DEPARTMENT OF TERRESTRIAL MAGNETISM J. A. Fleming, Director Scientific Results of Cruise VII of the CarNeciE during 1928-1929 under Command of Captain J. P. Ault CHEMISTRY — I Chemical Results of the Last Cruise of the Carnegie HERBERT W. GRAHAM ERIK G. MOBERG ~ CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION 562 Gc WASHINGTON, D. C. 1944 914-AA Gino. Atlas Shelf Pt.1 . copy 2 ae h TSLE900 TOEO O MMM A 1OHM/18lN mM ; C 7 yee 2, ‘ See ri , , A : : : 4f ‘ | i Bi cae . t S aay) : 3 us rr 7 : his ait ry ‘ 5 * 7 nie e ie ‘| t n v ee i ' . 7 ay = , " r an : 7 as b = j a 5 7 2 +k | ' 5 4 vy (ViMHez DEPARTMENT OF TERRESTRIAL MAGNETISM J. A. Fleming, Director Scientific Results of Cruise VII of the CarneGiE during 1928-1929 under Command of Captain J. P. Ault CHEMISTRY — I Chemical Results of the Last Cruise of the Carnegie HERBERT W. GRAHAM ERIK G. MOBERG CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION 562 WASHINGTON, D. C. 1944 This book first issued September 1, 1944 PREFACE Of the 110,000 nautical miles planned for the seventh cruise of the nonmagnetic ship Carnegie of the Carnegie Institution of Washington, nearly one-half had been com- pleted on her arrival at Apia, November 28, 1929. The extensive program of observation in terrestrial magnet- ism, terrestrial electricity, chemical oceanography, physical oceanography, marine biology, and marine me- teorology was being carried out in virtually every detail. Practical techniques and instrumental appliances for oceanographic work on a sailing vessel had been most successfully developed by Captain J. P. Ault, master and chief of the scientific personnel, and his colleagues. The high standards established under the energetic and re- sourceful leadership of Dr. Louis A. Bauer and his co- workers were maintained, and the achievements which had marked the previous work of the Carnegie extended. But this cruise was tragically the last of the seven great adventures represented by the world cruises of the vessel. Early in the afternoon of November 29, 1929, while she was inthe harbor at Apia completing the storage of 2000 gallons of gasoline, there was an explosion as a result of which Captain Ault and cabin boy Anthony Kolar lost their lives, five officers and seamen were injured, and the vessel withall her equipment was destroyed. In 376 days at sea nearly 45,000 nautical miles had been covered (see map, p.iv). In addition to the exten- sive magnetic and atmospheric-electric observations, a great number of data and marine collections had been obtained in the field of chemistry, physics, and biology, including bottom samples and depth determinations. These observations were made at 162 stations at an av- erage distance apart of 300 nautical miles. The distri- bution of these stations is shown in the map, which de- lineates also the course followed by the vessel from Washington, May 1, 1928, to Apia, November 28, 1929. At each station, salinities and temperatures were ob- tained at depths of 0, 5, 25, 50, 75, 100, 200, 300, 400, 500, 700, 1000, 1500, etc., meters, down to the bottom or to a maximum of 6000 meters, andcomplete physical and chemical determinations were made. Biological sam- ples to the number of 1014 were obtained both by net and by pump, usually at 0, 50, and 100 meters. Numerous physical and chemical data were obtained at the surface. Sonic depths were determined at 1500 points and bottom samples were obtained at 87 points. Since, in accord- ance with the established policy of the Department of Terrestrial Magnetism, all observational data and ma- terials were forwarded regularly to Washington from each port of call, the records of only one observation were lost with the ship, namely, a depth determination on the short leg between Pago Pago and Apia. The compilations of, and reports on, the scientific results obtained during this last cruise of the Carnegie are being published under the classifications Physical Oceanography, Chemical Oceanography, Meteorology, and Biology, in a series numbered, under each subject, I, Il, and I, etc. A general account of the expedition has been prepared and published by J. Harland Paul, ship’s surgeon and ob- server, under the title The last cruise of the Carnegie, and contains a brief chapter on the previous cruises of the Carnegie, a description of the vessel and her equip- ment, and a full narrative of the cruise (Baltimore, Wil- liams and Wilkins Company, 1932; xiii + 331 pages with 198 illustrations). : iii The preparations for, and the realization of, the pro- gram would have been impossible without the generous cooperation, expert advice, and contributions of special equipment and books received on all sides from inter- ested organizations and investigators both in America and in Europe. Among these, the Carnegie Institution of Washington is indebted to the following: the United States Navy Department, including particularly its Hydrographic Office and Naval Research Laboratory; the Signal Corps and the Air Corps of the War Department; the National Museum, the Bureau of Fisheries, the Weather Bureau, the Coast Guard, and the Coast and Geodetic Survey; the Scripps Institution of Oceanography of the University of California; the Museum of Comparative Zodlogy of Har- vard University; the School of Geography of Clark Uni- versity; the American Radio Relay League; the Geophys- ical Institute, Bergen, Norway; the Marine Biological Association of the United Kingdom, Plymouth, England; the German Atlantic Expedition of the Meteor, Institut fiir Meereskunde, Berlin, Germany; the British Admiral- ty, London, England; the Carlsberg Laboratorium, Bu- reau International pour 1’Exploration de la Mer, and Laboratoire Hydrographique, Copenhagen, Denmark; and many others. Dr. H. U. Sverdrup, now Director of the Scripps Institution of Oceanography of the University of California, at La Jolla, California, who was then a Re- search Associate of the Carnegie Institution of Washing- ton at the Geophysical Institute at Bergen, Norway, was consulting oceanographer and physicist. In summarizing an enterprise such as the magnetic, electric, and oceanographic surveys of the Carnegie and of her predecessor the Galilee, which covered a quar- ter of a century, and which required cooperative effort and unselfish interest on the part of many skilled scien- tists, it is impossible to allocate full and appropriate credit. Captain W.J. Peters laid the broad foundation of the work during the early cruises of both vessels, and Captain J.P. Ault, who had had the good fortune to serve under him, continued and developed that which Captain Peters had so well begun. The original plan of the work was envisioned by L. A. Bauer, the first Director of the Department of Terrestrial Magnetism, Carnegie Institu- tion of Washington; the development of suitable methods and apparatus was the result of the painstaking efforts of his co-workers at Washington. Truly, as was stated by Captain Ault in an address during the commemorative exercises held on board the Carnegie in San Francisco, August 26, 1929, ‘“‘The story of individual endeavor and enterprise, of invention and accomplishment, cannot be told.”’ Dr. H. W. Graham, chemist and biologist on board the Carnegie from August 1929 until the loss of the ves- sel at Apia, Samoa, in November 1929, was assisted in the preparation of the present chemical report by Dr. E. G. Moberg of the Scripps Institution of Oceanography. Dr. Moberg was guest chemist on the Carnegie from August through September 1929. This report on hydrogen ions, phosphate, silicate, and dissolved oxygen of sea water represents the most extensive investigation bearing on such matters ever undertaken in the Pacific Ocean. One hundred and twenty- eight stations were occupied in this Ocean. Considerable research in the chemical field had been undertaken in the Atlantic Ocean on earlier expeditions. Nevertheless, the thirty-four stations occupied by the Carnegie were in (SuoT}BIqiTeo AjIUTTes 10} pautej}qo osTe a1eM satdures JsJEM-IS Ont} @ poyxIeUl suorye3s coe ay} iV) 62-8261 “HIDANUVO AHL AO DA ASINUD ‘SNOILLVLS DIdVYDONVADO PB. 79014 T1I9IWAV? B® 150 QNVINSaH9 Q Ss) SY PREFACE v the central North Atlantic and the Caribbean Sea--regions not previously investigated. The data and their discus- sions are valuable contributions to our knowledge of the chemical conditions in different regions at various levels. It should be noted that this report contains no refer- ences to literature published later than the early part of 1935, at which time the final revision of the manuscript was made. It is realized, however, that more recently the results of a number of qceanographic investigations ‘dealing with both the Atlantic and the Pacific oceans, as well as with adjacent marine regions, have been published. Asa consequence of these recent investigations it is possible that some of the generalizations or conclu- sions based on the Carnegie and earlier data will need to be modified, but it is felt that the results of the observa- tions and analyses made bythe Carnegie are reliable and comparable with those subsequently reported. The present volume is the tenth in the series ‘‘Sci- entific results of cruise VI of the Carnegie during 1928- 1929 under command of Captain J. P. Ault.’ J. A. Fleming Director, Department of Terrestrial Magnetism eer pay ts ab ikke Ric ed Fa ara Mri oh Meee 4S Wi) at) Se CONTENTS Page Page Scope and Methods of the Chemical Investigations ..... 1 | The Distribution of Hydrogen Ions inthe Sea ....... 25 INtroduckionwewewweciece cede cided sechaucmaisd oivelieuian 1 Introductions ene cae) ser clase ee ees ne es e eneee 25 Historicalan-w-l cml emetic Morel MMs) uot met asin 1 CarnegieSections: 2003/02). nino io en ee ee 25 Methods ............. pee eee eee eee 2 WVerticalsDistributiony -y-eseieio oe ieee 27 Presentation of Data ....................4.- 3 RegionalsDistributionsy eee eee 28 Carnegie Sections: Geographic Positions and Hydrographic Conditions ................ 4 The Distribution of Oxygen in the Pacific Ocean ..... 31 The Distribution of Phosphate inthe Sea .......... 7 Introduction PaaS GURU Papa Ted PETE NIT GR EY ee 31 . WerticaléDistribution ts sict--i-i ene celine 31 HLECEOGEION 9 2.0 21918 6\e 9 G19 Bono 96 Bat bar aco d BushnelliSectionsee crs cee cta ua wae eer 33 Mertical Distribution 9-040 0 G0 6100-0 Gio olold arbi. b Oe if Hannibattendibioncerisectiona ane 34 Recional Distribution) oy cas ose 10 Regional Distribution ................000e 34 Regional Distribution at Various Levels ........ 12 Comparison of the Oxygen Content of the Atlantic The Distribution of Silicate inthe Sea............ 21 Be ee Oceans tor aaicicienais ieee. a6 Introduction yeesien meet -w el -ehh eam ictsknn-b iloesices aL Literature Citedsaniaiicns mo ywivssecteisre. sane 6 cee enol 37 Historicaler ore ie een eed oe eh ere ee heres eee 21 Garnepie Data ys oA ero ene lo oie eee 22 MYouresiC WA C23 ya ascsnet cucu cecil cuencr or cieaetel cate 41 VerticallDistributiong aici uemensael oes 22 ingalonell DIG sooo bo goon oe deoe dees 23 INGER 66 bo Foc on Ho DO Ook o OBO OOO So OO do Ga Oo 57 vii SCOPE AND METHODS OF THE CHEMICAL INVESTIGATIONS INTRODUCTION The chemical program of the Carnegie was organized primarily with a view of gaining information concerning the nature of the biological environment in the regions traversed, although some of the chemical data obtained . can be used as indicators of water movements. The chemical constituents determined include hydrogen ions, phosphate, silicate, and dissolved oxygen. Salinities were also determined but, since these were used princi- pally for the study of the physical properties of the water, the discussion of them has been included in an- other report. It has long been known that the major constituents of the dissolved salt in sea water occur in constant pro- portion, and that their quantities may be computed from the salinity or from one of its components--the chloride for example. Many of the minor constituents, especial- ly those involved in biological activities, do not occur in constant proportion to the total salt. and their concen- tration, as in the case of phosphate, may vary by several hundred per cent. Among the substances that play an important role in the metabolic cycle of the sea are nitrates, phosphates, silicates, carbon dioxide, and oxygen. The first four are extracted from the water by plants and liberated in the final decomposition of organ- ic remains. Carbon dioxide is absorbed by plants and oxygen is liberated during photosynthesis whereas the reverse occurs during the respiration of plants and ani- mals. Because of their intimate relation to the life in the sea, and because of the great variability in their quantities, it is essential to determine these substances in various localities and at various depths in order to obtain an adequate picture of the biological environment in any part of the sea. Aside from their importance in piological studies and as indicators of water movements and the origin of water masses, some of the substances determined as- sume a prominent part in geological processes taking place on the sea bottom. For example, silitate relation- ships are involved in the deposition of diatom shells; and pH relationships are involved in the solubility of calcium carbonate in sea water. HISTORICAL Prior to the last cruise of the Carnegie several of the chemical substances concerned with the growth of organisms had been investigated in various parts of the Atlantic, but for the Pacific there was little information available. This was particularly true for the open Pacific for which information was almost entirely lacking. The earliest records of any chemical investigations in the Pacific are those of the Challenger expedition in 1873 to 1876 (Dittmar, 1884). The reports of this expedition are classics in the pioneer study of the chemistry of sea water, as well as of other phases of oceanography, but its work was concerned chiefly with the major saline components of sea water. Dissolved oxygen was deter- mined on a few isolated water samples but the results are not adequate for any general conclusions. The Planet (Brennecke, 1909) in 1906 to 1907 made some chemical investigations of the water below the surface between New Guinea and Hong Kong. A.G. Mayor (1919, 1922) determined the hydrogen-ion concentration of the surface water between San Francisco and the Hawaiian and the Samoan islands. The Dana (Schmidt, 1925, 1929) determined the dissolved oxygen at various depths in the Gulf of Panama in 1922. Ito (1928) in 1926 de- termined the hydrogen-ion concentration of water from various levels between New Guinea and Japan. In cer- tain coastal areas more complete investigations had been carried out: for example, in the Strait of Georgia by the Pacific Biological Station of the Biological Board of Canada; in the Puget Sound region by the University of Washington; along the coast of southern California by the Scripps Institution of Oceanography of the Universi- ty of California; and off Monterey cooperatively by the Hopkins Marine Station of Stanford University, the Mu- seum of Comparative Zoology of Harvard University, the Scripps Institution of Oceanography, and the Cali- fornia Division of Fish and Game. Most of these local- ities cannot be considered as representing the open Pa- cific, however, and the chemical conditions in virtually the whole of this ocean were practically unknown until investigated by the Carnegie. Subsequent to the Carnegie’s cruise, further work has been carried out in the coastal areas mentioned by the Japanese in the waters adjacent to Japan, and by the Great Barrier Reef expedition in the Great Barrier Reef region of Australia. The following expeditions ana institutions have investigated certain chemical condi- tions in the open Pacific: the Willebrord Snellius expe- dition in the Dutch East Indies; the Dana expedition from Panama to the East Indies; the Japanese training ship, the Sintoku Maru, from Kobe to San Diego; the University of Washington in the Gulf of Alaska and, in cooperation with the United States Navy, in the Bering Sea; and the Scripps Institution of Oceanography in co- operation with the United States Navy off the coast of Central America and from the Aleutian Islands to the Hawaiian Islands. To the results of most of these in- vestigations reference will be made in the Carnegie chemistry reports. The Carnegie’s investigations in the Pacific are by far the most extensive ever undertaken in this ocean. One hundred and twenty-eight stations were occupied and samples for chemical analyses were taken from about twenty levels at each station, extending from the surface usually to several thousand meters. At nearly all the stations phosphate and hydrogen ions were deter- mined and at the last thirty-three stations also silicate and dissolved oxygen. As a result, a fairly complete picture was obtained of the distribution, vertical and horizontal, of plant nutrients in a large part of the North Pacific as well as in the tropical and southeastern South 2 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE Pacific, and of the oxygen content of the surface and the subsurface water of a large part of the open Pa- cific. In the Atlantic the Carnegie occupied only thirty- four stations. Hydrogen ions and phosphates were de~ termined at various levels at all stations and dissolved oxygen at two stations. Although the data obtained are not extensive when compared with those obtained in the Pacific, they constitute an important contribution to our knowledge of the chemical conditions in regions not pre- viously investigated, namely, the central North Atlantic and the Caribbean Sea. These data became particularly interesting when compared with those obtained by others in both the North and South Atlantic. On board the Carnegie, H. R. Seiwell had charge of the chemical investigations in the Atlantic and from Panama to Samoa in the Pacific (stations 1 to 93); J. H. Paul from this point to Yokohama and thence to San Francisco (stations 94 to 129); and H. W. Graham from San Francisco to the termination of the cruise at Samoa (stations 130 to 162). Between San Francisco and Hono- lulu, E. G. Moberg of the Scripps Institution of Oceanog- raphy, who was a guest investigator on board, made some of the analyses, especially of oxygen. METHODS Phosphate For the determination of phosphate, use was made of the colorimetric method of Denigés (1920, 1921) as adapted for sea water by Atkins (1923a, 1925). This method depends on the formation of an intense blue, on the addition of certain reagents to a solution containing phosphate, the intensity of the color being in direct re- lation to the quantity of dissolved phosphate. To 100 ml of the sample to be analyzed, were added 1 ml of a so- lution consisting of one part of 10 per cent ammonium molybdate and three parts of 50 per cent (by volume) sulphuric acid, and one or two drops of stannous chlo- ride solution freshly prepared from 0.1 gm of tin dis- solved in 2 ml of hydrochloric acid, in the presence of a small quantity of copper sulphate, and made up to 10 ml with distilled water. The blue color appearing in the sample was matched against that of a standard phos- phate solution similarly treated. For this comparison the sample and standard were placed in glass tubes about 300 mm long and about 25 mm in diameter and graduated in 125 units. These tubes were viewed in a colorimeter constructed to throw diffused light through the columns of liquid when standing in a vertical posi- tion and the levels of the liquids in the tubes were ad- justed until both showed the same intensity of the blue color. By using appropriate standards, the difference in the scale readings of the two tubes was kept to within twenty-five scale divisions and usually to much less. The working standards used were made up from a stock solution of potassium dihydrogen phosphate pre- served with toluene. A supply of this solution, which was thought sufficient to last until the Carnegie’s ar- rival in a home port, was prepared before the start of the cruise. This supply was almost exhausted on arriv- al in Japan (station 112), however, where a temporary standard was made up, calibrated with the old, and used for stations 113 to 129. A fresh standard, prepared at the Scripps Institution of Oceanography by Moberg, was used from San Francisco until the end of the cruise (stations 130 to 162). The old standards were checked against this standard and were found to have suffered no deterioration. Those who are familiar with this method will real- ize that the accuracy of the results, as expressed inper cent, decreases with decrease in concentration of phos- phate in the samples analyzed and that values of 5mg PO, per cubic meter or less should be regarded as indicat- ing merely the order of magnitude. For ‘‘salt error’’ ho correction was applied, and consequently our results are comparable with nearly ail the results of phosphate studies of sea water reported before 1930. The phosphate values are expressed as milligrams of POqg per cubic meter, because at the time the data were computed and tabulated this was the most common- ly used method. Many of the earlier data found in the literature are given as P905, whereas many of those published later are expressed as P or, more recently, as milligram atoms per kilogram or cubic meter. Silicate Silicate was determined by the method of Dienert and Wandenbulcke (1923) as modified by Atkins (1923a). This is a colorimetric method, similar to that used for phosphate. On the addition of certain reagents to a sil- icate solution, a yellow color like that of a picric acid solution is developed. In making the determination, 2 ml of a 10 per cent solution of ammonium molybdate and 6 drops of a 50 per cent (by volume) solution of sulphuric acid were added to a 100 ml sample of sea water. In the same colorimeter used for the phosphate determination, the sample thus treated was compared with a picric acid standard of a concentration such that the scale readings of the two tubes differed by less than 25 units. The standards were prepared as directed by King and Lucas (1928), who found that a solution of 25.6 mg of dry picric acid per liter has a color correspond- ing to that of a silicate solution equivalent to 50 mg SiOg per liter. Samples for the determination of silicate were drawn from the Nansen bottles into “‘citrate of magne- sia’’ bottles and analyzed the following day. Experi- ments carried out at the Scripps Institution of Oceanog- raphy have shown that sea water may be stored for at least this long in bottles of this type, if well seasoned, without undergoing any measurable increase in the sili- cate content. In order to insure that the bottles used on the Carnegie would not give off silicate to the water, they were filled with sea water and left standing for several weeks. Nevertheless, the water stored in a few of these bottles consistently gave results that obviously were too high. These bottles were finally discarded and the results obtained from water stored in them have been marked ‘‘rejected’’ in the tables and have not been included in the graphs. The results of silicate determinations are expressed as mg SiOg per cubic meter and, as in the case of phos- phate, correction for salt error has not been made. SCOPE AND METHODS OF THE CHEMICAL INVESTIGATIONS 3 Oxygen Dissolved oxygen was determined according to the method of Winkler (1888). The water to be analyzed was drawn from Nansen bottles (Oceanogr. 1-A, p. 3)! through a glass tube into green glass, patent-stoppered bottles having a capacity of approximately 100ml and calibrated by weighing distilled water to 0.1 gram. When drawing a sample, enough water was allowed to overflow to thor- oughly flush out any air-contaminated water. As soon as the bottle was filled with the sample, manganous chlo- ride and a sodium hydroxide-potassium iodide mixture was added. When the resulting precipitate had settled, hydrochloric acid was added. The samples were titrated within a few hours after collecting. The N/100 thiosul- phate solution used for the titration was standardized against N/100 potassium dichromate solution at every second oceanographic station, that is, every four days. The burette was read to 0.05 ml and the authors believe that the results are accurate to about 0.03 ml per liter. The results are expressed in milliliters per liter and in percentage of saturation. In computing the latter, the saturation values given by Jacobsen (1905) were used. His values are slightly below those of Fox (1909), and Whipple and Whipple (1911). For temperatures higher than those included in Jacobsen’s table (0° to 25°), the sat- uration values were obtained by extrapolation and by com- parison with the tablesof Fox and Whipple and Whipple. Hydrogen-ion Concentration The hydrogen-ion concentration was determined colorimetrically by means of a double-wedge compara- tor similar to one used at the Scripps Institution of Oceanography for a number of years (Moberg, 1926a), The comparator consists essentially of a rectangular glass box divided diagonally by a vertical glass partition into two wedge-shaped compartments, the dimensions being approximately those given by Barnett and Barnett (1920), namely, 35 cm long and 1.5 cm wide. In making a determination, one of the compartments is filled with an acid-indicator solution and the other with an alkaline solution of the same indicator. When viewed horizontal- ly, the comparator then presents the entire color range of the indicator, with the center representing the hydro- gen-ion concentration of the half-transformation point of of the indicator. A scale attached to the comparator and graduated into one hundred divisions thus gives the per- centage of transformation or apparent dissociation of the indicator. From the scale reading and the indicator constant, the corresponding degree of indicator trans- formation and hence the pH may be computed according to the following equation: x LS Ie reas where pK is the negative logarithm of indicator constant and X is the scale reading. After the addition of indicator to give the same con- centration as in the wedges, the sample to be analyzed is placed in a small glass box having the same liquid diameter as the total of the two wedges. This box is placed above the large box, which is moved until! the colors in the two match, and then the scale reading is taken. Both boxes are contained in a light-proof hous- ing, and artificial light is used for illumination. The instrument used on the Carnegie, with special modifica- tions required for use at sea, was designed by R. H. Seiwell. Cresol red was used as indicator and the value 8.14 was used for pK. This value previously had been determined by Moberg and agrees well with that ob- tained by Barnett and Barnett (1921), namely, 8.13. All the pH readings were corrected for salt according to Ramage and Miller (1925), the correction -0.27 being used for all Carnegie samples. The determinations of pH were made within a few hours after collecting the samples. Since the cruise of the Carnegie, Buch (1929) has shown that the pH of sea water changes slightly with the temperature, and that there is a similar change in the indicator constant. In the case of the Carnegie data, corrections for the temperature effect were not made. This, however, makes them comparable with most of the data previously published and, becduse the temper- ature values are available, corrections may be applied when desired. PRESENTATION OF DATA The results of the chemical investigations carried out by the Carnegie, together with those of the physical investigations, are presented in table 2 (I-B, pp. 183-257): and graphs 14 to 92 (I-B, pp. 16-55). The vertical and horizontal distribution of the chemical constituents are further shown by sections constructed along the path of the cruise. These correspond to the sixteen sections prepared by Sverdrup (I-B) to illustrate the distribution of tem- perature, salinity, anddensity. A chart showing the geo- graphic positions of the sections is given in figure C1. Frequent reference to this chart, which shows the various stations included in each section, will be necessary for a clear understanding of the discussions to follow. The exact positions of these stations can be obtained from the tables and graphs previously referred to. In the discus- sions of the chemical data, each constituent is taken up 1Qceanography I-A and I-B, volumes of the same series as the present volume, by H. U. Sverdrup, F. M. Soule, J. A. Fleming, and C. C. Ennis (1944), hereafter will be referred to in this report as I-A and I-B. separately and in the following order: phosphate, sili- cate, hydrogen-ion concentration, and oxygen. For each chemical constituent, a brief description of its distribution along the various sections is given at the beginning of the discussion. These descriptions fol- low, in general, a discussion of the vertical distribution of the substance in question, the conditions being dis- cussed in order from the surface downward. In examin- ing the sections, it will be noted that the vertical distri- bution of the chemical substances usually follows that of the physical conditions, that is, certain more or less distinct layers or zones can be recognized. The zones included in the discussions are as follows. 1. The convection or surface layer, in which the conditions are relatively uniform with respect to depth because of mixing of the water caused by temperature changes, winds,and other agencies. This layer is usual- ly less than 100 meters in thickness. 2. The transition zone or discontinuity layer, in which there is a rapid change from conditions prevailing in the convection layer to those characteristic of deep water. 4 ; CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE 3. Zones 1 and 2 correspond approximately to what Defant (1928) calls the troposphere, the stratum in which there is an active circulation with relatively large vari- ations in temperature and salinity. Its lower limit cor- responds, according to Sverdrup (I-A, p. 83), to the 10° isotherm. In the Pacific this is found at 500 to 650 me- ters below the surface. 4. The layer between the troposphere and the sea bottom, Defant designates as the stratosphere. Here the temperature and salinity changes are relatively small and the water movements are slow. Since the water layers enumerated above are based on the distribution of the physical conditions, and since CARNEGIE SECTIONS: Atlantic Ocean Section 1 (Stations 24 to 13).--Thisisa moreor less north and south section through the North Atlantic from the Grand Banks of Newfoundland to latitude 8° north. Station 13 is located on the Grand Banks, stations 14 to 16 are in the Western Atlantic Basin, stations 17 and 18 on the Atlantic Ridge, and stations 19 to 24 in the east- ern basin. The center of this section is in the Sargasso Sea which is characterized by warm water of high salin- ity. This is centered at stations 18 and 19. To the north, at station 15, there is a convergence of the cold water of the Grand Banks and the warm Atlantic water. This is shown by the temperature and salinity charts to a depth of 1500 meters. The stations south of the Sargasso Sea are in the North Equatorial Drift. The Intermediate Antarctic Current from the south comes in at 700 me- ters and extends as far north as station 20. The convec- tion layer is about 50 meters thick in the central part of the section and about 25 meters thick elsewhere. Section II (Stations 34 to 25).--This section runs approximately east and west in the tropical North Atlan- tic along the parallel of about 12° north from Panama to 37° west longitude. Stations 34 to 31 are in the Carib- bean Sea, stations 30 to 28 are in the western basin of the Atlantic, station 27 is on the Atlantic Ridge, and sta- tions 25 and 26 are in the eastern basin. The stations in the eastern part of this section are in the North Equato- rial Drift. Those in the western part are in the continu- ation of this drift into the Caribbean. In the salinity chart the Intermediate Antarctic Current is clearly seen coming in at the south at 700 meters and extending into the Caribbean beyond station 31. The convection zone throughout this section is about 25 meters thick. Miscellaneous Atlantic Stations.--Stations 1 to 12 have not been utilized in the construction of vertical sections. Stations 1 to 6 were occupied at the beginning of the cruise when the apparatus and technique were be- ing perfected so that the results at these stations may not be so accurate as at the later stations. ‘The stations are located between the United States, the British Isles, Iceland, and Newfoundland. Pacific Ocean Section III_(Stations 60 to 72 and 40 to 37).--This section lies in the southeastern Pacific. It begins at ap- proximately latitude 40° south and longitude 100° west and runs north-northeast to the coast of Peru at latitude 17° south whence it continues northward to the Gulf of the latter do not always correspond to the distribution of chemical substances, the names of the layers are not always used in their strict physical sense but often to designate only the distribution of the chemical sub- stances. The distribution of these, as will be shown later, is the result not only of physical forces but of bi- ological agencies as well. A brief description of the geographic sections, to- gether with some of the outstanding hydrographic condi- tions encountered, including the thickness of the convec- tion layer as determined by the depth to which uniform physical conditions were found, follows. GEOGRAPHIC POSITIONS AND HYDROGRAPHIC CONDITIONS Panama. Stations 60 to 65, south of 30° south, are.ina branch of the South Pacific East Drift whichis anappre- ciable current to a depth of 300 meters. Stations 66 to 72, between latitudes 30° and 10° south, are in the northward-flowing Peruvian or Humboldt Current. Sta- tions 39 to 37 are included in an anticyclonic movement in the Gulf of Panama. Stations 67 to 72 are ina region off the coast of Peru where upwelling occurs in the up- per 300 meters. The intermediate water off the South American coast flows westward between 600 and 700 meters. In this section the thickness of the convection layer is variable, ranging from a few to 40 meters. Stations 35 and 36.--Stations 35 and 36 in the Cen- tral American Bight were not included in any section. They are situated in the same latitude as that part of Section III which lies between stations 37 and 39 but are closer inland than the latter stations. Section IV. (Stations 51 to 45).--This section is also in the southeastern Pacific, approximately north and south from latitude 29° south to latitude 5° south and be- tween longitudes 115° and 105° west. In the northern part of the section the currents are westerly, in the southern part they are very indefinite with a possible easterly movement. The convection layer is somewhat thicker than in the last section. At station 48 it is 80 meters, at station 45 it exceeds 60 meters, but at station 51 it is less than 25 meters. Section V (Stations 162 to 148 and 134 to 130).--This section runs northeastward from the Samoan Islands (latitude 14° south, longitude 168° west) to San Francis- co (latitude 37° north). It cuts through several current systems. To the extreme northeast is the California Current, with upwelling within the upper 400 meters, off the coast of California. Stations 150 to 151 are in the westward-flowing North Equatorial Drift. Station 153 is in the most active part of the Equatorial Countercurrent, which is a swift current but extends only to a depth of 200 meters. Stations 154 to 156 are south of the most active part of this current but the water movement at these stations also is mostly easterly. South of the equa- tor the currents are westerly, stations 157 to 159 being in the strongest part of the South Equatorial Drift. In the equatorial currents there are irregular vertical water movements. Within the countercurrent there isa strong descending motion and at its borders, i.e., at the inner borders of the North and South Equatorial drifts, there are strong ascending movements, the more pro- nounced of these being in the North Equatorial Drift. The convection layer is about 50 meters thick from sta- tions 130 to 149 but decreases to less than 10 meters at SCOPE AND METHODS OF CHEMICAL INVESTIGATIONS 5 station 151. South of this it increases more or less regularly, reaching 100 meters at station 160. Section VI (Stations 130 to 125).--This section is in the northeastern Pacific and runs from San Francisco northwestward to a point south of the Gulf of Alaska (latitude 52° north, longitude 151° west). It lies in the eastern end of the North Pacific West Wind Drift and its south-flowing continuation, the California Current; both of which are noticeable to a depth of 400 meters. Sta- tions 129 and 130 are in the region of the coast of Cali- fornia where upwelling occurs above 400 meters. The convection layer is thin, reaching a depth greater than 50 meters only at station 129. Section VII (Stations 139 to 143).--This is a more or less north and south section in the central North Pa- cific approximately along the meridian of 160° west and extending from the Hawaiian Islands (latitude 22° north) to about latitude 34° north. In this section the currents are weak, being mostly easterly in the northern part, whereas in the southern part they are westerly. The convection layer is generally about 50 meters thick but varies from 40 meters at station 143 to 70 meters at station 140. Section VIII (Stations 94 to 104).--This section lies in the tropical western Pacific, running from the Samo- an Islands (latitude 13° south, longitude 172° west) north and west to station 104 (latitude 20° 12’ north, longitude 161° 19’ east). This is a section obliquely across the equatorial currents in the western Pacific similar to Section V in the central Pacific. Station 99 is in the center of the eastward-flowing Equatorial Countercur- rent which reaches a depth of 300 meters. To the north and south of this the water in the equatorial currents is moving in the opposite direction. As in Section V, there are vertical water movements descending in the counter- current and ascending at its borders. The convection layer is at least 250 meters thick at the most north- western station, station 104, but narrows to 100 meters at station 99. At station 98, near the equator, it is greater, approximately 150 meters, whereas south of the equator it is about 50 meters. Thus it will be seen that in the equatorial region this section differs consid- erably from Section V where the convection layer was extremely thin. Section IX (Stations 107 to 120).--This section runs from Guam (latitude 14° north, longitude 146° east) north to station 113 near Yokohama (latitude 35° north). From here it continues northeast to station 120 (latitude 47° 02’ north, longitude 166° 20’ east). Stations 107 and 108 in the southern part of the section are within the westerly-moving North Equatorial Drift, but farther north, at stations 109 to 111, there is a weak flow of water eastward. Stations 112 and 113 are in the Kuro- shio, a strong current of warm water flowing northward along the east coast of Japan. Stations 114 and 115 are located in the region where the Kuroshio and a south- flowing current of cold water, the Oyashio, meet, thus causing irregular currents. Stations 116 to 120 are in an easterly current of cold water formed partly by the turning eastward of water from the Oyashio and partly by water flowing out from the Bering Sea. -Sverdrup states (1931) that the source of the intermediate water of the North Pacific, which circulates clockwise like the water in the troposphere, is near stations 115 and 116, where the two above-mentioned currents con- verge. The convection layer to the south of station 112 is 40. to 50 meters thick, but to the north of station 112, it is less than 10 meters thick. Section X (Stations 51 to 52 and 55 to 60).--This sec- tion, in the southeastern Pacific, runs southeastward from about latitude 29° south and longitude 115° west, to latitude 40° south and longitude 98° west. In the tropo- sphere the currents run mostly to the southeast. The southern end of the section is in a part of the South Pa- cific East Drift. The convection layer is thin, exceeding 30 meters only at stations 55, 56, and 57. Stations 53 and 54.--Stations 53 and 54 are not suf- ficiently in line with other stations to be included in Sec- tion X. They lie to the north of station 56 and east of station 51, south of Easter Island. At stations 53 and 54 the convection layer is thin as at most of the stations in Section X. . Section XI (Stations 93 to 71).--This section runs practically east and west between latitudes 18° and 10° south, from the Samoan Islands (longitude 168° west) to Callao, Peru (longitude 78° west). The stations to the extreme east are in the Peruvian Current and the region of upwelling along the Peruvian coast. The general movement of the water, however, throughout the upper layers of this section is westward. From the coast to longitude 120° west (stations 71 to 80) divergent cur- rents are found to a depth of 100 meters, owing to as- cending motion in the region to the southwest of the Ga- lapagos Islands. Below a depth of 200 meters water from the northwest appears to flow toward this region. In the western part of the section between longitudes 120° and 170° west (stations 81 to 93) thecurrents have a considerable component from the south to a depth of 200 meters. The northward flow of water toward the equator is probably intermittent, thus causing vertical movements that may bring subsurface water to the sur- face. The convection layer is very thin off the South American coast, mostly less than 20 meters thick. It increases westward, reaching lower than 50 meters at several stations. Section XII (Stations 45 to 40).--This section lies in the equatorial southeastern Pacific, and extends approx- imately along the parallel of 2° south from longitude 105° west to the South American coast. The currents are weak and indefinite and the stations are in the area of low temperature which stretches westward from the coast of South America. The convection layer is thin at the coast but increases westward to almost 60 meters deep at the westernmost stations. Section XIII (Stations 107 to 101).--This section is in the tropical western Pacific. It runs eastward from Guam (latitude 14° north, longitude 146° east) to station 101 at latitude 13° 23’ north, longitude 177° 27’ east, forming a regular curve to the north with station 104 at latitude 20° 12’ north, longitude 161° 19’ east. This cur- vature toward the north decides the characteristic verti- cal distribution which appears in the central part of the section. The surface currents in this section are west- erly except at station 104 where, in the upper 50 meters, there is probably an easterly movement. The convection layer is at least 50 meters thick at all stations and ap- proaches 100 meters at some stations. Section XIV (Stations 140 to 130).--This section ex- tends from the Hawaiian Islands to San Francisco. Sta- tions 130 to 134 are included also in Section V, under which they were discussed. Stations southwest of station 134 are in aregion of weak and irregular currents flowing 6 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE mostlyfrom the north. From stations 138 to 140 there is a strong surface current toward the west, but this dimin- ishes rapidly belowthe surface. The convection layer is about 50 meters thickin the northeastern part of the sec- tion, but less than 40 meters in the southwestern part. Section XV_ (Stations 142 to 146).--This is an east- west section in the central North Pacific between longi- tudes 161° and 141° west at about latitude 33° north. The currents in this section are somewhat indefinite but are chiefly in an easterly direction with a possible com- ponent to the south. The convection layer is less than 40 meters in depth. Section XVI (Stations 118 to 125).--This section ex- tends in an east-northeasterly direction across the northern part of the North Pacific from station 118 (lat- itude 42° 29’ north, longitude 155° 24’ east) east of northern Japan to station 125 (latitude 51° 58’ north, longitude 150° 39’ west) south of the Gulf of Alaska, and extends along the Aleutian Islands from stations 122 to 124. The entire section lies in the northern part of the North Pacific West Wind Drift which is well developed to 500 meters. The convection layer is very thin, most- ly about 10 meters. THE DISTRIBUTION OF PHOSPHATE IN THE SEA INTRODUCTION Phosphate and inorganic nitrogen compounds are regarded by many oceanographers as factors regulating and limiting the production of life in the sea. For ex- ample, in the North Sea, Atkins (1930 and earlier pa- pers), Harvey (1926, 1928a) and Cooper (1933) found that during the summer either the phosphate or the nitrate content may be reduced to a point at which it cannot be detected by exceedingly sensitive methods. On the other hand, Moberg (1928) reports that the water along the coast of Southern California always contains a sufficient quantity of phosphate to support plant growth although the nitrate may be entirely lacking in the upper 15 me- ters or more during several months in the summer. The concentration of both substances in sea water is exceedingly small and varies considerably, not only with the season,but. with depth and locality as well. Because of this variability and because of their importance to the life in the sea, the determination of these substances, has been included in most recent oceanographic pro- grams concerned with the study of biological conditions in the sea. This is especially true for phosphate for which this method is more satisfactory than for nitrates. It is not always practicable to include in the same program the determination of all the plant-nutrient sub- stances that are present in sea water in sufficiently small quantities to be possible limiting factors of the growth of plants. It has been found, however, that as a rule all these substances parallel each other in their distribution. Consequently a reasonably clear picture of the biological fertility of sea water can usually be ob- tained by determining only one of these substances. The parallelism in the distribution of various plant nutrients can readily be understood since Redfield (1934) has pointed out that these substances occur dissolved in sea water in the same proportion as in the whole plank- ton. VERTICAL DISTRIBUTION In the illuminated water layers near the surface where adequate light permits an active growth of phyto- plankton, the phosphate conteni is less than at lower levels. The phosphates and other nutrient ions are taken up from the water in the synthesis of plant sub- stances. This drain on the nutrient ions may continue until their concentration becomes so low that they can no longer be utilized and plant activity is curtailed. If small quantities of nutrients are being supplied from greater depths by convective currents, however, or by decomposition of organic material within the photosyn- thetic zone, a slow growth of plants may occur, regu- lated by the amount of nutrients available. In this way a vegetable population may act to maintain a continuous depletion of nutrients in the upper water layers. This apparently occurs in certain tropical and subtropical latitudes where the additions of nutrients to the sur- face layer are small and where other factors control- ling the growth of plants, such as light and tempera- ture, are favorable. Thus, at many Carnegie stations the surface water contained 5 mg POq per cubic meter or less. Where the physical factors are not so favor- able for plant growth, or where convection or other ver- tical water movements carry larger quantities of nutri- ents to the photic zone (as in high latitudes particularly in the winter), the amount of nutrients brought into the upper layers may exceed that utilized by plants and as a consequence there will be an increase in the quantity of phosphate in these layers. At the Carnegie stations south of the Aleutian Islands, surface water containing more than 100 mg PO4 per cubic meter was found in the summer. . The depth to which photosynthesis takes place varies with the latitude, the season of the year, the turbidity of the water, the density of the plankton population, and probably other factors. In Oslo Fiord, Gaarder and Gran (1927) found that at 10 meters photosynthesis and respiration balanced each other, whereas Marshall and Orr (1927) found this condition at a depth of 20 to 30 me- ters north of Scotland in the summer. In lower latitudes and farther from the coast suitable conditions for photo- synthesis would undoubtedly be found at considerably greater depths. It should be realized, of course, that even at depths where respiration is more rapid than photosynthesis, phosphates and other inorganic sub- stances are consumed by plants. It is possible that all depths at which plants are found in good condition should be included in the photosynthetic zone. According to Steuer (1910) phytoplankton has been found at a depth of 400 meters but it is improbable that active growth oc- curs at this depth. In most localities it is probable that no great quantities of phosphates are consumed below a depth of 75 to 100 meters. The water, however, may be deficient in phosphate to much greater depths. The depth to which very low concentrations of phos- phate occur is greatly influenced by the depth of the convection layer. Throughout the convection layer the concentration of phosphate is more or less uniform, ow- ing to the thorough mixing of the water. If the lower limit of the convection layer is below the photosynthetic zone, uniformly low concentrations of nutrients will ob- tain at greater depths than if it is above this zone. Thus, less than 10 mg POgq per cubic meter were found at many stations in the North Pacific to depths greater than 200 meters. It is probable that this was not owing to active growth at that depth but rather to the unstable condition of the water in the upper 200 or more meters, which permitted a thorough mixing of the water down to these depths. This allowed the plants nearer the surface to maintain low concentrations of nutrients to depths much below the photosynthetic zone. It is also possible that in areas of sinking, water of low phosphate content may be carried to greater depths than otherwise would be the case. 8 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE Extremely low concentrations of phosphate canoccur in the photosynthetic zone or in the convection layer only when there is a marked thermal stratification of the water layers below this zone. Thus, in regions where a layer of water of low phosphate content occurs, there is always a strong density gradient beneath this zone. This prevents any great amount of mixing between the con- vection zone and the layers below and thus isolates the phosphate of lower levels from the photosynthetic zone. In regions where a strong thermocline does not develop, there is never an extreme reduction of the nutrient salts in the surface layers. In the layers of water below the photosynthetic zone phosphate is liberated by the decomposition of organic debris and excretory products of holozoic organisms. In our present state of knowledge of the bacteriology of the sea we are unable to state the nature of all the bac- teriological processes taking place at various depths but, judging from the vertical distribution of chemical substances in the sea, we are forced to conclude that one series of results of the biological processes occurring in the layers beneath the photosynthetic zone is a liber- ation of nutrient salts and carbon dioxide and a con- sumption of oxygen. Thus, the subphotic layers are characterized by high concentrations of phosphate rela- tive to that of the surface layer. In the Pacific thedeep- er water usually contains more than 250 mg PO,q per cubic meter. Assuming there is no horizontal water movement, the quantity of inorganic phosphorus occurring at any given level below the phytosynthetic zone depends on the rate at which it is being produced at that level and on the rate at which it is being transported back to the sur- face layer where the utilization of phosphate is taking place. Both these factors are influenced by the stability of the water column. The rate at which decomposition occurs-in any layer depends, among other things, on the amount of organic matter available. This, in turn, depends on the abun- dance of the plankton and on the rate of fall of the organ- ic debris. As the density of the water increases, the rate of fall decreases, and consequently it may be expect- ed that decomposition is more rapid in the thermocline or the stratosphere than in the convection layer. In sup- port of this we find that below the convection layer or photosynthetic zone there is a rapid increase in the quantity of dissolved phosphate with depth. The rate at which phosphate is returned to the photo- synthetic zone will also depend on the stability of the water since dissolved substances can be transported to any important extent only by the water. The process of dif- fusion of the dissolved substances themselves is too slow to be of any practical significance. There are var- ious forms of vertical water movements. Convection currents are found practically everywhere. They are caused by the settling of small, heavy particles of water that have been cooled by radiation or contact with cold air or have attained a high salinity because of evapora- tion at the surface, and by the corresponding rising of lighter particles. This type of circulation is probably not effective below the thermocline, but in high lati- tudes in the winter the density may become uniform throughout all depths so that convective movements may reach from the surface to the bottom. Another type of vertical circulation is caused by the turbulent character of the movement in horizontal cur- rents. The eddies transport dissolved substances from one layer to another. In the surface layers the eddies in the wind currents are especially effective. The depth to which this effect extends varies with the force of the wind, the latitude, and the density gradient, but only ex- ceptionally reaches below 200 meters. In addition one has to consider the mixing by waves which also takes place near the surface. Vertical components of currents are in some places transporting water from greater depths toward the surface or vice versa. Along the west coast of the Americas and off Africa there is an upwell- ing of water from intermediate depths (300 to 500 me- ters) to the surface. Any type of vertical circulation is effective in re- newing the phosphate content of the photosynthetic zone and reducing that of the lower layers so long as it brings water to the surface layer from the subphotic levels. Thus, we have two opposing phenomena tending to establish the vertical distribution of phosphate in the water column; the liberation of phosphate from sinking organic debris, and transportation of this phosphate to higher levels by vertical circulation. The exact depth at which the greatest amount of phosphate is liberated can- not be stated with any certainty on the basis of present knowledge. One would expect decomposition to be more rapid in warmer water and where the greatest amount of organic material is available, namely, in or immediately below the photosynthetic zone, but at these levels the circulation is stronger than at greater depths and this would tend to prevent the accumulation of phosphate. According to the information obtained by the Carnegie and others, however, it would appear that most of the organic material is decomposed at the lower boundary of, or below, the thermocline. The Carnegie data show that the maximum concen- trations of phosphate and carbon dioxide, as indicated by ' the pH, and a minimum concentration of oxygen occur at a depth varying from 250 to 1500 meters below the surface, depending on the locality. From this level to the bottom the concentrations of phosphate and carbon dioxide decrease with depth, whereas the concentration of oxygen increases. These facts contradict the state- ment often found in the literature, namely, that most of the organic material decomposes at the bottom. It is probable that where the water is sufficiently deep prac- tically all this material has been reduced to inorganic substances long before reaching the bottom. As to whether more decomposition takes place above the level at which the maximum phosphate content and minimum oxygen content are found, it is difficult to say because above this level convective circulation is more effective and it is possible that the accumulation of large quantities of nutrients or a marked reduction in the oxy- gen content is prevented by interchange of water with the surface layer, where nutrients are consumed by the phytoplankton, and oxygen is dissolved from the atmos- phere. In discussing the distribution of phosphate we have designated as the phosphate transition zone the layer of - water below the convection layer, and have defined it as the layer in which the increase in the phosphate content is greater than 0.1 mg PO4g per cubic meter per meter of depth. In this zone the concentration of phosphate in- creases from values near those at the surface to as much as 250 to 300 mg per cubic meter at its lower boundary. Since the rate of increase usually becomes less than 0.1 mg POgq per cubic meter per meter before the maxi- mum quantity is reached, the layer of maximum phosphate DISTRIBUTION OF PHOSPHATE IN THE SEA 9 content is in most cases below the lower limit of the transition zone, that is, it is found in the stratosphere. With respect to the relation of the phosphate transi- tion zone to the density gradient, it is interesting to in- spect figures C2 to C8, which show the close correlation existing between the phosphate and density gradients at seven Carnegie stations representing various localities of the Atlantic and Pacific oceans. Figure C2 represents conditions at station 137 (lati- tude 24° 02’ north, longitude 145° 33’ west). It has been selected as typical of the Pacific for regions in which there is a strong thermal stratification of the water and in which there are no prominent dynamic features. The density curve given in the figure shows a pronounced difference between the lighter water near the surface and the heavy, nearly uniform, water in the stratosphere From the surface to a depth of 200 meters the water is practically depleted of phosphate. In the phosphate tran- sition zone, which extends from 200 to 675 meters, the concentration of phosphate increases to 290 mg POg per cubic meter. At 1000 meters the maximum is attained, with about 300 mg PO, per cubic meter. This occurs at about the depth where the rapid increase in the density of the water ceases. At lower levels the phosphate con- tent diminishes more or less regularly, reaching 225 mg per cubic meter at 4000 meters. The phosphate curve shows no modifications attributable to subsurface currents. When other phosphate curves are referred to the curve for station 137 as a base, the anomalies due to cir- culation can readily be seen. Figure C3 represents the distribution of phosphate at station 17 (latitude 11° 57’ south, longitude 78° 37’ west), off the coast of Peru ina region of upwelling. Here the upper part of the curve is displaced toward the surface. The density curve shows a similar upward displacement. A high concentration of phosphate, as compared with station 137, occurs at the surface, and the surface layer is limited to the upper 20 meters. The transition zone extends to about 80 meters only. Another interesting feature at this station is the nature of the phosphate gradient between 80 and 900 me- ters, where the maximum might be expected (as shown by the dashed line), had all the upper 1000 meters of the curve been displaced. It is probable that the peculiar shape of the curve between 80 and 900 meters is owing to the Antarctic Intermediate Current which occurs here. For reasons which will be discussed later, this water may be expected to contain less phosphate than ordinarily occursas a maximum in this locality. This current also affects the density at these levels, as shown by the curves. Farther south the effects of the Antarctic Current are still more pronounced. At station 60 in latitude 40° 24’ south, longitude 97° 33’ west, (fig. C4), where there is no upwelling, this current is found between 400 and 1500 meters and its phosphate content is about 50 mg PO, per cubic meter less than at station 71. Hereagain there is a remarkable correspondence between the den- sity and phosphate curves. Station 130 in latitude 37° 05’ north, longitude 123° 43’ west (fig. C5), is in the region of the upwelling water off the coast of California. Here the distribution of phosphate corresponds to that in the similar region off the coast of Peru except that above 1000 meters the phosphate content shows no definite effect of an interme- diate current. The maximum shows the same develop- ment as that at station 137 but occurs at 700 meters in- stead of at 1000 meters. Figure C6 shows the distribution of phosphate at one of the most northern stations occupied in the Pacific, namely, station 122 at latitude 46° 16’ north, longitude 174° 03’ east. The phosphate curve for this station re- sembles that at station 137 except that the surface val- ues at station 122 are much higher and the transition zone is considerably nearer the surface than at station 137. The surface value is 130 mg POg per cubic meter and the surface layer is only 20 meters thick. The tran- sition zone extends to only 400 meters. Below this is the usual decrease in phosphate with increasing depth. The high surface values are undoubtedly attributable partly to the inflow of water rich in phosphate from the Bering Sea and partly to the fact that at this latitude the density gradient is considerably reduced during the win- ter, thus permitting a considerable amount of mixing among the various water strata. It may be noted that even for July, when this station was occupied, the density gradient is not well developed. This, too, may be owing in part to the relatively cold water entering from the Bering Sea. In the Atlantic, observations to great depths were obtained at a station located at a still higher latitude than station 122. Station 10 (fig. C7) is southeast of Greenland at latitude 50° 19’ north, longitude 34° 15’ west. Although these observations were made in July, both the phosphate and density gradients show the effect of vertical mixing during the previous winter. Below about 100 meters the distribution of phosphate is practi- cally uniform, as is the density, but above this depth the curves show a Slight reduction in phosphate as well as in density. The low phosphate content in the Atlantic deep water as compared with that in the Pacific will be discussed later under ‘‘Regional distribution,’’ (pp. 16- 17). At station 29 (fig. C8), located in the western trough of the Atlantic at latitude 13° 16’ north, longitude 52° 13’ west, the maximum quantity of phosphate which occurred at about 800 meters is much higher than would be expect- ed from the quantity at lower levels. Since the Antarctic Intermediate Current centers at about 800 meters, it is fairly certain that the water in this current originally had a high phosphate content although the quantity may have been augmented somewhat during its progress to- ward the north. It is interesting to note that antarctic water, when intruded at this level into the Atlantic, rep- resents a layer of relatively high phosphate content, but when extended into the Pacific, as at stations 70 and 71 (figs. C4 and C3), it represents water low in phosphate relative to the adjacent layers. 10 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE REGIONAL DISTRIBUTION Carnegie Sections Section I, stations 24 to 13: more or less north and south from Grand Banks of Newfoundland to latitude 8° north between longitudes 35° and 50° west.--At all sta- tions except the two most northerly stations, 13 and 14, the phosphate content in the surface layer is relatively low. In the central part of the section, where there isa sinking of warm water of high salinity, the line of 10 mg POq4 per cubic meter is found at a depth of more than 200 meters. In this area the transition zone also is much expanded, the increase in phosphate values with in- crease in depth being very gradual. ‘The maximum of phosphate occurs at 1000 meters and is represented by less than 125 mg POg per cubic meter. To the north and to the south of this area, much higher values occur in the upper layers. To the north, where the water is colder, values above 150 mg PO4 per cubic meter were observed. At station 15, where there is a convergence of cold and warm water (see p. 4), the lines of equal phosphate content are bent downward. In the southern part of the section, high values were observed in the Antarctic Intermediate Current, reaching 275 mg at 7000 meters at station 22. In the stratosphere the phosphate content is somewhat more than 125 mg PO, per cubic meter in the northern part of the section, but decreases to about 100 mg in the central part, and again increases slightly to the south. Section II, stations 34 to 25: approximately east and west in the tropical North Atlantic along the parallel of about 12° north from Fanama to longitude 37° west.-- There is a scarcity of phosphate at the surface through- out the section, water containing less than 10 mg PO4 per cubic meter extending to 50 and 100 meters at all the stations as shown by the 10-mg line. The transition zone is usually in the upper 500 meters in the western and central parts of the section but rises toward the east and at station 25 it is in the upper 200 meters. The max- imum phosphate values occur between 500 and 1000 me- ters and vary from about 125 mg to more than 275 mg POq per cubic meter. In the eastern part of the section high values are found in the Antarctic Intermediate Cur- rent at 700 meters. Two other areas of high phosphate, also due to antarctic water (I-A, pp. 88, 89, 96), occur in the central part of the section. In the stratosphere the phosphate values decrease below the maximum to about 100 mg POg per cubic meter. Section III, stations 60 to 72, 40 to 37: in the south- eastern Pacific, beginning at approximately latitude 40° south, longitude 100° west, extending north-northeast to the coast of Peru at latitude 17° 30’ south, thence north- ward to the Central American Bight.--Phosphate at the surface is nowhere reduced in this section. The surface values between stations 37 and 40 are from 15 to 25 mg POq per cubic meter. From stations 40 to 71 they range between 25 and 50 mg PO4 per cubic meter. At station 70 the concentration of phosphate reaches 103 mg PO4 per cubic meter. South of this it decreases but never reaches 20 mg POg per cubic meter. In the upper 300 meters the phosphate section shows a marked similarity to the temperature section, the line representing 75 mg POgq per cubic meter following the general course of the 15° isotherm. The effect of up- welling, which is shown by the temperature and salinity sections at stations 68 to 70, is quite evident also in the phosphate section where all the lines are raised toward the surface. The Antarctic Current of low salinity entering from the south at about 400 meters is not apparent in the phos- phate section but its effect is easily recognized in the curves showing the vertical distribution of phosphate (I-B, pp. 62-67). From stations 60 to 66 there is a zone of comparatively low phosphate centered at about 400 meters. The phosphate maximum occurs at about 1800 me- ters in the south but gradually rises to about 600 meters in the north. The phosphate content is variable, ranging from 225 to 325 mg POg per cubic meter. The Carnegie observations indicate that the bottom water in this re- gion contains between 200 and 250 mg POg4 per cubic meter. Stations 35 and 36: in the Central American Bight, east of the north end of Section IJI].--The phosphate con- tent of the water at these stations is very similar to that at the stations to the west, or to that of the northernpart of Section III. Section IV, stations 51 to 45: in the southeastern Pacific extending approximately north and south from latitudes 29° to 5° south, between longitudes 115° and 105° west.--In the surface layer the concentration of phosphate is everywhere 10 mg PO, per cubic meter or more. From south of station 46, however, and centering at station 48, the 25-mg POg line extends to almost 300 meters, indicating relatively low values in the upper levels The phosphate transition zone in general follows the thermocline, being found at increasingly low levels toward the south. The tongue of antarctic water from the south, which is shown in the salinity section, is not evident in the phosphate section but is indicated in the station curves of the vertical distribution. The level at which the phosphate maximum occurs, varies between 750 and 1400 meters. The magnitude of the maximum values increases from less than 175 mg at station 50 to more than 225 mg PO4q per cubic meter north of station 47. Section X, stations 51 to 52, 55 to 60: in the south- eastern Pacific extending southeastward from latitude 29° south, longitude 115° west to latitude 40° south, longitude 98° west.--At the surface the phosphate values show a continuous increase from northwest to southeast. Between stations 51 and 57 there is less than 10 mg PO4 per cubic meter, whereas in the southeastern part of the section the phosphate content is greater, being 50 mg per cubic meter at station 60. The layer of maximum phosphate is somewhat indef- inite, the concentration continuing to increase below 2000 meters at stations 55, 58, and 59. Stations 53 and 54: north of Section X, north of sta- tion 56, east of station 51, south of Easter Island.--At these two stations the vertical distribution of phosphate is very similar to that at stations 51 and 52 to the west. The surface values vary from 9 to 13 mg POg per cubic meter. The transition zone extends to 500 meters as at station 51 to the west, rather than to 350 meters as at station 56 to the south, indicating that the change in con- ditions in Section X, which extends from northwest to southeast, from stations 5i to 60, represents a change in a north and south direction rather than in an east and west direction. DISTRIBUTION OF PHOSPHATE IN THE SEA 11 Section XI, stations 93 to 71: practically east and west between latitudes 18° and 10° south, from the Sa- moan Islands (longitude 168° west) to Callao, Peru (lon- gitude 78° west.--In spite of the fact that this entire sec- tion lies in the tropics, there are no extremely low phosphate values. West of station 78 the surface water has a temperature above 25°, yet in that region many surface phosphate values are above 25 mg POg per cubic meter. The highest quantities of phosphate were found toward the east. The phosphate transition layer follows very closely the isotherms of 15° and 20°, and rises to near the sur- face toward the coast, where the richest surface water is found. The intermediate layer of antarctic water is not evident in the phosphate section but appears in the station curves of the vertical distribution. The layer of maximum phosphate lies between 600 and 1500 meters with values between 225 and 325 mg POg per cubic me- ter. The deeper water has a phosphate content of near- ly 225 mg per cubic meter. Section XII, stations 45 to 40: in the equatorial southeastern Pacific, extending approximately along parallel 2° south from longitude 105° west to the South American coast.--This section is another example of an area in the tropics with comparatively large quantities of phosphate at the surface. Although lying very close to the equator, all the surface values were above 25 mg PO4 per cubic meter. This is in accord, however, with the low temperatures observed here. At stations 42 and 43, where the coldest surface water is encountered, the phosphate values are highest, reaching 52 mg per cubic meter at station 43. The transition zone lies very close to the surface, above 200 meters in the western part of the section, and in the upper 100 meters in the eastern part. The line of maximum phosphate occurs between 500 and 1200 me- ters, the quantities at most stations being between 225 and 275 mg PO4 per cubic meter. Section V, stations 162 to 148 and 134 to 130: ex- tends northeastward from the Samoan Islands (latitude 14° south, longitude 168° west) to San Francisco (lati- tude 37° north).--This section demonstrates that the quantity of phosphate at the surface of the sea is not a function of the latitude and that the tropical zone is not necessarily a region of low fertility. It indicates, on the other hand, that the phosphate content of the upper water layers is intimately associated with vertical water movements occurring in the troposphere. Beginning with station 130 at the northern end of this section, we find 36 mg PO, per cubic meter at the surface in a region where there are upwelling of subsur- face water, a strong surface current, and relatively low temperatures. As the distance from the California coast . increases, the phosphate content of the surface water “decreases. Between stations 132 and 150 the phosphate content is extremely low, less than 10 mg per cubic me- ter, not only at the surface but usually to below 100 me- ters. Where these low values occur, there are no prom— inent currents. Continuing southward we find at station 152, in the North Equatorial Current, 20 mg PO4 per cubic meter at the surface, but at stations 153 and 154, in the Equa- torial Countercurrent, the values are again low. Higher values, about 25 mg POgq per cubic meter, are found at stations 155 and 156 which are near the southern border of that current. As previously stated, at the borders of the Equatorial Countercurrent there is probably irregu- lar water movement with vertical components. The relation of the phosphate content of the sea to the hydrographic conditions is demonstrated by the tran- istion zone in this section. For example, at stations 130 and 131 in the region of upwelling near the Califor- nia coast, the increase in the phosphate content below the surface layer is extremely rapid, as is also the case from stations 150 to 156 in the North Equatorial Drift and the Equatorial Countercurrent. Southwest of station 132 and northwest of station 150, the transition zone widens until, at station 134, the changes in the phosphate content are the most gradual. Similarly, southwest from station 154 the change in the phosphate content with depth becomes more gradual, although certain irregularities are encountered. The thermocline shows similar varia- tions with the ‘different regions. The axis of the phosphate maximum lies at about 750 meters from stations 130 to 157, but south of this it gradually descends, reaching 1200 meters at station 162. The maximum phosphate values decrease more or less regularly from 275 mg PO4 per cubic meter in the north- east to less than 225 mg per cubic meter in the south- west. The deeper water contains approximately 200 mg PO,q per cubic meter with slightly higher values toward the equator. Section VII, stations 139 to 143: more or less north and south in the central North Pacific, following approx- imately meridian 160° west from the Hawaiian Islands (latitude 22° north) to about latitude 34° north.--The line representing 10 mg PO4g per cubic meter shows a - marked deficiency of phosphate in the upper layers, the line reaching to a depth of 300 meters at station 140. The maximum phosphate content occurs at from 900 to 1600 meters, with over 300 mg PO4 per cubic meter. Below 3000 meters this concentration is from 225 to 250 mg PO, per cubic meter. Section XIV, stations 140 to 130: from the Hawaiian Islands to San Francisco.--Except at stations 130 and 132 which have already been discussed (Section V), the surface layer is extremely low in phosphate, the 10 mg PO,q per cubic meter line being found at 100 meters at station 133 and then gradually descending, reaching a depth of almost 300 meters at station 140. The transition zone usually extends to about 500 me- ters or more except at stations 130 and 132, where it comes much nearer the surface. The line of maximum phosphate runs for the most part between 500 and 1000 meters, with values between 250 and 325 mg PO, per cubic meter. Below a depth of 3000 meters the concen- tration is approximately 250 mg PO, per cubic meter- Section XV, stations 142 to 146: an east and west section in the central North Pacific, extending approxi- mately along the parallel 33° north between longitude 161° and 141° west.--The surface phosphate values are low, with the 10 mg PO, per cubic meter line running at about 100 meters except at station 146, where it is at 200 meters. The maximum values, ranging from 275 to 300 mg POq per cubic meter, are found at 800 meters at the easternmost station to about 1500 meters at the westernmost station. Below the maximum layer there are from 200 to 250 mg PO, per cubic meter. Section VI, stations 130 to 125: in the northeastern Pacific, extending from San Francisco northwestward to a point south of the Gulf of Alaska (latitude 52° north, longitude 151° west).--In this section, which lies north of longitude 37° north, the phosphate at the surface is above 25 mg PO, per cubic meter at all stations except 12 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE 129. In general, however, the phosphate content in the surface layer increases from southeast to northwest, reaching 125 mg per cubic meter at station 125. The lines of equal phosphate content bend downward from the two ends of the section, reaching their greatest depth at station 128. The line of maximum phosphate follows the same course, running from 350 meters at station 125, to 1350 meters at station 128, and to 750 meters at station 130. The maximum phosphate content ranges from 250 to 300 mg POg per cubic meter and in the deeper water it is 250 mg per cubic meter or slight- ly less. Section VII, stations 94 to 104: in the tropical west- ern Pacific, extending from the Samoan Islands (latitude 13° south, longitude 172° west) north and west to station 104 (latitude 20° north, longitude 161° east).--From stations 94 to 99 the phosphate values at the surface are about 10 mg per cubic meter, but at the other stations (toward the northwest) they are below this value, the 10 mg POgq per cubic meter line running from near the sur- face at station 100 to about 200 meters at station 104. The transition zone in this section shows conditions similar to those found in Section V. In the North Equa- torial Drift, between 100 and 200 meters, conditions are found at station 100 in this section which are similar to those at station 152 in Section V. The maximum values range from 225 and 275 mg POg per cubic meter and oc- cur at depths of from 700 to 1400 meters except at sta- tion 100, where it is at about 2000 meters. In the deep- er water the variation in the phosphate content is great- er than in most other regions, values between 175 and 275 mg POg per cubic meter occurring. Section XIII, stations 107 to 101: in the tropical western Pacific, extending eastward from Guam (lati- tude 14° north, longitude 146° east) to station 101 (lati- 13° 23’ north, longitude 177° 27’ east).--At all the sta- tions the phosphate content of the surface water is very low, the line representing 10 mg per cubic meter run- ning at about 200 meters except at station 107, where it is found at 100 meters. Relatively far from the surface and from each end of of the section the lines of equal phosphate content curve downward, reaching the lowest depth at station 104. The layer of maximum phosphate is at about 1000 meters ex- cept at station 101 where it is at 650 meters. The max- imum values range between 225 and 275 mg POg per cu- bic meter. No observations extend to 3000 meters but at 2500 meters the phosphate is about 225 mg per cubic meter. Section IX, stations 107 to 120: from Guam (latitude 14° north, longitude 146° east) north to station 113 near Yokohama (latitude 35° north), thence northeast to sta- tion 120 (latitude 47° 02’ north, longitude 166° 20’ east). --In this section the hydrographic conditions are com- plex and the phosphate content at most depths is varia- ble. From the southernmost station, 107, to station 113 the phosphate content in the upper 100 meters or more is less than 10 mg per cubic meter but north of this sec- tion the 10 mg per cubic meter line rises to about 100 meters and finally reaches the surface between stations 117 and 118. North of station 117 the phosphate content at the surface rapidly increases to more than 150 mg ‘PO4 per cubic meter at stations 119 and 120. In the southern half of the section the most rapid in- crease in phosphate with depth begins at about 300 me- ters, but in the northern half it begins immediately at the surface. Between stations 114 and 116 the concentration of phosphate with depth is variable, probably owing to the meeting of water masses of different temperatures. The axis of the maximum phosphate layer lies be- tween 1000 and 1500 meters in the southern half of the section, but at station 113 it rises, reaching 250 meters at station 120. In most of the section the maximum val- ues vary between 200 and 275 mg POgq per cubic meter but are above 275 mg at stations 109, 119, and 120. At greater depths they are between 200 and 250 mg PO4 per cubic meter. Section XVI, stations 118 to 125: extends in aneast- northeasterly direction across the northern part of the North Pacific from station 118 east of northern Japan (latitude 42° 29’ north, longitude 155° 24’ east) to station 125 south of the Gulf of Alaska (latitude 51° 58’ north, longitude 150° 39’ west), along the Aleutian Islands from stations 122 to 124.--Throughout this section there isno definite surface layer and the phosphate content at the surface is more than 125 mg per cubic meter except at station 118, where it is only 90 mg PO4q per cubic me- ter. The center of the maximum phosphate layer is about 500 meters except at station 118, where it is at 1000 meters. The maximum concentration varies between 250 and 300 mg PO4 per cubic meter, which is somewhat higher than in other regions. In the deeper water the quantity is about 250 mg POg4 per cubic meter. REGIONAL DISTRIBUTION OF PHOSPHATE AT VARIOUS LEVELS The regional distribution of phosphate is controlled by the same physical and biological factors that control the vertical distribution. It is probable that in the pho- tosynthetic zone plants which consume phosphate are always present except in high latitudes during the win- ter months. Likewise it is probable that below this zone the proper conditions for the decomposition of organic matter prevail throughout the year and in ail localities, resulting in the release of phosphate and other inorgan- ic nutrient substances. Consequently any differences that may exist in the horizontal distribution of these substances must be caused principally by the circula- tion of the water. Other factors, such as runoff from land and certain biological conditions, should not be lost sight of, but these can be regarded as local or tem- porary features. Consequently, the circulation of the water, vertical and horizontal, is the principal cause of the general differences in the phosphate content of the water in different regions of the oceans. In the subsequent discussion the regional variation in phosphate will be taken up for the following levels: (1) at the surface, (2) in the surface layer and transi- tion zone, and (3) at 2000 meters. Surface The distribution of phosphate at the surface at all Carnegie stations is shown by the chart, figure C9. The relative concentrations of phosphate are indicated by the shading. For regions where the surface water con- tained less than 10 mg PO4q per cubic meter this chart also shows the depth to which these low values extended. DISTRIBUTION OF PHOSPHATE IN THE SEA The chart also indicates the months during which the observations were obtained. It will be noted that, ex- cept in the tropics where there is little range in tem- perature, all the investigations in both hemispheres were carried out in the summer. Atlantic Ocean.--In the Atlantic, north of latitude 36° north, north of station 16, no surface values less than 10 mg PO4 per cubic meter were observed. Throughout this part of the Atlantic there is an active circulation and the thermal stratification is less pro- nounced than farther south. It is interesting to note that at station 2 in May the surface water contained 58 mg PO, per cubic meter whereas in August of the same year at station 15, which is in the same vicinity, only 11 mg PO, per cubic meter were found. This corresponds to the seasonal variation observed by Atkins (1930) in Brit- ish waters. He found that a concentration of phosphate of about 60 mg PO4 per cubic meter in the winter was regularly reduced to practically zero by July to Septem - ber. The low values in summer were attributed to the utilization of phosphate by phytoplankton and to the lack of a renewal from lower levels owing to the stratifica- tion of the water during that season. South of latitude 36° north all the Carnegie stations showed a low phosphate content at the surface and to considerable depths. In the Sargasso Sea, at stations 18 and 19, the water contained less than 10 mg PO4 per cu- bic meter to a depth of 225 meters. In the tropics this dearth of phosphate did not extend to quite such great depths, but occurred consistently. The distribution of phosphate observed in the Sargasso Sea may be attributed to the fact that in this area there is sinking of surface water poor in phosphate (see Wiist, 1928). The low phos- phate content in the tropics must be attributed to the well- developed thermocline and the absence of any complex currents to disturb the thermal stratification of the water. Stations 24 to 13, Section I, were occupied by the Carnegie in August and it is interesting to note that Sei- well and Seiwell (1934) report equally low surface values for February and March at six stations in the western North Atlantic and west of Carnegie Section I. At these stations concentrations of less than 10 mg PO4 per cu- bic meter were observed to even greater depths than at the Carnegie stations. At their station 1222 (latitude SoM 15’ north, longitude 67° 35’ west), such low values were observed to a depth of 470 meters. Pacific Ocean.--For the Pacific the distribution of phosphate at the surface has been summarized in a pre- vious paper by Moberg, Seiwell, Graham, and Paul (1930). The distribution is intimately associated with the current systems of that ocean. At all the stations lying north of latitude 40° north, the phosphate content was markedly high, ranging from about 25 to about 150 mg PO4 per cu- bic meter with the exception of station 117, east of Ja- pan. Between this station and the next station (118) toward the northeast, there was an extremely abrupt in- crease in the phosphate content, surface values at sta- tions 117 and 118 being 3 and 90 mg PO4 per cubic me- ter respectively. From between these two stations to near the Aleutian Islands there is a southerly flowing current which apparently originates in the Bering Sea. Mixing of water to great depths probably takes place dur- ing a considerable part of the year and an abundance of phosphate in the surface water consequently is to be ex- pected. Apparently this phosphate-rich water flows southward until diverted eastward by the North Pacific West Wind Drift (commonly called the Japan Current). 13 This drift carries the phosphate-rich water eastward and then southward by the California Current, which is formed in the area where the West Wind Drift reaches the Aleutian Islands. The highest phosphate content any- where obtained at the surface, 142 mg PO4q per cubic meter, was found at station 119, in latitude 45° 24’ north, longitude 159° 36’ east. From this station the concen- tration steadily diminishes eastward, to 25 mg per cubic meter at station 129. As regards the high phosphate content in this region, the fact must not be overlooked that in latitudes above 40° north there is considerable convective mixing of the water during the winter months, and this, as has been pointed out previously, will in- crease the phosphate content in the surface layer. The Carnegie observations were made in July when one would expect that much of the phosphate brought to the surface in this manner would be consumed were there no other source of supply. : Between latitudes 10° and 40° north, with the excep- tion of a few stations near the coast of California, the phosphate content was extremely low, never exceeding 10 mg per cubic meter and often less than half that amount. These low values in this area extended to con- siderable depths, being found in the upper 100 meters or more at practically all stations with the exception of a few northeast of Japan. The maximum depth to which they extended was 300 meters at station 140. The small quantities of phosphate observed in the North Pacific between latitudes 10° and 40° north, ap- pear to be associated with two hydrographic features of the region. First, there is a steep density gradient re- sulting in a minimum amount of mixing of deep water with the surface water. Second, in this part of the Pa- cific there are no well-developed current systems ex- cept near the coasts of California and Japan. It is prob- able that very little water enters or leaves the area except to a relatively small extent in the two localities mentioned. Thus there appears to be no agency that can materially augment the phosphate content in the surface layer. The relatively high phosphate values obtained off the coast of California in July and September may be at- tributed to the upwelling of subsurface water from inter- mediate depths and possibly also to the transport of phosphate-rich water from the north by the California Current. Matsudaira (1922) reports the results of phosphate determinations made on surface samples collected by the Japanese training ship, Sintoku Maru, on a cruise from Kobe to San Diego, from San Diego to Hilo, and from Hilo to Kobe, June to September, 1930. Apparently the samples were not analyzed until the vessel’s arrival in Japan. The phosphate values obtained are consider- ably higher than those obtained by the Carnegie in the open Pacific and by the Scripps Institution of Oceanog- raphy off San Diego. In these two cases the samples were analyzed soon after collection and it seems neces- sary to conclude that the values obtained by Matsudaira may be in error owing to prolonged storage of the sam- ples. South of latitude 10° north, the phosphate content was in general intermediate between that found in the other two parts of the Pacific discussed. In the whole region extending well over the southeastern and tropical Pacific, extremely low concentrations of phosphate occurred at only three stations south of latitude 7° north and these were south of EasterIsland. The highest values observed 14 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE in the tropical and South Pacific were off the coast of Peru, where 103 mg POq per cubic meter were obtained at station 70. In this region there is upwelling of sub- surface water similar to that off the coast of California and it is possible that the Peruvian Current also brings a supply of nutrients. Although the surface currents in the southern trop- ics flow westward from the Peruvian Coast, the source of the phosphate which causes the relatively high values throughout the tropics cannot be attributed to the region off Peru because there is not a continuous decrease in the phosphate content with increased distance from the coast. On the contrary there was a remarkably great variability of the phosphate content at the surface throughout the tropics. The complicated hydrographic conditions in this region probably account for the irreg- ular distribution of phosphate at the surface. For ex- ample, Sverdrup (I-A, pp. 102, 106) has shown that the cur- rents in the southern tropics at depths of 100 and 200 me- ters are irregular and intermittent and that eddies are formed which bring about mixing of water at various depths. Surface Layer and Transition Zone Under the discussion of the vertical distribution of phosphate, the phosphate surface and transition zones were defined (see p. 8). The regional variation in the thickness of these zones and in the quantity of phosphate occurring in them is shown in figure C10. In the prepa- ration of this chart the depth of the lower limit of the surface layer was taken as the depth to which the con- centration of phosphate was almost uniform. This level was uSually very definite as may be seen by reference to the curves of the vertical distribution of phosphate at each Carnegie station. As indicated above, the transi- tion zone was defined as the layer in which the increase in phosphate was greater than 0.1 mg PO4 per cubic me- ter per meter of depth but in some instances it was more logical to place its lower limit at a slightly different depth from the one so determined. Where the transition zone was thick the increase in phosphate with depth was less rapid than where the zone was thin, and often rep- resented an increase of less than 0.1 mg POg4 per cubic meter per meter. The phosphate content for each zone is represented in the chart as the average for all levels within the zone. | Atlantic Ocean.--At the five stations south of Ice- land both the surface layer and the transition zone were extremely thin. It is remarkable, however, that at these stations the phosphate content of the transition zone was not so great as that in the Sargasso Sea. The depth of the surface layer varied from 0 to 25 meters; the lower limit of the transition zone varied from 50 to 100 me- ters. The concentration of phosphate in the surface layer varied from 20 to 34 mg POg per cubic meter; that in the transition zone from 32 to 45 mg PO4q per cu- bic meter. The line of stations from stations 12 to 24 showsthe change in conditions from the Grand Banks of Newfound- land, across the eastern edge of the Sargasso Sea, to the North Equatorial Current. These stations are essential- ly those used in construction of Section I (see p. 10). At the two northern stations conditions resembled those south of Iceland where the zones were thin; the lower limit of the transition zone was above 50 and 100 me- ters. Southward the zones expanded. The surface layer reached a maximum depth of 350 meters at station 17, whereas the lower limit of the transition zone was mostly well over 500 meters at stations between latitudes 20° and 40° north. South of latitude 20° north the thickness of.the zones decreased until at station 24 the surface layer was only 50 meters thick and the lower limit of the transition zone was only 150 meters below the sur- face. The concentration of phosphate in the surface layer varied from 19 to 27 mg PO, per cubic meter at the two northern stations but was below 12 mg POg per cubic meter everywhere to the south. The mean concentration of phosphate in the transition zone was fairly uniform in this series of stations but showed a slight tendency to increase southward. The values varied from 40 to 114 mg PO4 per cubic meter. The third series of stations in the Atlantic are those included in Section II, stations 24 to 34 (see p.10). The depth of the surface layer was rather uniform, varying from 25 to 100 meters. The concentration of phosphate was uniformly less than 10 mg POg per cubic meter. The depth of the transition zone was greatest (625 me- ters) at station 31 just inside the Caribbean Sea. East and west of this it decreased, particularly to the east where it extended only to 150 meters at station 26. The concentration of phosphate in the transition zone through- out this section was the same or slightly higher than in the southern part of Section I; the values ranged from 48 to 144 mg POg per cubic meter. The variations in the thickness of the surface layer and transition zones in the Atlantic closely paralleled variations in the thickness of the thermocline. North of station 14 there was a thin layer of warm water, witha sharp density gradient to the underlying cold water. In these regions the increase in phosphate is confined chiefly to this narrow thermocline. Farther south, particularly between latitudes 20° and 40° north, although the surface water was warmer, the warm water extended to greater depths and there was a much more gradual change in temperature and density to the colder water below. Here, too, the increase in phosphate was confined chiefly to the thermocline but since the latter extended over several hundred meters of water, so like- wise the phosphate transition zone was very deep. The narrowing of the phosphate zones toward the equatorial regions and their variations in Section II followed simi- lar changes in the density gradients in those regions. The distribution of phosphate reported by Seiwell and Seiwell (1934) for their three stations west of Car- negie Section I agrees well with Carnegie data, although the transition zone at their station 1169, latitude 16° 22’ north, longitude 41° 10’ west, extends to about 375 me- ters, which is somewhat lower than that at Carnegie sta- tions in this latitude. At their three stations in the west- ern edge of the Sargasso Sea, however, between latitudes 22° and 34° north, longitudes 65° and 68° west, they show a much more pronounced expansion of both the sur- face layer and the transition zone than was found by the Carnegie in the eastern edge of that area. In one case their surface layer extended to more than 550 meters. Although their observations extended to 1000 meters, this was not deep enough to show the lower limit of the transition zone in all cases. Pacific Ocean.--In the Pacific we shall first consid- er the line of stations between Japan and California, sta- tions 113 to 130, all of which are north of latitude 35° north. At these stations the phosphate content was high in the transition zone as well as in the surface layer. The surface layer was everywhere narrow or entirely DISTRIBUTION OF PHOSPHATE IN THE SEA 15 lacking, especially in the central part of the section which includes the most northern stations occupied in the Pacific. The transition zone was relatively thick ex- cept for the stations off the Aleutian Islands, extending only to 175 meters at station 123. It will be noted that where the high surface values were obtained east of sta- tion 117 and where the transition zone extended to the surface, the layer of uniform phosphate content was en- tirely lacking. The mean phosphate values in the tran- sition zone ranged from 104 mg POgq per cubic meter at station 115 to 228 mg per cubic meter at station 120. In this region the great quantities of phosphate in the upper layers is the combined result of the partial elimination of the temperature gradient and of the addition of water from the Bering Sea. South of the above line of stations is the area in which phosphate was almost entirely lacking at the sur- face. We may consider two lines of stations within this region: (1) the line extending from California to Hawaii, then north and east to station 146, (2) the line starting with station 101 at latitude 13° 23’ north, longitude 177° 27’ east, and extending west and north to Japan. Except near the coast of California all these stations showed a deficiency of phosphate in the surface layer which ex- tended to considerable depths, usually to more than 100 meters and to as much as 200 meters in many places. At these stations also the transition zone was relatively thick, which means that below the surface layer the in- crease in phosphate with depth was comparatively slow. North of Hawaii at stations 139 to 142, and again in the western Pacific between Guam and Japan at stations 108 to 113, the transition occurred at lower levels than in any other regions investigated, extending to more than 800 meters at all these stations and reaching 1000 me- ters at stations 142 and 109. The phosphate content of the transition zone at these stations was variable, but nowhere attained the high values observed north of lati- tude 35° north. It varied from 80 mg PO4 per cubic me- ter at station 105 to 188 mg per cubic meter at station 139. From station 134 to the coast of California there was a gradual narrowing of the surface layer and toa slight extent of the transition zone, together with an in- crease in the phosphate content of both zones. At sta- tion 130, where the most pronounced effect of upwelling of subsurface water was shown, the surface layer was only 25 meters thick with a mean phosphate content of 35 mg PO4 per cubic meter. The transition zone had its lower limit at about 475 meters and contained an aver- age of 207 mg PO, per cubic meter. Proceeding southward we next take up two lines of stations that cross the equatorial currents. The eastern one extends from stations 149 to 161, and the western one from stations 94 to 103. Station 153 in the eastern series of stations, and station 99 in the western series, are in the center of the Equatorial Countercurrent. On either side of this current the North and South Equatori- al currents flow in the opposite direction to the counter- current. The relation of these currents to the distribu- tion of phosphate is more fully discussed onpp.11 and 12 under the description of sections V and VIII. The note- worthy features of the surface and transition zones in this area are the relative thinness of the layers, partic- ularly in the vicinity of the countercurrent, the absence of extremely low values in the surface layer, and the variability of the concentration of phosphate in both lay- ers. 5 At station 152, at the northern border of the counter- current, the lower limit of the phosphate transition zone was at a depth of 175 meters, and that of the surface layer at a depth of only 10 meters. Over the whole area between stations 150 and 155 the entire transition zone was above 300 meters. The average phosphate content of the transition zone in the eastern line of stations var- ied between 79 and 179 mg PO4 per cubic meter. In the surface layer the average phosphate content was above 10 mg PO4 per cubic meter except in the extreme north and reached 60 mg per cubic meter at station 157. Sim- ilar but not quite so extreme conditions were found in, the western series of stations, with the center of the thin zones at about station 99. In the absence of disturbances due to horizontal cur- rents, the distribution of phosphate at the stations just discussed would no doubt be quite different from that actually found. These stations lie within the tropics where there is intense insolation of the surface water throughout the year and this normally would be expected to resuit in thick surface, as well as transition, zones, with consequent reduction of vertical mixing. This would lead to a low concentration of phosphate in the upper layers similar to that found in many of the stations in the North Pacific. It is evident that in the equatorial regions the ef- fects of the circulation far outweigh the effects of the insolation. According to Sverdrup (I-A, p.105) there is a strong upward movement of the water along the bounda- ries of the Equatorial Countercurrent which probably accounts for the proximity to the surface of the transi- tion zone and for the high concentration of phosphate near the surface in the vicinity of the countercurrent. Similar conditions prevail to some degree, however, over the whole equatorial region. The explanation is no doubt to be found in the horizontal water movements, which, according to Sverdrup, produce eddies and possi- bly other forms of vertical circulation. This may ac- count for the relatively high phosphate values in the sur- face layer but probably does not contribute to the thin- ness of the transition zone unless this northward-flowing water has a decided upward component. The line of stations from Samoa to Peru also lies in the tropics but farther south than the two series just discussed. It includes all the stations presented in Sec- tion XI (see p. 11). In general both the surface layer and the transition zone deepen from the coast westward. The lower boundary of the transition zone was 75 meters at station 71 near the Peruvian coast, and 650 meters at station 83 in latitude 17° 00’ south, longitude 129° 45’ west. As was the case in other sections in the tropics, the phosphate content in both layers was variable. The western part of the line lies in the same longitude as the most easterly of the two series of stations crossing the equatorial currents. Here the transition zone extended to somewhat greater depths than in the other two lines of stations just mentioned. This is probably because the more southern stations are in a region of less disturbed hydrographic conditions than prevail farther north. The depth of the surface layer at these stations was the same or greater than that at the more northern tropical sta- tions. The narrow transition zone in the eastern part of the section is probably caused, in part at least, by the Ant- arctic Intermediate Current. Nearer the coast the dis- tribution of phosphate is further affected by upwelling and by the Peruvian Current. In the line of stations run- ning from station 60 in latitude 40° 24’ south, longitude 16 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE 97 43’ west, to Callao, Peru, the effects of the upwelling along the coast of Peru are more pronounced. There is also a decrease in the thickness of both the surface lay- er and transition zone with decreasing distance from the coast. Near the offshore end of the line the surface layer was 100 meters or more in depth at several sta- tions, but near the coast only 25 meters deep. The low- er limit of the transition zone was at 375 to 475 meters at the outer stations and was at 75 to 100 meters near the coast. As Callao was approached, there was a con- siderable increase in the quantity of phosphate ranging from 30 mg PO, per cubic meter in the southern part of the line to 106 mg per cubic meter at station 70 near Callao. Similarly, the average phosphate content of the transition zone ranged between 94 and 159 mg PO4g per cubic meter at the stations remote from land but was above 200 mg per cubic meter along the coast. The last line of stations on this chart to be discussed extends from station 60, latitude 40° 24’ south, longitude 97° 33’ west, more or less northward and then eastward to near the coast of South America, slightly south of the equator. In this line the phosphate distribution south of Easter Island, stations 60 to 55, resembled that at the same latitudes to the east. From stations 55 to 45, lati- tude 4° 35’ south, longitude 105° 03’ west, the layers were deeper and their phosphate content less than at the stations to the east. In this part of the series the con- centration of phosphate was mostly under 20 mg PO4 per cubic meter in the surface layer which extended to 200 meters in several places. The transition zone extended to about 500 meters and had an average phosphate con- tent less than 100 mg POg per cubic meter. Station 47, where observations were made in November, in the same vicinity as station 79, latitude 12° 36’ south, longi- tude 112° 14’ west, was occupied three months later. At the latter station the concentrations of phosphate in both the surface layer and transition zone were considerably greater and the zones somewhat thinner than at station 47. The temperature at the two stations also showed a wide difference. Very little seasonal variation in the hydrographic conditions of the water can be expected at this latitude except as caused by differences in the cir- culation which, in turn, may be caused by seasonal changes in other localities. At the stations running near the equator from longitude 105° 03’ west to near the coast, remarkably high phosphate values were observed at the surface. At the three stations nearest the coast the transition zone began immediately at the surface. At these stations, as at other stations along the South American coast, the high phosphate content near the surface probably was owing to upwelling of subsurface water and to the Peruvian Current. The 2000-meter Level The 2000-meter level was selected for a comparison of the phosphate content of the deep water of the various parts of the oceans. It would have been preferable to use a lower level had sufficient observations been available from below 2000 meters. This level, however, is fairly representative of the deep water as it is well below the transition zone and the tropospheric circulation. Figure C11 shows the scaled values of phosphate in mg PO4 per cubic meter at 2000 meters for each station at which ob- servations extended to that depth. The mean phosphate values at 2000 meters for certain latitudinal areas inthe Atlantic and the Pacific are given in table Cl. Table Cl. Comparison of concentrations of phosphate in Pacific and Atlantic at 2000 meters according to Carnegie observations [Pacific Atlantic Region ae mg/m3 PO, aa tions tions N of 40N 11 260 7 79 20 - 40N 25 258 3 111 0-20N 20 240 12 120 0-20S 42 238 Nat 20 - 40S 19 220 Mean for all stations 117 242 22 106 Atlantic Ocean.--In the Atlantic the phosphate con- tent of the deep water increased from north to south practically as far as the observations extended. As will be seen from the table, north of latitude 40° north the average value at 2000 meters was 79 mg POg per cubic meter, between 40° and 20° north it was 111 mg, and south of 20° north 120 mg PO4 per cubic meter. The explanation of this distribution must be sought in the nature of the circulation of the North Atlantic (I-A, pp. 79, 81), This subject will be discussed further in connection with the discussion of the phosphate content at the 2000- meter level in the Pacific. Pacific Ocean.--In the Pacific no consistent regional variation in phosphate at 2000 meters is evident from an inspection of the scaled station values. There was a considerable variation from station to station but a pro- gressive change in any direction is difficult to discern. The means for different latitudinal areas (see table C1), however, show a progressive increase from south to north in the concentration of phosphate, the values in- creasing from 220 mg POg per cubic meter between lati-, tudes 20° and 40° south to 260 mg POq per cubic meter north of latitude 40° north. This south-north phosphate gradient is in accord with the assumption that practically all the deep water of the Pacific originates in the antarc- tic and not to any important extent at the surface in the warmer areas and that this water is slowly moving north- ward. Comparison of Oceans.--The most interesting fea- ture of the phosphate distribution at 2000 meters is the great difference in the values obtained in the Pacific and in the North Atlantic. The mean value for all Carnegie Atlantic stations was 106 mg POg per cubic meter, whereas for the Pacific it was 242 mg per cubic meter, or more than twice as high as in the Atlantic. The high- est value obtained in the North Atlantic, 166 mg POq per cubic meter, was only slightly above the lowest value, 154 mg, obtained in the Pacific. Thomsen (1931a) also found twice as much phosphate in the Pacific at 2000 me- ters as in the Atlantic at that depth. Furthermore, he found that the deep water of the Indian Ocean contained approximately the same amount of phosphate as that of the Pacific. If regions of similar latitude in the North Atlantic and the North Pacific be compared, the difference is equally striking. This is clearly shown in table Cl. At 2000 meters in the eastern North Atlantic, Atkins (1926b) found a phosphate content corresponding to the DISTRIBUTION OF PHOSPHATE IN THE SEA 17 Carnegie results in the central part of that ocean. Ata station at latitude 37° 44’ north, longitude 13° 21’ west, he found 104 mg PO, per cubic meter, which agrees well with 111 mg per cubic meter as a mean for the Carnegie stations in that general latitude. According to the phosphate section which Deacon (1933) constructed along the 30th meridian, this deep water of low phosphate content extends southward to about lati- tude 25° south at 2000 meters and beyond 30° south at 3500 meters. In this section, however, there was a minimum phosphate concentration at about 3000 meters below which there was an increase toward the bottom. Such a feature has not been found anywhere in the Pacif- ic Ocean. In connection with the difference in the quantities of phosphate in the Atlantic and Pacific it is interesting to compare the concentration of phosphate in the Arctic and and Antarctic oceans. In the Atlantic east of Greenland the oceanic polar front, or region of sinking, extends to latitude 60° north (Meyer, 1928). The Carnegie at sta- tion 10, which was in this vicinity, obtained a vertical series of phosphate determinations to a depth of 3000 meters. At this station the phosphate content of the water was almost uniformly 60 mg PO4q per cubic meter from 500 to 3000 meters (see fig. C7). Similarly, Brujewicz (1931) found in the Barents Sea, which is north of the oceanic polar front, 90 to 105 mg PO4 per cubic meter at the bottom and considerably less than that amount near the surface. Sverdrup (1933) at nine stations in the Arctic north of Spitzbergen found equally low values. Below 100 meters at all stations the phos- phate was rather uniformly distributed with depth. Most of his values were below 97 mg PO4 per cubic meter and only one was as high as 134 mg per cubic meter. Kreps and Verjbinskaya (1930, 1932) investigated the seasonal variation in the concentration of nutrients in the Barents Sea. Even in August and September when there was an accumulation of phosphate in the bottom water they never found concentrations exceeding 85 mg PO, per cubic meter. The Antarctic, on the other hand, contains much more phosphate than the Arctic. At fourteen stations in the Weddell Sea, Ruud (1930) found at 450 meters more than 240 mg PO, and at most stations about 260 mg PO4 per cubic meter as compared with less than 60 mg PO4 per cubic meter in the North Polar Front. Even at the surface Ruud found high values, ranging from 121 to 208 mg POg per cubic meter. Wattenberg (1927a) found similar conditions in the Atlantic at about 50° south. Deacon (1933) reported 187 to 203 mg PO, per cubic meter in the deep water of the Antarctic. Thus, it seems to be well established that the North Atlantic and Arctic oceans have a lower phosphate con- tent than do the other oceans of the world. According to the distribution of salinity (Meyer, 1928) it is apparent that from the equator to latitude 40° south the water of the South Atlantic between the depths of 2000 and 3000 meters is typically North Atlantic wa- ter, originating in the sinking area between latitudes 30° and 40° north. As this water moves southward from the central North Atlantic its phosphate content is grad- ually augmented by the decomposition of sinking detri- tus. In the South Atlantic this water is overlain by the Antarctic Intermediate Current which is rich in phos- phate and which probably contributes some phosphate from its lower border to the water below. Thus Deacon (1933, p. 233) points out that the maximum amount of phosphate occurs at the boundary between these two cur- rents. He also indicates that ‘“‘the greatest vertical mixing between the two currents takes place between latitudes 38° and 43° south so that the phosphate is not lost from the antarctic zone but is returned to it in the deep current.’’ In the North Atlantic, on the other hand, there is a slow increase in the concentration of phos- phate to great depths, although it always remains rela- tively low. This distribution of phosphate appears to be peculiar to the North Atlantic. It does not occur in the South Atlantic nor in the Pacific. The deep water of the North Atlantic is poor inphos- phate because practically none of the water from which it originates contains any great quantities of phosphate. The sinking water in the Sargasso Sea contains very lit- tle phosphate because of the peculiar hydrographic con- ditions and because of the phytoplankton at the surface. The North Atlantic Drift consists of warm surface water with a low phosphate content. The Arctic water hasbeen shown by Brujewicz (1931) and Sverdrup (1933) to be relatively poor in phosphate. The cold water in the northernmost part of the Atlantic has a low phosphate content as indicated by the Carnegie observations at sta- tion 10. The only source from which the North Atlantic receives water of a phosphate content corresponding to that of the other oceans is the Antarctic Intermediate Current which enters the tropical North Atlantic, but the amount of water contributed by it to the North Atlantic must be regarded as relatively small as compared with the other sources. The South Atlantic Ocean is rich in phosphate be- cause the main body of water between 2000 and 3000 me- ters has traveled a comparatively great distance at a level at which phosphate is being liberated, and because the intermediate water above and the bottom water be- low originate in the Antarctic where the concentration of phosphate is high. The deep water of the Pacific Ocean is rich in phos- phate partly because it does not receive any large quan- tities of water from other oceans that are poor in phos- phate, and partly because it has lacked contact with the convection layer for a long period of time. That the lat- ter is true is indicated by the low oxygen content and the remarkably uniform distribution of salinity and temper- ature which prevail throughout the deep water of the Pa- cific. The greater concentration of phosphate in the Ant- arctic than in the Arctic can probably be accounted for by the fact that the former ocean is in closer contact with the deep water of the oceans adjacent to it. Sver- drup (1931) has described the probable nature of the mix- ing of the deep water of the Antarctic with that of the oceans surrounding it. The Arctic, on the other hand, because it is separated from the other oceans by land masses and oceanic ridges, does not receive water from other oceans rich in phosphate. The water which it does receive from the Atlantic and the Pacific must be from relatively near the surface, where the phosphate content is low. 18 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE Table C2. Distribution of phosphate for surface, suriace layer, transition zone, and 2000 meters at Carnegie stations mg/m3 m mg/m3 m mg/m3 mg/m3 1 34 eee 66000 ven 2 58 HOO iene Leonor BEOA 3 99 cae eanree 62 4 92 See es, Varecees oot 5 16 Fees ale he cutee cee 61 6 21 BPO i Betas Sone UE 79 tf 34 25 34 100 45 meee 8 13 0 eu 100 32 ‘ 9 20 10 20 50 40 10 28 10 28 90 37 60 11 PAL 25 27 50 45 68 12 27 10 27 100 74 90 13 19 20 19 50 40 14 11 20 11 500 84 134 15 11 5) 9 825 32 107 16 8 75 200 11 600 59 ANT. 9 100 350 11 450 34 18 5 225 200 6 700 50 116 19 5 225 200 6 700 42 111 20 5 130 100 5 750 84 130 21 4 120 100 5 300 99 111 22 8 60 50 8 200 114 166 23 4 40 25 5 200 82 99 24 4 50 50 4 150 70 107 25 5 40 25 5 200 106 143 26 5 60 50 5 150 72 27 4 80 50 4 200 63 96 28 4 60 75 4 300 48 88 29 3 100 a5 3 400 81 103 30 2 100 100 4 500 86 87 31 2 100 90 3 625 144 32 2 80 75 2 525 136 833} 4 90 75 4 475 87 158 34 2 90 75 3 525 110 146 35 15 See 6 15 425 195 193 36 16 ‘ PAR) 16 350 175 245 37 15 30 ity 500 192 254 38 20 25 20 450 200 268 39 16 30 17 500 186 245 40 24 0 575 198 41 32 0 400 175 42 45 0 275 148 236 43 52 30 48 300 94 168 44 38 50 35 375 157 235 45 38 100 42 550 189 200 46 36 100 oT 500 175 215 47 iyi 100 19 375 76 207 48 13 200 16 475 80 191 49 13 200 14 550 90 186 50 13 200 14 500 86 158 51 16 abe 100 16 500 63 175 52 8 150 100 8 500 69 194 53 13 wens iis) 13 350 42 190 54 9 5 200 19 400 93 205 55 12 100 12 300 41 182 56 9 16) 1a) 9 400 54 154 57 20 100 23 B35) 94 226 58 20 75 283 400 93 220 59 38 50 38 325 109 248 60 50 75 53 375 123 224 61 46 0 Sil) 111 295 62 32 rds) 32 400 135 252 63 21 100 743) 400 112 284 64 21 100 30 475 108 242 65 24 75 26 400 129 260 66 29 100 28 300 94 245 DISTRIBUTION OF PHOSPHATE IN THE SEA Table C2. Distribution of phosphate for surface, surface layer, transition zone, and 2000 meters at Carnegie stations--Continued Depth of layer 10 mg/m? Surface layer Transition zone P04 at Mean PO4 Depth Mean PO4 2000 m@ POgq at surface mg/m% m m mg/m3 m mg/m3 mg/m? 68 29 AOE 75 29 300 159 245 69 62 eels 25 64 200 211 289 70 103 aus 25 106 100 201 276 71 58 ales 25 58 75 162 225 72 52 atts 25 52 175 156 225 73 44 ase 0 B60 200 164 232 74 68 obo 25 64 175 174 240 75 44 gene 75 45 275 171 234 76 50 see 100 46 325 129 236 17 16 men 100 14 275 85 242 78 32 Sse 100 33 275 110 242 719 34 Amon 75 34 275 100 310 80 36 100 32 375 130 264 81 38 100 37 350 78 240 82 34 100 34 475 154 249 83 29 100 25 650 151 280 84 24 150 24 475 104 234 85 40 100 41 675 168 284 86 20 150 18 §50 110 220 87 17 200 19 850 152 246 88 16 300 16 775 165 240 89 21 100 14 675 117 247 90 21 100 21 700 142 258 91 21 100 23 625 140 288 92 28 100 28 475 117 286 93 28 100 28 475 107 292 94 14 75 14 475 68 190 95 14 75 16 375 72 198 96 12 75 12 375 79 228 97 24 100 23 300 61 228 98 24 100 26 400 95 277 99 12 19 12 300 107 271 100 10 70 100 11 300 158 268 101 8 170 175 8 525 158 BONO 102 8 175 175 8 600 124 254 103 5 235 200 6 650 91 unos 104 7 200 200 Uf 700 98 217 105 5 180 150 5 625 80 232 106 5 210 175 6 600 118 239 107 5 90 200 9 475 120 240 108 4 280 200 4 925, 137 208 109 3 130 100 4 1000 140 268 110 5 90 75 5 950 118 244 111 5 90 75 5 800 109 241 112 7 130 75 7 800 97 245 113 5 130 50 5 875 118 220 114 7 10 0 Yes 550 143 234 115 4 30 0 675 104 227 116 4 30 10 4 125 109 211 117 3 40 25 4 475 145 255 118 90 50 91 375 152 248 119 142 0 niece 325 231 256 120 137 0 oye 250 228 266 121 141 25 142 225 212 275 122 130 25 130 275 194 255 123 113 10 114 175 197 AAG 124 103 25 105 200 205 250 125 125 0 nae 350 219 258 126 76 25 76 400 170 275 127 43 25 43 500 156 270 128 29 50 29 550 147 250 129 25 75 26 625 190 269 130 36 25 35 475 207 261 131 PASM ants coke oeleine Sac0 aaah 132 15 6 100 15 475 142 251 133 7 135 100 7 625 136 240 CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE Table C2. Distribution of phosphate for surface, surface layer, transition zone, and 2000 meters at Carnegie stations--Concluded Surface layer Transition zone Depth of POgq at layer PQ4 at mg/m? m m mg/m3 m mg/m3 mg/m3 135 7 140 100 5 650 135 263 136 3 170 125 3 675 137 275 137 4 220 200 5 675 165 279 138 5 250 200 4 650 148 274 139 6 200 200 6 650 188 284 140 7 300 275 7 (475) (176) 141 5 100 100 6 950 167 255 142 5 110 100 5 1000 164 301 143 6 90 75 5 875 98 144 6 160 175 ui 650 105 252 145 6 120 100 6 650 134 286 146 6 200 200 7 750 179 295 147 8 180 175 7 625 182 277 148 Batne eee ak pc mm Uf ABTA sates 149 6 210 200 6 575 ile (ry 251 150 7 10 100 10 250 130 256 151 sae aD ae Sey Bek) ates Sane 152 20 Aen 10 20 175 140 216 153 u/ 80 75 7 200 123 241 154 i 80 75 7 275 128 227 155 29 aed 100 33 275 95 214 156 28 Lace 125 43 475 171 228 157 47 seu 100 60 475 179 250 158 36 sane 100 47 650 133 198 159 15 tee 75 15 375 719 215 160 12 els 150 15 475 115 219 161 23 vee 100 23 475 102 214 162 11 Leee 100 11 500 87 205 4 Values scaled from graphs. THE DISTRIBUTION OF SILICATE IN THE SEA. INTRODUCTION The silicate dissolved in the sea is involved in a number of biological and geological processes. Many marine organisms utilize silicate for the construction of their tests or shells, and many bottom sediments contain a high percentage of silica. Of marine organisms, the diatoms are the most important consumers of silicate. ' To show the dependence of diatoms on dissolved silicon compounds, culture experiments have been conducted by a number of workers; for example, Murray and Irvine (1891), Richter (1906), Allen and Nelson (1910), and Cou- pin (1922). As regards the form in which these com- pounds can be utilized, these workers are not in agree- ment, however, and the question of the nature of the compounds utilized by the diatoms in natural waters is yet to be solved. HISTORICAL In the sea a correlation between the abundance of diatoms and the quantity of silicate in the water fre- quently has been observed. Raben (1905a, 1905b, 1910, 1914) found a seasonal fluctuation in the silicate content of the water of the North Sea and the Baltic correspond- ing to the seasonal fluctuation in the abundance of phyto- plankton. This is strikingly shown in a diagram by Johnstone (1908). Over a period of years Raben found a maximum of silicate in November and February with a minimum im April and May, the minimum following the maximum abundance of diatoms. A similar correlation was later noted by Brandt (1920) in the Baltic. Inthe Gulf of Maine, Wells (1922) found concentra- tions of silicate during the winter nearly ten times high- er than in May. In this region maximum diatom growth occurs in March and April. Following this growth sili- cate increases but is reduced again during the latter part of August, when a second period of diatom growth occurs. During a number of years Atkins (1923b, 1926a, 1928, 1930) has observed a marked seasonal variation in silicate in the English Channel. For example, during 1923 to 1926 a winter maximum of 260 to 3104 mg SiO9 per cubic meter fell to 50 and 100 mg in April and June. Thompson and Johnson (1930), in Puget Sound, observed a reduction in the silicate content in May and June; and, in the Strait of Georgia, near the mouth of the Fraser River, Hutchinson, Lucas, and McPhail (1929) noted that the silicate content varied with the growth of diatoms. It was found that the greatest consumption of silicate at depths where diatoms were abundant occurred in August. Conditions here, however, are complicated by the fresh- water discharge from the Fraser River. According to investigations carried out at the Scripps Institution, the seasonal variation in silicate along the coast of southern California is less pronounced than in the other localities referred to, probably because of upwelling of subsurface water. Considerable changes in the silicate content at the surface may occur at any time of the year. Since diatoms can grow only in the photysynthetic zone and since they are the chief consumers of silicate in the sea, we should expect to find a lower concentration of silicate in the upper water layers than in the deeper water. That this is the case has been observed by sev- eral workers. Atkins (1926a) presents data for vertical series of samples taken off the south of Ireland, and off Portugal, in the Bay of Biscay, and in the Faroe-Iceland and Faroe-Shetland channels. All theseshow an increase in the concentration of silicate with depth. The concen- 21 trations increased with depth from 1202 to 190 mg Si09 per cubic meter at the surface to about 400 mg per cubic meter at 500 meters. At 1000 meters at the station off Portugal a value of 580 mg SiOg per cubic meter was ob- tained, but at the other stations the concentration at that level was 520 mg SiOg per cubic meter or less. At 3000 meters at a station at latitude 30° north, longitude 15° west, the concentration of silicate was 1560 mg SiO9 per cubic meter. In the English Channel a similar increase of silicate with depth down to 60 meters was observed (Atkins, 1930). A marked increase in the concentration of silicate with depth was found by Moberg (1926b, 1928) off the coast of southern California and by Bigelow and Leslie (1930) in Monterey Bay. The results of these investigators will be discussed later in a comparison of their data with those of the Carnegie. Hutchinson (1928) studied the silica-diatom relation in the upper 20 to 30 yards in the Strait of Georgia. The decrease in the concentration of silica at the depth where the maximum number of dia- toms occurred was very striking. At one station in par- ticular the concentration of silicate decreased from about 4000 mg SiOg per cubic meter? at the surface to less than 1000 mg SiOg per cubic meter at 4 yards be- low the surface, the depth at which the maximum diatoms were most numerous. Below this the silicate content in- creased to 2000 mg SiOg per cubic’ meter at 10 and 20 yards. At two other stations a similar correspondence between the abundance of diatoms and silicate and depth was found. In this same locality Hutchinson, Lucas, and McPhail (1929) later determined the silicate content to a depth of 250 yards. The concentration of silicate was 1500 mg SiOg per cubic meter at the surface, only 500 mg at 6 yards, and reached a maximum of 2800 mg per cubic meter at 100 yards. Below this there was a slight decrease. Okada (1932) gives the results of the analyses of sixty-eight vertical series of samples taken in the southern part of the Japan Sea by the Syunpu Maru in the summer of 1929. At one station, 37, which is represent- ative of the other stations in that region, the silicate con content at the surface was 187 mg SiOg per cubic meter. ato be comparable with Carnegie and other data, Atkins’ figures are multiplied by the factor 1.3. See At- kins (1930, p. 848). On page 301 Hutchinson states his results are ex- pressed in ‘parts, er thousand”’ but he obviously means ‘parts per million’’ as shown by his graphs on the next page where the results are given in mg per liter. 22 CHEMICAL RESULTS OF LAST CRUSE OF CARNEGIE er cubic meter, but below this it m- y to the lowest depth from which samples | were ee . At 1500 meters the silicate content | = ic ched = value of 2450 mg Si09 per cubic meter. id Subsequently 200 300 eee ae ee FIG. C4—VERTICAL DISTRIBUTION PHOSPHATE AND DENSITY FIG. C5—VERTICAL DISTRIBUTION PHOSPHATE AND DEN- AT CARNEGIE STATION 60 (40° 27’ SOUTH, 97° 33’ WEST) SITY AT CARNEGIE STATION 130 (37°05’ NORTH, 123°43' AND PHOSPHATE AT CARNEGIE STATION 137 (24° 02 WEST) AND PHOSPHATE AT CARNEGIE STATION 137 NORTH, i45 33’ WEST) f (24° 02’ NORTH, 145° 33’ WEST) SCALE OF of ———_+—___1 25 27 SCALE OF PO, IN mg/m? 200 300 44 fo} WDEPTH IN METERS) Ul a STATION 137 Uy SCALE OF % 25 SCALE OF OF 25 3 SCALE OF PO, IN mg/m 200 3 SCALE OF PO, IN mg/m 200 FIG. C6B—VERTICAL DISTRIBUTION*PHOSPHATE AND DEN- FIG.C7—VERTICAL DISTRIBUTION PHOSPHATE AND DEN- SITY AT CARNEGIE STATION 122 (46°16’NORTH, 174°03' SITY AT CARNEGIE STATION 10 (59°19 NORTH, 34°15’ EAST) AND PHOSPHATE AT CARNEGIE STATION 137 WEST) (24°02° NORTH, 145° 33’ WEST) FIG.C8-VERTICAL DISTRIBUTION PHOSPHATE AND DEN- SITY AT CARNEGIE STATION 29 (13° 16’ NORTH, 52° 13° WEST) . 45 6261-826! 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CIS—VERTICAL DISTRIBUTION pH AND PHOS- CARNEGIE STATION 137 (24°02' NORTH, 145 33° WEST) PHATE AT CARNEGIE STATION 71 (II°57’ SOUTH, 78°37” WEST) ® 49 6261 - 4 SLINS3Y SISINYVS WOU FOWIUNS LV NOILVYLNIONOD NOI-N9OYNGAH NOILAGIMLSIG TWLNOZINOH 7ee e szoe® ig 92190 C8 G2G6 {maewo Pid *ebe LEB /k 8 SNOILVLS DIHAVYSONVSDO ZISSNYVD 3LVDIGNI s3T0uID ywovle w rend 09 er 3 sae aac SE \ Temwny- °ore 2/80 e160 ye evee® o/z'8 22 eeree 9229 mre ner 0 £2°9 £206 . si bret 7, 023 | b2G0 cze ° 2/e 2 5%8 ore 608, BES S28 PDD ees czee 09/8 pm HOY eced ip £206 0628 628 ee ee 0/278 Ce es a ° ee 98° 17@ 0 (z7¢0 = = 2 vege Rate 6ce, ste eres, | AB, Be ree, ee “ode 6261—826| ‘SIINS3Y SIOINBVD WOH SH3LIN 0002 ‘NOLWYIN3ONOD NOI-N39OUGAH NOILNBINLSIC WINOZIMOH—SI9 ‘914 eer ==] == SNOILVLS DIHdVYSONVIDO EISELELS) BLVSIONI SBIDYID YOVIE wore °0LL 02lZ ello eel 692° ° oSLZ eilerl. ozzy vomaragep mT COLL gZe 92° %, eLL° a2) on'Fry 69Le Lop : pe ) Py foe bLL oz rll \ elt ; O22 eorsbog il: 5» @0LL LL ORL ° m0 * oye eed 162. 264 9LL eed £62? 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A et 4 , a ' eo i ‘TV ; 7 : % ao : g Ov Waa y z 75 Age: A fbn ve (Od) LN3LNOD- 3.LWHdSOHd (Hd) NOILWY1LN3ONOD NOI-N390NAAI r z 09 - H 3 ‘ y ‘ R +50 m H 4 7 08 3 ‘ E-¢ s ‘ R 2 = i? 001 3 Ss EL m 08! | — -830uv3 | HLINOWAId ov! — rind || } OL oa VOnVS -n8ad quad - © oF Sor ~ 8,9 POI-V'St 40 SOT -WNVD VrYNVd-M,LEdN)I-N,O2 EN ,O1-N ODEN ,OP-CNY TID) jOLONIHSYA og fox 09 og or I of 0% oF \DN NOLLWs 52 140 Bp Bo Bni4iBm_ Bl 142 Bk Bj Bi Bh Be Br Be Bd Bc Bb B a el —_——— —— el ae Ch a iaram c ———s 5.0 1 15.9 ea 1 4 a N i} 1 i} i} Lt 1 | 4.0 eee aoe aH Alan Po es 2.0 ren I ] 1.0 : 1000 1 ' \ | 1 i} A H on 0.50 y es 1 ! liane ' i 1.0 2000 M4 n 1 1 1s i} I ( ' ' 4 y i \ | 2.0 & t 1 z ! Y f= é i) WA a a at \ a 3000 4 28} 4} — Beat i} 1 i] ! i] i) 1 i] T 1 t i] ! | i] 4000 | D Z HORIZONTALTSCALE? (=u aces eer AM BUSHNELL SECTION FIG. CI7—DISTRIBUTION OF OXYGEN BETWEEN ALEUTIAN ISLANDS AND HAWAII, FROM BUSHNELL, AUGUST 1934 53 a ———— ' 2 3 4 40 60 Si oO, IN mg PER LITER oe Si oO, IN mg PER LITER P= ~ | SS eg aN H x N q ne N 100 » *. \ 4 ~~ LA JOLLA \ \ : elaen ‘ MONTEREY BAY : \- 0 =STATIONS 133-149 ‘ \ : TWEEN 20°8 34°N -200 & te bs Oren ocean] ‘ x \ \ Ip=sTATIONS 150- Poe ss a Nm BETWEEN 20°N wi \ Hy 3 \ z \ x \ & x \ foo “h e \ = Vv \ \ \\ n \ o : \ g 500 ae \ z at \ 2 \ 2 \ \ \ he \ FIG.CIB—VERTICAL DISTRIBUTION OF SILICATE IN UPPER 600 METERS AT MONTEREY BAY (AFTER BIGELOW AND LESLIE, 1930), OFF LA JOLLA (FROM UNPUBLISHED DATA BY MOBERG), AND IN OPEN PACIFIC (CARNEGIE DATA); CARNEGIE CURVE IS MEAN OF |6 VERTI- CAL SERIES OF OBSERVATIONS MADE NORTH OF 20° NORTH LATI- SINGLE VALUE} FIG.CI9-MEAN VERTICAL DISTRIBUTION OF SILICATE AT CARNEGIE STATIONS NORTH OF 20° NORTH AND AT STATIONS SOUTH OF 20° NORTH ° 8 2 1) (4 wi e w = = FS - a w i.) wo SCALE OF 021N mI/1] SCALE OF pH 8.0 SCALE OF PO, IN mg/m? 200 FIG C2O—VERTICAL DISTRIBUTION OXYGEN, PHOSPHATE, AND pH AT CARNEGIE STATION 137 (24°02’ NORTH, 145°33' WEST) 54 [kite \_carnecie Neus iis N 137 DEUTSCHLAND. STATION 12 Vv] 2000 \ 2000 7 & @ e = 2 2 iN z z x z \ re & \ 3 a 5 3000 x iL 4 4000 iy SCALE-OF pH_| 78 80 a2 f SEALE) OF 0, IN mY ! SCALE OF 0, IN ml/1 3 SCALE OF, Po, IN mg/m: 2 4 6 200 39 FIG. C2I-VERTICAL DISTRIBUTION OXYGEN, PHOSPHATE, AND FIG. C22—VERTICAL DISTRIBUTION OXYGEN AT CARNEGIE pH AT CARNEGIE STATION 152 (10°05 NORTH, 139°44’ WEST) STATION 137 (24°02’ NORTH, 145° 33° WEST) AND AT DEUTSCHLAND STATION 12 (27°46 NORTH, 27°36 WEST) 8 2 n i wl = w = = ee - a w ray 3 8 SCALE OF POs in mg/m? — 200 SCALE OF SiO, IN mg/L 8 (2 FIG. C23—VERTICAL DISTRIBUTION PHOSPHATE AND SILICATE AT CARNEGIE STATION 137 (24° 02° NORTH, 145° 33° WEST) 55 A ean 7 gto Te i , + j ; = i a i : t, > ror | Dee x 0 U Ts A ae) : : i} 4 7 ’ BY ¥ a a“ , ? F “Fe ‘. 7 - . ay] : b . =? ¢ a ‘ a ' z 7 g 4 7] : o - . 2 - Path Y. r) i" j ; i 8 +5 o ; i’ an " ‘ Sere SM Gui, «th tai al a ha nithien Se ih.) tae Atlantic Ridge, 4 Antarctic Intermediate Current, 9, 10, 15, 17, 25 Antarctic water, 9, 10 Bay of Biscay, 21 Bottom water, hydrogen-ion, 28 oxygen, 33 phosphate, 17 Bushnell, 31, 33-34, 35 California coastal area, 1, 4, 9, 13, 14, 15, 21, 23, 24, 28, 31 California Current, 4, 5, 13 Carbon dioxide, cycle, 27 effect on hydrogen-ion, 25 maximum concentration, 8 photosynthetic zone, 27 solubility, 28 Carnegie sections, geographic positions, and hydrographic conditions, 4-6 Central American Bight, 4, 10, 25 Challenger, 1, 31 Chemical data, hydrogen-ion, 25-29 oxygen, 30-35 phosphate, 7-20 Silicate, 21-24 vertical distribution, zones, convection or surface layer, 3 stratosphere, 4 transition or discontinuity layer, 3 troposphere, Chemical investigations, program, 1 Convection layer, hydrogen ion, 27, <8 oxygen, , phosphate, 7, 8, 14-16 Silicate, 22 Dana, 1, 31, 36 Data, plan of presentation, 3 Deep water, hydrogen ion, 28, 29 oxygen, 31-32, 35-36 phosphate, 16-17 illustrated, 48 silicate, 22, 23, 24 Density gradient, effect on photosynthetic zone, 8 relation to phosphate transition zone, 9 Deutschland, 36 Diatoms, consumers of silicate, 21 dissolution, 23 English Channel, 21 Equatorial Countercurrent, 4, 5, 11, 15, 35 Equatorial regions, 15 Faroe-Iceland Channel, 21 Faroe-Shetland Channel, 21 Geological processes, 1 Geographic positions, Carnegie sec- tions, 4-6 Grand Banks of Newfoundland, 4, 10, 14, 25 INDEX Great Barrier Reef, 1 Gulf of Alaska, 1, 5, 6, 11, 12, 26, 27, 31 Gulf of Maine, 21 Gulf of Panama, 1, 4, 31, 34 Hannibal, 31, 34 Humboldt Current (see Peruvian Cur- rent) Hydrogen ion Atlantic, 2 bottom water, 28 buffer mechanism, 25 Carnegie sections, 25-27 comparator, 3 convection layer, 27, 28 data, 25-29 deep water, 28, 29 effect of carbon dioxide, 2¢ effect of upwelling, 28 equation, 3 indicator, 3 Pacific, 1 regional distribution, comparison Antarctic and Arctic, 29 correlation with phosphate, 28 salt error, 3 surface water, 27, 28 temperature effect, 3 transition zone, 28 vertical distribution, 27, 28 correlation with phosphate, 28 Hydrographic conditions, Carnegie sections, 4-6 Inorganic nitrogen and plant growth, limiting factor, Intermediate Antarctic Current, 4, 28, 35 Intermediate antarctic water, 32 Intermediate water, North Pacific, 5 Japan Current (see North Pacific West Wind Drift) Kuroshio Current, 5 Metabolic cycle of sea, 1 Monterey Bay, 21, 23 North Atlantic Drift, 17 North Equatorial Drift, 4, 5, 11, 12, 14, 15, 32, 35 North Pacific West Wind Drift, 5, 6, 13, 33 Nutrient ions, 7 Oslo Fiord, 7 Oxygen, bottom water, 33 Comparison Atlantic and Pacific oceans, convection layer, 33, 34 data, 30-35 deep water, 31-32, 35-36 maximum content, 32, 34 method of determination, 3 accuracy, 3 percentage of saturation, 3 standard, 57 Oxygen, minimum content, 8, 32, 35 Pacific, 1, 2 photosynthetic zone, 31 regional distribution, 34-36 saturation, 34 supersaturation, 34 stratosphere, 32, 35-36 surface water, 33, 34 transition zone, 31, 35 troposphere, 35 vertical distribution, 31-33 controlling factors, 31 in deep water of Pacific, 31 Oyashio Current, 5 Peruvian Current, 4, 5, 14, 15, 16 Phosphate and plant growth, 7 as limiting factor, 7 Atlantic, 2 bottom water, 17 convection layer, 7, 8, 14-16 data, 7-20 deep water, 16-17 illustrated, 48 effect of upwelling, 9, 13, 14, 15, 16 method ot determination, 2 accuracy, 2 colorimeter, 2 reagents, 2 standards, 2 Pacific, 1 regional distribution, 10-17 Carnegie sections, 10-12 seasonal variation, 13 stratosphere, 9 surface, 17, 12-14 transition zone, 14-16 tropesphere, 16 vertical distribution, 7-9 decomposition, 8 maximum content, 8 mixing, 7 surface, 7 utilization, 8 vertical water movements, 8 Photosynthesis, ‘1, 7, 31 Photosynthetic zone, 8, 12 carbon dioxide, 27 convective currents, 24 effect of density gradient, 8 oxygen, 31 Phytoplankton, 7, 8, 13, 17, 21, 34 Pioneer, 31, 34 Planet, 1, 31 Plankton, 7, 8, 23 Plant nutrients, 1, 2,7 Puget Sound, 1, 21 Radiolarians, effect on silicate content, 23 in photosynthetic zone, 23 Respiration of plants and animals, 1, 7, 27, 31 Salts in sea water, major constituents, 1 minor constituents, 1 Sargasso Sea, 4, 13, 14, 17 Seasonal variation, phosphate, 13 Sections, Carnegie, geographic posi- tions, chart, Silicate, bottom sediments, 21 Carnegie sections, 22 comparison Antarctic and Arctic, 24 comparison Atlantic and Pacific, 24 conditions affecting distribution, 23 content of deep water, Pacific, 24 convection layer, 22 data, 21-24 deep water, 22, 23, 24 effect of upwelling, 21, 24 maximum, time of, 21 method of determination, 2 colorimeter, 2 reagents, 2 salt error, 2 standard, 2 minimum, time of, 21 photosynthetic zone, 21 stratosphere, 23 INDEX Silicate, surface, 21, 22, 23 vertical distribution, illustrated, 55 Sintoku Maru, 1, 13 22 South Equatorial Drift, 4, 15 South Pacific East Drift, Strait of Georgia, 1, 21 Stratosphere, 4, 8 hydrogen ion, 28 oxygen, 32, 35-36 phosphate, 9 Silicate, 23 Subphotic layers, 8 Surface water, hydrogen ion, 27, 28 oxygen, 33, 34 phosphate, 7, 12-14 Silicate, 21, 22, 23 Syunpu Maru, 21 4,5 Thermal stratification, 8, 9, 1% Thermocline, 8, 13, 14, 32 Transition zone, 3 hydrogen ion, 28 oxygen, 31, 35 phosphate, 14-16 relation of density gradient, Troposphere, 4, 5 oxygen, 35 phosphate, 16 Upwelling, effect on, hydrogen ions, 28 oxygen, 35 phosphate, 9, 13, 14, 15, 16 Silicate, 21, 24 Western Atlantic Basin, 4 Willebrord Snellius, 1 9 ? i . ueayoy Are. 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