made with nonconservative species. 
To approach a realistic model of the chemical and particulate interac- 
tion processes in the sea, efforts should be made to develop three- 
dimensional models for describing oceanic processes. More emphasis 
on this aspect of chemical oceanography is urgently required to guide 
the future development of the subject and to insure a continual interac- 
tion with the developments made in physical oceanography. 

Measurements of constituents of global fallout in the upper layers 
of the Pacific during the past decade have suggested that distributions 
of certain species may be dominated by lateral advection and lateral 
mixing in certain large areas, notably in the North Pacific Ocean. Large 
fractions of passive materials such as radiocesium have remained in 
the upper 300 for more than 10 years after entering as fallout (Folsom 
et al., 1968; Folsom et al., 1970; Hodge et al., 1972). For a period as 
long as this, one must expect advections of thousands of miles and take 
into account geographic and seasonal variations of inputs before attempt- 
ing interpretations of vertical profiles. The sampling required for a model 
of this scale needs specialized procedures and specialized analytical 
methods. Nevertheless, a knowledge of the behavior of a passive material 
such as cesium or tritium seems essential for any study of the progress 
and chemical behavior of many other chemical species in the upper 
ocean layers. The advective parameter simply cannot be ignored in 
the model; however, chemical procedures can be evoked to discover their 


Session B 

Chemical Fluxes Through 
the Marine Environment, Including Air-Sea 
and Sediment-Sea Exchanges 

Dr. Edward D. Goldberg, Discussion Leader 


How much material is being added to the present-day ocean by each 
of the various sources, and how much is being removed to each of the 
various sinks? For which components are these addition and removal 
rates changed as functions of time? These questions serve as a basis 
for investigating fluxes in the marine environment relative to further 
understanding chemical oceanography. 

We must know how uniform the composition of seawater has been 
over geologic time intervals to interpret earth history from a study of 
ancient marine sediments. We must know the fates of various natural 
constituents added to the marine environment to predict how the ocean 
will respond to materials introduced by man. 

A simple calculation using the area of the earth's surface covered by 
the ocean and the average depth of the ocean gives the volume of the 
ocean. The volume of river water added to the ocean each year is more 
difficult to determine, but recent estimates are in reasonable agreement. 
It appears that present-day river inflow would equal the volume of the 
ocean in about 40,000 years. Hence, water cycles from ocean to atmo- 
sphere and back vary rapidly on a geologic time scale. 

The total dissolved salt content of seawater can be easily and ac- 
curately determined and is found to average about 35,000 ppm. The 
average total dissolved salt content of river water is much more difficult 
to estimate and is deserving of additional study, but recent estimates 
cluster around 115 ppm. Assuming no losses from the ocean through 
sedimentation, and with seawater about 300 times saltier than average 
river water, 300 transfer cycles from the continents to the oceans would 
be required to produce seawater salinity. This would take 300 x 40,000 
years = 12 million years, which is a short time, geologically. 


This kind of calculation is less meaningful than one which could be 
made considering each constituent individually, because seawater is 
different from river water in the ratios of its various components. The 
calculation, nevertheless, illustrates the point that the total salt content 
of the sea can be added in a very short time. It thus raises such questions 
as. What regulates seawater composition? and. Have such regulatory 
mechanisms been constant over geologic time periods? 

Careful study of ancient marine sediments, their pore waters and 
fossils contained in these sediments, give little indication of any changes 
in seawater composition. Thus, a considerable effort has gone into ex- 
planations of mechanisms for maintaining a constant composition in 
seawater. The best known of these are the equilibrium models first 
proposed by Sillen (1961), and expanded by Holland (1965), Siever 
(1968), Garrels and MacKenzie (1971), and others. All of these models 
are somewhat vague in detailing the exact reactions occurring in the 
ocean, and little evidence has been found to indicate that the suggested 
reactions are occurring. At the same time, the models have been criticized 
on theoretical grounds (e.g., Pytkowicz, 1972) and seem not to be 
consistent with the actual solid phases found at the sea floor. Further 
work is needed on the interaction of minerals with seawater, as deter- 
mined from their solubilities and rates of solution and precipitation. 
The available literature on this topic, including the effects of pressure 
which are vital for our understanding of the deep oceans, has been 
summarized in part by Pytkowicz and Kester (1971). 

Broecker (1971) has proposed a kinetic model for the chemical 
composition of seawater, but he gives few specific examples of either 
supply or removal mechanisms for the major constituents of seawater, 
concentrating rather on the biologically active elements carbon, nitrogen, 
phosphorus and silicon. If we are to extend this approach, we need 
better data on the rate of supply and removal of various constituents 
from seawater. As mentioned above, the rate of supply of the major 
components by river water is not as well known as we would hke. 

The rate of supply of minor constituents dissolved in river water is 
even more poorly known, and the rates of supply of both major and 
minor elements as particulate matter and their subsequent release to 
the water are almost completely unknown. In the same way, the amounts 
of materials added to the oceans from undersea volcanic exhalations, 
springs, weathering of solid volcanic material, and the like, can only 
be grossly estimated at the present time. 

Our knowledge of how dissolved materials are removed from the sea 
is little better than that of how they are added. The factors involved have 
been commented on elsewhere in this document (e.g. see Session C), 
and it is sufficient to note here that well-defined removal mechanisms 
exist for bicarbonate and calcium but for none of the other major con- 


stituents. Sulfate is thought to be removed following biochemical re- 
duction to sulfide, but the quantitative importance of this mechanism 
has not been evaluated. 

Sodium and chloride leave the ocean waters primarily dissolved in 
pore water of sediments, and potassium by uptake by clays, but the 
quantitative aspects remain to be worked out. Practically none of 
the details of how magnesium or any of the minor constituents are 
removed from the system is known. 


Plutonium is an extremely toxic, radioactive man-made element 
whose behavior in the marine environment is inadequately known, 
although it has been studied intensively in connection with production 
of weapons and power sources (Olafson and Larson, 1963; Miner, 1964; 
and Colemen, 1965). Only a few determinations of its concentration 
in seawater and in associated organisms and sediments have been made, 
the first being as recent as 1964 (Pillai et al., 1964). Its chemical be- 
havior in the marine environment will be difficult to predict from that 
observed on land, especially its involvement with the organisms of the 

Plutonium is a member of the actinide series and chemically similar 
to the rare earths. It forms insoluble fluorides and hydroxides, and a 
quite insoluble oxide. It can exist in several oxidation states, commonly 
as tri- and tetravalent cations, or in the hexavalent form Pu02+^. It 
forms soluble complexes with citrate and is strongly chelated (Olafson 
and Larson, 1963). 

The use of plutonium is expected to expand so rapidly that several 
serious hazards and management problems can be foreseen. Two of 
its nuclides, Pu-239 and Pu-238, are employed as fuels. Accidents 
released both of these into the environment, and, considering the large 
scale of projected nuclear power programs, more such accidental re- 
leases can be expected. The transport of this valuable major fuel across 
oceans and continents may invite thievery and hijacking. 

It is important to accelerate studies of background levels and to 
investigate chemical phenomena that might suggest the results of large 
additions of plutonium nuclides to the ocean. These studies should 
include consideration of its enrichment within the marine biosphere 
and its known affinities for inorganic surfaces and particles. 

Present Conditions in the Ocean 

The time of entry of most of the ocean's plutonium is fairly well 
known, as is its probable character on arrival at the sea surface. The 
largest fraction originated during 1950-1970 as global fallout which has 


been documented by air and soil analyses (Hardy et al., 1972), or has 
been inferred from records of other bomb wastes. 

Plutonium, similar to many metals, is enriched 1000-fold or more in 
many plants and animals. It appears to be retained for many years 
(Olafson and Larson, 1963; Miner, 1964) in larger terrestrial animals. 
Plutonium appears in the food of the larger marine animals; however, 
it has been found in much higher concentrations in members of the lower 
trophic levels. It has not been estabUshed which organs and tissues are 
involved in plutonium uptake by plankton. It may be that only surface 
adsorption is involved at these levels. Suggestions of this have come 
from findings of high plutonium concentrations on certain living and 
dead surfaces. The highest concentrations so far have been found in 
the outer 0.2mm layer of giant brown algae (Wong et al., 1972). 

In seawater, the present plutonium-239 radioactivities are only 
roughly 2% of strontium-90 and cesium- 137 radioactivities. The radio- 
activity of the shorter Hved nuclide plutonium-238 is at present only 
2 or 3% of the longer hved nuclide. Dialysis studies in Russia (Zlobin 
and Mokanu, 1970), suggest that plutonium may exist in seawater as 
colloidal particles (less than 0.1 to 0.3 microns), unless attached to 
larger particles. 

Vertical distributions need to be known for chemical budgeting and 
other purposes, but the vertical distribution of plutonium is not well 
known. Sensitivity and precision are so low that many earlier measure- 
ments of deeper waters are suspect. However, there are several indirect 
measurements that suggest a loss from the upper layers that is more 
rapid than would occur with a completely passive material (one not 
associating itself with particulate materials, living or dead). Budgeting 
of concentrations in the Atlantic Ocean has yielded some scavenging 
rate estimates (Noshkin and Bowen, 1972). Likewise, some model- 
fitting of concentrations found by monitoring tissue concentrations in 
large oceanic fish in the Pacific Ocean has suggested a loss from the 
upper layers (where these fish live) of plutonium at the rate of half of 
that present in about 4 years, in contrast with about 10 years suggested 
for cesium (Folsom, 1972). 

One outcome of recent plutonium studies has been the establishment 
of a large-scale turnover model for heavy metal nuclides in some special 
regions of the ocean. These studies suggest that one could follow minute 
changes for perhaps another decade in the upper layers of the Eastern 
Pacific Ocean. One now has some idea where to sample in order to 
detect a relatively small accidental increase of plutonium. The failure 
of SNAP-9A (in outer space in 1964) introduced about one kilogram of 
plutonium-238 into the ocean. This roughly tripled the amount already in 
the ocean (Hardy et al., 1972), and the addition can be measured with 
present methods. 


Chemical and Radioactive Properties 

Physical radiometric methods are now adequate for the two important 
alpha-emitting nuclides (Miyake and Sugimura, 1968), and although 
internal standards have been used in most cases, there is little indication 
that equilibration with the plutonium in seawater has been estabUshed. 
Plutonium's attraction to surfaces may be one of its most characteristic 
properties and needs additional study, beginning with the relatively 
simple surfaces of the large algae. 

Describing oceanic distributions has been limited by low and variable 
analytical yields, especially in sediments and complex living tissues. 
Improved analytical methods are needed; one promising technique is 
the recovery of traces of plutonium from tissue by electroplating. 

There are still other puzzles related to plutonium in the ocean. Why 
is it often associated with high concentrations of natural polonium on 
surfaces, and what brings them to these surfaces? Are the concentrating 
agencies physical, chemical, or biological? Do the nuclear properties 
(the alpha emissions) contribute anything to the processes? Has natural 
polonium-210 been significant in shaping the biosphere? Will the plu- 
tonium that may be added significantly increase the ionizing burdens? 



The intermittently ice-covered polar seas may be areas of strong 
air-sea gas exchange, as evidenced by the intense air-sea gradients 
observed there. These areas have been poorly investigated because 
of the sampling difficulties. The freezing process and the biota, unique 
to the ice-seawater system, many produce chemical conditions distinct 
from those of open sea regions. 

The freezing of seawater and its eifect on the chemistry of the water- 
ice interface is not well understood. There have been too few systematic 
field observations of the composition of surface seawater under freezing 
conditions to compare with data from laboratory investigations (Wiere, 
1930; Thompson and Nelson, 1956; and Bennington, 1962). 

Marine plants are abundant within and under the sea ice (ApoUonio, 
1961, 1965; Meguro et al., 1967; and Clasby et al., 1972), and their 
chemical interactions may differ noticeably from those of open ocean phy- 
toplankton. It is important to determine the horizontal chemical gradients 
that may be produced under the ice and within the open water, and the 
rates of transfer of gases across the water-air interface in the open 
water. Adequate investigations of horizontal chemical gradients on 
scale lengths of a few meters to kilometers and of small-scale vertical 
gradients directly under the ice are difficult to carry out. The difficulty 
arises from 


1 . Hazards in working on an ice flow close to its edge 

2. The inability to evaluate properly the physical, chemical and 
biological nature of the undersurface of the ice 

3. The loss of sampling integrity caused by the borehole and contact 
of the seawater with the atmosphere 

4. Serious disturbances that arise when making boundary-layer 
chemical observations from surface ships operating within the ice. 

In regions that undergo surface freezing there are intense seasonal 
changes in dissolved carbon dioxide (Kelley, 1970) and probably in 
dissolved oxygen to a lesser extent. With the exception of major up- 
welling areas (Gordon et al., 1971; Kelley and Hood, 1971; and Kelley 
et al, 1971) and shallow coastal systems (Gordon, 1973), seasonal 
carbon dioxide variations in surface waters of the polar seas have 
shown the largest temporal variations in the world's oceans. 

Many sampling problems might be overcome by using a research 
submersible that can maneuver under the ice as well as in the open 
water. This capability could be coupled with the use of in situ sensors 
(for salinity, temperature, pH, and dissolved oxygen), with control 
and visible observation of the sampling location, and with facilities for 
on-board data readout. Such capability would allow for the design of 
experiments addressed to the measurement of horizontal and vertical 
gradients under and at the margins of the ice and rates of formation 
and decay of these gradients. Information of this kind would provide 
valuable data bearing on the physical, chemical, and ecological pro- 
cesses acting in the polar seas. 


The quantitative aspects of the transfer of particles from the upper 
layers of the ocean to its depths and the relative importance of each 
of the mechanisms of transfer are unresolved questions in chemical 

Vertical transport by settling particles is significant in governing 
the distributions of chemical species in the ocean. Such transport hastens 
the downward movement of radioactive contamination, pesticides, 
herbicides, or other products of man's activities. Our present knowledge 
of particles is largely confined to bulk compositional analyses, light- 
scattering properties, and theoretical settling rates. We need the ability 
to predict the properties of zones of high particulate load (i.e. nepheloid 
layers), the extent to which various substances in the sea will be incor- 
porated in or upon settling particles, the rate of downward transport, and 
whether such material ultimately remains with the particle or escapes 
into the surrounding water. 


Particles play a special role in the ocean. Such materials are introduced 
primarily by weathering processes and biological activities, but also 
by volcanism and chemical processes in the upper layers. Once formed, 
these materials settle, usually slowly, toward the seafloor and provide 
a site for various reactions. The bulk composition, size distribution and 
light-scattering properties have received considerable attention, par- 
ticularly by Soviet investigators. However, we have only limited under- 
standing of the changes that occur in and on particles after formation. 
Such particles play a key role in heavy metal transport, but the relative 
role of various particle types is not well understood, nor are we certain 
of the importance or rates of surface reactions on the particles. 

Particles entering the sea and particles residing in the upper layers 
may be collected into aggregates with greater settling velocity and 
less areal exposure to seawater. Filter feeders ingest, grind, and digest 
particles, ultimately expelling them as fecal pellets, which settle far 
faster than the individual component particles. Moreover, the pellets 
are largely isolated from seawater by coatings, but they are fragile, often 
breaking soon after formation, and they may in turn be reingested, 
digested, and reformed. Nevertheless, a vast rain of such materials 
moves toward the seafloor. Their role in vertical transport depends on 
transfer across their boundaries, and their ability to remain intact under 
physical stress and bacterial attack. 

Those pellets that reach the seafloor are broken or altered, with their 
contents subsequently being transformed by bacteria and ultimately 
released to the water and sediment. Most settling pellets are probably 
broken up by collection methods, and gentler collection techniques 
and more careful studies of the amounts, settling rates, and surface 
chemistry of such materials are needed. 

Particles of continental detritus may settle rapidly in the coastal 
zone or slowly into the abyss. During settling these particles undergo 
varying degrees of equihbration with dissolved species in the water, 
exchanging ions, adsorbing, and even to some extent dissolving. Since 
the bulk of inorganic detritus enters at the ocean surface, rapid reactions 
will aff'ect surface water chemistry, whereas slower reactions may have 
greater efl'ect during the long slow fall into the depths. Our understanding 
of the rates of these reactions and their response to temperature and 
pressure is poor. The influence of squeezing temperatures, when diff'erent 
from the in-sitii temperature, on the apparent composition of interstitial 
waters shows that many equilibria are markedly altered by temperature 
changes. Such factors influence the role of particles in redistributing 
chemicals in the sea, but we cannot assign quantitative values to this 

The sinking of the tests of marine organisms plays a well-established 
role in the distribution of the nutrients in the ocean. A spectrum of trace 


elements (e.g. barium, radium, and strontium) is carried along with the 
particulate silicates, carbonates, phosphates, nitrogen compounds and 
organic materials. Re-solution of sinking carbonates may affect the 
alkalinity, carbon and oxygen isotope ratios, and trace-element patterns. 
The kinetics of the dissolution and the true oceanic sinking rates need 
more study. Likewise, silicate tests are subject to dissolution as they 
sink, but there is little agreement on the balance between in-transit 
solution and bottom solution followed by upward mixing. The nature of 
this balance will affect the associated trace elements as well as the silicate 

Casts of marine organisms discarded in the surface water during moult- 
ing may be rich in nutrients or trace metals. The rapid descent of such 
materials may constitute a significant transport mechanisms, but it also 
lacks quantitative evaluation. 

Yet another problem is the fluxes of dissolved substances across 
the sediment-water interface. What are the magnitudes of these fluxes 
relative to other input or removal processes? Predictive models are 
needed to estimate the sink and source potentials of different sediment 
types for a given solute. It is also necessary to understand when a mate- 
rial that has settled to the seafloor is no longer chemically in contact with 
the ocean. 

Models for solute flux across the sediment-seawater interface that 
balance supply and removal by dissolution/precipitation/relax reactions 
have been proposed (Crank, 1956; Shishkina, 1964; Berner, 1964,1971; 
Duursma, 1966; Anikouchine, 1967; Lerman, 1971; Tzur, 1971; 
and Hurd, 1972a,b). The apparent diffusion coefficient of a solute is a 
function of temperature, tortuosity, and any interaction the solute may 
have with the surface of the solid phase. These solid-solute interactions 
are being investigated (Duursma, 1970; Manheim, 1970; and Lerman, 
1971), but the results have not been rigorously applied to real sediments. 
Present results, however, suggest that these corrections may reduce the 
value of the apparent diffusion coefficient of ions by as much as 3 to 
5 orders of magnitude. If solids are dissolving or precipitating within 
the sediments, determinations of the heterogeneous solution rate con- 
stants must be made to compare laboratory data with models based 
on suspended matter and sediment. In the case of biogenic opal (Hurd, 
1972a,b), dissolution rate constants of acid-cleaned radiolarians in 
seawater differed by 3 to 6 orders of magnitude from rate constants 
for sediments estimated by the models mentioned above. Other biogenic 
minerals such as calcium carbonate and apatite need to be similarly 
modeled because of the more rapid turnover through biogenic mineral 
formation than through inorganic precipitation of the same elements 
(Ca, C, O, Si, and P). 


Sulfate reduction has been extensively studied (Berner, 1964) in 
recent sediments. It would be valuable to know the kinetics of particulate 
and dissolved organic carbon oxidation to complement such studies. 
Silicates are being modeled for equilibrium and kinetic considerations 
(Wollast, 1967; Helgeson, 1971; Luce et al., 1972), but the actual 
kinetics have been studied on few of these minerals. In every study 
using concentration gradients in sediments for modeling, the physical 
properties of sediments should be determined to allow at least first-order 
tortuosity corrections for the diffusion term using porosity measurements 

Estuarine and shelf sediments are less completely studied than deep- 
sea sediments. Because of the higher sedimentation rates, larger pH-Eh 
fluctuations, more active bioperturbation of sediments and their higher 
organic contents, their chemistries are more varied and invite additional 
study. The sediment-water interface must also be studied more closely 
to understand the transition from particulate suspended matter to actual 
sediment. Concentration profiles in the water above the sediment have 
only been measured by sampling devices that disturb the system sampled. 
While such devices provide useful information for large-scale gradients 
(e.g., 1 to 10 m), it may be possible to observe the actual interface gradi- 
ents only by using in-situ devices over 1- to 3-month periods. Measure- 
ments of the radon flux should be attempted to estimate mixing and 
turbulence for the bottom waters. 


Much remains to be learned about regional and mesoscale air-sea 
transport of gases. Predictive models related to man's modification of 
the atmosphere and ocean depend vitally on information of this sort. 

Human activities have brought about changes in the balance of gases 
dissolved in the oceans and present in the atmosphere (Bolin and Eriks- 
son, 1959; Broecker et al., 1971; and Machta, 1972). These changes 
range from the introduction of trace and bulk constituents, such as 
by-products of civilization, to the possible alteration of natural processes 
by agricultural and industrial activities (Goldberg, 1971). Since the 
International Geophysical Year, continuous clean-air baseline measure- 
ments of several atmospheric gases have led to the discovery of secular 
increases in their content in the atmosphere. These increases have 
been most evident in the case of carbon dioxide (Brown and Keeling, 
1965; Pales and KeeHng, 1965) and more recently in tropospheric 
ozone (Komhyr et al., 1971; and Kelley, 1972). 

For carbon dioxide, it is estimated that 30 to 40% of the input by man 
to the atmosphere has entered the sea (Machta, 1972; Broecker et al., 


1971). Regional rates of exchange, however, have been estimated only 
from a few calculations, based on local carbon dioxide partial pressure 
and wind data (Teal and Kanwisher, 1966), from changes inferred in 
surface-water oxygen content resulting from biological processes, 
based upon consideration of changes in nutrient distributions (Red- 
field, 1948), from recent indirect measurements utihzing tracer gases 
(Broecker and Kaufman, 1970), and from in situ cuvette techniques 
(Coyne and Kelley 1972). 

Aside from the human input of gases to the atmosphere and the sea, 
there is the unresolved set of questions about gases produced by natural 
processes in the sea, their genesis, and transport associated with their 
distribution and exchange across the ocean-atmosphere interface 
(Swinnerton et al., 1970; and Hahn, 1972). The processes involved in 
the interaction of these gases with other chemical constituents of the 
sea and with the marine biosphere are not well understood. In addition, 
rivers and streams are an important means of removing such gases as 
carbon dioxide from the continents and introducing them into the sea 
(Gordon et al., 1971 : and Kelley and Hood, 1971). 

Gases may be either chemically reactive or nonreactive in seawater. 
Carbon dioxide, sulfur dioxide, ammonia, nitrogen oxides, etc., are 
acid or base anhydrides and their air-sea transport mechanisms are 
more or less afi'ected by their aqueous chemistry (Quinn and Otto, 
1971). The class of nonreactive gases represented by methane, carbon 
monoxide, hydrogen, and helium have transport processes unaffected 
by an aqueous chemistry of this type. However, the nature of their roles 
as solutes may depend largely upon the formation of hydrates of clathrate 
structures in seawater, especially in cold and high pressure environments. 

Because the gases whose balances are upset by man include both 
reactive and unreactive, the air-sea exchange mechanisms and rates 
of exchange should be examined for both classes. In particular, air- 
sea transfer coefficients of these gases should be studied. These data 
could then be used with field observations to calculate regional and 
mesoscale fluxes on a time-dependent basis. Global-scale fluxes in some 
cases where human and natural production figures are available are 
perhaps better approached by calculation (Craig, 1957; Revelle and 
Suess, 1957; Broecker et al., 1971; and Machta, 1972), but this ap- 
proach might not be applicable to the question of the partitioning of 
biologically important gases (e.g. carbon dioxide) between the terrestrial 
biosphere and the oceans (Machta, 1972). 

It has long been known that the sea surface, in general, is not in 
equilibrium with the atmosphere with respect to carbon dioxide and 
oxygen, although the departure is not large for oxygen (Craig, 1957). 
The greater carbon dioxide disequilibrium is related to its lower rate 
of exchange with the atmosphere. Of basic importance in any attempt 


at estimating the regional air-sea exchange of any of the gases is a 
knowledge of the spatial and temporal variations in these air-sea dis- 
equilibria in surface seawaters, together with the respective transfer 
coefficients for the gases as functions of observable variables. 

Much research remains to be conducted on the chemically reactive 
gases to elucidate the processes governing their distributions, and 
most importantly, the kinetics of their rate controlling reactions. Of 
classical importance is dissolved oxygen, which has been measured in 
the oceans to a tremendous extent, yet whose reaction kinetics have 
been directly measured only recently (Packard, 1971), although indirect 
inferences have been made for decades. 

Many other gases eventually will prove increasingly important in 
studies of the oceans, including man's impact upon them. Examples in- 
clude methane, relevant to petroleum exploration; carbon monoxide, 
relevant to undersea work and habitation; and nerve gas, relevant to 
waste disposal at sea. We know Uttle of the kinetics of the rate controlling 
mechanisms governing the steady state and transit concentration levels 
of these gases in the oceans. 


Organic matter in all its manifestations plays an important part in 
marine chemistry (see pp. 45). The formation of organic tissue involves 
the uptake of elements from the aqueous medium into discrete pack- 
ages, which may become enriched in those elements by many orders 
of magnitude. An extreme example is the enrichment of polonium by 
a factor of 2 x 10^ in certain organs of the North Pacific albacore (Fol- 
som et al., 1972). Both during life and after the death of the organisms, 
dissolved and particulate organic and inorganic constituents are pro- 
duced that continue to redistribute chemicals in the ocean. This redis- 
tribution may be active by scavening chemicals from the water, or passive 
by decomposing, settling, and being carried along with the water. Under- 
standing the fluxes of organic carbon, therefore, aids in the understanding 
of the distribution of many other elements and compounds, for example, 
heavy metals, DDT, and radioactive material from fallout. 

Organic matter not associated with living organisms in the sea exceeds 
the amount of all living matter on earth by a factor of ten. Yet we do 
not know the chemical composition of most of this material, nor its 
rate of passage through the ocean. Since most of the organic matter is 
formed in the upper layers of the ocean, the rate of passage of the large 
amount of dead organic matter through the ocean depends critically on 
the recycling efficiency of the upper layers if a steady state is maintained. 


Similarly, the rate of injection into the deep sea of those chemical 
constituents that "travel" in association with organic matter depends 
critically on the fraction of organic matter not oxidized in the upper 
layers. Therefore, important questions to be answered are as follows: 

1. What is the recycling efficiency (ratio of oxidation to production) 
in the upper layers and how does it vary with depth, geographic position, 
and season? 

2. What are the chemical and physical forms of organic matter in- 
jected into the deep sea? 

3. At what rates are they injected. 

4. What are the modes and rates of their interactions with one another 
and with the inorganic constituents? 

5. What is the rate of oxidation of organic matter in the deep sea? 

6. What quantities and what forms of organic matter reach the bottom? 

7. How much is oxidized or solubihzed at the bottom? 

8. What is the rate of loss of carbon to the sediment? 

Some of these questions can be answered by stable and radioactive 
isotope studies (e.g. carbon- 13 and carbon- 14) coupled with measure- 
ments of concentration changes in inorganic and organic phases. Others 
require sophisticated methods of organic analyses, of which some are 
available and others are being developed or need to be developed. 


What effect do the dissolved gases in ocean water have on life proceses 
and how are they related to boundary conditions for models involving 
advective and convective mixing in deep waters? What are the diagenetic 
processes in marine sediments, including the formation of gases in sedi- 
ments? These are fundamental questions yet unanswered. There is ample 
indirect evidence for the diffusion of noble gases from the sedimentary 
column to the overlying waters. Helium, produced in the earth's crust 
as a result of radioactive decay of isotopes of the uranium and thorium 
series, is found in higher concentrations in deep seawater than expected 
from solution of air. Further, there appears to be diffusion of noble 
gases in the sedimentary column as a consequence of thermal gradients. 
Quantitative measurement of fluxes of gases such as the noble gases 
are yet to be made, even though such numbers would provide important 
boundary conditions for models of the mixing and movements of deep 


Low-molecular-weight organic molecules such as methane and carbon 
dioxide are produced during the microbiological decomposition of 
organic matter, but few measurements of these gases have been made 
in the sedimentary column. Their presence in the overlying waters 
could affect life processes in them. An inventory of such gases and 
flux calculations should be made, for in addition to contributing to the 
properties of the overlying waters as mentioned above, it is postulated 
that layers of gases (possibly as clathrates) are responsible for certain 
strong acoustic reflectors observed in sediments. 

The recent development of in situ interstitial water samplers allows 
for measurements of these gases dissolved in the interstitial waters in 
the top of the sedimentary column, and makes possible the calculation 
of fluxes. The methods for the analysis of these gases by mass spectros- 
copy and by gas chromatography are well developed. However, sampling 
devices for deeper portions of the sedimentary column still need to be 


Session y^ 

Impact of Life Processes on the 
Chemistry of the Ocean 

Dr. Francis A. Richards, Discussion Leader 


In identifying areas of research interest within the indicated area of 
chemical oceanography, a systematic discussion is presented, evaluating 
progress in four stages: 

• Inventory of chemical variables altered by life processes 

• Processes, rates, and mechanisms of those processes 

• Synthesis with knowledge from other areas and disciplines 

• Applications, prediction, and impacts. 

In oceanography the inventory step has always had to await suitable 
analytical methods, but a scientific raison a fair e has generally preceded 
the development of those analytical methods. As an example, Brandt 
( 1 899) suggested the importance of phosphorus and nitrogen compounds 
in limiting the productivity of the oceans, but analytical methodology 
appropriate to the problem was not developed until the early 1920's. 
Thus, although one cannot safely assume that the distribution of any 
specific constituent is unimportant to life processes and vice versa, 
areas of more probable importance can be identified. 

Progress in chemical oceanography has produced inventories of some 
constituents that are adequate for the solution of many oceanographic 
problems, but there are many biologically altered and biologically 
important variables of which there is little or no knowledge. For example, 
repeated references are made to chelating materials that are almost 
wholly unidentified and yet are probably biologically highly significant. 
There are essentially no adequate analytical methods for determining 
these materials and no start on inventories of them. On the other hand, 
continued observations of many of the variables altered by life processes 
such as dissolved oxygen and the major nutrients that are made on a 
routine basis and continue to enrich their inventories. 

It is evident that the inventory of chemical variables includes the 
problems of chemical speciation, particularly matters of complexation, 
chelation, and ligand formation. For example, the coordination of 


metals with inorganic ions and organic ligands is certainly critical to 
the biological availabihty of the metals. These coordinations are in 
turn altered by changes brought about by biological processes, such as 
pH changes accompanying photosynthesis and respiration, and by 
biologically produced chelators. 

The development and application of appropriate analytical methods 
is a necessary prerequisite to the development of inventories of chemical 
variables. Many sophisticated, sensitive, rapid, and automatic analytical 
methods have been developed in recent years, and we can now estimate 
the levels of many constituents of seawater that were unknown a few 
years ago. Nonetheless, the need for new techniques continues, es- 
pecially in areas of biologically active substances, chelating agents, 
and the specific estimation of chemical species — particularly in reference 
to the state of metals in solution. Advances in qualitative organic analy- 
sis seem urgently needed. 

Our understanding of the biological processes that alter the chemistry 
of the ocean, their mechanisms and their rates, tends to lag behind the 
inventory of chemical variables. Good progress has been made in some 
areas. The changes in dissolved oxygen, carbon dioxide, and the con- 
centration of nutrients during photosynthesis and respiration are rea- 
sonably well understood and correlated. The complications of the 
additive effects of these life processes and of advection and diffusion 
on local changes in concentrations are sometimes amenable to explana- 
tion and modeling. With the advent of routine methods that yield inven- 
tories of chlorophyll, the phytoplankton biomass responsible for photo- 
synthesis could be systematically estimated and limits could be placed 
on the photosynthetic potential of phytoplankton populations. The 
introduction of the carbon- 14 method for estimating rates of photo- 
synthesis and extensive studies of the photosynthetic process (generally 
not carried out by oceanographers) have provided considerable insight 
into the mechanism of this basic process. 

It is probably the exception rather than the rule to have a good work- 
ing knowledge of the biological processes that produce measurable 
changes in the chemistry of the ocean. Historically, the changes more 
often have been measured, and from them reconstruction of the bio- 
logical processes producing those changes has been attempted. In some 
cases, one can now chemically characterize or estimate the potential 
of a biomass to carry out a biochemical process (through enzyme activity 
assays), and following the research required to relate the biochemical 
potential and the pertinent environmental parameters, one can estimate 
in-situ rates of processes, such as metabolic oxygen consumption. It 
is probably accurate and pertinent to point out that the evaluation of 
advective, diffusive, and biological terms in the equation for the local 
time change in chemical variable has always proved too complex to 


make possible the general application of the equation. It is, therefore, 
necessary to seek other means for evaluating rates of biochemical 
changes in the oceans. In some instances, water masses can be isolated 
or identified and physically traced to give, when coupled with the proper 
chemical observations, rates of change, but these cases are few and 
far between, and generally this approach is not useful for determining 
reaction rates in the open ocean. 

An understanding of the ocean cannot result from knowledge, however 
complete, of the chemical makeup of the ocean alone. The physics, 
biology, geology, and chemistry are so intimately interwined that 
the amalgamation of knowledge from all these fields is essential to 
understanding the impact of life processes on the chemistry of the 
ocean. This is probably well understood by chemical oceanographers, 
but the synthesis of knowledge from such fields as biochemistry, organic 
chemistry, physical chemistry, and radiochemistry will be essential in 
applying chemical knowledge to the solution of important chemical 
problems. The impact of man's activities on the chemistry, biology, 
and geology of the ocean cannot be assessed or predicted without the 
application of such knowledge. It is also pertinent to point out that 
the converse is true for biology and geology, as has already been indicated 
in the Preface of this document. The short- and long-term eff'ects of 
pollution on marine organisms, for example, will be the results of complex 
interactions among water, biota, and sediments. 

The ultimate goal for research is to apply our knowledge to the pre- 
diction of changes in the ocean, the possible control of those changes, 
and predicting the impact that biological events, stimulated naturally 
or artificially, will have on the chemistry of the oceans. One attempt has 
been made to identify areas of research that will increase our ability 
finally to predict and apply the impacts of life processes on the chemistry 
of the ocean. 


For the purposes of this discussion, the major ionic constituents in 
seawater are those whose concentrations are at least 1 mg/liter and 
include chloride, sodium, sulfate, magnesium, calcium, potassium, 
bicarbonate, bromide, borate, strontium, and fluoride ions. 

Life processes in the sea fall broadly into the categories of photo- 
synthesis and respiration, where the latter includes the consumption 
of organic material as food by the various trophic levels of the food 
web. Although they might also be listed as respiratory processes, the 
formation of skeletal material by organisms in the sea and sulfate re- 
duction are important life processes that have an impact on the major 
constituents. The processes listed above may be shown diagrammatically 
as follows: 


i. Photosynthesis-Respiration 


CO2 + H2O + Nutrients + Energy ^ (1) 


nC(H20)«nutride + O2 

ii. Skeletal Mineral Formation 

Organic Activity + lonicConstituents 


Coral Skeletal Material 

■ — > 


Pteropods [Ca (Mg, Sr, etcOCOa] (2) 

Minor Minerals 

Barite (BaS04) 

Celestite (SrS04) 

Phosphorite (Ca2P04F) 
iii. Bacterial Activity in Anoxic Water and Sediments 

Organic Material + Sulfate + Iron * (3) 

Pyrite + H2S + HS" + S= 

Dissolved inorganic carbon is the only one of the major constituents 
(as defined) that is directly influenced by photosynthesis and respiration. 
The decrease in carbon dioxide in surface water caused by photosyn- 
thesis and the increase in carbon dioxide in intermediate and deep waters 
caused by respiration are routinely measured as part of many investi- 
gations and are relatively well understood. 

In skeletal mineral formation, biological activity acts to bring about 
the formation of minerals that are near saturation in the sea. The reasons 
for the formation of a specific mineral in preference to another (i.e. 
high magnesium calcite over argonite, etc.) are not well understood, 
but may be attributed to the amino acid or other organic makeup of the 
organisms. Since calcium carbonates are "sinks" for magnesium and 
strontium as well as for calcium and carbon, a change in the species 
of carbonate-depositing organisms may result in a change in the relative 
amounts of magnesium, strontium, and other elements being removed 
through geologic time. 

Similarly, phosphorites are the result of organic activity in areas of 
upweUing. Recent evidence (Kolodny and Kaplan, 1970) indicates that 


phosphorites have not been deposited for the last 100,000 years, and so 
this mechansism for the removal of calcium and fluoride is not active 
at the present time. 

Sulfate reduction by bacteria and the formation of pyrite, particularly 
in deltaic sediments, is apparently the major life process that significantly 
changes sulfate concentrations in the sea over long time periods (Berner, 
1971). Further studies of this important "sink" are necessary for a 
total understanding of the impact of life processes on the major con- 

In considering the impact of life process on the major constituents, 
the inverse relationship, that is, the effect of the major constituents on 
life processes, should not be neglected. Questions remain concerning 
the changes in the chemical composition of the ocean with time, whether 
or not life processes had a part in changing the concentrations of the 
major constituents, and changes in inputs and sinks for the major con- 
stituents. These are all chemical oceanographic research areas requiring 
further investigation. 


Heavy metals, important trace components of the ocean, may func- 
tion in both the regulation and stimulation of biological processes. 
Seven metals (Mn, Cu, Zn, Mo, Co, Mg, and Fe) have known biological 
functions and are required in varying concentrations for growth and 
metabolism of all organisms. Of this group, copper and zinc have been 
found in toxic concentrations in the marine environment. Other heavy 
metals (including Sb, As, Pb, Cd, Cr, Hg, Ni, Ag, Sn, Se, and V) are 
found in organisms in concentrations that are high in comparison to 
the surrounding medium (Brooks and Rumsby, 1965). Many of these 
elements are highly toxic; lead, chromium, mercury, selenium, silver, 
and antimony have been identified as agents of the greatest environ- 
mental concern. Perturbations to the natural flux of trace elements 
into geochemical cycles are imposed by man's activities, and these are 
important to ecosystem functions. Natural control of ecosystems may 
well depend upon synergism and antagonism of heavy metal interactions, 
and relatively small perturbations caused by man may overload normal 
cycles and temporarily drive the system in a nonequilibrium direction. 
Uncontrolled stresses may drive the system beyond its ability to recover 
and could result in long-term or permanent damage. 

Contemporary State of Knowledge 

Our knowledge of the distribution, chemical forms, and fate of the 
trace metals in the oceans is inadequate to relate their chemistry to 


biological processes involving stimulation, control, genetic changes, 
or toxicity. Little information is available even as to the total amounts 
of some elements such as antimony, cadmium, chromium and selenium. 
Probably copper, zinc, and iron have had more study than any other 
heavy metal and, although there is some evidence on their chemical 
speciation, there is no information on the importance of a given chemical 
species to a biological process. There is also little certain knowledge 
of the rates of interchange between chemical species of this group in 
the environment. There is evidence (Button, 1971) that the level of 
copper in ocean water (about 3 /u,g/liter) decreases the assimilative 
capacity of a laboratory yeast culture, unless some complexation occurs. 
The problem of "good" and "bad" ocean waters is thought to be closely 
related to trace metal complexation, which converts toxic forms, such as 
Cu+^, to nontoxic ligand-bound forms. Data now being obtained on many 
of the heavy metals in the oceans will no doubt enhance our knowledge 
of the distribution of the specific chemical forms being examined, but 
they will have limited value in assessing their role in biological pro- 
cesses, the importance of the various chemical species to those processes, 
or the dynamics of the coastal processes that largely determine the fate 
of heavy metals in the ocean (National Academy of Sciences, 1971a). 
Increased research related specifically to the biology, biochemistry, 
chemical oceanography, and geochemistry of heavy metals in the ocean 
environment is required to gain an understanding of the effect of biologi- 
cal processes on trace-metal chemistry, and conversely, the chemistry 
of trace metals on biological processes. 

Processes, Rates, and Mechanisms 

A process that influences the heavy metal concentration of the oceans 
is the biological removal of oxygen from the sediments, which leads to 
the production of hydrogen sulfide and precipitation of insoluble heavy 
metal sulfides or the solubilization of elements such as iron and man- 
ganese. The rates of such removal, the status of the equilibrium, and 
the mechanisms of chemical and biological cycling in the sediments 
and through the sediment-water interface are subject of great importance 
in heavy metal chemistry. 

The biota concentrate many heavy metals relative to their environment. 
Some of these elements have no apparent biological function, and it 
appears that the organisms have little capability for selective uptake 
or excretion. Such metals may not be toxic to the host organism, such 
as zinc or copper in oysters, but they may be passed up the food chain 
to higher organisms, including man. 

Concerns about heavy metals in the environment often arise from a 
lack of understanding of the effects of perturbations on the natural 


system imposed by man-made additions. Although it appears that the 
recent social concern with open-ocean pollution from these sources 
was not fully justified, local regions can be subjected to trace-metal 
contamination and associated environmental hazards. One of the serious 
problems is that of assessing the increase of trace metals in the marine 
environment because so little is known of their natural variations. 
Further complication arises from the geochemical dissimilarity of 
fluvial, estuarine and coastal regions by the dependency of organisms 
on trace metal availability, from the chemical forms of the metals in 
the water, and from the presence of other antagonistic or synergistic 
elements. Perspective can be gained of man's relative influence on trace- 
metal additons to the environment by comparing man-induced with 
natural inputs (Table 4). It is evident that man plays an important part 
in the mobilization of many of the heavy metals of concern. Fortunately, 
the coastal region, because of the intimate sediment-water interaction, 
appears best able to absorb excessive heavy metal input. 

Table 4 
Annual Rates of Mobilization 


Geologic Rate (G) 
(10^ metric tons)* 

Man-Induced Rate (M) 
(103 metric tons) t 















































*Bowen (1966). 

t United Nations (1968). 

The influence of biological processes on the chemical state of trace 
metals in ocean water is not clear. However, the indirect influence is 
probably profound, because the organic matter that is responsible 


for much of the complexing of metals in seawater is biologically derived. 
The organic moiety involved in complexing is not generally known; 
however, zinc has been found associated with a fulvinic acid type of 
residue in seawater (Hood, 1967), and part of the copper in some waters 
is extractable in organic solvents (Slowey et al., 1967). Variable frac- 
tions of copper, manganese, and zinc occur in nondialyzable forms 
implying organic complexation (Slowey et al., 1971). 


Modeling of the distribution of heavy metals in the ocean has had 
limited success because the basic knowledge indicated above is lacking 
(also see pp. 27). The construction of models should be encouraged — 
but only after our understanding of their interactions with the biota 
is improved. 

Future Efforts 

The most clearly identified problem in relating biological systems to 
the chemistry of heavy metals in the ocean is that of chemical speciation 
and the effects of these species in controlling or stimulating biological 
activity. Not until we are aware of the chemical form in which heavy 
metals interact with biological membranes and are involved in vital 
life processes, can we obtain useful working models of the manner in 
which biological processes are controlled by heavy metals or provide 
detoxification systems against their deleterious effects. 

The complexation of heavy metals with organic molecules has been 
urmed. The source and structures of the organic portion, the stability 
of such complexes, and the availability of these complexes to biological 
systems need careful investigation. The attack must be coupled with 
biological experimentation that is sensitive to ultrasmall quantities of 
added trace elements, but this approach must await development of 
suitable techniques for it to be successful. 

Studies of the spatial and temporal distributions of heavy metals in 
the ocean are needed, particularly near coasts. These studies should 
identify the chemical species, ratios of dissolved to particulate matter, 
association with sediments, and (where possible) the rate of movement 
between phases. The hypothesis should be carefully tested that sediment 
removal controls heavy-metal concentrations in the water column at 
the coastline. 


The organic chemistry of the marine environment is extremely com- 
plex. The ocean presumably contains most, if not all, of the compounds 


that are formed by marine organisms. In addition, there are products of 
in-situ chemical reactions and natural materials derived from atmospheric 
sources. To an increasing degree, the sea contains residues of fossil 
fuels and synthetic organic compounds. The organic components of 
the marine environment interact with its other constituents through 
continuous destruction, new synthesis, and exchange with the atmo- 
sphere, the biosphere, and the lithosphere. 

We can now begin to describe partially the composition of organic 
matter dissolved in seawater (DOM; 0.2 to 1.0 mg/liter), because of 
recent advances in analytical techniques, such as the combination of 
mass spectrometry with gas chromatography. The question of whether 
or not DOM from various locations and depths is the same can now be 
attacked. The bulk of this material may have a fairly simple structure, 
but this seems unhkely. It has been suggested that DOM is a polymer- 
like material condensed from amino acid and sugar subunits. Specific 
research is needed to determine what soluble polymers exist in seawater. 

Dissolved organic matter requires more study for the following 

• It is the largest reservoir of organic matter in the sea and one of 
the largest on earth. 

• It probably modifies the chemical and biological properties of other 
seawater components, especially the trace metals. 

• It may serve a function for marine organisms. 

• It may be of use to man (e.g., drugs from the sea). 

Regional studies of the organic chemistry of a few complex systems 
can increase our understanding and allow us to advance to larger systems. 
Intensive studies should be fruitful in oceanic areas where processes 
are relatively more rapid, such as 

• Polar areas where the chemical character of water masses is con- 
tinually changed. 

• Continental margins where biological processes and rapid sedi- 
mentation help control the makeup of the sea. This includes upwelling 

A study of the organic matter in marine sediments that have been 
deposited in the last one million years is needed. A chemical record of 
how life adjusted to ice ages may be recorded in the proteins and amino 
acids of carbonate shells, and the optical activity of these amino acids 
may provide a new dating technique. Although amino acid levels in 
carbonate depostis are low (~ 100 ppm), the analytical methods are 
well developed (gas-liquid chromatography and ion exchange). Using 
new colorimetric reagents, amino acids can be detected in seawater 


One aim of the marine chemist is to inventory the organic chemicals 
in the sea and to understand their origin, role, and fate in terms of oceanic 
processes. When correlated with data from other scientific disciplines, 
models of oceanic processes can be developed and tested. 

Progress in the different areas of marine organic chemistry (Table 5) 
has been uneven. In some areas (synthesis and turnover by microor- 
ganisms; marine polymers) we lack much basic information. In other 
areas (marine lipids), existing knowledge may permit modeling marine 
processes in some regions. 

The understanding of marine processes, and specifically of mechanisms 
and rates, is critically important to the further development and appHca- 
tion of marine chemistry. The reaction rates and mechanisms determine 
the magnitude of the "standing crop" of organic compounds in the 
dynamic system of the sea and the magnitude of the impact of natural 
and synthetic materials on marine ecology. Rates and mechanisms 

Table 5 
Organic Compounds of the Marine Environment 

Medium for 
Organic Compounds 

Basic Questions 

Urgent Research 

Applications and Relevance 

Bacteria, Fungi 

Origin, composition. 

Inventory needed 

Pollution baselines and control coastal 

variability, role 

Turnover and decomposi- 
tion rates 

and deep ocean disposal 

Selectivity and efficiency 

Knowledge rudimentary 

Reworking of organic matter in sediments 

in transfer processes 

and seawater 


Origin, composition. 

Some existing knowledge; 

Pollution baselines; low-level 

variability, role 

extended geographic and 

effects of pollution; primary production of 

compositional range 

marine organic matter 

Selectivity and efficiency 

Little known 

Dynamics of food web 

in transfer processes 


Origin, composition. 

Some existing knowledge; 

Pollution baselines, low-level effects of 

variability, role 

extended geographic and 

pollution; intermediary in marine food 

compositional range 

web; transfer of organics 

Selectivity and efficiency 

Little known 

Dynamics of food web, population 

in transfer processes 

dynamics and migration 

Higher food web 

Origin, composition. 

Some existing knowledge. 

Pollution baselines, human nutrition. 

variability, role. 

extended geographic and 

public health, aquaculture, recycling 

compositional range. 




Sources, composition 

Little known in recent 

Pollution baselines, identification of 

variability, interaction 

sediments, especially in 

low-level pollution, preservation of 

deep ocean 

organics, recycling capacity, modification 
of acoustic properties 

Preservation, destruction. 

Reaction mechanisms, rates 

new formation 

and intermediates largely 

Seawater, dissolved. 

Origin, composition. 

Little known, especially 

Dynamic processes; physical oceanog- 

and particulates. 

variability, fate, and 

in deep ocean; predictive 

raphy; pollution baselines and control; 

surface films 


models; rates and 

air-sea interaction; remote sensing 


Origin, composition. 

Little known; baselines 

Air-sea interaction; global exchange of 

variability, fate, and 





need to be studied both in areas where we expect rapid turnover (inter- 
faces between sea and air, seawater and fresh water, seawater and 
sediments, and water and particulates) and in areas of low reactivity, 
such as the deep sea, where waste materials may persist indefinitely. 

Organic compounds in the sea interact with other components of the 
ocean in ways that require, in most cases, further study. Thus, certain 
organic compounds play a role in the speciation of inorganic ions and 
determine their availability; other compounds may mediate processes 
that affect the life cycles of organisms (chemotaxis). Therefore, marine 
organic chemistry relates directly to oceanic productivity and to the 
capability of the ocean to recover from perturbations. 

The great complexity of the marine organic matter presents an analyti- 
cal challenge. Much development is needed to insure clean sampling, 
sample preservation, and initial separation of the concentrates into 
type compounds. For some classes of compounds (e.g., lipids, amino 
acids, carbohydrates), adequate analytical techniques are available 
from related fields. In other areas (e.g., marine polymers such as humates, 
fulvates, alginates, metal complexes) progress still depends on the 
development of methods for rapid routine analysis during large-scale 
oceanographic studies. 

Table 5 classifies the sites of organic matter in the sea; it states some 
basic questions and suggests research areas and applications that deal 
with the impact of life processes on the organic chemistry of the ocean. 


Life processes in the ocean alter the composition of seawater, and 
the changes thus produced impart distinguishing characteristics to the 
water in which they take place. The perturbation of the chemical medium 
may be apparent and easily detectable by chemical means, or it may be 
subtle, but nonetheless biologically significant in a long or short time 
scale. The former kinds of changes have made possible one of the classi- 
cal activities of chemical oceanography — the characterization and tracing 
of water masses in the ocean. Continued research in this field appears to 
be essential, not simply to improve our knowledge of fields of motion in 
the ocean, but to predict the effects of biologically induced chemical 
changes on processes (chemical, biological, physical, geological) down- 
stream from the sites of the biological events. Among questions to be 
resolved are prediction of plankton blooms as the result of nutrient 
fertilization, the detoxification of metals by chelation, and the stimula- 
tion of growth processes by the injection of vitamins and other bio- 
chemically active substances into a water mass. The changes brought 
about by life processes on the chemistry of the ocean are important for 


their causative and diagnostic potentials and can be identified as impor- 
tant research areas. The commonly recognized water mass characteris- 
tics, such as the original temperature-salinity relationships among the 
conservative and nonconservative properties such as O2, alkalinity, 
pH, silicate, etc., will continue to be useful water mass tracers. However, 
many other biologically imparted characteristics can be used to give us 
more detailed knowledge of fields of motion and, perhaps even more 
importantly, of the fate and eff'ects of biologically active substances in 
the ocean — whether they be naturally produced or artifically introduced. 

Water mass properties that may be important both in describing fields 
of motion and in predicting oceanographic environments are listed below 

1. Departures in the ratios of the major constituents resulting from 
alkaline-earth uptake, sulfate reduction, and similar processes 
2. Trace-element concentrations and the ratios of the various ionic and 
molecular species in which the trace elements occur 

3. The ratios of biologically altered nutrient substances, e.g. C:N, 
N:P, P:Si, and the concentrations of particulate and organic carbon 

4. The presence of biologically active materials probably will be 
detected in the immediate future by bioassays. It is evident that these 
substances, along with toxic materials, have important consequences. 

5. Petroleum and the identification of petroleum fractions might give 
important clues as to the origin of water masses and their course through 
the oceans. Persistent synthetic chemicals may prove useful as tracers. 

6. The use of dissolved O2 as a water mass tracer is historical and 
well documented. In specific areas where nitrogen fixation or denitri- 
fication alters the nitrogen content, precisely determined N2/Ar ratios 
should be useful tracers. 

7. Alkalinity and pH have been shown to be useful in tracing upwell- 
ing waters, estuarine waters, and in evaluating biological changes in 
such waters. 

8. Man-made radioactive isotopes were the first artificially introduced 
water mass tracers useful over wide oceanic areas. Changes in the 
ratios of stable isotopes concurrent with biological processes could 
also be useful in this connection. 

The growth and composition of plankton and micro-organism popula- 
tions are subject to chemical controls. In turn, these biological processes 
significantly alter the chemistry of the water through both obvious and 
subtle feedback mechanisms. Indeed, the two biological processes of 
primary production and microbiological degradation are fundamental 
to the chemistry of the sea by displacing the equilibrium of the system 
and by catalyzing reactions back toward equilibrium. 

Early realization of the importance of nutrients (P, N, and Si) to 
primary production and the hope of a fairly direct link to locations of 


fishery resources led to extensive surveys of spatial and temporal 
variations of these nutrients. Gross inventories have been defined on 
a world basis and gross rates of reaction rates have been measured, 
especially in favorably hydrographic situations where information about 
physical movement and mixing of water masses has been available. 
Global estimates of primary productivity have also been accomplished. 

Recent mathematical modeling of microscopic processes coupled 
with careful experimentation at natural (low) levels of chemical con- 
stituents have produced unexpected and useful results (Droop, 1968; 
Sieburth, 1969; Button, 1971, 1972; Caperon and Meyer, 1972a,b; 
Thomas and Dodson, 1972). Instead of growth rates being simply 
related to water composition, such systems are quantitatively described 
by transport relations describing the simultaneous flux of several nutri- 
ents to the cell surface (up concentration gradients of 10^ — 10^ by 
active transport mechanisms), back-diffusion relations of nutrients 
and organic waste products, and internal nutrient regulation of growth 
through kinetic enzyme relations, (Button, 1972). These models are 
fairly simple and can be handled by computer techniques. Network 
models of such systems are feasible. Such models should be used to 
guide the design of laboratory and field experiments. 

Some early results may serve as an example of the type of guidance 
that can be expected. The low controlling levels of chemical constituents 
and the competitive nature of the membrane transport sites imply that 
very low concentrations of nutrients (and of antimetabolites such as 
arsenate, trace metals, etc.) must be considered simultaneously. Rates 
of backleakage of nutrients and of organic metabolites significantly 
aff"ect water chemistry as well as the flux relations in the models. Diff'er- 
ences in continuous and batch incubation results should be examined 
in regard to field methods. The models and their results should also be 
examined as aids in the design of experiments on the eff'ects of pollution. 

Nutrients and Dissolved Gases— T\iQ abundances of the nutrient 
salts, phosphate, silicate, nitrate, nitrite and ammonia, plays a major 
role in controlling the productivity of the sea. Previous research has 
been focused on the development of suitable analytical methods and 
the application of these methods to the definition of the temporal and 
spatial distribution of nutrients in the ocean. Much of this definition 
has been accomplished, and it is now time to focus research on the 
rates and regulation of those processes that control and determine the 
characteristics of the nutrient fields, to construct mathematical expres- 
sions to describe these processes, and to nest these expressions in a 
predictive mathematical model. The mathematical model cannot be 
constructed or verified from our present knowledge of the rates and 
regulation of these processes, and since this inadequate understanding 


is the result of our inability to make real-time rate measurements, re- 
search should be focused on developing our capacity to make such 
rate measurements, analagous to our present ability to make real-time 
concentration measurements. 

The rates that must be measured are those of nutrient uptake by plank- 
ton and nutrient release by bacteria and zooplankton. These processes 
are modulated by environmental factors such as light, temperature, and 
pressure, plus biological factors such as biomass, species, and age. 
Our ability to measure fluxes in and out of living particles is limited to 
incubation techniques that are based on questionable assumptions, 
that are not suitable for the study of time-dependent processes, and 
that are too slow to be compatible with real-time data acquisition systems. 
The use of enzyme analysis in oceanographic research can relieve this 
reliance on incubation techniques by substituting in-vitro techniques 
that are amenable to continuous chemical determination. The use of 
enzyme analyses to estimate rates of biochemical process depends on 
the identification of the enzyme system that regulates the process and 
the measurement of its in-vitro substrate transformation rate, i.e., its 
activity. These measurements are sensitive and fast, and when properly 
calibrated, are as accurate as the more classical in-vivo incubation 

In addition, the dynamics of consumption and production of oxygen, 
carbon dioxide, hydrogen sulfide, nitrogen, hydrogen and methane 
are also controlled by intracellular enzymes of marine organisms. As 
a result, real time measurement of the rates of these fluxes and their 
variation in time and space can only be realized by determining the 
activity of these enzymes. To implement this research we must: 

1 . Identify the enzyme or enzyme systems that control the utilization 
and the formation of POi^, NOs", NOj, NHt and Si02. These will prob- 
ably be phosphatases, nitrate reductase, intrite reductase, and glutamate 
dehydrogenase, which control the fluxes of P and N. The enzymes 
regulating silicate fluxes are not known. 

2. Develop analytical techniques to measure the activity of these 
enzymes and automate and interface the analyses with existing com- 
puter-controlled data-acquisition systems. 

3. Derive mathematical expressions for the regulatory mechanisms 
by which light, substrate level, temperature, and physiology control 
the activity of these enzymes. 

4. Determine the pattern of variation of enzyme activities in the 
marine environment and relate it to changes of the nutrient fields and 
to the biological and physical parameters. 

5. Construct both conceptual and mathematical models of the nutri- 
ent cycles and the processes that control them in: 

a. Upwelling areas 


b. The deep-sea 

c. Oligotrophic open-ocean gyres 

d. The top 10 cm of the water column 

e. The near-bottom nepheloid layer 

f. The interstitial water of sediments. 

Synthetic Organic Materials — Synthetic organic chemicals are sub- 
stances produced from naturally occurring raw materials. They usually 
do not occur in nature, and are developed and produced for some chemi- 
cal or physical property that makes them useful, or they are produced 
as by products. 

The wide variety of plastics, synthetic fibers, and pesticides, such 
as the chlorinated hydrocarbon DDT and polychlorinated biphenyls 
are examples. Several hundred synthetic organic chemicals are being 
produced in multi-ton quantities (see Table 6). 

In the manufacture, transportation and use of these materials a prob- 
ably substantial, but unknown, fraction of the total is injected into the 
marine environment. Life processes have an impact on these materials 
and vice versa. In some cases they are biologically degraded, which 
can be useful in the disposal of unwanted substances. Because of their 
solubility in lipids, they may become more concentrated in organs and 
organisms as the trophic levels are ascended. It has become evident 
during the past few years that some of these synthetic chemicals have 
an impact on marine life that constitutes a potentially serious threat. 
Several recent workshops have drawn attention to this problem and 
suggested plans for major research efforts to evaluate their impact 
(SCEP, 1970; Ketchum, 1972; and National Academy of Science, 
1971, b). 

We are in a strong position to formulate and carry out specific research 
directed at specific problems. Several pollutants of global concern 
have been identified. DDT and its decomposition products and poly- 
chlorinated biphenyls are examples. Others may be identified. The 
factors that combine to yield a potentially significant pollutant are: 
high production rates by industry; resistance to degradation in the 
environment; a route of transfer such as atmospheric transport from 
source to site; significant biological uptake; and toxicity for some 
level of life. These factors also allow a research program to be defined. 
At the present time the research needs are as follows: 

1. Measurements of the levels of suspected toxic materials should 
be made in water, biota, and sediments. This research may require only 
local studies for some pollutants, or it may need global studies for 
pollutants such as DDT and the PCBs. Analytical methods are available 
for such research. 


Table 6 
(National Academy of Sciences, 1971b) 
Estimated Involvement of Organic Substances 
with the Marine Environment 

Lost to Marine 

Organic Substances 

World Production 

Environment through 

and Sources 

(million tons/yr) 

Man's Activities 
(million tons/yr) 

Petroleum (1969) 



Lost to the marine environment 

through man's activities 

Offshore oil production 


Tanker operations 


Other ship operations 




Deliberate dumping 


Refinery operations 


Industrial and auto 




DDT and Aldrin — toxaphene 

Lost to marine environment 



Polychlohnated biphenyls 

Lost to marine environment 



2. Investigation of the pathways and rates at which known synthetic 
organic chemicals are disseminated and how they move through the 
ecosystem should be conducted. 

3. Research is needed on the toxicity and biological impact of known 
levels of pollutants. Such studies should go beyond determining lethal 
levels of pollutants. The overall welfare of marine communities such as 
primary production rates or the genetic pool, may be greatly influenced 
by sub-lethal concentrations. 

4. The fate of pollutants at the sites of final deposition and rates of 
degradation need to be determined and appropriate models developed. 



Occurrence, Formation and Degradation 

Both recent, biosynthetic, and fossil hydrocarbons occur in the sea; 
the latter are observed increasingly along tanker routes of the open 
ocean and in coastal areas receiving chronic spills. We lack fundamental 
data on the residence times of hydrocarbons in the open ocean, on 
beaches, in bottom sediments, and in organisms. The degradation and 
solution processes that disperse and destroy hydrocarbons are unknown, 
as is how recent and fossil hydrocarbons move through the biosphere, 
the hydrosphere, and the marine food web. 

A closely allied problem is understanding the diagenesis of organic 
matter in sediments that leads to hydrocarbon accumulation. Changes 
in organic matter with depth in sediments of inland seas of the geologic 
past have been studied, but there have been only limited studies of cores 
from the present continental margins and deep sea. These studies 
indicate that some of the conversion processes may be slower because 
of lower temperatures and that different products may result because 
of differences in amounts and type of organic matter in the open ocean 
and in inland seas. We need more definitive studies of the mechanisms 
and rates of change of organic constituents of open ocean sediments. 

Hydrocarbon Gases 

Inventories of hydrocarbon gases in waters and sediments have 
been made in selected marine environments, but little is known of the 
processes and rates of their formation, accumulation, and decomposi- 
tion. Methane, ethylene, and propylene are commonly present in near- 
surface waters of coastal margins and inland seas. The methane probably 
originates from anaerobic decay of organic matter, and the low-molecu- 
lar-weight olefins are believed to be metabolic byproducts of plankton 
growth, but there is no clear evidence of these processes. We need studies 
to define mechanisms and rates of hydrocarbon production from biota in 
both shallow coastal and deep sea environments. 

In reducing waters and sediments methane, ethane, and propane are 
the dominant hydrocarbons produced. Although the production of 
methane by micro-organisms utilizing carbon dioxide and hydrogen is 
established, there is no evidence of how ethane and propane are formed. 

Transport mechanisms resulting in the migration and accumulation 
of hydrocarbons in sediments and waters are also poorly understood. 
Hydrocarbons may migrate either as bubbles or as part of a solution 
by convection and diffusion. In the Black Sea, methane formed in 
sediments and bottom waters migrates through the anoxic to oxic 


waters, where methane-oxidizing bacteria convert part of it to carbon 
dioxide. In the Red Sea, hydrocarbon gases (methane through the 
butanes) are brought up by hot springs in contact with organic sediment 
at depth. Major rivers carry dissolved methane from the continents 
to the oceans. The movement of hydrocarbon gases has been traced 
in a few specific areas, but httle is known of fluxes in and out of the 

Transport of dissolved hydrocarbon gases from more deeply buried, 
compacting sediments to permeable, near-surface beds is particularly 
important. A phenomenon of these accumulations is the formation 
of gas hydrates (solids resembling ice), with the approximate formula 
CH4(H20)6. Methane hydrates form from 0° to 24°C and at pressures of 
400 to 6000 psi (equivalent to a total water-sediment column of about 300 
to 4667 meters). They are believed to be widespread in sediments of 
continental margins, where bottom temperatures and pressures are 
conducive to their formation. They can cause sub-bottom reflections 
because of the high velocity of seismic waves in the crystalline hydrate 
layers, which can reach thicknesses of 500 meters. We need to know 
more about the origin, occurrence, and distribution of these gas hydrate 
layers in sub-bottom sediments. Core barrels need to be built that can 
take and retain samples at their subsurface pressures. Such equipment 
is available from the oil industry, but it needs modification for research 


For some elements the formation and concentration of chemical 
species depend on biological processes that directly or indirectly alter 
the redox potential, the pH, and the alkalinity. These processes can be 
nonbiological, biological, or some combination of both. 

Redox Potential 

The oceans are in a dynamic state with respect to oxidation and 
reduction. There are significant differences in the redox environment 
of the surface in contact with oxygen in the atmosphere, the deep waters 
that bathe the sediments. In between are intermediate zones resulting 
from diff"usion and advection, or the lack of them, and from varying 
biological activities. Most redox reactions in the oceans depend on the 
activities of the biota. Redox levels within microenvironments close to 
biological surfaces may diff"er from those in the macroenvironment. 
Marine organisms internally mediate redox reactions by acting as 
centers of variant oxidation potential (e.g., the photosynthesizing cell 
is a center of low pE, permitting the reduction of CO2 to glucose). 


Externally, changes in pH as a result of photosynthesis and respiration 
and the precipitation and solution of calcium carbonate may affect the 
rate of abiotic redox reactions. 

Carbon, nitrogen, oxygen, sulfur, iron, and manganese are the main 
elements that participate in oceanic reduction-oxidation reactions. 
These "redox elements" and the principal redox reactions mediated 
by plants and microbes are summarized in Table 7 in a form which 
focuses on the chemical species associated with each biological process. 
These reactions play an essential role in the vitality and chemistry of 
the ocean and need to be investigated in more detail. 

Direct measurement of Eh values in the ocean is complicated and 
limited by practical problems. Quantitative interpretation of the results 
has been disappointing and has given only a general picture of the 
redox level. A better understanding may be obtained by directing more 
effort to biochemical studies of electron transport systems of the organ- 
isms that mediate or catalyze the transfer of electrons between the 
oxidizing and reducing substances. Once we understand the fundamental 
roles of these processes and know their location and magnitude in the 
ocean, we will better understand the essential chemical fluxes in the 
marine ecosystem and the practical problems of corrosion and recycling 
of pollutants. 


The chemistry of the oceans depends on the indirect influence of the 
biological assimilation and sorption or secretion and excretion of com- 
pounds that react with elements in the water. For example, pH changes 
depend on the amount of carbon dioxide taken up or released during 
photosynthesis and respiration. Also, pH is influenced by the secretion 
and dissolution of calcium carbonate by marine plants and animals. 
Diurnal variations in the euphotic zone change the pH of the surface 
layers. These changes, although small in the water column, may be 
significant in micro-environments close to biological and particulate 
surfaces. They may be significant to the following: 

1. Degree of protolysis of acids in solution: The distributions of 
carbonate species, borates, phosphates, sulfides, hydrous oxides of 
iron and aluminum, and organic acids are determined by pH. 

2. Precipitation reactions: Biologically induced changes in the pH 
of seawater may result in the precipitation of species that are at or 
near saturation. The coprecipitation of other elements is an important 
secondary effect, e.g., coprecipitation of Sr+^, Pb+^, and Zn+^ with 

3. Complexation: Since many complexing agents are also conjugate 
bases of weak acids, the degree and stability of complexes in solution 
depends on pH. 


Table 7 
Principal Plant and Microbially Mediated Redox Reactions 


Biological Process 

Mechanisms (rates) 

Impact (species) 



Green plants mediate the 
reduction of C to the 
higher free energy state 

H.O, CO.^CH.O, O2 


* Respiration/ 

Oxidation of organic 
matter mediated by 
microbial aerobic 

0., CH.O-^CO., HoO 


Nitrate Reduction/ 

Mediated by microbial 
nitrate reducers; 
organics are oxidized by 
nitrate ions 




Mediated by microbial 
denitrifiers; organic 
compounds are oxidized 
by nitrate ions 



Nj — fixation 

Mediated by photosyn- 
thetic blue-green algae 
and other microorgan- 



Mn — reduction 
(or Oxidation*) 

Mn bacteria 



Fe — reduction 
(or oxidation*) 

Fe bacteria 




Mediated by microbial 

H.O. CH.O-^CH:,OH,H- 



Methane Fermentation 

Mediated by Hj forming 
bacteria and 
methane bacteria 

CH»O^CH4, CO2 

(H.?) (C2 H4?) 


Sulfate reduction 

Microbially mediated by 
sulfate reducers organic 
compounds are oxidized 
by sulfate ion 




Microbially mediated by 
nitrogen oxidizing 

NHT ^NO.-^NOr 


*Sulfide oxidation 

Microbially mediated by 
sulfur bacteria and 
photosynthetic sulfur 

HS— >S04-' 

*These reactions take place in oxygenated regions. The other reactions, with the exception ot~ photosynthesis, generally occur in 
anoxic regions and are initiated in a sequentially decreasing order as the Eh decreases. 


4. Rate of reaction for "redox" elements: The rates of reactions 
that are normally slow may be substantially increased, e.g., at the 
surface of algae during photosynthesis and at the surface of CaCOa 

5. Determination of reaction products: pH may control products 
where alternate or sequential pH-dependent reactions take place. 

6. Sorption: Sorption of an element by suspended particulate matter 
may be influenced by hydrogen ions, which compete for or modify 
sorption sites. The influence of pH on the degree of protolysis of the 
sorbing solute should also be considered. 

7. Flocculation: The degree of incorporation of solutes may depend 
on the pH at which flocculation takes place. 

There is no general agreement on how pH should be measured nor 
on the precision or accuracy of the results. There is further complica- 
tion because pH varies if the water sample is brought to a different 
pressure and temperature during measurement. Careful studies of 
the technique of pH measurement and of the eff^ect of temperature and 
pressure are needed. The development of in-situ pH measurements 
should give new understanding of this important nonconservative 
property of seawater. 


The major anions in seawater are chloride, sulfate, bromide, bicar- 
bonate, carbonate, and borate. Only the latter three have any appreciable 
power as bases. Phosphate and siHcates (i.e. H2POI, HP04"^, POr^, 
H2Si04"^ and HaSiOr) are moderately eff'ective as bases, but are gen- 
erally present in minor concentrations (<1 ppm) except in anoxic 
waters where sulfides (i.e. HS" and S^^) and ammonia may become 
appreciable. The total concentration of these "Lewis Bases," in addi- 
tion to the small excess of hydroxide ions, are referred to as the "alka- 
linity" of seawater — the capacity of seawater to neutralize the addition 
of a strong acid without an extreme change in pH. It is a property of 
seawater that prevents large disturbances to life processes in the ocean. 
Alkalinity may be at times a main variable in the chemical composition 
of seawater. The secretion of calcium carbonate shells by organisms 
and their subsequent dissolution seem to be the main factors influencing 
the alkalinity. Changes can arise from the complexing of carbonate 
species, boric acid volatility, biological production of organic matter 
and ammonia, and others. The ratio of alkalinity to the chlorinity (the 
specific alkalinity) varies significant with depth, in anoxic basins, near 
coasts, and in shallow tropical seas where calcium carbonate precipitates. 
A better understanding of the species contributing to the total alkalinity 
in diff'erent regions is needed. Moreover, since calcium carbonate is 


present in all living things, a study of metabolic influences on the forma- 
tion of calcium carbonate is important. A study of the impact of life 
processes on the calcium chemistry and alkaUnity of seawater should 
be concerned with the biochemistry of the organism as well as the physi- 
cochemical influence of the medium. Finally, because of the many reac- 
tions that are influenced by pH, the buff"ering aspect of the alkalinity 
is important to the chemistry of seawater and its stability as a biological 

Impact of Life Processes on Radioactive and Stable Nuclides 

Radionuclides in the ocean may be naturally occurring or manmade. 
Naturafly occurring radionuclides are the cosmic-ray-produced species, 
such as carbon-14, hydrogen-3, berylUum-10, uranium-238, uranium- 
235, and thorium-232, and their many daughter products, such as 
thorium-230, radium-226, lead-2, radium-228, protactinium-231, etc. 
Manmade radionuchdes consist of the fission and fusion products given 
off' by nuclear-weapon tests, controlled nuclear reactors, and power 
generators. Some of the most important in the ocean are carbon-14, 
hydrogen-3, strontium-90, cesium- 137, zinc-65, and plutonium-238 and 
239 (see pp. 33). 

Life processes are important in transporting many of these nuclides 
from surface into deep water. For example, "bomb" carbon-14 has been 
found in the tests of foraminifera at great depths in the sea. High levels 
of fission products have been found in fish caught in the open ocean, 
and these fish must be important agents for transporting these nuclides. 
(see pp. 33). 

Life processes are important in transferring radioactive elements. 
For example, photosynthesis transfers "bomb" carbon- 1 4 from inorganic 
to organic carbon in the marine ecosystem. Although life processes 
have a tremendous influence on radionuchdes, the inverse relationship 
is as much, if not more, important, but these influences are poorly 
understood. Some fission products and plutonium may be concentrated 
to high and possibly deleterious levels in various organs of fish and 
higher organisms (Folsom, 1972). The effects of these radionuclides on 
organisms needs to be assessed. 

The field of stable isotope geochemistry has an excellent record of 
providing answers to specific questions. For example: 

1. Paleo-temperatures based on O'^/O'^ ratios. 

2. Sulfur dome origins based on S^VS^- ratios. 

3. Oil field and oil source bed correlation based on C^^/C^^ ratios. 

4. Water cycles based on O^^/O'® ratios. 

Several parts of stable isotope geochemistry are now ready to yield 
important information: 


1. N'^/N^"* natural variations may provide valuable insight into the 
marine nitrogen cycle. 

2. C^^IO^ ratios can suggest the kind of processes that put organic 
matter into marine sediments now and especially during the last two 
ice ages. These ratios can also help to demonstrate that different types 
of photosynthesis (at least two) are going on. 

3. O'^/O^^ data on dissolved O2 can help explain the oxygen cycle in 
the sea. 

Radionuclides in seawater are characterized by their extremely high 
dilutions, and when higher concentrations are encountered, it should 
always be suspected (and frequently is demonstrated) that life processes 
have been involved. Some of the most spectacular examples of trace- 
element accumulations have been demonstrated by following the uptake 
of radionuclides of certain metals by living systems. For example, the 
living interfacial region between seawater and certain brown algae ac- 
cumulates concentrations of both natural polonium and artificial pluton- 
ium by orders of magnitude above ambient water; polonium-210 by 
90,000-fold, and plutonium-239 by 3,000-fold (Wong et al. 1972). (See 
p. 65) 

In the case of polonium, additional buildup occurs in specific organs 
of animals high in the tropic level. An extreme case is the 2.2 x 10^- 
fold buildup (over seawater) of polonium-210 in one organ of a tuna fish 
(Folsomet al. 1972). 

Life processes may afford powerful tools for understanding the dis- 
tributions certain trace elements in the ocean. Even information on 
major currents, and also information concerning mixing rates, can come 
from chemical and radiochemical inspections of concentration buildup 
in living systems. These often are most conveniently followed through 
their radioactive properties (Folsom et al. 1968, 1970, Hodge et al. 


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Dr. Neil R. Andersen, Convener 
Ocean Science and Technology Division 
Office of Naval Research 
Arlington, VA 22217 

Dr. Gordon Atkinson 
Department of Chemistry 
University of Oklahoma 
Norman, OK 73069 

Dr. Max Blumer 

Woods Hole Oceanographic Institution 

Woods Hole, MA 02543 

Dr. James H. Carpenter 
Oceanography Section, Room 317 
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Dr. Keith E. Chave 
Department of Oceanography 
University of Hawaii 
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Dr. Harmon Craig 
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University of California, San Diego 
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Dr. Werner G. Deuser 

Woods Hole Oceanographic Institution 

Woods Hole, MA 02540 

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Department of Earth & Planetary Science 
Massachusetts Institute of Technology 
Cambridge, MA 02139 

Dr. Frederick H. Fisher 
University of California, San Diego 
P.O. Box 109 
LaJolla, CA 92037 

Dr. Theodore R. Folsom 
Scripps Institution of Oceanography 
University of California, San Diego 
La Jolla, CA 92037 

Dr. Edward D. Goldberg, 

Discussion Leader 
Chemical Fluxes Through the Marine 

Environment, Including Air-Sea and 

Sediment-Sea Exchanges 
Scripps Institution of Oceanography 
University of California, San Diego 
LaJolla, CA 92037 


Dr. Louis I. Gordon 
School of Oceanography 
Oregon State University 
Corvallis, OR 97331 

Dr. Michael L. Healy 
Department of Oceanography 
University of Washington 
Seattle, WA 98105 

Dr. Donald W. Hood 
Institute of Marine Sciences 
University of Alaska 
College, AK 99735 

Dr. David C. Hurd 
Department of Oceanography 
University of Hawaii 
Honolulu, HI 96855 

Dr. John M. Hunt 

Woods Hole Oceanographic Institution 

Woods Hole, MA 02543 

Dr. Lela M. Jeffrey 
Department of Oceanography 
Texas A & M University 
College Station, TX 77843 

Mr. John J. Kelley 
Institute of Marine Sciences 
University of Alaska 
College, AK 99701 

Dr. Dana R. Kester 
Narragansett Marine Laboratay 
University of Rhode Island 
Kingston, RI 02881 

Dr. Patrick Kinney 
Institute of Marine Sciences 
University of Alaska 
College, AK 99701 

Dr. Lawrence H. Larsen 
Oceanography Section, Room 3 1 7 
National Science Foundation 
1800 G Street, N.W. 
Washington, DC 20550 

Dr. Frank J. Millero, Discussion Leader, 
Processes and Mechanisms Governing the 

Inorganic Composition of Seawater 
Institute of Marine and 

Atmospheric Sciences 

■if U.S. GOVERNMENT PRINTING OFFICE: 1973-728-08S/643 3-1 

University of Miami 
Miami, FL 33149 

Dr. Theodore T. Packard 
Department of Oceanography 
University of Washington 
Seattle. W A 98105 

Dr. Patrick L. Parker 
International Decade for Ocean 
Exploration, Room 710 
National Science Foundation 
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Washington, DC 20550 

Dr. Bobby J. Presley 
Department of Oceanography 
Texas A & M University 
College Station, TX 77843 

Dr. Charles Culberson 
School of Oceanography 
Oregon State University 
Corvallis, OR 97331 

Dr. Francis A. Richards, 

Discussion Leader, 
Impact of Life Processes on the 

Chemistry of the Oceans 
Department of Oceanography 
University of Washington 
Seattle, WA 98105 

Dr. William M. Sackett 
Department of Oceanography 
Texas A & M University 
College Station, TX 77843 

Dr. David R. Schink 
Department of Oceanography 
Texas A & M University 
College Station, TX 77843 

Dr. Robert E. Stevenson 
Office of Naval Research 
Scripps Institution of Oceanography 
LaJolla, CA 92037 

Dr. Eugene D. Traganza 
Department of Oceanography 
Naval Postgraduate School 
Monterey, CA 93940 

Dr. Karl K. Turekian 

Department of Geology and Geophysics 

Yale University 

New Haven, CT 06520