903R871fl? United, States Environmental Protection Agency
Vff CBP/TRS 14/87
September 1987
U S. environmental Protection f
Regiun ill information Resource
CeittBr (3PM52)
841 Ch8S?r,ut Street
Survey of Tributyltin and
Dibutyltin Concentrations at
Selected Harbors in
Chesapeake Bay—Final Report
TD
225
.C54
Chesapeake
Bay
Program
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* -
SURVEY OF TRIBUTYLTIN AND DIBUTYLTIN
CONCENTRATIONS AT SELECTED HARBORS
IN CHESAPEAKE BAY -
FINAL REPORT
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DISCLAIMER
This report has- been reviewed for technical accuracy and approved for publication
by the Chesapeake Bay Program, U.S. Environmental Protection Agency. Approval
does not signify that the contents necessarily reflect the policies of the U.S. Envir-
onmental Protection Agency, nor does mention of trade names or commercial prod-
ucts constitute endorsement or recommendation for use.
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ACKNOWLEDGEMENTS
The author would like to acknowledge the technical support and contributions of:
James Moore and the analytical chemistry staff of the U.S. EPA Environmental Pro-
tection Laboratory at Gulf Breeze for the chemical analysis of the samples; Melvin
Nolan, U.S. EPA Office of Research and Development, and John Tice, Michael Fire-
stone, and Robert Hitch of the U.S. EPA Office of Pesticide Programs for their tech-
nical review and guidance; Elizabeth Gates, Chesapeake Research Consortium, and
Robert Vallandingham, U.S. EPA Central Regional Laboratory, for their field sample
collection efforts; and Nina Fisher and Ricky Price of Computer Sciences Corporation
for their work on technical editing of the report and computer graphics and
analysis, respectively.
ill
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ABSTRACT
The U.S. Environmental Protection Agency's Chesapeake Bay Liaison Office devel-
oped and carried out a small-scale sampling program to measure concentrations of
tributyltin (TBT) and dibutyltin (DBT) at four selected harbor sites in northern
Chesapeake Bay - Annapolis, Solomons, Oxford and Plaindealing Creek. The 20-week
study documented levels of TBT and DBT at a series of stations which were situated to
measure gradients in concentrations from selected harbors out into the adjacent
riverine/estuarine areas. The range in levels of in-water boating and shoreline
marina activity which the four harbors were chosen to represent resulted in a cor-
responding range of observed TBT and DBT concentrations. The study documented a
statistically significant gradient in concentrations originating from within three of
the harbors out into the adjacent river system.
Beyond an initial peak in TBT concentrations at the beginning of the survey
period, no significant upward or downward trend was observed in concentration
over the boating season. A constant range of concentrations was observed after the
initial peaks in May at the Annapolis and Solomons study sites. No initial peak in
concentration was observed at the Oxford study site.
The measurement of TBT and DBT concentrations at the Plaindealing site indicates
that localized sources of TBT within a relatively undeveloped harbor can result in de-
tectable concentrations which can be traced throughout a small creek system, even
when the levels are not maintained beyond a two-week time frame.
Based on analysis of the laboratory quality assurance and control data for the
study, the results reported in this document should be considered conservative esti-
mates of the TBT and DBT concentrations measured in the analyzed samples. The
reported levels of TBT and DBT for the four harbors in northern Chesapeake Bay
should be considered the lower range of concentrations for existing conditions
during the study period.
From the study results, it is concluded that sources of TBT measured in the harbor
areas are directly linked to local boating and marina activity and specifically to TBT
leachate from antifouling paints. The sampled harbors are a source of TBT to the
estuarine environment beyond the boundaries of the harbors. TBT concentrations in
several of the harbors were high and sufficiently constant to pose a threat to organ-
isms living in the harbor areas. Finally, sustained concentrations of TBT at the levels
found in the rivers adjacent to the sampled harbors causes an additional, unneces-
sary environmental stress to shellfish larvae and the plankton upon which they
prey.
iv
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TABLE OF CONTENTS
Disclaimer ii
Acknowledgements iii
Abstract iv
Figures vi
Tables vii
Introduction 1
Study Sites 1
Site Selection 1
Site Descriptions 2
Sample Collection Schedule 10
Materials and Methods 18
Sample Bottle Preparation 18
Field Sample Collection Procedures 18
Sample Handling 19
Analytical Method and Quality Assurance 19
Results 21
Solomons Tidal Cycle 21
Annapolis Site 36
Solomons Site 39
Oxford Site 42
Plaindealing Site 42
Discussion 47
Findings 57
References 58
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FIGURES
1 Chesapeake Bay Tributyltin Sampling Sites 3
2 Annapolis Site 4
3 Annapolis Sampling Stations 5
4 Solomons Site 7
5 Solomons Sampling Stations 8
6 Oxford Site 11
7 Oxford Sampling Stations 12
8 Plaindealing Creek Site 14
9 Plaindealing Sampling Stations 15
10 Example of a Completed Chain of Custody Form 20
11 Tributyltin Concentration vs. Hour for All Solomons Stations
over a Tidal Cycle 34
12 Dibutyltin Concentration vs. Hour for All Solomons Stations
over a Tidal Cycle 35
13 Tributyltin Concentrations vs. Week for All Annapolis Stations 37
14 Dibutyltin Concentrations vs. Week for All Annapolis Stations 38
15 Tributyltin Concentrations vs. Week for All Solomons Stations 40
16 Dibutyltin Concentrations vs. Week for All Solomons Stations 41
17 Tributyltin Concentrations vs. Week for All Oxford Stations 43
18 Dibtuyltin Concentrations vs. Week for All Oxford Stations 44
19 Tributyltin Concentrations vs. Week for All Plaindealing
Stations 45
20 Dibutyltin Concentrations vs. Week for All Plaindealing
Stations 46
vi
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TABLES
1 Latitude/Longitude and Narrative Station Location Descriptions for
the Annapolis Site 6
2 Latitude/Longitude and Narrative Station Location Descriptions for
the Solomons Site 9
3 Latitude/Longitude and Narrative Station Location Descriptions for
the Oxford Site 13
4 Latitude/Longitude and Narrative Station Location Descriptions for
the Plaindealing Creek Site 16
5 Summary of the Random Field Duplicate Collection Schedule 17
6 TBT Concentration Ranges and 20-Week Average for All Stations 22
7 DBT Concentration Ranges and 20-Week Average for All Stations 23
8 Field and Analytical TBT/DBT Data: May 5-September 16, 1986 24
9 Field and Analytical TBT/DBT Data for the August 13, 1986
Solomons Tidal Cycle Survey 33
10 Two-way Factorial Analysis of Variance of TBT Water Column Data 48
11 Duncan's Multiple Range Test of TBT Water Column Data by Site 49
12 Duncan's Multiple Range Test of TBT Water Column Data by Week 50
13 Two-way Factorial Analysis of Variance of DBT Water Column Data 51
14 Duncan's Multiple Range Test of DBT Water Column Data by Site 52
15 Duncan's Multiple Range Test of DBT Water Column Data by Week 53
16 Duncan's Multiple Range Test of TBT Water Column Data by Station 55
17 Duncan's Multiple Range Test of DBT Water Column Data by Station 56
vii
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INTRODUCTION
At the request of the U.S. Environmental Protection Agency's Office of Pesticide
Programs, the EPA Chesapeake Bay Liaison Office developed and carried out a small-
scale sampling program to measure the concentrations of tributyltin (TBT) and
dibutyltin (DBT - a degradation product of TBT) for 20 weeks in selected harbors of
northern Chesapeake Bay during the 1986 summer boating season. The study was
designed to determine the levels of TBT in the estuarine environment resulting from
the use of TBT-based antifouling paints on recreational vessels. The EPA Office of
Pesticide Programs will use data from the study in its ongoing special review of all
pesticide products with tributyltin active ingredients used as paint antifouling ad-
ditives.
STUDY SITES
SITE SELECTION
Annapolis, Solomons, Oxford, and Plaindealing Creek, Maryland were selected as
the study sites for the sampling program (Figure 1). These sites were selected on the
basis of the following criteria:
• Representation of different levels of in-water boating and shoreline
marina activity;
• Availability of background information on harbor/marina facilities
(slips, permanent moorings, railways, travel lifts);
• Anticipated use of TBT-based paints on water craft in the harbor
area;
• Site specific documentation that potential TBT sources were from
leachates originating from in-water boating and shoreline marina
activities and not from other use patterns (power plants, plastic
companies, textile mills and sewage treatment plants);
• Availability of historical information relative to water chemistry
and hydrodynamics; and,
• Enhancement of the spatial and temporal coverage of existing and
and planned TBT monitoring studies in Chesapeake Bay.
The study sites were not selected to specifically represent other harbor areas in
the Chesapeake Bay: they were chosen only to represent a range of boating and mar-
ina activity. Since many environmental factors may affect ambient concentrations
of TBT, there was no attempt in this study to identify those specific environmental
parameters and processes which influenced the TBT or DBT concentrations with the
exception of tidal mixing.
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The objective of the study was to determine the level and extent of TBT in the estu-
arine environment resulting from boating and marina activity within defined
harbor systems. Four equidistant sampling stations were located to measure the gra-
dient of TBT concentrations from the harbor areas into the adjacent river system.
Using National Oceanic and Atmospheric Administration National Ocean Service
(NOAA NOS) navigational charts, stations were spaced along a transect that followed
the predominant current pattern of harbor waters flowing into their associated
riverine/estuarine system. Two stations were designated within the confines of the
harbor adjacent to areas considered to have the most intense boating and/or marina
activity. A third station was located at the confluence of the harbor waters with the
adjoining river. The fourth station was located within the adjacent river system.
SITE DESCRIPTIONS
Annapolis
The four sampling stations of the Annapolis study site (Figure 3 and Table 1)
(NOAA NOS Chart no. 12283) were located on Spa Creek and the Severn River, a trib-
utary of Northern Chesapeake Bay (Figure 1 and 2).
Spa Creek and adjacent reaches of the Severn River have high levels of private
water boating and shoreline marina activities during the spring, summer and fall
months as well as a large number of in-water overwintering boats (Annapolis
Harbormaster Office, Personal Communication, 1986). In the lower third of Spa
Creek, there are reportedly 793 permanent permitted slips (K. Brown, Annapolis
Planning and Zoning, Personal Communication, 1986) as well as several active mari-
nas, boat yards, and private slips and moorings. Throughout the year, there is . sub-
stantial in-water transient boating activity.
There are no permitted industrial or municipal effluent discharges into Spa Creek
(K. Brown, Annapolis Planning and Zoning, Personal Communication, 1986). How-
ever, because the Annapolis Water Reclamation Facility's final discharge mixing
zone is located in the Severn River in proximity to the study site (Carter 1965),
triplicate water samples were collected from the facility's treated effluent. Fresh-
water inflow to the study site is restricted to stormwater runoff.
Solomons
The Solomons study site is located on Back Creek and the Patuxent River, two miles
from the Chesapeake Bay mainstem (Figure 1 and 4). The Solomons site represents a
harbor area with high levels of boating and shoreline marina facility activity. The
sampling stations were located on Back Creek, the confluence of Back and Mill
creeks, and the Patuxent River (Figure 5 and Table 2) (NOAA NOS Chart no. 12284).
The boating and shoreline marina activities are concentrated in the lower two-
thirds of Back Creek and in the Narrows. Approximately 1300 marina slips are located
in Back Creek and the Narrows with 7 active marine railway and travel lift marina
operations (S. Zahniser, Zahniser's Marina, Personal Communication, 1986).
There are no permitted industrial or municipal effluent discharges into Back
Creek or the Narrows. The surrounding residential community discharges into
private septic systems (M. Garreis, Maryland OEP, Personal Communication 1986).
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Figure 1 Chesapeake Bay Tributyltin Sampling Sites
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Figure 2. Annapolis Site
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Table 1: Latitude/Longitude and Narrative Station Location Descriptions for the
Annapolis Site
STATION LATITUDE LONGITUDE
AH-1 38.9728 76.4907
STATION DESCRIPTION: Single pier piling lined up with the center of Compromise
Bridge (drawbridge control office) crossed with the green "3" channel marker lined
up with the right hand edge of the Amoco building on the transect between the 6
mph wake sign and the middle of the adjacent bulkhead (and the green house).
STATION LATITUDE LONGITUDE
AH-2 38.9728 76.4850
STATION DESCRIPTION: The green "3" channel marker lined up with the first
bridge abutment to the right of the center of Compromise Bridge crossed with a direct
sighting down the Annapolis Yacht Club pier.
STATION LATITUDE LONGITUDE
AH-3 38.9769 76.4805
STATION DESCRIPTION: The green "1" can transected with the lamp post at the
corner of the Naval Academy seawall crossed with the red "14" nun lined up with the
left leg of the left radio tower (of the "double tower").
STATION LATITUDE LONGITUDE
AH-4 38.9774 76.4750
STATION DESCRIPTION: The green "1" can transected with green light across the
Severn River crossed with the transect from the edge of the bulkhead on Horn Point
(at the tan house) to the corner of the Naval Academy seawall, where the edge lines
up with the white house on the hill. The red nun lines up with the left leg of the left
radio tower (of the "double towers") when on station.
-6-
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Rgure 4. Solomons Site
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Table 2: Latitude/Longitude and Narrative Station Location Descriptions for the
Solomons Site
STATION LATITUDE LONGITUDE
SI-1 38.3303 76.4576
STATION DESCRIPTION: Midchannel on the transect between the gray flat roofed
marina building and the two crossed pilings at the end of the marina pier at the site
where the red marker lines up with the middle of the 2-story gray building.
STATION LATITUDE LONGITUDE
SI-2 38.3254 76.4573
STATION DESCRIPTION: Midchannel on the transect between the green "5"
channel marker and the end of the bulkhead (at the sandbar) crossed with transect
between the red "4" channel marker and the left edge of the Calvert Marina building.
STATION LATITUDE LONGITUDE
SI-3 38.3219 76.4522
STATION DESCRIPTION: Midchannel at the mouth of the Back Creek on the transect
between the red/green channel marker and the red "4" channel marker crossed with
the transect between the "No Wake" marker and the tallest of the four storage tanks.
STATION LATITUDE LONGITUDE
SI-4 38.3195 76.4490
STATION DESCRIPTION: Located on the transect between the end of the Chesapeake
Biological Laboratory pier to the green "3" channel marker crossed with the site
where the red "2" channel marker lined up with the red channel marker.
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Oxford
The Oxford study site is located adjacent to the Tred Avon River, 2 miles from its
confluence with the Choptank River, a tributary to Chesapeake Bay (Figures 1 and 6).
The Oxford study site is a harbor area which has medium levels of private boating and
marina activity in comparison with the Annapolis and Solomons sites, with limited
in-water transient boat activity. The sampling stations were located on Town Creek
and the Tred Avon River (Figure 7 and Table 3)(NOAA NOS Chart no. 12266).
Oxford Harbor has at least 640 marina slips and 5 active railway and travel lift
systems in (S. Zahniser, Zahniser's Marina, Personal Communication, 1986), with
limited commercial boating activity in the Town Creek area.
A municipal lagoon system with minimal flow discharges into the Oxford Harbor
(M. Garreis, Maryland OEP, Personal Communication, 1986). The effluent is primarily
from residential use; no known industrial effluent is treated at the plant. No samples
were collected from the lagoon system during the study period due to the minimal
impact of discharge on Town Creek.
Plaindealing
Plaindealing Creek is located north across the Tred Avon River from Oxford
(Figures 1 and 8). The Plaindealing Creek site was selected as a sampling area with
minimal boating activity and no shoreline marinas. There are a few private moor-
ings and docks on the creek. The four sampling stations were located on Plaindealing
Creek and the Tred Avon River (Figure 9 and Table 4)(NOAA NOS Chart no. 12266).
There are no known domestic or industrial discharges into Plaindealing Creek or
the adjacent sampling area of the Tred Avon River (E. Bauereis, BG&E, Personal
Communication, 1986).
SAMPLE COLLECTION SCHEDULE
For a 20-week period from May 5 - September 16, 1986, single grab water samples
were collected weekly at high tide slack water (defined as within +/- 30 minutes of
the predicted time of high tide) at each of the 16 designated stations. Four field
replicated samples were collected at each station during the second week of the
survey period. These four samples were used to identify potential environmental
interferences with the analytical method at the beginning of the study by the use of
standard additions. Beginning with week 5 of the study period, one field replicate
sample was taken from a randomly selected station at the Solomons, Annapolis and
Oxford sites (Table 5).
For every eight water samples collected, three additional samples were taken to
serve as a field spike, a laboratory spike and a laboratory blank, respectively. These
samples were all collected from the Plaindealing Creek station designated PC-1.
Over the period of a full tidal cycle, hourly water samples were collected at all four
stations at the Solomons study site on August 13, 1986. Samples were collected over a
13-hour period which began at high tide slackwater.
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Figure 6. Oxford Site
Plaindealing Creek
Scale 1:120,000
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Table 3: Latitude/Longitude and Narrative Station Location Descriptions for the
Oxford Site
STATION LATITUDE LONGITUDE
OH-1 38.7005 76.1683
STATION DESCRIPTION: Midchannel on the transect from the end of the private
dock to the boatyard building up the creek from the green "13" channel marker.
STATION LATITUDE LONGITUDE
OH-2 38.6971 76.1673
STATION DESCRIPTION: Midchannel at the site where the red "10" and red "12"
channel markers line up crossed with the site where the end of the red wooden
building lines up (Bates Marina Basin building).
STATION LATITUDE LONGITUDE
OH-3 38.6907 76.1682
STATION DESCRIPTION: Midchannel on the transect from the green "3" channel
marker to the green "7" channel marker intersecting with the site where the red "6"
channel marker lines up with the octagonal wooden house.
STATION LATITUDE LONGITUDE
OH-4 38.6867 76.1697
STATION DESCRIPTION: Equidistant on the transect between the red "2" and red "4"
channel markers.
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Figure 8. Plaindealing Creek Site
Plaindealing Creek
Scale 1:120,000
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Table 4: Latitude/Longitude and Narrative Station Location Descriptions for the
Plaindealing Creek Site
STATION LATITUDE LONGITUDE
PC-1 38.7252 76.1685
STATION DESCRIPTION: Midchannel on the transect between the point of land (up
from the sandbar) to the end of the private dock just up the creek from the yellow
house.
STATION LATITUDE LONGITUDE
PC-2 38.7176 76.1716
STATION DESCRIPTION: Midchannel on the transect between the white house and
the point of land crossed with the site where the blue Oxford water tower lines up
with the last piling on the dock near the mouth of Plaindealing Creek.
STATION LATITUDE LONGITUDE
PC-3 38.7092 76.1686
STATION DESCRIPTION: Midchannel at the mouth of Plaindealing Creek at the site
where the green "1" channel marker lines up with the blue Oxford water tower (to
the creekward side of green "1" channel marker).
STATION LATITUDE LONGITUDE
PC-4 38.7064 76.1689
STATION DESCRIPTION: Off the mouth of Plaindealing Creek at the site where the
red "4" nun lines up with the left side of the octagonal building at the mouth of Town
Creek crossed with the side where the end of the private dock on Pecks Point lines up
with the red nun.
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Table 5: Random Field Duplicate Collection Schedule (1)
WEEK
Week 5
Week 6
Week 7
Week 8
Week 9
Week 10
Week 11
Week 12
Week 13
Week 14
Week 15
Week 16
Week 17 (2)
Week 18
Week 19
Week 20
SAMPLE DATE
June 3
June 9
June 17
June 24
June 30
July 7
July 16
July 21
July 29
August 6
August 12
August 19
August 26-28
September 2
September 10
September 15
SITE
Oxford
Solomons
Annapolis
Annapolis
Solomons
Oxford
Annapolis
Oxford
Oxford
Solomons
Oxford
Solomons
-
Solomons
Solomons
Solomons
STATION
OH2
SI2
AH3
AH4
SI3
OH3
AH3
OH1
OH2
SI2
OH2
SI3
-
SI1
SI4
SI3
1. Methodology for random selection of stations designated for duplicated
sampling was based on assignment of a numerical value to all stations
at the Annapolis, Solomons and Oxford sites. Random selection was per-
formed according to the procedure described by Steel and Torrie (1980)
(Page 10; Table A.I).
2. No random field duplicate was collected during Week 17.
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Sediment samples were collected at each station twice during the survey period:
July 22-29 and September 15-16, 1986. Replicate grab samples taken at each station
were composited to produce a final sample.
MATERIALS AND METHODS
SAMPLE BOTTLE PREPARATION
One liter, wide-mouthed polycarbonate bottles (Nalgene) with teflon lined caps
were used for storage of the collected water and sediment samples. Laboratory
experimentation has indicated that polycarbonate is the most suitable material for
the storage of organotin contaminated environmental samples (Blair et al. 1986).
The bottles and caps were cleaned by soaking them for one hour in dilute reagent-
grade nitric acid (10%) and then rinsing thoroughly with 18 megaohm-cm deionized
water. After cleaning, each bottle was labeled and assigned a unique number for the
purpose of sample custody and identification.
FIELD SAMPLE COLLECTION PROCEDURE
At each station, water samples were taken by submerging the sample bottle at
arm's length below the water surface (a minimum of six inches), unscrewing the
bottle cap under the water surface, allowing entry of water into the bottle, and
replacing the cap with the bottle still submerged. With the bottle above the water
surface, enough water was poured out to allow a space of 1 cm to ensure adequate
space for expansion during freezing. Prior to replacement, the cap was lined with a
separate square sheet of 0.002 inch teflon.
The water samples were immediately placed in cooled ice chests and transported to
shore for storage in a laboratory freezer unit at -20 degrees celcius. Prior to
freezing, the designated field spike samples were spiked via pipette with one
milliliter of 0.10 mg tributyltin chloride/ml methanol solution. The spike solution
was prepared by the EPA Environmental Research Laboratory (Gulf Breeze) and
renewed on a monthly basis throughout the survey period.
Measurements of temperature, dissolved oxygen, pH and conductivity (salinity)
were taken at 0.5 meters below the water surface at each station concurrent with the
collection of the weekly water samples using a Hydrolab 8000 meter and probe
system.
A stainless steel box core sampler was used to collect sediment samples. Prior to
collection, on station, the box core was rinsed thoroughly with deionized water and
then with estuarine water. After collection of sediment, the box core was secured on
deck and the overlying water was carefully removed. A flat, non-metallic scoop was
used to collect the top 2 cm of sediment. Sediments from two successive box core
samples were composited on site by placing them in a single 1 liter polycarbonate
sample bottle. These sediment samples were immediately placed in cooled ice chests
and transported to shore for storage in a laboratory freezer unit at -20 degrees
celcius.
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SAMPLE HANDLING
All samples were shipped by overnight air express to the EPA Environmental
Research Laboratory in Gulf Breeze, Florida. The samples, previously stored in a
laboratory freezer unit, were placed into styrofoam-lined dry ice shipping boxes
before transport. Ten pounds of dry ice and styrofoam fill material were packed
around the bottles. The appropriate chain of custody form accompanied the samples
(Figure 10). Laboratory personnel immediately inspected the bottles upon arrival of
each shipment to ensure no thawing or damage to the bottles had occurred during
shipment.
Chain of custody forms were maintained for all the bottles from the collection of
the samples to the time the bottles reached the analytical laboratory. The analytical
laboratory's internal chain of custody procedure was enacted upon receipt of the
samples from the overnight delivery service.
ANALYTICAL METHOD AND QUALITY ASSURANCE
The analytical method followed for determing of TBT and DBT concentrations in
water was a simultaneous hydrization/extraction followed by gas chromatography
coupled with a flame photometric detector (Matthias et al. 1986). A tributyltin
hydride (TBTH) external standard was used for quantitation of TBT+. Quantitations of
DBT+2 residues were initially performed using standard curves. The curve contained
four different concentrations of dibutyltin chloride spiked in Gulf of Mexico, sea-
water ranging from 50-200 ng/1 and analyzed with simultaneous hydri-
zation/extraction. A dibutyltin hydride (DBTH) external standard was later used for
quantitation of DBT+2.
During each week that analyses were performed, samples collected from
Plaindealing Creek station PCI were analyzed as field blanks to determine if TBT or
DBT residues were present or if other contaminants were present that would inter-
fere with their quantitation. Results from only one of the thirty field blanks showed
detectable TBT residues whereas three samples contained detectable DBT residues. As
only one sample contained TBT residues, with source of this residue potentially from
the sampled environment, these data show that no contamination was introduced into
the samples through the field collection and storage procedures and that the analyti-
cal system (i.e. glassware, solvents, and columns for gas chromatographs) did not
contain residues of contaminants that interfere with quantitation of TBT and DBT
residues.
A separate set of samples, collected at Plaindealing Creek station PCI, were shipped
to the laboratory spiked with 100 ng tributyltin chloride/liter and dibutyltin di-
chloride/liter and analyzed along with the experimental samples as laboratory
spikes. Results from these spiked analyses indicated that the average percent recov-
eries and standard deviations were 53 ± 20 (n = 39) for TBT and 73 +_ 35 (n = 37) for DBT.
Matthias et al. (1986) reported a 5 to 6 instead of the expected 8 to 10-fold lowering of
detection limit when scaling up from 100 milliliter sample volume to the 800-1000
liter sample volumes. Matthias and coworkers further reported that this discrepancy
may be due in part to the loss of the analyte to the large surface area in the separa-
tory funnel walls. The loss of TBT and DBT, as demonstrated by the low percent
recoveries, may also be attributed to the emulsions that formed during the
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extractions of the samples. These emulsions would cause incomplete recovery of the
extracting solvent which could lower residue recoveries.
An additional set of Plaindealing Creek samples, collected concurrently at station
PCI, were spiked in the field with tributyltin chloride to determine if degradation of
TBT occurred during sample storage. Two concentrations of spiked solutions were
used: mean recoveries and standard deviations for these two concentrations were 62 +.
32 for 100 micrograms TBT/liter (n = 6) samples and 32 ±. 9.3 for 100 nanograms
TBT/liter (n = 14). Results from these analyses show that some loss may have
occurred during sample storage as indicated by comparing recoveries (32%) of TBT
from Plaindealing samples spiked in the field with recoveries (53%) of TBT residues
spiked in the laboratory. Some loss during storage at -20 degrees celcius may have
occurred as the samples were stored for periods up to 4 months in duration. However,
the reduced average recovery may reflect inaccuracy in the field spiking technique
at the ng/1 concentration level. Ideally, the laboratory technicians performing the
analysis should have performed the field spike procedures, but this was not possible
given the study location.
The analytical limit of quantitation achieved by the laboratory was a function of
the composite sensitivity of the equipment used for analysis. Sensitivity varied from
day to day and, therefore, the limits of quantitation were variable and had to be
determined for each daily set of samples. These limits were calculated by selecting
three times peak-to-peak noise level as the minimum quantifiable analyte signal.
Time constraints placed on completion of the required analyses prevented the lab-
oratory from maintaining a single maximum limit of quantitation because of delays
inherent in modifying instrument conditions to achieve the desired level of sensi-
tivity.
All the detectable concentrations of TBT and DBT are reported with two significant
figures in nanograms per liter (or parts per trillion) of TBT+ and DBT+2, respectively.
RESULTS
The results of the water column sample analyses are discussed in this section. Two
summary tables compare the range and 20-week average TBT (Table 6) and DBT (Table
7) concentrations for all 16 stations. The sediment samples collected as part of this
study had not been analyzed when this report was written. A complete list of all the
field and analytical TBT and DBT data for the May 5 - September 16, 1986 survey is
given in Table 8. Table 9 lists the field and analytical data for the August 13, 1986
tidal cycle sampling at the Solomons site.
SOLOMONS TIDAL CYCLE
The station located adjacent to the area of greatest boating activity (SI1) displayed
the strongest correlation to the tidal cycle. TBT concentrations at this station
decreased over time with the onset of low tide and increased with the return of high
tide (Figure 11). TBT concentrations at the station also located adjacent to the area of
high boating activity but closer to the mouth of the harbor (SI2) showed a similar but
delayed response to tidal stage. Since a majority of the TBT concentrations were
below the limit of detection, the stations at the mouth of Back Creek (SI3) and in the
Patuxent River (SI4) demonstrated no observable response to tidal stage.
-21-
-------
Table 6: TBT Concentration Ranges and 20-week Averages for All Stations (ng/1)
SITE STATION
Annapolis
Annapolis
Annapolis
Annapolis
Solomons
Solomons
Solomons
Solomons
Oxford
Oxford
Oxford
Oxford
Plaindealing
Plaindealing
Plaindealing
Plaindealing
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SI4
OH1
OH2
OH3
OH4
PCI
PC2
PCS
PC4
HIGHEST LOWEST
TBT CONC. TBT CONC.
(1) (2)
510 23
530 34
100 <16
31 <10
120 <18
170 <12
39 <12
<39 <12
52 <18
60 <13
<49 <12
<50 <12
<29 <10
<34 <10
91 <10
<22 <10
20-WEEK
AVERAGE
TBT CONC.
(3)
99.3
120.6
46.7
22.3
51.8
47.4
20.5
19.1
33.6
30.3
22.6
23.9
17.7
18.6
28.0
16.0
1. Highest detectable value or highest limit of quantitation.
2. Lowest detectable value or lowest limit of quantitation.
3. Values stated as less than the limit of quantitation were
set at the limit of quantitation and included in the
calculation of the 20-week average.
-22-
-------
Table 7: DBT Concentration Ranges and 20-week Averages for All Stations (ng/1)
SITE STATION
Annapolis
Annapolis
Annapolis
Annapolis
Solomons
Solomons
Solomons
Solomons
Oxford
Oxford
Oxford
Oxford
Plaindealing
Plaindealing
Plaindealing
Plaindealing
AH1
AH2
AH3
AH4
SI1
SI2
SI3
SI4
OH1
OH2
OH3
OH4
PCI
PC2
PC3
PC4
HIGHEST LOWEST
TBT CONC. TBT CONC.
(1) (2)
100 <13
130 <14
61 <14
73 <10
110 <14
78 <15
120 <10
29 <14
120 21
120 <10
<67 <10
<69 <10
<26 <11
92 <11
53 <10
<36 <11
20-WEEK
AVERAGE
TBT CONC.
(3)
52.2
49.5
33.9
30.5
45.2
38.7
30.8
24.3
40.4
39.7
29.0
28.6
18.1
21.6
24.4
17.1
1. Highest detectable value or highest limit of quantitation.
2. Lowest detectable value or lowest limit of quantitation.
3. Values stated as less than the limit of quantitation were
set at the limit of quantitation and included in the
calculation of the 20-week average.
-23-
-------
Table 8: Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE
STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
SI1
SI2
SIS
SI4
AH1
AH2
AH3
AH4
AH1
AH1
AH1
AH1
AH2
AH2
AH2
AH2
AH3
AH3
AH3
AH3
AH4
AH4
AH4
AH4
SI1
SI1
SI1
SI2
SI2
SI2
SI2
SI2
SIS
SI3
SI3
SIS
SI4
SI4
SI4
SI4
05MAY86
05MAY86
05MAY86
05MAY86
05MAY86
05MAY86
05MAY86
05MAY86
06MAY86
06MAY86
06MAY86
06MAY86
07MAY86
07MAY86
07MAY86
07MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
12MAY86
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
34
23
<20
<19
<20
<15
91
<16
68
170
39
<39
57
180
59
3-1
140
150
110
86
150
180
140
100
94
100
98
46
<17
<15
<27
<27
57
33
<21
58
<34
42
34
38
<28
<17
<28
<28
<17
<16
<16
<13
24
120
<15
<15
<15
<13
53
<14
21
48
26
<18
23
37
21
15
81
85
63
93
60
82
57
51
38
42
61
<19
<21
<22
<22
<22
28
26
<19
40
<18
21
<17
<18
<40
<24
<41
<40
<24
<23
<23
<19
7.3
7.7
7.5
7.3
6.8
7.0
7.3
7.7
8.2
8.3
8.3
8.3
9.1
8.9
8.7
8.6
9.1
9.1
9.1
9.1
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.6
8.2
8.2
8.2
8.2
7.7
7.7
7.7
7.7
8.1
8.1
8.1
8.1
8.1
8.1
8.1
8.1
9.3
10.0
9.4
9.2
9.1
9.2
9.3
9.3
10.4
10.2
10.2
9.8
17.0
13.7
13.7
13.1
14.3
14.3
14.3
14.3
11.2
11.2
11.2
11.2
10.8
10.8
10.8
10.8
10.3
10.3
10.3
10.3
10.2
10.2
10.2
10.2
10.1
10.1
10.1
10.1
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.75
10.83
10.86
10.80
10.85
10.78
10.75
10.64
11.11
11.04
11.21
11.37
8.43
8.41
8.80
8.78
*
*
*
*
8.69
8.69
8.69
8.69
8.79
8.79
8.79
8.79
7.37
7.37
7.37
7.37
7.56
7.57
7.58
7.56
*
*
*
*
8.13
8.13
8.13
8.13
*
*
*
*
-24-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data - May 5 - September 16, 1986
SITE STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OKI
OKI
OKI
OKI
OH2
OH2
OH2
OH2
OH3
OH3
OH3
OH3
OH4
OH4
OH4
OH4
PCI
PCI
PCI
PCI
PC2
PC2
PC2
PC2
PCS
PCS
PCS
PCS
PC4
PC4
PC4
PC4
SI1
SI2
SIS
SI4
OH1
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH4
AH1
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
14MAY86
19MAY86
19MAY86
19MAY86
19MAY86
20MAY86
20MAY86
20MAY86
20MAY86
20MAY86
20MAY86
20MAY86
20MAY86
21MAY86
21MAY86
21MAY86
21MAY86
27MAY86
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
<21
<21
<35
<34
<21
22
28
32
<18
<17
<15
<16
<18
<18
<19
27
<16
<22
<17
<29
<34
<34
<22
<21
<20
<19
<32
<34
<19
<22
<19
<21
120
100
<22
<23
30
<27
<30
<21
A
A
A
A
510
530
52
<30
77
53
58
21
21
22
56
56
53
<21
<21
24
<20
<20
<20
<36
24
<20
<16
<24
<42
<18
<18
<16
<15
<37
<36
<34
<18
<35
<16
<36
<16
95
78
<16
<17
30
<48
<53
<40
A
A
A
A
96
130
<47
<54
41
7.5
7.5
7.5
7.5
7.6
7.6
7.6
7.6
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.3
7.3
7.3
7.3
7.4
7.4
7.4
7.4
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
8.0
8.0
7.9
7.9
7.1
7.3
7.3
7.3
7.2
7.2
7.3
7.3
9.2
8.9
8.6
8.5
8.4
9.6
9.6
9.6
9.6
8.9
8.9
8.9
8.9
8.7
8.7
8.7
8.7
8.6
8.6
8.6
8.6
8.0
8.0
8.0
8.0
8.1
8.1
8.1
8.1
8.5
8.5
8.5
8.5
8.6
8.6
8.6
8.6
9.0
10.3
8.6
8.6
7.9
7.6
7.8
7.7
7.4
7.3
8.1
7.9
16.7
12.6
11.3
10.7
8.5
10.95
10.95
10.95
10.95
8.82
8.82
8.82
8.82
10.94
10.94
10.94
10.94
11.19
11.19
11.19
11.19
11.23
11.23
11.23
11.23
11.33
11.33
11.33
11.33
11.06
11.06
11.06
11.06
10.89
10.89
10.89
10.89
*
*
*
*
11.51
11.53
11.53
11.57
11.61
11.68
11.48
11.49
8.76
8.76
9.56
9.56
9.04
-25-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE
STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
AH2
AH3
AH4
OH1
OH2
OH3
OH4
PCI
PC2
PCS
PC4
SI1
SI2
SIS
SI4
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SI4
OH1
OH2
OH2
OH3
OH4
PCI
PC2
PCS
PC4
SI1
SI2
SI2
SIS
SI4
AH1
AH2
AH3
AH4
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
27MAY86
27MAY86
27MAY86
28MAY86
28MAY86
28MAY86
28MAY86
28MAY86
28MAY86
28MAY86
28MAY86
29MAY86
29MAY86
29MAY86
29MAY86
02JUN86
02JUN86
02JUN86
02JUN86
02JUN86
02JUN86
02JUN86
02JUN86
03JUN86
03JUN86
03JUN86
03JUN86
03JUN86
03JUN86
03JUN86
03JUN86
03JUN86
09JUN86
09JUN86
09JUN86
09JUN86
09JUN86
11JUN86
11JUN86
11JUN86
11JUN86
12JUN86
12JUN86
12JUN86
12JUN86
12JUN86
12JUN86
12JUN86
12JUN86
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
. 5
5
5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
69
<26
<26
<41
<16
<21
<36
A
A
A
A
<28
<28
<17
<16
180
230
<24
<24
59
62
<32
<32
<37
<36
29
<36
<26
<10
<10
<10
<10
48
38
69
<26
<26
150
100
<56
<58
39
45
<49
<50
A
A
A
A
44
37
<47
<34
<31
<39
<42
A
A
A
A
61
58
<33
<32
100
120
<39
<40
110
60
<30
<30
<43
<42
<31
<41
<29
<11
<11
<11
<11
<37
39
62
<30
<29
74
40
<36
<36
34
40
<34
35
A
A
A
A
8.2
8.3
8.4
7.0
7.1
7.2
7.2
7.2
7.2
7.4
7.1
7.5
7.6
7.5
7.6
8.7
8.6
8.1
7.8
7.8
7.8
7.7
7.9
8.0
7.6
7.6
7.5
7.5
7.6
7.6
7.5
7.5
8.2
8.2
8.2
8.1
8.1
8.5
7.8
7.7
7.7
7.1
7.2
7.2
7.4
7.4
7.4
7.4
7.3
7.7
7.4
7.7
5.3
6.7
7.1
7.4
6.4
7.0
7.4
7.1
8.5
7.5
7.2
8.0
11.5
10.0
7.1
5.0
8.1
7.7
6.6
7.2
11.1
9.3
9.3
8.3
7.6
8.4
8.6
8.3
7.9
10.8
10.1
10.1
10.1
9.6
12.1
7.6
7.1
6.9
5.6
6.8
6.3
7.4
6.8
6.9
7.1
6.9
8.99
8.65
8.73
11.48
11.69
11.68
11.70
11.68
11.69
11.70
11.46
13.06
13.06
15.41
13.39
9.13
9.07
8.98
9.19
12.99
12.93
11.80
12.86
11.49
10.43
10.43
*
*
*
*
*
*
13.26
13.39
13.39
*
*
9.95
9.83
9.89
9.80
12.13
*
*
12.40
12.33
*
12.40
12.40
-26-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH3
AH4
SI1
SI2
SIS
SI4
SI1
SI2
SIS
SI4
AH1
AH2
AH3
AH4
AH4
OH1
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH4
sn
SI2
SIS
SIS
SI4
OKI
OH2
OH3
OH4
PCI
PC2
16JUN86
16JUN86
16JUN86
16JUN86
16JUN86
16JUN86
16JUN86
16JUN86
17JUN86
17JUN86
17JUN86
17JUN86
17JUN86
17JUN86
17JUN86
17JUN86
17JUN86
23JUN86
23JUN86
23JUN86
23JUN86
24JUN86
24JUN86
24JUN86
24JUN86
24JUN86
25JUN86
25JUN86
25JUN86
25JUN86
25JUN86
25JUN86
25JUN86
25JUN86
30JUN86
30JUN86
30JUN86
30JUN86
30JUN86
30JUN86
30JUN86
30JUN86
30JUN86
01JUL86
01JUL86
01JUL86
01JUL86
01JUL86
01JUL86
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
<50
<22
<21
<22
A
A
A
A
42
76
35
29
<28
65
65
<19
<18
82
77
<30
<30
<30
49
<30
<17
<16
22
22
<35
<34
<10
<10
<10
<10
57
41
<16
<16
42
54
<16
<16
<16
28
<43
<41
<42
A
A
<35
<31
<30
<30
A
A
A
A
44
41
<29
39
<18
98
83
<30
<29
72
77
<34
<34
36
<33
<34
<30
<17
29
<31
<31
<30
<11
<11
<11
<11
36
36
30
73
41
49
<29
120
<29
120
L
<47
<47
A
A
7.3
7.4
7.4
7.4
7.5
7.5
7.6
7.5
7.9
8.1
7.7
7.7
7.8
7.9
7.9
7.8
7.7
*
*
*
*
7.0
7.2
7.3
7.7
7.7
7.7
7.1
7.2
7.2
7.3
7.3
7.2
7.2
8.0
8.0
8.0
8.1
7.8
7.9
7.8
7.8
7.8
7.7
7.4
7.5
7.4
7.5
7.5
6.8
7.0
7.0
7.0
7.2
7.2
8.0
7.4
8.5
10.1
7.5
7.5
7.4
7.8
7.9
7.3
7.3
*
*
*
*
5.6
6.5
7.2
7.8
7.8
5.3
6.2
6.8
6.9
6.9
6.9
6.8
6.8
9.7
9.6
8.8
10.2
8.3
8.3
7.6
7.6
7.5
8.0
7.1
7.4
7.2
7.2
7.6
12.46
12.73
12.59
12.59
12.73
12.66
12.79
12.59
9.78
*
9.59
9.59
9.98
14.40
14.46
14.13
*
*
*
*
*
*
*
*
*
*
12.93
13.06
12.99
12.99
*
12.93
12.86
12.93
9.93
10.02
10.11
10.17
14.80
14.93
14.40
14.40
15.07
13.06
*
13.06
13.33
13.19
13.13
-27-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE
STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
PLAINDEALING
PLAINDEALING
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
PC3
PC4
OKI
OH2
OH3
OH3
OH4
PCI
PC2
PCS
PC4
SI1
SI2
SB
SI4
AH1
AH2
AH3
AH4
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH3
AH4
SI1
SI2
SIS
SI4
OKI
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
SI1
SI2
SIS
SI4
01JUL86
01JUL86
07JUL86
07JUL86
07JUL86
07JUL86
07JUL86
07JUL86
07JUL86
07JUL86
07JUL86
08JUL86
08JUL86
08JUL86
08JUL86
09JUL86
09JUL86
09JUL86
09JUL86
15JUL86
15JUL86
15JUL86
15JUL86
15JUL86
15JUL86
15JUL86
15JUL86
16JUL86
16JUL86
16JUL86
16JUL86
16JUL86
16JUL86
16JUL86
16JUL86
16JUL86
21JUL86
21JUL86
21JUL86
21JUL86
21JUL86
21JUL86
21JUL86
21JUL86
21JUL86
22JUL86
22JUL86
22JUL86
22JUL86
9
9
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
12
12
12
12
12
12
12
12
12
12
12
12
12
A
A
<61
<63
<17
<16
<31
A
A
A
A
<31
49
L
L
L
L
L
<38
<38
<38
<37
<38
A
A
A
A
80
72
42
45
<21
45
<12
<12
<12
25
22
20
<12
<12
<12
<12
<12
<12
79
44
<13
<13
A
A
<46
<48
<12
<12
<19
A
A
A
A
23
31
L
L
L
L
L
<^70
68
<69
<67
<69
A
A
A
A
<45
<45
<45
<45
<45
51
<38
<38
<38
40
<38
<38
<38
<39
<13
<13
<13
<13
91
50
<34
<34
7.5
7.4
9.3
8.3
7.9
7.9
7.9
8.0
7.9
8.0
8.0
8.0
8.1
8.0
8.0
8.0
7.8
7.9
8.0
7.0
7.3
7.3
7.3
7.5
7.5
7.3
7.3
8.3
8.1
8.1
8.1
8.0
7.9
7.8
7.8
7.8
8.3
8.3
8.2
7.7
7.8
8.2
8.1
7.8
7.6
8.2
8.3
8.1
8.1
7.6
6.8
15.5
13.6
9.9
9.9
10.0
9.6
9.7
10.8
10.1
9.7
10.8
9.8
10.1
9.7
8.9
8.7
8.6
4.1
6.3
6.8
6.6
7.4
7.4
6.8
7.3
12.2
9.7
9.6
9.6
9.2
8.5
7.7
7.2
7.5
14.1
14.1
11.9
8.3
8.7
10.5
10.2
8.7
7.9
10.8
11.2
9.7
9.1
13.19
13.26
13.06
13.26
13.46
13.46
13.39
13.53
13.53
13.33
13.46
15.07
15.14
13.39
15.27
10.56
10.63
10.56
10.76
13.59
13.33
13.46
13.59
13.46
13.53
13.66
13.59
11.15
11.27
11.47
11.47
11.54
15.14
14.53
14.53
14.46
13.86
13.86
13.93
13.86
13.86
13.79
13.86
13.93
13.93
15.27
15.41
15.75
15.88
-28-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE
STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
OXFORD
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
AH1
AH2
AH3
AH4
OKI
OH2
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH4
SI1
SI2
SI3
SI4
OH1
OH2
OH3
OH4
PCI
PC2
PC3
PC4
AH1
AH2
AH3
AH4
SI1
SI2
SI2
SI3
SI4
AH1
AH2
AH3
AH4
OKI
OH2
OH2
OH3
OH4
PCI
PC2
23JUL86
23JUL86
23JUL86
23JUL86
29JUL86
29JUL86
29JUL86
29JUL86
29JUL86
29JUL86
29JUL86
29JUL86
29JUL86
30JUL86
30JUL86
30JUL86
30JUL86
30JUL86
30JUL86
30JUL86
30JUL86
04AUG86
04AUG86
04AUG86
04AUG86
04AUG86
04AUG86
04AUG86
04AUG86
05AUG86
05AUG86
05AUG86
05AUG86
06AUG86
06AUG86
06AUG86
06AUG86
06AUG86
11AUG86
11AUG86
11AUG86
11AUG86
12AUG86
12AUG86
12AUG86
12AUG86
12AUG86
12AUG86
12AUG86
12
12
12
12
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
15
15
15
15
15
15
15
15
15
15
15
23
46
48
<18
<18
34
44
<18
<15
A
A
A
A
29
59
47
<10
46
60
<15
<15
21
24
<12
<12
<12
<12
<12
<12
110
89
55
<12
37
38
31
<12
<12
58
44
21
<14
34
31
20
<14
<14
A
A
<45
<45
<45
<45
<45
<45
<45
<45
<37
A
A
A
A
44
68
<15
23
55
55
<37
<37
47
<26
<26
<26
<13
<13
<13
<13
45
<26
<26
<26
32
36
23
20
18
24
<23
<23
<23
<23
29
<23
<16
<16
A
A
7.6
7.7
7.9
8.0
7.3
7.9
7.9
7.9
7.7
8.0
7.8
7.7
7.5
7.7
7.7
8.0
8.0
7.7
7.8
7.6
7.5
8.5
8.1
7.7
7.8
8.3
8.2
7.9
7.7
8.2
8.0
8.1
8.1
8.0
8.0
8.0
7.9
7.9
8.0
7.9
7.7
7.6
7.1
7.3
7.3
7.3
7.3
7.6
7.6
6.5
6.7
7.8
8.6
5.9
9.0
9.0
8.6
7.7
8.9
8.4
7.0
7.4
6.8
7.6
9.4
8.7
6.8
7.7
6.5
6.5
13.2
10.6
8.1
8.6
12.0
11.5
9.2
8.0
8.8
7.2
8.0
8.1
8.0
8.7
8.7
7.9
7.3
7.4
7.2
6.1
6.2
3.0
6.1
6.1
6.2
6.2
6.2
6.5
11.15
11.41
11.67
11.93
13.86
13.93
13.93
13.93
14.13
13.86
13.99
13.73
13.99
12.46
12.46
12.66
12.33
16.56
16.63
16.84
17.25
14.19
14.60
14.60
14.73
14.33
14.33
14.60
14.53
12.13
12.20
12.26
12.53
17.18
17.18
17.18
17.38
17.31
12.79
12.86
12.99
13.06
14.19
14.53
14.53
14.66
14.60
14.06
14.19
-29-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data - May 5 - September 16, 1986
SITE
STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
PLAINDEALING
PLAINDEALING
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
PC3
PC4
SI1
SI2
SIS
SI4
OKI
OH2
OH3
OH4
PCI
PC2
PC3
PC4
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SIS
SI4
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SI4
AH1
AH2
AH3
AH4
SI1
sn
SI2
SIS
SI4
OKI
12AUG86
12AUG86
13AUG86
13AUG86
13AUG86
13AUG86
18AUG86
18AUG86
18AUG86
18AUG86
18AUG86
18AUG86
18AUG86
18AUG86
19AUG86
19AUG86
19AUG86
19AUG86
19AUG86
19AUG86
19AUG86
19AUG86
19AUG86
26AUG86
26AUG86
26AUG86
26AUG86
26AUG86
26AUG86
26AUG86
26AUG86
28AUG86
28AUG86
28AUG86
28AUG86
28AUG86
28AUG86
28AUG86
28AUG86
02SEP86
02SEP86
02SEP86
02SEP86
02SEP86
02SEP86
02SEP86
02SEP86
02SEP86
03SEP86
15
15
15
15
15
15
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
17
17
17
17
17
17
17
17
17
17
17
17
17
17
17
17
18
18
18
18
18
18
18
18
18
18
A
A
42
15
<13
<14
52
L
L
<18
A
A
A
A
46
34
<20
<20
74
L
<18
<22
<18
45
60
<22
<25
A
A
A
A
40
190
<26
<18
37
27
<26
<26
70
67
20
<18
<18
42
<26
<18
<18
20
A
A
44
27
<19
<17
<38
L
L
<19
A
A
A
A
48
<14
<28
<28
51
L
17
<31
18
22
<21
<31
<21
A
A
A
A
24
64
21
<14
39
26
<20
20
<14
<14
<14
<14
<14
<14
<20
16
<14
33
7.4
7.3
7.3
7.3
7.3
7.5
8.4
8.4
7.6
7.7
8.0
8.0
7.8
7.5
8.5
8.1
8.1
8.0
7.9
7.9
7.6
7.6
7.6
8.0
8.1
7.7
7.5
8.0
7.9
7.5
7.5
7.3
7.8
7.6
7.6
7.7
7.7
7.6
7.5
8.2
8.0
8.1
8.0
7.9
7.9
7.9
7.9
7.9
7.4
6.4
6.0
4.4
4.0
3.8
5.1
14.2
10.0
7.3
7.5
9.4
9.2
8.0
6.7
12.6
9.4
10.0
8.3
8.3
8.1
5.8
5.8
5.9
8.2
10.5
8.2
7.8
8.2
8.1
7.3
7.3
5.0
6.9
6.7
6.4
6.7
6.8
6.5
6.3
10.0
8.9
9.7
9.4
8.9
8.9
9.2
9.2
9.1
5.9
14.46
14.53
17.73
17.66
18.00
17.93
14.19
14.73
14.73
14.87
14.19
14.40
14.87
14.87
11.41
11.93
11.74
12.46
17.45
17.31
17.93
17.93
18.07
15.34
15.61
15.75
15.81
15.07
15.34
15.41
15.27
13.26
13.33
13.66
13.59
17.52
17.59
17.79
18.07
12.07
12.73
13.39
13.19
17.45
17.45
17.79
17.79
18.06
*
-30-
-------
Table 8 (cont.) - Field and Analytical TBT/DBT Data -- May 5 - September 16, 1986
SITE STATION SAMPLE WEEK TBT DBT pH DO SALINITY
DATE
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
ANNAPOLIS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
OXFORD
OXFORD
OXFORD
OXFORD
PLAINDEALING
PLAINDEALING
PLAINDEALING
PLAINDEALING
OH2
OH3
OH4
PCI
PC2
PCS
PC4
OKI
OH2
OH3
OH4
PCI
PC2
PCS
PC4
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SI4
SI4
AH1
AH2
AH3
AH4
SI1
SI2
SIS
SIS
SI4
OH1
OH2
OH3
OH4
PCI
PC2
PCS
PC4
03SEP86
03SEP86
03SEP86
03SEP86
03SEP86
03SEP86
03SEP86
09SEP86
09SEP86
09SEP86
09SEP86
09SEP86
09SEP86
09SEP86
09SEP86
10SEP86
10SEP86
10SEP86
10SEP86
10SEP86
10SEP86
10SEP86
10SEP86
10SEP86
15SEP86
15SEP86
15SEP86
15SEP86
15SEP86
15SEP86
15SEP86
15SEP86
15SEP86
16SEP86
16SEP86
16SEP86
16SEP86
16SEP86
16SEP86
16SEP86
16SEP86
18
18
18
18
18
18
18
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
24
<21
<21
<24
<20
<24
<19
34
20
<18
<18
<20
<20
59
<19
70
130
50
<20
48
23
<20
<20
<20
69
78
82
15
94
31
17
<18
<20
44
<13
<13
<14
<20
<13
<13
<13
23
<19
<19
<19
29
^1 Q
^1 4
37
^1 4
^1 4
^1 4
18
92
38
<14
<13
37
60
<18
28
<15
<18
<18
<18
74
<21
<21
<10
22
<18
-------
NOTES (cont.):
the individual sample was collected but lost as a result of complications
during the analytical procedure.
2. DBT concentrations are listed as nanograms/liter DBT+2. The "<" symbol
denotes that the DBT value listed is less than the given limit of
quantitation. The "A" symbol denotes that the individual sample was
collected but not analyzed (archived). The "L" symbol denotes that
the individual sample was collected but lost as a result of complications
during the analytical procedure.
3. Dissolved oxygen concentrations are listed as milligrams/liter. The
"*" symbol denotes that the dissolved oxygen value is missing.
4. Salinity values are listed as parts per thousand (0/00), calculated
from conductivity and temperature. The "*" symbol denotes that the
salinity value is missing.
-32-
-------
Table 9: Field and Analytical TBT/DBT Data for the August 13, 1986:
Solomons Tidal Cycle Survey
SITE STATION SAMPLE
DATE
WEEK TBT DBT pH DO SALINITY
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SOLOMONS
SI1
SI1
SI1
SI1
SI1
SI1
SI1
SI1
SI1
SI1
SI1
SI2
SI2
SI2
SI2
SI2
SI2
SI2
SI2
SI2
SI2
SI2
SI3
SI3
SI3
SIS
SI3
SI3
SI3
SI3
SI3
SI3
SIS
SI4
SI4
SI4
SI4
SI4
SI4
SI4
SI4
SI4
SI4
SI4
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
13AUG86
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
38
35
27
19
<19
<22
L
<39
L
L
46
18
25
20
28
<17
<18
<39
<39
<18
L
<22
<14
<14
<13
<10
<14
<22
L
<25
<19
L
L
<14
<14
<10
<10
<17
<19
<25
L
21
L
L
29
<17
28
25
<38
<39
L
<50
L
L
42
<17
<17
24
26
<33
<33
<50
<50
<19
L
<30
<17
<17
<13
<14
<18
<39
L
<21
<38
L
L
<17
<17
<14
<14
<33
<33
<21
L
<25
L
L
7.4
7.5
7.4
7.4
7.5
7.5
7.6
7.6
7.6
7.7
7.9
7.4
7.4
7.6
7.6
7.6
7.6
8.0
8.0
7.9
7.9
7.9
7.3
7.3
7.5
7.5
7.5
7.6
7.7
7.7
7.7
7.7
7.7
7.4
7.5
7.5
7.4
7.5
7.5
7.9
7.8
7.6
7.5
7.5
4.7
5.2
4.2
3.8
4.5
4.7
5.0
5.4
5.0
6.2
7.9
4.7
5.3
5.1
5.3
5.3
5.8
8.1
8.6
7.0
7.3
7.4
4.1
4.2
4.4
4.8
4.7
5.0
6.0
5.8
5.9
5.8
5.8
5.0
4.9
4.7
5.9
5.1
4.8
7.2
7.1
4.8
4.7
4.8
17.52
17.73
17.73
17.52
17.73
17.66
17.73
17.66
17.73
17.59
17.73
17.73
17.79
17.79
17.59
17.66
17.66
17.59
17.73
17.73
17.73
17.66
17.93
17.93
17.79
17.79
17.73
17.73
17.86
17.45
17.86
17.93
17.93
17.93
17.93
17.86
17.86
17.79
17.73
17.79
17.52
17.93
17.93
17.93
-33-
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DBT concentrations for all four stations over the tidal period reflected the pattern
observed in the TBT concentrations (Figure 12). DBT concentrations at the station
adjacent to areas of highest boating activity (SI1) again displayed a strong corre-
lation with tidal stage, while the other stations showed a delayed response. Overall,
the lowest DBT concentrations (with the exception of SI2) were found at low "tide slack
water.
ANNAPOLIS SITE
TBT concentrations at the first of the two stations adjacent to the areas of highest
boating activity (AH1) peaked at 510 ng/1 during the third week of the survey (May
21) (Figure 13). By week 7 (June 17), overall concentrations decreased and leveled
off (23-110 ng/1) for the remainder of the 20-week survey. The 20-week total aver-
age TBT concentration for this station was 99 ng/1.
TBT concentrations measured at the second harbor station (AH2), also located ad-
jacent to areas of greatest boating activity, closely matched those measured at station
AH1. The maximum TBT concentration (530 ng/1) was also measured on week 3 (May
21). TBT concentrations leveled off by week 7 (June 17) and ranged from 34-190 ng/1
until the end of the survey. The average TBT concentration for this 14-week period
was 56 ng/1. For the entire 20-week survey, the total average TBT concentration was
121 ng/1.
At the station located at the mouth of the Spa Creek at its confluence with the
Severn River (AH3), TBT concentrations ranged from < 16-100 ng/1 with a total aver-
age concentration of 47 ng/1 over the entire survey period. There was no discernible
upward or downward trend in TBT levels at this station over the 20-week period. A
high level of mixing between waters of the harbor and the Severn River combined
with a relatively constant level of in-water boating activity caused the narrow and
constant range of TBT concentrations observed at this site.
The same situation applies to the station located in the Severn River off the mouth
of Spa Creek (AH4), where TBT concentrations ranged from <10-31 ng/1; a total aver-
age concentration of 22 ng/1 TBT. As with the station located at the mouth of Spa
Creek (AH3), the area adjacent to the Severn River also experiences a relatively
constant level of in-water boating activity. However, TBT concentrations at station
AH4 were more likely to be influenced by physical mixing processes in the Severn
River than the other Annapolis stations and, therefore, to have undergone a higher
degree of dilution. Although the station (AH4) is adjacent to Spa Creek, the source of
the TBT present in the collected samples may have been: 1) in-water boating activity
in proximity to the station, 2) wind-driven and/or tidal waters coming from Spa
Creek, 3) wind-driven and/or tidal waters from the Severn River above or below the
station, or 4) a combination of all these potential sources.
DBT concentrations peaked at 100 ng/1 on week 5 (June 2) at the first harbor
station adjacent to areas of high boating activity (AH1) (Figure 14). Subsequently,
DBT concentrations ranged from <13-74 ng/1 through the end of the survey. The total
average concentration at this station was 52 ng/1 DBT.
At the second station located on Spa Creek (AH2), DBT concentrations peaked
during weeks 3 (May 21) and 5 (June 2) at 130 and 120 ng/1, respectively, DBT
concentrations leveled off by week 6 (June 11) and ranged from <14-64 ng/1 through
-36-
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the end of the sampling period, a pattern also reflected in the data from the adjacent
harbor station (AH1). The total average DBT concentration at this station was 50 ng/1.
DBT concentrations ranged from < 14-61 ng/1 at the station at the mouth of Spa
Creek (AH3), resulting in a total average concentration of 34 ng/1. At the Severn
River station (AH4), a range of < 10-73 ng/1 DBT resulted in 20-week total average
concentration of 31 ng/1.
SOLOMONS SITE
Concentrations of TBT over the survey period ranged from < 18-120 ng/1 at the first
of the two stations adjacent to the areas of highest boating and marina activity (SI1)
(Figure 15). The total average TBT concentration was 52 ng/1 at this station. No
detectable upward or downward trends were found at this station. The relatively
constant levels of shoreline marina and in-water boating activities within the con-
fines of Back Creek observed during the summer boating season, combined with the
minimal influence of wind or tidal mixing of the harbor waters support the
measurement of a constant range of TBT concentrations throughout the summer
boating season.
A similar situation is present at the adjacent station also located within the harbor
but closer to the mouth of the creek system (SI2) where the TBT concentration range
(<12-170 ng/1) and the total average concentration (47 ng/1) reflect the the range
and the 20-week total average measured at station SI1.
There was a strong correlation found between the weekly TBT concentrations
measured at stations located at the mouth of Back Creek and in the Patuxent River.
The station at the harbor mouth (SI3) had a range of TBT concentrations from < 12-39
ng/1 resulting in a total average concentration of 21 ng/1 TBT. The Patuxent River
station (SI4) also had a range of <12-39 ng/1 and a similar total average concentration
of 19 ng/1 for the 20-week survey.
The TBT concentrations at both of these stations responded similarly to physical
mixing as both stations were located within an identifiable 20-23 foot natural
channel. In addition, the levels of in-water boating activity at both stations are also
similar as both were located in the main navigation channel for entering Back and
Mill creeks from the Patuxent River.
Due to the hydrography of Back Creek, there is little tidal flushing of the water
upstream of station SI2. The sources of the measured TBT levels at stations located
within the harbor are considered to originate from within the confines of the upper
Back Creek system and undergo minimal dilution. The lower range of TBT levels
measured at the stations at the mouth of the harbor and in the Patuxent River
resulted from mixing with waters from Mill Creek or the Patuxent River and the
increased distance from areas of higher in-water boating and shoreline marina
activity.
DBT concentrations at the station located next to the area of high boating activity
(SI1) exhibited a maximum range of <14-110 ng/1 which decreased in size through the
end of the survey period (Figure 16). The total average DBT concentration was 45
ng/1 for the 20-week survey.
-39-
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A similar pattern, on a reduced scale, was seen in the data from the adjacent sta-
tion also located in the harbor but closer to the harbor entrance (SI2). DBT concen-
trations ranged from <15-78 ng/1, resulting in a total average DBT concentration of 39
ng/1.
Weekly DBT concentrations were very similar at the harbor mouth (813) and the
Patuxent River (SI4) stations (with the exception of week 9 where the value reached
120 ng/1 at station SI3). The range of DBT concentrations, <10-26 ng/1 (except week 9)
and < 14-29 ng/1, respectively, for stations SI3 and SI4, resulted in total average
concentrations of 31 ng/1 for station SI3 and 24 ng/1 for station SI4.
OXFORD SITE
For the 20-week period, TBT concentrations at the first station adjacent to the area
of highest boating activity (OH1) ranged from <18-52 ng/1; a total average
concentration of 34 ng/1 (Figure 17). At the adjacent station (OH2), located closer to
the harbor mouth, concentrations of TBT ranged from a low of <13 ng/1 to a high of 60
ng/1. The average TBT concentration at this station was 30 ng/1. The weekly TBT
concentrations at both stations corresponded closely.
The narrow range of TBT concentrations makes establishing an overall trend at
the two harbor stations difficult. The range of TBT concentrations measured over the
entire 20-week period was held constant by the small size of the harbor entrance in
relationship to its area, minimal tidal flushing of the creek system and a consistent
local source of TBT leachate.
No TBT was detected at the station located at the harbor mouth (OH3) where the
limit of quantitation ranged from 12-49 ng/1 over the 20-week survey period. At the
station located in the Tred Avon River (OH4), TBT was detected in only one of the
analyzed samples on week 2 (27 ng/1). The limit of quantitation on the remaining
samples ranged from 12-50 ng/1.
At the station located adjacent to areas of highest boating activity (OH1), DBT
concentrations ranged from 21-120 ng/1, a total average concentration of 40 ng/1
(Figure 18). A similar range and total average concentration of <10-120 ng/1 and 40
ng/1, respectively, were observed at the adjacent station (OH2).
At both the harbor mouth (OH3) and the Tred Avon River (OH4) stations, DBT was
detected in only one of the analyzed samples on week 2 (24 ng/1). Then limit of
quantitation at station OH3 ranged from 10-67 ng/1. At station OH4, the limit ranged
from 10-69 ng/1.
PLAINDEALING SITE
There were no detectable concentrations of TBT measured at the station located
farthest up the creek (PCI) during the 20-week survey where the limit of quanti-
tation ranged from 10-29 ng/1 (Figure 19). At the adjacent creek station (PC2), no TBT
- was detected in any of the analyzed samples. The limit of quantitation ranged from
10-34 ng/1 at this station.
At the station located at the mouth of Plaindealing Creek (PCS), TBT concentrations
of 91 ng/1 and 53 ng/1 were measured during week 1 (May 5) and week 19 (September
-42-
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-46-
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9), respectively. No detectable levels of TBT were found in the remaining samples
collected at this station. The limit of quantitation ranged from 10-34 ng/1. The
occurrence of these two peaks in TBT concentration is not reflected in TBT concen-
trations measured at any of the other Plaindealing stations for the same weeks. These
isolated peaks indicate the presence of an unknown localized source of TBT near the
station during those specific weeks.
There were no detectable concentrations of TBT measured at the station located in
the Tred Avon River off the mouth of Plaindealing Creek (PC4) during the 20-week
survey. The limit of quantitation ranged from 10-22 ng/1.
At the station farthest up Plaindealing Creek (PCI), DBT was detected in only one of
the analyzed samples 18ng/l during week 19 (September 9) (Figure 20). The limit of
quantitation for the remaining samples ranged from 11-26 ng/1.
DBT was detected at the adjacent station (PC2) during weeks 19 (September 9) and
20 (September 16) when concentrations of 29 and 92 ng/1 DBT were measured. DBT
concentrations were non-detectable in the remaining samples. The limit of quanti-
tation ranged from 11-18 ng/1.
At the creek mouth station (PCS), DBT was detected in samples collected during
weeks 1 and 19 when DBT concentrations of 53 and 37 ng/1, respectively, were mea-
sured. The limit of quantitation for the remaining samples ranged from 10-37 ng/1.
DBT was detected in the sample collected during week 20 (12 ng/1) at the Trcd Avon
River station (PC4). No DBT was detected in any of the remaining samples collected at
this station where the limit of quantitation ranged from 11-36 ng/1.
DISCUSSION
Results from the tidal cycle sampling substantiate the survey design decision to
sample only at high tide slack water in an attempt to measure TBT and DBT concen-
trations at their highest concentrations during the tidal cycle. A correlation
between TBT and DBT concentrations and tidal stage was observed at the Solomons
sampling station located adjacent to the area of highest boating activity (SI1). The
highest TBT and DBT concentrations were measured at high tide with the lowest con-
centrations observed at low tide. No significant results were observed at the other
three stations due to the high number of non-detectable values.
The TBT water column data were analyzed using a two-way factorial analysis of
variance (ANOVA) (Table 10) and Duncan's Multiple Range Test to determine the
effect of station location, date and site on TBT concentration. The highest average
concentrations of TBT by site were found at Annapolis (70.6 ng/1) followed by
Solomons (34.7 ng/1), Oxford (27.7 ng/1) and Plaindealing (20.1 ng/1) (Table 11). In
the range test for week, week 3 (May 19-21) had a significantly higher average TBT
concentration when compared to the other 19 weeks (Table 12). There was no statis-
tically significant difference among the remaining TBT concentrations averaged by
week. However, weeks 1-7 grouped together, as did weeks 12-20 (with the exception
of week 17). Beyond these groupings, no consistent upward or downward trend in
TBT concentration was observed upon analysis by sampling week. Analysis of the
-47-
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-48-
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Table 11: Duncan's Multiple Range Test of TBT Water Column Data by Site
DUNCAN GROUPING
A
B
C
D
MEAN
(ng/1)
70.598
34.717
27.705
20.063
N
92
92
95
48
SITE
ANNAPOLIS
SOLOMONS
OXFORD
PLAINDEALING
-49-
-------
Table 12: Duncan's Multiple Range Test of TBT Water Column Data by Week
DUNCAN GROUPING
C
C
C
C
C
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
A
B
B
B
B
B
E
E
E
E
E
E
E
E
E
E
E
I
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I
I
I
I
I
I
I
D
D
D
D
D
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
MEAN
(ng/1)
124.583
58.000
55.062
49.824
45.167
42.234
38.250
37.846
37.846
35.824
33.417
33.353
32.923
32.200
31.538
30.176
27.647
25.692
24.882
22.692
N
12
13
16
17
12
64
8
13
13
17-
12
17
13
10
13
17
17
13
17
13
WEEK
3
6
1
5
17
2
10
11
7
19
4
20
9
16
13
14
18
15
12
8
-50-
-------
cs
Q
e
c
-j
"o
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t/1
*oo
13
c
^
"«3
|
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6
*
H
—
2
a
H
^
U
w
•
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W en
C/3 >O
2 OO
O oo
O°o
tf CN
OO
oo
oo
oo
oo
en
VO
r-H
O oo
O
O en
«o •*
vo ^
• ^r en
O en
en iri
vo cs
en
Q
^ EJ J
fa.
A
w
t/3
O
fa.
Q
O
C/2
O O O O O
o o o o o
o o o p o
d d d d d
CN ~ CN C~ CN
—i •— CS
TJ- en
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Os en
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CN CN CN
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-51-
-------
Table 14: Duncan's Multiple Range Test of DBT Water Column Data by Site
DUNCAN GROUPING
MEAN
(ng/I)
N
SITE
B
B
B
41.130
34.826
34.511
20.292
92
92
94
48
Annapolis
Solomons
Oxford
Plaindealing
-52-
-------
Table 15: Duncan's Multiple Range Test of DBT Water Column Data by Week
DUNCAN GROUPING
MEAN (ng/1)
N
WEEK
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
B
B
B
B
B
E
E
E
E
E
E
E
E
E
E
E
E
E
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
A
A
A
A
A
D
D
D
D
D
D
D
D
F D
F D
F D
F D
F D
F
F
F
F I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
C
C
C
C
C
C
C
C
C
C
C
G
G
G
G
G
G
G
G
G
G
G
G
G
58.667
54.750
51.000
44.647
42.385
41.583
41.308
40.462
37.294
33.797
32.625
29.875
29.200
27.412
26.917
25.235
24.231
23.615
19.588
18.176
12
12
13
17
13
12
13
13
17
64
8
16
10
17
12
17
13
13
17
17
3
9
11
5
13
4
7
6
12
2
10
1
16
19
17
14
8
15
20
18
-53-
-------
DBT data by ANOVA (Table 13) and Duncan's Multiple Range Test for site (Table 14)
and week (Table 15) yielded similar results.
A significant pattern was observed in the results of the analysis of variance for
TBT concentration by station (Table 16). The highest average TBT concentrations
were found at the two Annapolis stations located adjacent to the area of highest
boating activity (station AH2 followed by station AH1). Closer statistical examination
revealed a pattern in the grouping of the stations. Within each study site, the two
stations located within the confines of the harbor system tended to group as did the
two stations located at the harbor mouth and in the adjacent river. Although these
groupings are not statistically significant because of the narrow range of TBT
concentrations, these station groupings add evidence to the patterns observed in the
graphical comparisons and described in the results section. A similar pattern in the
DBT data is seen in the results of the Duncan's Multiple Range Test for station (Table
17).
The relative TBT concentrations measured correspond closely because the
separately grouped stations (i.e. the two stations located within the confines of the
harbor system as one group and the two stations located at the harbor mouth and in
the adjacent river as the other group) are affected by similar physical mixing
events. It can be further hypothesized that TBT levels measured at these grouped
stations are from the same general "sources". Exceptions to these discussions were
the Annapolis stations located at the mouth of the harbor (AH3) and in the Severn
River (AH4) for reasons previously discussed. The Plaindealing stations, at the mouth
of the creek system (PCS) and in the Tred Avon River (PC4), did not group together
due to the spikes in TBT measured at creek mouth stations during weeks 3 and 19.
At the Annapolis and Solomons sites, significant concentrations of TBT were
measured throughout the entire 20-week study within the harbors. Detectable
concentrations of TBT were also measured at the entrance to these harbors and in the
adjoining river system. In the case of the Annapolis site, the sources of the TBT
measured in the Severn River could have been TBT-contaminated water from the
harbor, TBT-contaminated water from the Severn River or a combination of both.
The TBT concentrations detected in the Patuxent River at the Solomons site originated
from within the Back Creek system with Mill Creek being a potential additional
source of TBT.
At the Oxford site, the concentrations of TBT detected within the harbor originated
from within the confines of the Town Creek system. The TBT measured at the harbor
entrance and in the adjoining Tred Avon River also originated from sources within
the harbor. The lower concentrations measured at these two stations resulted from
physical mixing of water from Town Creek with the Tred Avon River.
Measurement of the levels of TBT observed at several of the Plaindealing stations
was not expected due to the lack of shoreline marinas and potential for only minimal
in-water boating activity. Sources of the TBT observed must have originated from lo-
calized in-water boating activity prior to sample collection on the weeks TBT was
detected.
The TBT concentrations observed at the Plaindealing Stations could not have
originated from Oxford harbor, located south across the Tred Avon River from the
mouth of Plaindealing Creek. On the weeks that TBT was detected in samples collected
at the station located at the creek mouth (PC3) (weeks 1 and 19), no detectable concen-
trations of TBT were detected at the station located in the Tred Avon River (PC4). If
-54-
-------
Table 16: Duncan's Multiple Range Test of TBT Water Column Data by Station
DUNCAN GROUPING
E
E
E
E
E
E
E
E
E
A
B
C
C
C
C
C
D
D
D
D
D
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
F
F
F
F
F
F
F
F
F
F
F
F
F
MEAN
(ng/1)
120.636
99.273
51.826
47.391
46.708
33.583
30.280
28.000
23.913
22.565
22.333
20.500
19.091
18.583
17.667
16.000
N
22
22
23
23
24
24
25
12
23
23
24
24
22
12
12
12
STATION
AH2
AH1
SI1
SI2
AH3
OKI
OH2
PCS
OH4
OH3
AH4
SI3
SI4
PC2
PCI
PC4
-55-
-------
Table 17: Duncan's Multiple Range Test of DBT Water Column Data by Station
DUNCAN GROUPING
B
B
B
B
B
B
B
E
E
E
E
E
E
E
E
E
G
G
G
G
G
G
G
G
G
A
A
A
A
A
C
C
C D
C D
C D
C D
C D
D
F D
F D
F D
F
F
F
F
F
F
F
F
F
F
MEAN
(ng/1)
52.182
49.455
45.217
40.375
39.667
38.696
33.958
30.833
30.542
28.957
28.565
24.417
24.273
21.583
18.083
17.083
N
22
22
23
24
24
23
24
24
24
23
23
12
22
12
12
12
STATION
AH1
AH2
SI1
OKI
OH2
SI2
AH3
SI3
AH4
OH3
OH4
PC3
SI4
PC2
PCI
PC4
-56-
-------
the source of TBT was Oxford harbor, one would expect to see a gradient of concen-
trations from the Tred Avon River into the mouth of Plaindealing Creek. This was not
the case. In addition, the tidal action of the Tred Avon River would prevent the
exchange of water from Town Creek to Plaindealing Creek.
The source of the TBT measured at the creek mouth station (PCS) had to be within
close proximity to the station as TBT was not detected at the other Plaindealing
stations. However, detectable concentrations of DBT were measured on week 1 at the
creek mouth station (PCS) and on week 19 at both stations on the creek (PCI and PC2)
and at the creek mouth (PCS), corresponding in time with the measurement of
significant TBT concentrations at the creek mouth station. Detectable levels of DBT
were also observed at one of the creek stations (PC2) and at the Tred Avon River
station (PC4) during week 20. As DBT is a degradation product of TBT, measurement of
DBT indicates previous presence of TBT in the water column.
FINDINGS
The 20-week study documented levels of TBT and DBT at a series of stations located
to measure gradients in concentrations. Variation in the amounts of in-water
boating and shoreline marina activity, which the four harbors were chosen to
represent, resulted in a corresponding range of observed TBT and DBT concen-
trations. The study did document a statistically significant gradient in concentration
originating from within three of the harbors out into the adjacent river systems.
Beyond a peak in TBT concentrations at the beginning of the survey period, no
significant upward or downward trend was observed in the concentration over the
boating season. The consistency of this range of concentrations was observed after
the initial peak in May. This constant range indicates either there is a constant
source of TBT leachate within the harbors or degradation of TBT in the harbor system
is not rapid enough to be observed over the summer boating season. The measured
TBT levels may have resulted from a combination of both of these situations.
The measurement of TBT and DBT concentrations at the Plaindealing site indicates
that localized sources of TBT within a relatively undeveloped creek can result in
detectable concentrations which can be traced throughout a small creek system,
even when the levels are not maintained beyond a two-week time frame.
Based on analysis of the laboratory quality assurance and control for the study,
the results reported in this document are considered conservative estimates of the
TBT and DBT concentrations measured in the analyzed samples. The reported levels of
TBT and DBT for the four harbors in northern Chesapeake Bay should be considered
the lower range of concentrations for actual environmental conditions for the 1986
boating season.
From the study results, it is concluded that sources of TBT measured in the harbor
areas are directly linked to local boating and marina activity and specifically to TBT
leachate from antifouling paints. The sampled harbors are a source of TBT to the
estuarine environment beyond the boundaries of the harbors. TBT concentrations in
several of the harbors were high and sufficiently constant to pose a threat to organ-
isms living in the harbor areas. Finally, sustained concentrations of TBT at the levels
found in the rivers adjacent to the sampled harbors cause an additional, unnecessary
environmental stress to shellfish larvae and plankton upon which they feed.
-57-
-------
REFERENCES
1. Blair, W.G. et al. 1986. An international butyltin measurement methods
intercomparison: sample preparation and results of analysis.
National Bureau of Standards, Gaithersburg, Maryland. NBSIR 86-3321.
2. Carter, H.H. 1965. A method for delineating an exclusion area around
a sewage outfall in a tidal estuary based on water quality with
application to the Severn and Choptank rivers. Special Report 9.
Chesapeake Bay Institute, Johns Hopkins University.
3. Matthias, C.L., G.J. Olson, F.E. Brinckman, and J.M. Bellama. 1986.
A comprehensive method of determination of aquatic butyltin and
butylmethyltin species at ultra-trace levels using simulateous
hydrization/extraction with gas-chromatography flame photometric
detection. Environmental Science and Technology, 20:609-615.
4. Steel, R.G. and J.H. Torric. 1960. Principles and Procedures of Statistics.
McGraw-Hill, Inc., New York, New York.
-58-
-------
APPENDIX A
GRAPHS OF TRIBUTYLTIN AND DIBUTYLTIN
CONCENTRATION VERSUS SAMPLING WEEK
FOR ALL STATIONS
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