Special Technical Report

Application of in situ

UV Spectrometry for
Characterization of Harbor
Sediment

DATALI

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Contribution 127
February 2000

US Army Corps
of Engineers.

b New England District
ae

form approved
OMB No. 0704-0188

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1. AGENCY USE ONLY (LEAVE BLANK) _|2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
February, 2000 FINAL REPORT

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
APPLICATION OF IN SITE UV SPECTROMETRY FOR CHARACTERIZATION OF HARBOR
SEDIMENT

6. AUTHOR(S)
Gregory A. Tracey, Donald C. Rhoads, and Drew A. Carey

7. PERFORMING ORGANIZATION NAMK(S) AND ADDRESS(ES) 8. PERFORMIGORGANIZATION
Science Applications International Corporation REPORT NUMBER
221 Third Street SAIC-455
Newport, RI 02840

10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
DAMOS Contribution No. 127

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
US Army Corps of Engineers-New England District

696Virginia Rd

Concord, MA 01742-2751
11. SUPPLEMENTARY NOTES
Available from DAMOS Program Manager, Regulatory Branch
USACE-NAE , 696 Virginia Rd, Concord, MA 01742-2751

12b. DISTRIBUTION CODE

12a. DISTRIBUTION/AVAILABILITY STATEMENT
Approved for public release; distribution unlimited

13. ABSTRACT

Polycyclic Aromatic Hydrocarbons (PAHs) are common constituents of aquatic sediments in navigable waterways.
The need for maintenance dredging and concern over proper disposal of dredged sediments requires that the distribution and

concentration of chemicals such as PAHs be known. This report presents preliminary findings from laboratory and field tests
of a portable fluorescence imaging system for mapping PAH distribution in sediment.

The UltraViolet-Remote Ecological Monitoring Of The Seafloor (UV-REMOTS®) instrument collects a vertical
profile image of the top 6-8 cm of sediment at the sediment-water interface. Adapted from the photo REMOTS® system, it is
designed to provide a two-dimensional digital image wherein each component pixel constitutes a full spectral characterization
of fluorescence emission in response to a UV light source. The excitation and emission frequencies are selected to optimize

for the known PAH fluorescence response to UV light. Because PAHs are composed of many different compounds, variation
in intensity and spectral pattern correspond to changes in PAH concentration and composition.

Results of the laboratory tests with spiked sediments indicate the UV-REMOTS® system can detect differences in
PAH concentration and composition in the range of 10-100 ppm (ug/g dry weight) and above. Field results from the
Providence River suggest measurable differences in fluorescence between sampling locations as well as small-scale variation
in fluorescence within the image of a single sample. Based these results, it is concluded that UV-REMOTS® shows good
promise as a tool for rapid assessment of PAH concentration, composition and spatial distribution.

14. SUBJECT TERMS Polycyclic Aromatic Hydrocarbons (PAHs), portable 15. NUMBER OF TEXT PAGES: 11

fluorescence imaging system, UV-REMOTS®

16. PRICE CODE

17. SECURITY CLASSIFICATION OF|18. SECURITY CLASSIFICATION |19. SECURITY CLASSIFICATION {|20. LIMITATION OF
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APPLICATION OF IN SITU UV SPECTROMETRY
FOR CHARACTERIZATION OF HARBOR SEDIMENT

CONTRIBUTION #127

February 2000

Submitted to:
Regulatory Branch
New England District
U.S. Army Corps of Engineers
696 Virginia Road
Concord, MA 01742-2751

Prepared by:
Gregory A. Tracey, Donald C. Rhoads,
and Drew A. Carey

Submitted by:

Science Applications International Corporation
165 Dean Knauss Drive
Narragansett, RI 02882

and
Admiral's Gate
221 Third Street
Newport, RI 02840
(401) 847-4210

US Army Corps
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TABLE OF CONTENTS

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LIST OF FIGURES
(Figures located in Appendix)

Figure 1. Locations of UV-REMOTS® for characterization of harbor sediment

Figure 2. Results of UV-REMOTS® laboratory analysis of anthracene (ANT) spiked
water and sediments: A)Reference sediment in seawater; B) ANT and
seawater; C) ANT and sediment; and D) Sediment PAH mix with ANT

Figure 3. Inter-comparison of full sediment area spectra at each location for each
excitation wavelength

Figure 4. Inter-comparison of entire imaged area spectra for each excitation
wavelength
Figure 5. RGB Images at Shooters Dock, Site 2, State Pier, and Sassafras Point showing

full mask (i.e., complete imaging) and spatial location of individual ROIs
Figure 6. Inter-comparison of the six ROIs at Shooters Dock and Site 2

Figure 7. Inter-comparison of the Middle Left ROI at the three locations for all four
excitation wavelengths

Figure 8. Inter-comparison of the Middle Right ROI at the three locations for all four
excitation wavelengths

Figure 9. Inter-comparison of the Bottom Left ROI at the three locations for all
excitation wavelengths

Figure 10. _‘Inter-comparison of the Bottom Right ROI at the three locations for all four
excitation wavelengths

Figure 11. _Inter-comparison of each ROI at the three locations for the 299 nm excitation
wavelength

Figure 12. Inter-comparison of each ROI at all three locations for the 314 nm excitation
wavelength

Figure 13. _Inter-comparison of each ROI at all three locations for the 335 nm excitation
wavelength

Ul

LIST OF FIGURES (continued)

Figure 14. _ Inter-comparison of each ROI at all three locations for the 365 nm excitation
wavelength

LIST OF TABLES
(Tables located in Appendix)

Table 1. PAH Concentrations from the Providence River (PR) and Harbor (November
1992)
Table 2. Statistical Summary of Non-Zero Pixel Abundance by Excitation Wavelength

and Region of Interest (ROI) for UV-REMOTS®

Table 3. Statistical Summary of Non-Zero Pixel Abundance by Excitation Wavelength
and Sample Location for UV-REMOTS®

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EXECUTIVE SUMMARY

Polycyclic Aromatic Hydrocarbons (PAHs) are common constituents of aquatic
sediments in navigable waterways. The need for maintenance dredging and concern over
proper disposal of dredged sediments requires that the distribution and concentration of
chemicals such as PAHs be known. This report presents preliminary findings from
laboratory and field tests of a portable fluorescence imaging system for mapping PAH
distribution in sediment.

The UltraViolet-Remote Ecological Monitoring Of The Seafloor (UV-REMOTS®)
instrument collects a vertical profile image of the top 6-8 cm of sediment at the sediment-
water interface. Adapted from the photo REMOTS® system, it is designed to provide a
two-dimensional digital image wherein each component pixel constitutes a full spectral
characterization of fluorescence emission in response to a UV light source. The excitation
and emission frequencies are selected to optimize for the known PAH fluorescence
response to UV light. Because PAHs are composed of many different compounds,
variation in intensity and spectral pattern correspond to changes in PAH concentration and
composition.

Results of the laboratory tests with spiked sediments indicate the UV-REMOTS®
system can detect differences in PAH concentration and composition in the range of 10-
100 ppm (ug/g dry weight) and above. Field results from the Providence River suggest
measurable differences in fluorescence between sampling locations as well as small-scale
variation in fluorescence within the image of a single sample. Based these results, it is
concluded that UV-REMOTS® shows good promise as a tool for rapid assessment of PAH
concentration, composition and spatial distribution.

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1.0 INTRODUCTION

One of the essential missions of the U.S. Army Corps of Engineers (USACE) is to
monitor and maintain navigable waterways. Particulates originating from rivers, land
runoff, and atmospheric deposition accumulate in harbors and channels. Dredging is
required to restore the depth and width of these channels and harbors. A variety of
chemicals of concern (CoCs) are associated with these particulates which may pose a
problem for aquatic biota depending upon their concentration. One of the major classes of
CoCs is Polycyclic Aromatic Hydrocarbons (PAHs). PAHs enter the environment in raw
(i.e., petrogenic) form as oil and fuel products or in a combusted (i.e., pyrogenic) form
such as stack ash and automobile exhaust.

As part of the regulatory requirements for dredging, the USACE must characterize
the quantity and type of sediments that require dredging and determine their suitability for
land or aquatic disposal. Although the ultimate determination of suitability rests on
biological effects testing (e.g., EPA/USACE 1994, 1998), the measurable levels of CoCs
in surface sediments provide a critical guide for project scoping and sample location.

Traditional analyses (e.g., for PAHs) in bottom sediments for purposes of
contaminant characterization typically involve sample collection, chemical extraction, and
instrumental analysis (e.g., UV spectrometry, gas chromatography/mass spectrometer,
and/or high performance liquid chromatography). These traditional methods have the
advantage of low analytical detection limits but are laborious, expensive, and time
consuming. The sheer number of sediments requiring characterization as well as the long
analytical time-frame and high cost per sample of chemical analysis present an increasingly
formidable challenge to the USACE in executing its responsibilities for characterizing
harbor sediments. As a result, the USACE has expressed a need for field instrumentation
that can be rapidly and inexpensively deployed to characterize and quantify PAH
concentrations in sediment.

Science Applications International Corporation (SAIC) has developed a prototype
field instrument called UV-REMOTS® (UV-R) which shows great promise for the rapid
evaluation of PAH composition and concentration in sediment. The basic format for the
technology is based on the original REMOTS® sediment profile camera which produces a
photographic image of the sediment-water interface (to 20 cm depth) such that various
habitat attributes (sediment, grain-size, fabric, depth of mixture, and community structure)
can be ascertained. In UV-R, the analog visible (white light) camera system of REMOTS®
was replaced with a digital camera and UV-light source such that chemicals that fluoresce
under UV light can be detected and quantified (Rhoads et al. 1995).

In this report, the results of the first substantial field deployment of UV-R in the
Providence River of Narragansett Bay are presented. The objectives of the study were 1)
to assess the operational performance characteristics of the instrument under field

conditions; 2) to evaluate the fluorescence properties of field sediments in relation to
expected (laboratory-based) PAH distribution/concentration measurements; 3) evaluate the
spatial patchiness of PAHs in undisturbed (i.e., in-situ) material sediments; and 4) evaluate
the ability of UV-R to distinguish differences in PAH distribution within the sediment
column. The results of the investigation will be discussed relative to these four objectives;
recommendations for additional system improvements, data analysis, and data needs are
also provided.’

' Funding for this work was provided primarily by the USACE Waterways Experiment Station, Vicksburg, MS
with supplemental funding from the NAE DAMOS Program.

2.0 MATERIALS AND METHODS

Field test objectives were evaluated in the Upper Providence River, Rhode Island at
selected stations. Spectral data on PAHs in sediment were collected using UV-R and
qualitatively compared with existing bulk sediment chemistry. Prior to the field test, the
response characteristics of UV-R were determined in a series of laboratory bench tests in
which ambient sediments were mixed with known concentrations of PAHs of interest.

2.1 Laboratory Studies

In the development of the UV-R technology, SAIC as part of its Internal Research
and Development (IR&D) program, conducted a series of experiments since 1993 to
evaluate PAH fluorescence properties and optimized the UV-R hardware and software
systems for PAH detection and analysis. For this report, example laboratory data sets
derived from anthracene-spiked water and sediment matrices are included to provide a
comparison for interpretation of field results. Results of four treatments are presented:

1) seawater only;
2) seawater + 1000 ppm anthracene; and
3) anthracene + seawater + sediment at 1000 ppm final concentration.

2.2 Field Sampling

Field deployment of the UV-R system was carried out from November 22-26,
1997, at nine stations shown in Figure 1 including one site each at Sassafras Point, Fields
Point Bulkhead, State Pier, and Station E Pipes, and two sites each at the Shooters Dock
and the Hurricane Barrier. The sites were selected based on historical measurements of
PAH concentration within the general study area. No traditional chemical analyses of
PAH concentration were made at the time of UV-R deployment.

2.3 Camera Operation

Deployment of the UV-R camera is similar to the deployment of the white light
REMOTS® camera (Rhoads and Germano 1986). The UV-R camera is lowered to the
bottom and the prism descends to the seafloor, slowed by hydraulic pistons, and is allowed
to penetrate the sediment. When the optical prism is in the mud, the camera first collects a
digital RGB image consisting of 640 x 480 pixels to allow for visualization of objects in
the sediment as well as the sediment/water interface. The 640 x 480 image is divided into
“bins,” four pixels on each side. The 4 x 4 pixel binning is applied to increase signal
strength for fluorescence detection while still providing adequate image resolution. A
mercury (Hg) vapor light source sequentially emits four separate excitation wavelengths of
299, 314, 335, and 365 nm. The PAHs in the sediment absorb energy at these

wavelengths and, depending on concentration and composition, will emit “red shift” light
(i.e., fluoresce) across a broad spectrum of wavelengths. Based on prior investigation and
literature values, specific wavelengths were selected to measure the fluorescence response
and hence characterize the PAH composition of the sample. Before the red shift light is
collected for spectral measurement, a blocking filter is used to block-out all excitation
light. The selected emission endpoints include 17 total narrow wavelengths including 15
wavelengths between 350-500 nm (at increments of 10 nm) and two additional wavelengths
at each of 550 nm and 600 nm bandwidths. In this manner, up to 68 intensity images (17
emission X 4 excitation bands) for each image replicate can be obtained.

Also collected on each sampling day are dark field (camera on, no light) and white
field images (camera on, white surface illuminated) for the purpose of correcting internal
electrical noise and variation in target illumination, respectively. The resulting data are
internally stored then relayed to the surface computer after one or several samples are
collected.

2.4 Data Processing and Analysis

The primary method of correcting raw image (RI) data for variance in electronic
noise and sample illumination is described in Equation 1:

CI (i,j) = (RI Gj) - DF (i,j) / WF Gj) (1)

where CI = corrected image matrix, DF = dark field image matrix, and WF = white field
image matrix, and i,j is the row and column location of pixels. In the above corrections,
the DF matrix is used to remove electrical noise in the camera system, while the WF
matrix permits correction of individual pixels for differences in pixel illumination across
the image. Except where noted, the above corrections were applied to all data sets
included in this report.

MATLAB programs (Mathworks, Inc.) were written to visualize the data and
perform the above corrections. The program permits further examination of the data using
area, intensity, and spectral quality filters for specified Regions of Interest (ROI) within the
image. ROIs are selected by the user and depend on the camera penetration depth and
other features readily visible in RGB images taken at the same location. For example,
ROIs are used to mask out the water column part of each image and to limit the ROI to
only those parts of the sediment profile that exhibit fluorescence.

3.0 RESULTS
3.1. Laboratory Studies

Laboratory investigations with anthracene in water and sediment were performed to
evaluate the spectral sensitivity of the UV-R system to PAH concentration. Typical spectra
of clean ‘reference’ sediment from Central Long Island Sound for four excitation
wavelengths show corrected fluorescence intensity ranges from 10-80 units (Figure 2A).
Measured anthracene concentration for this sediment was <1 ppm. In contrast, the spectra
obtained when 1000 ppm anthracene is added to seawater (0 to 1200 units; Figure 2B) or
sediment (0 to 1100 units; Figure 2C) show a characteristic anthracene signature (note
change in intensity scale). The 365 nm excitation band (1100-1150 ADU) exhibits a
strong peak at 420 nm, (i.e., dropping sharply for higher and lower excitation
wavelengths) and a secondary peak at 450 nm. Little difference in the anthracene spectra
is observed whether the carrier matrix is water or sediment.

The spectral signature of a PAH mixture containing approximately 500 ppm
anthracene, benzo(a)pyrene and pyrene in sediment is more complex (Figure 2D). The
latter two PAHs are known to have peaks at 420 nm as well as broader peaks in the 450-
500 nm range. The peak for anthracene at 420 nm is retained, although apparently
augmented by fluorescence at this wavelength from either benzo(a)pyrene and pyrene.
These data illustrate the need for a spectral PAH library so as to permit the deconvolution
(i.e., spectral unfolding) of the PAH mix spectra into its component parts.

3.2 Field Data

Preliminary analysis of the RGB images taken at the locations shown in Figure 1
indicated that only three of the locations had sufficient camera penetration to produce data
for analysis. These locations included Shooters Dock site 2 (A), State Pier (C), and
Sassafras Point (E), (Figure 1).

Data images from the above locations were inspected to characterize both between
and within-station differences in PAH distributions. Between station characterizations were
conducted to address horizontal gradients of PAH distribution which might be correlated
with known PAH gradients in the Providence River. Within-station analyses focused on
investigation of PAH vertical distribution in the sediment column, particularly the existence
of potential “hot spot” areas which might be caused by aggregations of PAH particulates
(e.g., coal tar) or bioturbation patterns. Horizontal and vertical spatial analyses are
presented separately below.

3.2.1 Horizontal Characterization

To test for between station differences in PAH concentration and composition,
images collected at three stations (Shooters Dock, Site 2 [A], State Pier [B], and Sassafras
Point [D]) were spectrally analyzed. Results are presented by station and excitation band
in Figures 3 and 4, respectively. In Figure 3, the three stations show that the 365 nm
excitation wavelength generated the largest fluorescence intensities, exceeding by a factor
of 3 to 4 those contributed by other wavelengths.

A comparison across stations at the same excitation wavelength is shown in Figure 4.
Two notable features in the data are the peak at 314 nm excitation/400 emission band (B) at
Shooters, and the higher emission for the Shooters or Sassafras Point samples relative to the
State Pier sample at 299, 314, and 365 nm (A,B,D). Higher fluorescence returns for
Shooters/Sassafras vs. State Pier is probably related to total PAH concentration in the
sediment; the State Pier station is generally lower in Total PAH and constituent analytes
than the other two locations based on 1992 analyses of PAH concentrations (Table 1). An
alternative explanation is the presence of dissolved humic or chlorophyll/phaeophytin
substances which exhibit a broad fluorescence emission peak centered between 420 and
460 nm. The discrimination between the two potential fluorescing agents will require
further characterization. The 314 excitation/400 emission peak (B) may be explained by
high pyrene in the sediment (13 ppm) (Table 1), as this compound has peak emission at 398
nm (Rudnick and Chen 1998), although a similar pyrene peak was not observed for the
laboratory PAH mix discussed in Section 3.1.

3.2.2 Vertical Characterization

To test for within-station difference in PAH concentration and composition, four
Regions of Interest (ROI) were selected for each of the three stations (Shooters Dock 2,
State Pier, and Sassafras Point) as indicated by open circles in the RGB images of
Figure 5. Possible variation may be due to the history of sediment deposition and/or
localized bioturbation. The ROI locations were selected to maximize area while avoiding
image edges. These ROIs have the same size (pixel population) and spatial orientation.
The ROIs are designated in the results below as Middle Left (ML), Middle Right (MR),
Bottom Left (BL), and Bottom Right (BR). An additional two ROIs were selected for
Shooters Dock, Site 2 to characterize the water column immediately above the sediment.
These ROIs were designated as Top Left (TL) and Top Right (TR).

Spectral analysis of each ROI allowed for an inter-comparison of each site and also
allowed for spectral comparison of ROIs containing just water and/or just sediment. An
analysis was performed on the six ROIs at Shooters Dock, Site 2, to compare the two ROIs
located entirely in the water column with the sediment signals (Figure 5A). Results are
shown in Figure 6. The purpose of this analysis was to determine how fluorescence
returns in the water column (a shade was used to cover the camera prism’s optical window

to minimize infiltration of visible light) compared with the intensities of the
sediment/interstitial water. From Figure 6, it is seen that ambient light leakage intensities
are similar to those found in the sediment for emission spectra of 350-450. However,
emission wavelengths of 500-600 (visible light wavelength) had much larger intensities.
This observation underscores the importance of having an efficient “shade” on the camera
to prevent visible light contamination.

In order to exclude water column light noise in the analysis of sediment-associated
PAH spectra, the remainder of the analyses focus on the Middle and Bottom ROIs as these
areas encompass only sediment. Each of these ROI is presented separately by station in
Figures 7-10. As found for the whole sediment samples, the 365 nm excitation band
produces highest emission intensities for each of the locations.

The same data presented by excitation wavelength in Figures 11-14 do reveal some
ROI-specific phenomena. For example, unique peaks are observed:

1) at 299 excitation /430 emission for bottom left (BL) and bottom right (BR) ROI for
Sassafras and State Pier (Figure 11E,F);

2) at 314/380, 314/420 and 314/450 nm combinations for Middle left ROI at State Pier
(Figure 12C); and

3) at 335/440, 335/450 combination for Middle Left and Middle Right ROI at State
Pier and Sassafras Point, respectively (Figure 13 [C,D]).

Finally, the 365 nm peak for the BR-ROI is higher for Shooters/Sassafras as found
previously for the whole sediment, but in the three other regions, Shooters emission was at
or below State Pier (Figure 14). Hence, the bottom right portion of the spectra was
dominating the return observed for the full image, possibly indicating a locally higher PAH
concentration.

3.3. Intensity Analysis

The data sets presented above have been processed using the full correction
algorithm (Equation 1) without regard to the intensity of the fluorescence emission. That
is, the data results represent average fluorescence emission over the entire ROI. In this
section, the variance of the fluorescence emission pattern are analyzed to discern whether
highly localized (i.e., pixel-scale) emissions occur which may relate to small amounts of
PAH materials (e.g., soot particles, oil droplets). The inspection of pixel returns within
ROIs reveal that relatively few of the pixels in each ROI actually contained detectable
emission data (Table 2). For example, the average number of non-zero pixels ranged
about 1-9% at Shooters 2; the other two sites were found to have similar statistical
distributions. It is also apparent that the number of non-zero pixels for the entire sediment

image increases proportionately with number of sampled pixels (Table 3).

As seen in Tables 2 and 3, the area of emission (number of non-zero pixels)
resulting from 335 nm excitation was typically 3X lower and 365 nm 2X higher than either
the 299 nm or 314 nm bands. Such differences may be related to the optical density of the
excitation filters and/or lamp intensity at the particular wavelength. The relatively low
number of non-zero pixels is attributed to low PAH signal in comparison to camera and
background noise.

4.0 DISCUSSION

Laboratory studies have demonstrated the capability of UV-R to detect various PAH
analytes and quantify concentrations in the range of 10-100 ppm and higher. PAH data
determined on traditional chemical analyses of grab samples, show the concentrations of
total PAHs at State Pier and Sassafras Point (20 and 30 ppm, respectively) have directly
proportional fluorescence intensities (365 nm excitation; 400 and 600 maximum ADU,
respectively; Figure 3). This suggests a possible correlation between the total PAH field
concentrations and the derived intensity spectra from the UV-R, although obviously a more
rigorous experimental design is needed to establish this apparent correlation.

Spectral differences were observed between stations which may be related to the
relative concentration of specific PAH analytes, particularly pyrene. Again, definitive
analysis of PAH composition will require more extensive field and laboratory testing.
Here, one of the primary needs is the development of PAH spectral libraries and non-
parametric statistical analysis routines (e.g., signal theory) to decode the PAH signature
into its component parts. In this effort, a focus on a few PAH analytes which are
surrogates for overall PAH transport pathways (e.g., pyrene for pyrogenic compounds,
anthracene for petrogenic compounds) may be sufficient for field reconnaissance mapping
to permit characterization of Total PAH concentration.

Results of sediment column characterizations also show that ambient PAH
concentrations at selected locations are near the present detection limit of the instrument.
For these locations, approximately 3% of the pixels in the ROI are above internal camera
noise and illumination variance. This would suggest that the selected ROI should be kept
sufficiently large so as to incorporate an adequate sample size to characterize PAH
composition. Increased binning and emission reading times can also increase S:N ratios.
In the present data set, the full sediment image (excluding water column) had > 100 pixels
for three of four excitation bands (Table 3), which should represent a large enough sample
for spectral analysis. The more limited data density for individual ROI (generally <20
pixels/ROI; Table 2) would reduce the certainty of spectral characterization.
Notwithstanding, smaller ROIs used in the present investigation have permitted the
elucidation of more spatially isolated spectra (e.g., “hot spots”) which would otherwise be
lost in the signal obtained from a full sediment image.

10

5.0 CONCLUSIONS

From the results of UV-R field demonstration, the following conclusions can be
drawn:

> The prototype field system shows good promise of detecting PAHs in water and
sediment in the range of 10-100 ppm and above. With further development, a rapid
means of assessing PAH distributions may be feasible in the next several years;

> The optical/mechanical system was proven to be field-ready;

> The system has detected station to station differences which may be related to PAH
concentration and composition;

> The system has detected small sediment column spatial variations, which suggest
micro scale variation in PAH distribution within the top 0-15 cm of surface
sediments.

The UV-R camera system developed by SAIC is still in its experimental stages.
Recommendations for improving the overall quality of the results include modifying the
camera system to reduce internal noise, stray reflections, and hot spots (replacing scratched
lenses, dirt on the first-surface reflecting mirror and higher quality RGB filters). The
second recommendation arises in the processing of the image data. A non-parametric
approach should be developed to characterize and isolate the internal noise to better permit
the separation of this signal from the sample data. Such noise reduction algorithms are
commonly employed in signal processing of acoustic data, for example, and could be
readily applied to the UV-R data sets. At present, the parametric method for signal
correction, while applicable to high PAH environments (e.g., oil spills) is too severe for
lower PAH environments created by non-point sources. This system was developed for
synchronous spectral analysis (i.e., emission intensity averaged over time). Future
configurations might consider application of this “time-resolved” spectrometry (i.e.,
emission growth and decay rate) such as employed in other systems (Rudnick and Chen
1997).

I]

6.0 REFERENCES

Rhoads, D. C.; Germano, J. D. 1986. Interpreting long-term changes in benthic
community structure: a new protocol. Hydrobiologia. 142:291-308.

Rhoads, D. C. 1995. Measuring Hydrocarbon Contaminants on the Seafloor. Sea
Technology. August 1995.

Rhoads, D. C.; Muramoto, J.A.; Coyle, C.; Ward, R. H.; Anderson, R. 1996. Rapid In-
Situ assessment of Organic Contaminants in Aquatic Sediments with the REMOTS®
UV Imaging Spectrometer. Presentation. Proceedings of “Conference on Challenges
and Opportunities in the Marine Environment, Marine Technology Society.’
Washington, D.C.

Rudnick, S. M.; Chen, R. F. 1997. Real time, in situ instrumentation for the detection of
pollutants in the coastal environment. Coastal Zone 97 Conference Proceedings, ed.
M. C. Miller and J. Cogan, Vol 1:408-410, Boston, MA July 19-15, 1997.

Rudnick, S.M.; Chen, R. F. 1998. Laser-induced fluorescence of pyrene and other
polycyclic aromatic hydrocarbons (PAH) in seawater. Talanta 49:907-919.

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disposal site
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gas chromatography (GC), 1
habitat, 1
hurricane, 3
organics
polyaromatic hydrocarbon (PAH), iii, v, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
REMOTS®, 1, 3, 11
sediment
chemistry, 3
sediment sampling
grabs, 9
statistical testing, v, 8, 9

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Appendix

QO Figure |. Locations of UV-REMOTS for characterization of harbor sediment.

Sp
=a BAe BROVIDENGE

A. Shooters Dock
B. Hurricane Barrier
C. State Pier

D. Station E Pipes
E. Sassafras Point
F. Fields Point

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Shooters Dock 2

Location : Entire Area

LEGEND
(excitation wavelengths)
—— 2g99nm ~----- 314 nm
— -- 335nm -—- 365nm
State Pier Sassafras Point
B 0 — COD pia
|
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400: ok ‘i |
| we 500} \
= 300: | : \ r= | : :
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oe o \ ;
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IN
200 Wea
[ l COQ SOR INN \
100 | Co ee
| eS a a
ee ee Eee 0 =
350 400 450 500 550 600 350 400 450 500 550 600

emission wavelengths (nm)

Figure 3 A-C. Inter-comparison of full sediment area spectra at each location for each excitation
wavelength.

Wavelength :

299 - 365

299 nm
200
i
150 Vag eo
He aaa
100 i SS
maf ~
a ee oa
350 400 450 #500
335 nm
200
150 Pa
Fieve Kas
100° [is
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5O), et,
350 400 450 #500

600

LEGEND
—-—— Shooters 2
— -- State Pier

-- Sassafras Point

314 nm
300
200 - Ne GOES
/ ONG
100-9 ae:
350 400 450 500
365 nm
800
600 e
if \
400 fa
ig TaN
i | SS
200 - i

a0
Y!
a

0:
350 400 450 500

emission wavelengths (nm)

Figure 4 A-D. Inter-comparison of entire imaged area spectra for each excitation wavelength.

A) Shooters Dock, Site 2

Upper top ROIs (both left and right) are
in the water column. Bottom four are the
sediment-water interface

B) State Pier C) Sassafras Point
All ROIs are in the sediment All ROIs are in the sediment

Figure 5 A-C. RGB Images at Shooters Dock, Site 2 (A), State Pier (B), and Sassafras Point (C)
showing full mask (i.e., complete imaging) and spatial location of individual ROIs.

Station: Shooters Dock, Site 2

LEGEND
(location of ROIs (see also Figure 5 A-C))
re © top left * * top right
— - -— middle left -—-— middle right
—— bottomleft ----- bottom right

299 nm - all locations - 314 nm - all locations

B_ 1000

500

Intensity

os ye
350 400 450 500 550 600 350 400

450 500 550 600
335 nm - all locations

Ae:
350 00 450 500 550 600
emission wavelengths (nm)

Figure 6 A-D. Inter-comparison of the six ROIs at Shooters Dock and Site 2. Note the high

intensities above 500 nm present in the top ROIs due to visible light contamination
from the overlying water column.

Shooters Dock 2
ROI Location : middle left A

LEGEND
=
=e LOOMM) ae = 314 nm c
=
— -- 335nm -—- 365nm
State Pier
B 1200 Cc
£ =
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emission wavelengths (nm)

Figure 7 A-C. Inter-comparison of the Middle Left ROI at the three locations for all four
excitation wavelengths.

Intensity

ROI Location : middle right

LEGEND
—— 299nm ~~ ----- 314 nm
— - - 335nm -—- 365nm
State Pier
500:
A
400 Lior
300! Loe aaa
| | .
200} \

Intensity

i
{
1

Shooters Dock 2

ee Ae |
i

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350 400 450 500 550 600

emission wavelengths (nm)

excitation wavelengths.

Figure 8 A-C. Inter-comparison of the Middle Right ROI at the three locations for all four

Shooters Dock 2
ROI Location : bottom left 0.

LEGEND
2
——— 299nm }} ----- 314 nm S
i=
—-- 335nm -—- 365nm
State Pier Sassafras Point
es a a ae ee dee ee
| |
A ! 1

Intensity

emission wavelengths (nm)

Figure 9 A-C. Inter-comparison of the Bottom Left ROI at the three locations for all four
excitation wavelengths.

Shooters Dock 2
ROI Location : bottom right A

LEGEND

=
(7)

—— 299nm }7 -----= 314 nm =
i=

— - - 335nm -—- 365nm

State Pier
B_ 800 CS

Intensity
Intensity

-
350 400 450 500 550 600
emission wavelengths (nm)

Figure 10 A-C. Inter-comparison of the Bottom Right ROI at the three locations for all four
excitation wavelengths.

Excitation Wavelength : 299 nm

ROI = middle left
A 800

0 B = =
350 400 450 500 550
ROJ = bottom left

LEGEND
-—— Shooters 2
— -- State Pier

Sassafras Point

ROI = middle right

0
350 400 450 500 550 600
ROI = bottom right

D 600 $A j

400 f

200

Figure 11 A-D. Inter-comparison of each ROI at the three locations for the 299 nm

excitation wavelengths.

Excitation Wavelength : 314 nm

ROI =middle left
A 1000 $A

0 = =
350 400 450 500 550 600
RO] = bottom left

LEGEND
— Shooters 2
— -- State Pier

aaSce Sassafras Point

ROI = middle right

qi
350 400 450 500 550 600
ROI = bottom right

as
350 400 450 500 550 600

emission wavelengths (nm)

Figure 12 A-D. Inter-comparison of each ROI at all three locations for the 314 nm

excitation wavelength.

Excitation Wavelength : 335 nm

ROI = middle left

0 Bie é = ey =
350 400 450 500 550 600
ROI = bottom left

LEGEND
— §Shooters 2
— - -— State Pier

SSSos Sassafras Point

ROI = middle right

; \
a
CA

AleaNe MG
350 400 450 500 550 600
ROI = bottom right

0
350 400 450 500 550 600

emission wavelengths (nm)

Figure 13 A-D. Inter-comparison of each ROI at all three locations for the 335 nm

excitation wavelength.

Excitation Wavelength : 365 nm LEGEND

— Shooters 2
— -- State Pier

=Ss5e Sassafras Point

ROI= middle left ROI = middle right

9 — (yee
350 400 450 500 550 600 350 400 450 500 550 600
RO] = bottom left ROI = bottom right

) c z H { > ————
350 400 450 500 550 600 350 400 450 500 550 600

emission wavelengths (nm)

Figure 14 A-D. Inter-comparison of each ROI at all three locations for the 365 nm
excitation wavelength.

Table |. PAH concentrations from the Providence River (PR) and Harbor (November, 1992).

Upper PR State Pier Sassafras Point
Analyte DQ

otal PAHs*

units: ppm

* sum of detected values and detection limits

Data Qualifier (DQ):

U = undetected

B = analyte also detected in method blank

J = estimate value; less than Practical Quantitation Limit

Table 2. Statistical summary of non-zero pixel abundance by excitation wavelength and Region
of Interest (ROI) for UV-REMOTS.

Excitation Wavelength

mex
—— ee

Total sla Mean of
Pixels vee % Total aes % Total Beis % Total arcs % Total | % Total

ROI - Region of Interest

Table 3. Statistical summary of non-zero pixel abundance by excitation wavelength and sample
location for UV-REMOTS.

ee Wavelength _ td

LE Bisse le a
Pixels anes % Total pee % Total % Total} Pixels | % Total} % Total

100 | 2.20

400 | 4.70

1.20

eR SCI A a 0.63 ae |

ROI - Region of Interest