903R93100
CBP/TRS 95/93
July 1993
Chesapeake Bay
Water Column Contaminants
Critical Issue Forum
Proceedings
Basinwide Toxics Reduction Strategy Reevaluation Report
TD
225
.C54
W17
copy
Chesapeake Bay Program
i Tnnied on recycled }>aper
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Chesapeake Bay
Water Column Contaminants
Critical Issue Forum
Proceedings
Sponsored by the
Chesapeake Bay Program Toxics Subcommittee
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April 14, 1993 FI; 1- a,FA
Produced for the Chesapeake Bay Program
under Interagency Agreement No. DW64943642-01
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
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PROCEEDINGS OF THE
CHESAPEAKE BAY PROGRAM
TOXICS SUBCOMMITTEE
SPONSORED
CHESAPEAKE BAY WATER COLUMN CONTAMINANTS
CRITICAL ISSUE FORUM
U.S. EPA Chesapeake Bay Program Office
Chesapeake Bay Information and Conference Center
Annapolis, Maryland
April 14, 1993
1. CRITICAL ISSUE FORUM OBJECTIVES/PROCESS
Rich Batiuk, EPA Chesapeake Bay Program Office, described the objectives of the critical
issues forum, the questions posed to the forum participants by the Toxics Subcommittee, and the
process for incorporating forum findings into the reevaluation of the 1988 Basinwide Toxics
Reduction Strategy. The forum questions were presented as follows:
• From the critical review of available data, have we defined or can we define the relative
magnitude (concentration) and extent (geographical distribution) of water column
contamination within Chesapeake Bay? within the Bay basin?
• Does this definition of the magnitude and extent of water column contamination within the
Bay tidal waters/Bay basin give us reason to believe this identified (potential) toxics issue is
causing or can cause an adverse impact (e.g. bioaccumulation, toxicity) on the Chesapeake
Bay system on a basinwide, baywide, regional or local scale?
• If there is insufficient data or information to answer the above questions, identify the
additional data/research required to answer the questions.
To ensure the findings from the Chesapeake Bay Water Column Contamination Critical Issues
Forum are fully considered in continuing efforts to reevaluate and revise the Basinwide Toxics
Reduction Strategy, the following process will be undertaken:
• A written summary of the forum proceedings, discussions and findings will be prepared by
CBPO staff and distributed for review by the forum speakers.
• The forum summary will be presented to the Toxics Subcommittee for the Subcommittee's
consideration and incorporation into the continuing Strategy reevaluation.
• The forum summary will be published by the Subcommittee as a Chesapeake Bay Program
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• The forum summary will be published by the Subcommittee as a Chesapeake Bay Program
Technical Report.
2. STATE WATER COLUMN CONTAMINANT MONITORING FINDINGS
Representatives from the Bay basin jurisdictions prest ned findings from their respective
water column contaminant monitoring programs, with emphasis on concentration ranges observed
at Bay tidal water stations. No formal presentations of water column data from the New York,
Delaware, and West Virginia portions of the Chesapeake Bay basin were made as the available data
were very limited.
Pennsylvania
Rod Kime, Pennsylvania Department of Natural Resources, described Pennsylvania's Water
Quality Network and the resultant water column contaminant data. The network includes 168
stations statewide; 69 stations are in the Susquehanna River basin, and 4 stations are in the Potomac
River basin. Prior to 1988, most stations were sampled monthly, however, metals analyses were
only conducted once a year, during the August low flows. As samples were missed during the
annual sampling schedule and detection limits varied year to year, only very obvious trends could
be detected with this data.
Since 1989, all stations have been sampled monthly for all parameters, including aluminum,
copper, lead, nickel, and zinc. Detection limits have been fixed at the lowest possible consistent
value. The trends observed in the data collected since 1989 will be reported in the upcoming 1994
Pennsylvania 305 (b) report. In addition, each station is surveyed annually for macroinvertebrates,
using rapid bioassessment protocols
The metals observed are those primarily associated with acid mine drainage in the upper
Susquehanna River watershed: such as aluminum, cadmium, zinc, and lead. In addition, there are
also problems associated with Mirex, PCBs and dioxin, which have caused fish consumption bans
to be issued for the specific stream segments in the Susquehanna River watershed where these
compounds have been found: Spring Creek in Centre County (Mirex), Susquehanna River in
Luzerene County (PCBs), and Codorus and South Branch Codorous Creek in York County (dioxin).
Metals data collected since 1988 from the Water Quality Network's three stations on the
mainstem Susquehanna River, the Juniata River station, the Octoraro Creek station, and all four
stations in the Potomac River basin were presented (Table 1). The data showed significant
exceedances (10% or more of the observations) of Pennsylvania water quality standards at all nine
stations for aluminum, at two stations for copper (Octoraro and Little Wills/Potomac River), and at
one station for lead (Little Wills/Potomac River). Sampling for cadmium and chromium at most
stations was discontinued because these metals were not detected and, therefore, determined not to
be a problem.
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Table 1. Summary of water column metals concentration data from selected Pennsylvania
Water Quality Network Stations 1988 to 1992.
Metal
Al (ug/L)
Al (ug/L)
Al (ug/1)
A! (ug/L)
Al (ug/L)
Al (ug/L)
Al (ug/L)
Al (ug/L)
Al (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Cu (ug/L)
Ni (ug/L)
Ni (ug/L)
Ni (ug/L)
Station name
Lower Susquehanna
Lower Susquehanna
Lower Susquehanna
Juniata-Susq. Trib.
Octoraro-Susq. Trib.
Potomac-
Conococheague
Potomac-Licking Creek
Potomac-Little Wills
Potomac-Rock Creek
Lower Susquehanna
Lower Susquehanna
Lower Susquehanna
Juniata-Susq. Trib.
Octoraro-Susq. Trib.
Potomac-
Conococheague
Potomac-Licking Creek
Potomac-Little Wills
Potomac-Rock Creek
Lower Susquehanna
Lower Susquehanna
Lower Susquehanna
Median
cone.
492.5
312.0
257.0
187.0
278.0
271.5
177.0
135.0
237.5
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
25.0
25.0
25.0
Maximum
cone.
11600.0
4940.0
3600.0
3950.0
5910.0
6850.0
5320.0
4510.0
16800.0
50.0
50.0
31.0
32.0
50.0
21.0
25.0
29.0
32.0
100.0
88.0
73.0
Percent
exceeding
criteria
46%
40%
25%
18%
25%
24%
13%
12%
21%
7%
2%
2%
0%
10%
2%
2%
10%
' 2%
2%
0%
2%
Less
than
detect
4%
16%
9%
22%
9%
20%
24%
21%
14%
30%
48%
34%
39%
32%
41%
50%
32%
36%
38%
53%
44%
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Table 1. Summary of water column metals concentration data from selected Pennsylvania
Water Quality Network Stations 1988 to 1992.
Metal
Ni (ug/L)
Ni (ug/L)
Ni (ug/L)
Ni (ug/L)
Ni (ug/L)
Ni (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Pb (ug/L)
Zn (ug/L)
Zn (ug/L)
Zn (ug/L)
Zn (ug/L)
Zn (ug/L)
Station name
Juniata-Susq. Trib.
Octoraro-Susq. Trib.
Potomac-
Conococheague
Potomac-Licking Creek
Potomac-Little Wills
Potomac-Rock Creek
Lower Susquehanna
Lower Susquehanna
Lower Susquehanna
Juniata-Susq. Trib.
Octoraro-Susq. Trib.
Potomac-
Conococheague
Potomac-Licking Creek
Potomac-Little Wills
Potomac-Rock Creek
Lower Susquehanna
Lower Susquehanna
Lower Susquehanna
Juniata-Susq. Trib.
Octoraro-Susq. Trib.
Median
cone.
25.0
25.0
25.0
25.0
25.0
L_ 25.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
17.0
11.0
15.0
10.0
10.0
Maximum
cone.
84.0
118.0
108.0
85.0
98.0
47.0
10.1
15.6
13.9
283.7
6.5
10.0
6.9
6.6
10.9
70.0
63.0
145.0
57.0
51.0
Percent
exceeding
criteria
0%
0%
2%
2%
0%
2%
2%
2%
2%
3%
0%
2%
3%
37%
2%
2%
0%
2%
0%
0%
Less
than
detect
51%
40%
48%
49%
30%
57%
37%
53%
51%
46%
45%
58%
61%
39%
56%
9%
27%
19%
42%
29%
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Table 1. Summary of water column metals concentration data from selected Pennsylvania
Water Quality Network Stations 1988 to 1992.
Metal
Zn (ug/L)
Zn (ug/L)
Zn (ug/L)
Zn (ug/L)
Station name
Potomac-
Conococheague
Potomac-Licking Creek
Potomac-Little Wills
Potomac-Rock Creek
Median
cone.
10.0
10.0
10.0
10.0
Maximum
cone.
99.0
86.0
87.0
65.0
Percent
exceeding
criteria
2%
2%
0%
2%
Less
than
detect
47%
47%
34%
40%
Maryland
Deirdre Murphy, Maryland Department of the Environment, explained that Maryland does
not routinely monitor water column contaminant concentrations because the concentrations are highly
variable over time, many parameters are routinely below the detection limits, and it is expensive to
properly characterize water column contaminants. The state relies on sediment, tissue and biological
monitoring programs for assessment of contamination problems.
Results from three specific water column contaminant studies carried out by Maryland within
the past five years were discussed by Deirdre Murphy. These three studies were: a 1988-1990
monitoring project which supported the development of Maryland's 304(1) list, a 1992 pilot pesticide
monitoring project, and a 1992 urban pesticide monitoring project.
304(1) Monitoring Project
The locations of sampling sites selected for the Maryland 304(1) monitoring project were
based on a review and analysis of existing water column contaminants data. Sites were selected
where previously collected data indicated elevated contaminant levels. A total of 237 grab samples
were collected over two periods during 1988-1990 from 41 sub-basin segments, where past sample
collection and analysis detected concentrations of water column contaminants. Most of the samples
were surface water column samples, although some bottom water column samples were also collected
for analysis. Samples were analyzed for all 126 priority pollutants, except for dioxin and asbestos.
Samples were not filtered so results were for whole water samples.
Detection limits (or ranges) for classes of organic priority pollutants are given below in ug/L.
Organochlorine Pesticides
PCB Aroclors
PAHs
Chlorinated Benzenes
0.02-0.1
0.5- 1
2- 10
2- 10
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Chlorinated Ethanes/Ethylenes
Halo Ethers
Phenols
Halomethanes
Nitrosamines
Phthalates
Other Organics
1 -5
2 - 10
10
2 - 10
1 - 10
5- 10
1 -200
No detectable quantities of the organic priority pollirants were found in any of the 237
samples at the above ranges of detection limits. As three different laboratories conducted the sample
analyses, there was some variation in detection limits. The total recoverable metals analyses did
yield some detectable results, however, the number of samples with detectable levels varied among
the metals (Table 2).
Table!. Percent detections of metals in water column samples collected from 1989-1990 during
the Maryland 304(1) Monitoring Project.
Metal
Aluminum
Arsenic
Antimony
Beryllium
Cadmium
Chromium
Chromium(+6)
Copper
% Detection
91%
5%
<1%
18%
8%
16%
1%
14%
Metal
Iron
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
% Detection
99%
17%
9%
19%
10%
5%
1%
68%
Those metals closely associated with soils, aluminum, iron, and zinc, were detected in most
samples. The majority of the metals, however, were detected in less than 20 percent of all samples
collected. In the case of several metals, the detections were 1 percent or less of the samples (e.g.
antimony, hexavalent chromium, and thallium). Such results may be related to the range of the
detection levels, as well as the contaminant levels in the samples. In most cases, the detection levels
were not below the relevant EPA water quality criteria.
Of the total recoverable metals concentrations detected, some exceeded EPA water quality
criteria. The primary contaminants for which this occurred were copper and cadmium at the
freshwater sites. These sites were added to Maryland's 304(l)a(ii) list. The results of the 304(1)
monitoring project provided conservative estimates of locations where total recoverable contaminant
concentrations approached or exceeded EPA water quality criteria on the occasion sampled. As
EPA's criteria are more directly relevant to dissolved metal concentrations, the availability of
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dissolved metals data would have provided a better assessment of criteria exceedances.
1992 Watershed Pesticide Monitoring Project
The 1992 Maryland pilot watershed pesticide monitoring project assessed water column
pesticide concentrations at a total of eleven stations in three regions: Eastern Shore (Little Northeast
Creek, East Fork of Langford Creek, Morgan Creek, and German Branch), Central (White Marsh
and Honeygo runs), and Western (Monocacy River, Big Pipe Creek, and Fishing Creek (control
site)).
All stations were sampled on 4 to 5 occasions - during the late winter, spring, summer, and
fall. Samples were analyzed for triazines and their metabolites, organochlorines, chlorpyrifos,
carbofuran, pyrethroids, diflubenzuron, alachlor, and metolachlor, using EPA methods where
available. These pesticides were chosen on the basis of use patterns within the sampled watersheds,
potential toxicity, water solubility, and their presence on the Chesapeake Bay Toxics of Concern
List.
Detection limits (or ranges) for these classes of pesticides are given below in ug/L:
Organochlorine Pesticides
Triazines
Alachlor, Metolachlor
Carbofuran
Diflubenzuron
Pyrethroids
0.01 - 1.0
0.1 - .44
0.01-0.1
1.50
0.025
0.2- 1.0
No detectable levels of organochlorine pesticides, pyrethroids, or diflubenzuron were found
at any of the eleven sample stations. Of the pesticides that were detected (Table 3), all
concentrations were below all available EPA surface water criteria and drinking water criteria.
Table 3. Number of 1992 Maryland pilot watershed monitoring stations at which pesticides were
detected in water column samples.
Pesticide
Alachlor
Atrazine
Carbofuran
Chlorpyrifos
Cyanazine
Number of stations
at which pesticides
were detected
2
2
1
1
2
Sampling events during
which detectable concentrations
were reported
spring and summer
spring, summer, and fall
spring
spring
spring
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Pesticide
Metolachlor
Simazine
Number of stations
at which pesticides
were detected
8
3
Sampling events during
which detectable concentrations
were reported
all collections at least 1 station
spring and summer
Urban Watershed Pesticide Monitoring Project
The Maryland Urban Pesticide Monitoring Project, which is in its initial stages, involves
determining pesticide use and monitoring pesticide concentrations in stream baseflow and storm
runoff within three Baltimore City sub-watersheds. A pesticide use survey, which was conducted
during the summer of 1992, was followed by limited sample collection and analysis efforts to screen
for detectable concentrations of pesticides. From this information, a list of pesticides targeted for
analysis was compiled. Followup sampling based on this list will be conducted this year.
Although Maryland does not routinely monitor for water column contaminants, but rather
relies on sediment, tissue, and biological monitoring programs for water quality assessments. Water
column monitoring is done only as part of more focused assessment efforts, such as the 304(1) and
pesticides monitoring projects previously described.
While Maryland has only limited water column data, and those data indicate contaminant
concentrations in the water column are ephemeral, more intensive sampling is necessary to get a
broader picture of water column contamination.
In the discussion that followed, Deirdre Murphy stated that one limitation to the 304 (1) list
was that entire river segments often get identified, because of contaminant data for a single site.
About half of the sites sampled during the 1988-1990 monitoring project were placed the 304 (1) list.
Other sites on Maryland's 304(1) list were identified from evaluations of existing ambient and effluent
data.
District of Columbia
Anita Key, District of Columbia Department of Consumer and Regulatory Affairs, described
the District of Columbia's water column toxics monitoring program. Since October 1982, water
column samples have been collected quarterly from the following locations: Potomac River and its
tributaries, Anacostia River and its tributaries, Washington Ship Channel, Rock Creek, C & O
Canal, Kingman Lake, Watts Branch, and the Tidal Basin. Samples are analyzed for arsenic,
cadmium, chromium, copper, iron, lead, mercury, selenium, and zinc.
The assessment of heavy metal contamination in the District of Columbia waters has been
restricted by the level of detection achievable by the analytical laboratory relative to the concentration
criterion specified in the District's water quality standards (Table 4). A substantial portion of water
column metals results have been reported as below detection limits, likely due to high detection
limits. Determination of whether results were often above certain criteria was not possible
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particularly with the detection limits for lead, mercury, cadmium, and copper.
A review of metals data collected from the Potomac and Anacostia Rivers in 1989 and 1990
showed that chromium and zinc concentrations were at levels exceeding the District's water quality
standards. In 1989, chromium concentrations were found to be in violation on two dates in the
Potomac River and on three dates in the Anacostia River. In comparison, zinc concentrations were
found to be in violation twice in 1989 and once in 1990 in the Potomac. In the Anacostia River, zinc
levels were in violation of the water quality standard on four dates in 1989 and on two dates in 1990.
Water column concentrations of iron were also above the District's water quality standard
of 1000 ug/L on several occasions in both the Potomac and Anacostia rivers in 1989 and 1990. Clay
deposits in the Potomac watershed are rich in iron. Water samples containing clay particles have
been found, at times, to exceed the District's water quality standard for iron.
Table 4. District of Columbia water quality standards and detection limits for metals monitored
through the District's water column toxics monitoring program.
Metal
Arsenic
Cadmium*
Chromium
Copper*
Iron
Lead*
Mercury
Selenium
Zinc
District water
quality standard (ug/L)
90
1.17 (1989)
1.33 (1990)
10
12.23 (1989)
14.01 (1990)
1000
3.34 (1989)
4.1 (1990)
0.012
40
50
Range of detection
limits (ug/L)
5-100
10- 100
10- 100
25 - 2,000
50- 1,000
0.2 - 20.2
10 - 2,000
Criteria calculation for: Cadmium (e<°-7ll52'-0"»'«->- 3 -490> Ug/L); Copper (e(0 -
Lead (e"-™0^ *•«'•-> -«-™s>Ug/L); where hardness = 104 (1989) or 122 (1990).
Virginia
• ' -46S)
Ug/L);
John Kennedy, Virginia Department of Environmental Quality, presented findings from
Virginia's water column monitoring efforts based on data contained in two reports: "Comprehensive
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Review of Selected Toxic Substances - Environmental Samples in Virginia, 1990", and the "Elizabeth
River Toxics Initiative First Biennial Progress Report, 1990." Copies of either report are available
upon request from the Virginia Department of Environmental Quality.
Ambient Network Synthesis Report
The review and synthesis of data from the past twenty i ars from Virginia's Ambient Water
Quality Monitoring Network focused on the analysis of data for arsenic, beryllium, cadmium,
copper, lead, mercury, aldrin, chlordane, DDT, dieldrin, and !CBs. These toxic substances were
selected from an initial list of 88 contaminant parameters. Thioi.gh this review process, baseline
levels of water column contaminants were established for present and future comparisons, areas for
recommended source identification were identified, and recommendations for future ambient
monitoring were established.
Summaries of the water column contaminant results reported in "Comprehensive Review of
Selected Toxic Substances - Environmental Samples in Virginia, 1990" for statewide data are
provided below.
Arsenic: Majority of the data (86%) were below detection limits; more than 99% of the data
were below EPA and Virginia chronic water quality criteria.
Beryllium: Only 2% of the data were above detection limits; all data were below EPA and
Virginia acute and chronic water quality criteria.
Cadmium: Majority of the data (94%) were below detection limits; a limited number of data
exceeded acute chronic water quality criteria for freshwater and saltwater.
Copper: Approximately 35% of the data were above detection limits, with 20% of the data
exceeding the acute freshwater or saltwater criteria.
Lead: About 50% of the values were below detection limits, with a limited number of
exceedances of EPA freshwater acute criteria.
Mercury: Majority of the data (94%) were at or below the applicable detection limits; all the
reported detection limits were above the EPA water quality criteria.
Aldrin: Majority of the data (94%) were below detection limits; a limited number of data
exceeded Virginia's acute water quality criteria.
Chlordane: Majority of the data (98%) were below detection limits; a very limited number of
data exceeded EPA and Virginia chronic water quality criteria.
DDT: Majority of the data (> 99 %) were below detection limits, with most of the detections
from samples collected prior to the ban on DDT use.
Dieldrin: Majority of the data (95%) were below detection limits; a limited number of data
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exceeded Virginia and EPA chronic water quality criteria.
PCBs: Majority of the data (95%) were below detection limits; all the data above the
detection limits exceeded EPA and Virginia chronic water quality criteria for
freshwater and saltwater.
Elizabeth River Initiative
Through the Elizabeth River Initiative, water column total recoverable and dissolved
concentrations of priority pollutant metals and organics were measured in March and June of 1989
at 12 stations. Detection limits for the metals analyzed were: cadmium - 9.3 ug/L; chromium - 50
ug/L; copper - 2.9 ug/L; lead - 5.6 ug/L; nickel -10 ug/L; silver - 0.05 ug/L; zinc - 58 ug/L; and
selenium - 54 ug/L; and mercury - 0.25 ug/L. In most cases the detection limits are set at the
Virginia water quality criteria, which is also the EPA criteria. In the case of mercury, however, the
detection limit is 0.25 ug/L, the state criteria is 0.10 ug/L and the EPA marine chronic criteria is
0.025 ug/L.
Results from the metals analyses were as follows:
• Total recoverable copper was detected during both sampling events at all stations, with
concentrations ranging from 3.0 to 19.4 ug/L. These values were all above the Virginia
water quality criteria of 2.9 ug/L.
• Total recoverable lead was detected at one Eastern Branch station at a concentration of 6.6
ug/L; this value exceeded the Virginia water quality criteria of 5.6 ug/L.
• Data from one Southern Branch station indicated levels of mercury above the Virginia water
quality criteria of 0.10 ug/L.
• Total recoverable and dissolved nickel concentrations were detected at every monitoring
station during the June sampling event.
The analyses for priority and non-priority organic contaminants resulted in the detection of
very few compounds in the water column, with the concentrations detected being relatively low.
Light weight aromatic compounds, typical of refined petroleum products, were detected at one station
in the Elizabeth River and one station in the Southern Branch during June. These stations are in the
vicinity of the Craney Island Naval Fuel Facility, the Craney Island Coast Guard Base and the
Virginia Power Chesapeake Plant, respectively. Polynuclear aromatic hydrocarbons were found in
samples from one station in the Elizabeth River (February sampling period only) as well as all five
Southern Branch stations. The only other contaminants identified were plasticizers, or phthalates,
observed at one Elizabeth River station and three Southern Branch stations.
Other Water Column Monitoring Programs
The majority of Virginia's continuing ambient monitoring efforts are focused on sediment and
fish tissue sample collection and analysis and not on water column sampling. Two programs directed
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at specific water column contaminants are the James River kepone monitoring program and tributyltin
(TBT) monitoring in Hampton Roads.
The TBT monitoring program has been in effect for almost two years. Although its use has
been restricted, TBT is still being detected in concentrations in excess of the Virginia water quality
standard. This is probably due to the fact that TBT-based paints can be used legally on boats over
25 meters and on outboard motor shafts. In addition, in-place sediments may still be a source of
TBT to the overlying water column.
3. FALL LINE TOXICS CONCENTRATION FINDINGS
Geological Survey
Linda Zynjuk, U. S. Geological Survey (USGS), presented findings from the Chesapeake Bay
Fall Line Toxics Monitoring Program and the USGS National Stream Quality Accounting Network
(NASQAN) program for concentrations of toxics substances measured at the Bay's major fall lines.
The fall line is the geological point at which the piedmont meets the coastal plain; where free flowing
freshwater streams and rivers meet tidally influenced surface waters. Concentrations of toxic
substances measured at the fall line reflect the cumulative inputs of all point and nonpoint sources
from the above fall line watershed, providing an ideal place at which to measure fluvial transports
of toxic substances into the Bay's tidal waters.
Through the Chesapeake Bay Fall Line Monitoring Program, baseflow and storm events
samples have been collected and analyzed at the Susquehanna and James River fall line stations since
1990 and at Potomac River fall line station since 1991. Combined, these rivers comprise 80 percent
of the freshwater entering the Bay and, therefore, are fairly representative of majority of fall line
loadings of toxic substances to the Bay. Additional quarterly sampling of metals has been conducted
through the USGS NASQAN program at the Susquehanna, Patuxent, Potomac, Choptank,
Rappahannock, Pamunkey, Mattaponi, James and Appomattox river fall lines over the past 13 years.
USGS NASQAN Program
Through a review of the USGS NASQAN data, Linda Zynjuk presented the following
findings. In the data summary provided below, values below detection limits were set to the
detection limit for calculation of the mean concentrations. All data are total recoverable (metals) or
total (pesticides, organics) water column measurements.
• Mean chromium concentrations were highest at the Choptank, Rappahannock and Pamunkey
River fall lines, where mean concentrations ranged from 17-21 ug/L in both cases. Mean
chromium concentrations were the lowest at the Susquehanna and James River fall lines,
where concentrations were less than 8 ug/L.
• No water quality criterion exists for total recoverable chromium. However, for the trivalent
and hexavalent forms the EPA water quality criteria is 210 ug/L and 11 ug/L, respectively.
The majority of total recoverable chromium is in the trivalent form, in which case the highest
concentrations observed (60 ug/L) are low relative to the criteria.
12
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• Mean copper concentrations ranged from 3.5 - 7.6 ug/L, all below the EPA water quality
criteria of 12 ug/L. The highest value recorded (84 ug/L) was at the James River fall line.
• Mean lead concentrations ranged from 4.9 - 59.2 ug/L among all the river fall lines, except
for the Appomattox River fall line which had a mean concentration of 3.0 ug/L. The EPA
freshwater chronic water quality criterion for lead is 3.2 ug/L.
• Atrazine concentrations were not analyzed for at the Appomattox, Mattaponi, Rappahannock,
or Patuxent River fall lines. The Susquehanna River fall line had the highest concentration
(1.2 ug/L), with mean concentrations ranging below 0.18 ug/L. While there is no water
quality criterion for atrazine, the EPA drinking water criterion is set at 3 ug/L.
Note: During the resultant discussion, Lenwood Hall mentioned that most of the atrazine in
the water column is not available to organisms. Much higher levels than what were reported
here would be needed for organismal effects.
• Mean total PCB concentrations ranged from 0.02-0.9 ug/L. The EPA freshwater chronic
criterion for total PCB is 0.014 ug/L. Total PCB concentrations were not analyzed at the
Appomattox, Mattaponi, Rappahannock, or Patuxent River fall lines.
• The range of mean Chlordane concentrations was 0.01 - 0.09 ug/L. The EPA freshwater
chronic criterion is 0.0043 ug/L. Chlordane concentrations were not analyzed for at
Appomattox, Mattaponi, Rappahannock, or Patuxent River fall lines
Bay Fall Line Toxics Monitoring Program
Linda Zynjuk also presented a summary of trace metal and pesticide concentration data
collected at the Susquehanna River at Conowingo, Maryland during the 1990-1991 (Tables 5 and 6).
Elevated lead and copper concentrations were measured, however, the observed concentrations were
close to the EPA freshwater criteria. Chromium concentrations were low enough not to indicate a
problem. Seasonal-based temporal patterns were observed for atrazine.
Trace metals and pesticide data from the James River at Cartersville, Virginia for the period
of 1990-1991 showed that elevated levels of copper and lead occurred during the two year period,
significantly exceeding the EPA freshwater chronic criteria for both metals (Tables 5 and 6).
Chromium concentrations did not indicate a problem. Patterns in atrazine concentrations were
related to season and high flow.
Metropolitan Washington Council of Governments
Adrienne Nemura, Metropolitan Washington Council of Governments, presented pesticide,
PCB, and trace metal data, collected from March through September of 1992, for the Potomac,
James and Susquehanna Rivers fall lines. The data collection was a cooperative effort between the
Maryland Department of the Environment, the U. S. Geological Survey, the Occoquan Watershed
Monitoring Laboratory, George Mason University, and the Metropolitan Washington Council of
Governments. One important aspect of the sampling program was the development of appropriate
13
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detection limits for all parameters to increase the number of detects. Adrienne Nernura presented
both the percent of observations which were greater than the detection limits, as well as the
maximum observed concentration for most of the parameters that were sampled. It was stressed that
the data collection was only for six months and represented only a limited range for both storm and
base flows.
The application of ultraclean field sampling technique, at the Susquehanna River fall line
station resulted in below detection limit data for the following previously detected metals: arsenic,
barium, cadmium and mercury. However, for some metals, such as zinc, chromium, lead, nickel
and copper, ultraclean sampling may not have been necessary. Organonitrogen and
organophosphorus pesticides data were presented for all three fall lines. Of the pesticides which
were screened, only simazine, atrazine, alachlor, metolachlor, and cyanide were present in
measurable quantities. Preliminary loading estimates for trace elements for Potomac River fall line
revealed a wide range in loading estimates, depending on how measurements below the detection
limits are treated. Simazine, metolachlor, cyanazine, and especially atrazine all had a wide range
of concentrations, which could be season and flow dependent.
Dissolved organic concentrations of organochlorine pesticides were highest at the
Susquehanna river fall line, although a high dissolved concentration of oxy-chlordane was measured
at the Potomac River fall line. Aldrin, oxychlordane, gamma-chlordane, alpha-chlordane, and
dieldrin were present in all three rivers in both the dissolved and particulate forms. Permethrin,
fenvalerate, and 4,4'-DDT were not present in measurable amounts in any river sampled. PCBs
(112 congeners) were present in both dissolved and particulate forms in all three rivers, with the
highest total PCB concentration of 39 mg/L was measured in a storm flow sample collected at the
Potomac River fall line.
Reliable load estimates could not be developed using the present 6 month data set as
correlations with flow and season are crude at best. The additional three months of data being
collected will still only provide order of magnitude estimates. In order to gain confidence in load
estimates, it is necessary to know if the detection limits are consistent with the bulk of the observed
concentrations. Additional data is needed for most parameters to draw any conclusions about
confidence in load estimates.
Ms. Nemura summarized the researchers' preliminary recommendations on future fall line
toxics monitoring, which included: (1) comparison of discrete and automated sampling, (2) increased
base flow monitoring, (3) increased number of storm events sampled, (4) increased sampling of
organics in April through June, and (5) a special study of toxic substances present in sediments
behind the dams on the Susquehanna River. Preliminary program recommendations included: (1)
continuation of sampling programs on all three rivers to extend data set, (2) expanding the sampling
program to include other representative tributaries, (3) assess possible cost savings (from dropping
parameters consistently below detection limits), and (4) assess future data needs reflecting revised
Bay Program directions for reducing toxics.
14
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Table 5. Summary of conbined 1990-1991 fall line trace metal concentration data collected the
Susquehanna River at Conowingo Dam, Maryland and the James River at Cartersville,
Virginia. Diss = dissolved, TR = total recoverable.
Metal
Aluminum, Diss
Arsenic, Diss
Arsenic, TR
Barium, TR
Cadmium, Diss
Cadmium, TR
Chromium, Diss
Chromium, TR
Copper, Diss
Copper, TR
Iron, Diss
Iron, TR
Lead, Diss
Lead, TR
Lithium, TR
Magnesium, Diss
Manganese, TR
Mercury, Diss
Mercury, TR
Nickel, Diss
Nickel, TR
Selenium, TR
Susquehanna River
Percent
detections
85%
17%
4.8%
25%
17%
0%
18%
79%
98%
100%
86%
100%
30%
95%
0%
100%
100%
20%
17%
98%
100%
0%
Concentration
range (ug/L)
< 10 - 70
<1 - 1
<1 - 1
< 100 - 100
<1 - 1
<1
<1 -2
<1 - 10
<1 -8
2 - 11
<3-67
160 - 690
<1 -5
<1 - 17
<1
3.6- 14
90 - 190
<.l - .2
<.l - .1
1 -5
2-23
<1
James River
Percent
detections
92%
0%
3.8%
6.7%
0%
1.9%
15.4%
72%
88%
98%
100%
100%
56%
100%
0%
100%
94%
0%
3.6%
59%
94%
1.9%
Concentration
range (ug/L)
< 10 -260
<1
<1 -3
< 100 - 100
<1
<1 - 1
<1 -2
<1 -18
<1 -9
<2-84
50 - 150
30-7000
<1 -5
1 -96
<1
3.1 -8.3
10 - 450
<.l
<.l - .1
-------
Table 5. Summary of conbined 1990-1991 fall line trace metal concentration data collected the
Susquehanna River at Conowingo Dam, Maryland and the James River at Cartersville,
Virginia. Diss = dissolved, TR = total recoverable.
Metal
Silver, TR
Strontium, TR
Zinc, Diss
Zinc, TR
Percent
detections
0%
100%
25%
55%
Concentration
range (ug/L)
<1
100 - 240
<10-20
< 10 - 50
Percent
detections
1.9%
100%
13.8%
70%
Concentration
range (ug/L)
<1 - 1
10 -120
<10-30
< 10 - 90
Table 6. Summary of combined 1990-1991 fall line pesticide concentration data collected
at the Susquehanna River at Conowingo, Maryland and the James River at
Cartersville, Virginia.
Pesticide
Alachlor
Atrazine
Cyanazine
Diazinon
Dicamba
DDT
Malathion
Metolachlor
Picloram
Prometone
Simazine
2,4 -D
Susquehanna River
Percent
detections
7.2%
70%
44%
NM
NM
NM
9.1%
30%
NM
7.4%
44%
NM
Concentration
range (ug/L)
<.l - 1
<.l - .9
<.l .7
NM
NM
NM
<.01 - .01
<.l - .5
NM
<.l - .2
<.l - .1
NM
James River
Percent
detections
2.9%
43%
23%
3.5 %
8.3 %
3.5 %
3.5%
8.7%
17%
2.9%
34%
8.3%
Concentration
range (ug/1)
<.l - 1.0
<.l -.3
<.2- .4
<.01 - .01
<.01 - .01
<.01 - .01
<.01 -.01
<.l - .1
<.01 - .08
<.l - .2
<.l - .1
<.01 - .08
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4. AMBIENT TOXICITY TESTING WATER COLUMN FINDINGS
Lenwood Hall, University of Maryland-Wye, presented findings on water column
contaminant concentrations from the U.S. Fish and Wildlife Service Emergency Striped Bass
Contaminants Program sites in Chesapeake Bay and the Chesapeake Bay Pilot Ambient Toxicity
Testing Study.
In-Situ Striped Bass Contaminant Studies
The objectives of the in-situ striped bass contaminant studies were:
• To evaluate survival of larval striped bass during in-situ studies in Maryland spawning areas
within Chesapeake Bay; and
• To evaluate water quality conditions and contaminant concentrations concurrently with the
in-situ studies.
The research program involved in-situ striped bass contaminant studies in Maryland spawning
areas from 1984-1990 in the following areas: Nanticoke River (1984), Choptank River (1987),
Upper Chesapeake Bay (1985, 1987, 1988, 1989, 1990), and Potomac River (1986, 1988, 1989,
1990). The specific striped bass spawning areas that were also tested included Possum Point on the
Potomac River, C& D Canal (later sampled the mouth of the Sassafras River), and Vienna on the
Nanticoke River.
The organic contaminants and metals that were evaluated during the striped bass studies were
selected on the basis of background data (i.e. toxicity, occurrence in ambient systems). From 1984
to 1990, 352 metals measurements and 186 organics measurements were carried out. The measured
analytes and their detection limits were:
Contaminant Approximate Detection Limit (ug/L)
Aroclor 1248 0.014
Aroclor 1254 0.024
Aroclor 1260 0.028
DDE 0.002
Toxaphene 0.06
Chlordane 0.01
Perylene 0.04
Fluorene 0.04
Phenanthrene 0.04
Anthracene 0.04
Fluoranthrene 0.04
Pyrene 0.04
Benzo (a) anthracene 0.04
Chrysene 0.04
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Contaminant Approximate Detection Limit (ug/L)
Aluminum 1
Arsenic 3
Cadmium 0.5
Chromium, total 1
Copper 1
Lead 3
Nickel 5
Selenium 2
Tin 1
Zinc 5
The contaminants study included striped bass larval survival bioassays. Survival was
generally good in upper Bay, low in the Potomac River, and mixed in Choptank and Nanticoke
rivers. Acidification may have influenced larval survival in the Choptank and Nanticoke rivers; low
Ph levels (mid 6 range) are toxic to the younger life stages of striped bass.
Contaminants data were presented for arsenic (As), cadmium (Cd), chromium (Cr), copper
(Cu), lead (Pb), nickel (Ni), selenium (Se), and zinc (Zn); maximum values were compared with the
applicable EPA water quality criteria values. Exceedances of EPA water quality criteria were noted
for cadmium, copper, lead, zinc, chromium, and nickel. The following locations had exceedences
of EPA chronic freshwater criteria (except for the upper Chesapeake Bay, where chronic saltwater
criteria were exceeded).
• Nanticoke River:
1984 - 10 exceedences: Cd - 1; Cu - 6; Pb - 3.
• Choptank River:
1987 - 4 exceedences (April): Cd - 1; Cu - 3.
• Potomac River:
1986 - 16 exceedences (April and May): Cd - 5; Cr - 4; Cu - 6; Zn - 1.
1988 - 19 exceedences; Cd - 7; Pb - 8: Zn - 4.
1989 - 1 exceedence: Cr.
1990 - 12 exceedences: Cd -1; Cr - 2; Cu - 2; Pb - 2; Ni - 2; Zn - 3.
• Upper Chesapeake Bay:
1985 - 15 exceedences: Cr - 1; Cu - 9; Ni - 5.
1987-3 exceedences: Cd - 3.
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1988 - 4 exceedences: Pb - 4.
1989 - 8 exceedences: Cd - 3; Cr - 2; Cu - 2; Pb - 1.
1990 - 3 exceedences: Pb - 3.
There were many exceedances for copper in the C & D Canal in 1985, which was due to the
application of EPA saltwater criteria (2.9 ug/L), which is lower than Maryland's estuarine water
quality standard used in the Bay (6.0 ug/L).
In summarizing data for the organics detected in the water column during striped bass studies,
Lenwood Hall stated that no organics were detected in samples collected from the Nanticoke (1984),
Choptank (1987), C & D Canal (1985, 1987), Upper Bay (1988), Potomac (1986, 1989).. However,
the following organics were detected, at the concentrations given:
• Upper Chesapeake Bay (1989): Heptachlor epoxide = 0.008 ug/L
Endosulfan 1 = 0.006 ug/L
Dieldrin = 0.005 ug/L
4,4 DDT = 0.014 ug/L
• Upper Chesapeake Bay (1990): Pyrene = 0.42 ug/L
• Potomac River (1988): Chlordane = 0.152 ug/L
ODD = 0.097 ug/L
• Potomac River (1990): 9-octodecane = 1.1 ug/L (tentative identification)
The striped bass in-situ toxicity data were summarized as follows:
• Potentially toxic concentrations of metals were reported in the Potomac River concurrently
with high mortality of larval striped bass.
• The occurrence of potentially toxic contaminants in the upper Chesapeake Bay was less and
survival of larvae during upper Bay in-situ tests was generally higher than in the Potomac
River.
• Acidic conditions, leading to potentially toxic concentrations of monomeric aluminum,
reported in the Nanticoke and Choptank rivers were observed to reduce survival of striped
bass larvae; however, these conditions do not occur every year.
Ambient Toxicity Testing Program
The objectives of the Chesapeake Bay Ambient Toxicity Testing Program were:
• To use a battery of water column and sediment toxicity tests to determine if toxic conditions
exist in ambient habitats in the Chesapeake Bay; and
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• To measure a suite of inorganic and organic contaminants in the water column at each station
during the toxicity tests.
Ambient toxicity tests were conducted in the Elizabeth (1990), Patapsco (1990, 1991), Wye
(1990, 1991), and Potomac (1990, 1991) rivers. The organisms used were Eurytemore affinis,
Palaemoneta pugio, Cyprindon variegatus, Ceriodaphnia sp., and Pimephales promelas; however,
not all organisms were used at all stations.
The 1990 ambient toxicity water column data reflect significant mortality in two of the test
species in the Elizabeth River, one of three test species in the Patapsco River, and no effects from
the three species in the Wye River. Generally, no effects were reported in the three tidal fresh
stations in the Potomac River. Significant mortality was reported from one of the three tests at both
the Morgantown and Dahlgren (saltwater) stations in the Potomac River.
In presenting the water column metals data collected during the 1990 ambient toxicity tests,
Lenwood Hall noted values which exceeded the EPA chronic saltwater water quality criteria. In the
Elizabeth River, copper (3.3 ug/L, 3.7 ug/L) and mercury (0.22 ug/L) exceeded the criteria. At the
Patapsco River sites, nickel (10.8 ug/L) exceeded the criterion. For the Wye River, copper (5.4.
ug/L) and nickel (18 ug/L) were above the EPA criteria. Other exceedances were: Indian Head -
cadmium (1.32 ug/L); Freestone Point - cadmium (1.48 ug/L); and Morgantown - mercury (.29
ug/L), nickel (8.4 ug/L).
The 1990 water column data were summarized as follows:
• The number of potentially toxic concentrations of metals was highest at the Elizabeth River
site where the greatest number of toxic effects were reported from toxicity tests.
• The second most toxic area, the Patapsco River, also contained potentially toxic
concentrations of metals in the water column.
• Toxic effects in the Potomac River were reported in ambient toxicity tests with and without
measured concentrations of toxic substances at levels associated with adverse effects (i.e.
concentrations elevated above EPA water quality criteria).
Testing continued in 1991 using the mysid shrimp in addition to Eurytemore affinis,
sheepshead minnow, and grass shrimp. Four stations were tested two times each.
In 1991, exceedances of EPA water quality criteria were found at the following stations:
Dahlgren - copper (3.4, 4.5, 3.7 ug/L); Morgantown - copper (5.5, 4.2. ug/L); Wye River - copper
(2.9 ug/L), nickel (9.3 ug/L); Patapsco River - copper (3.7, 3.7 ug/L).
The 1991 water column data are summarized as follows:
• Significant mortality occurred during the first sheepshead minnow larval test at the Wye
River concurrently with the presence of potentially toxic concentrations of metals and a
suspected toxic dinoflagellate.
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• Significant mortality of another test species at the Wye River site (Eurytemore affinis)
occurred without concurrent measurement of concentrations of toxic substances above EPA
water quality criteria.
• A sublethal effect, reduced growth of sheepshead minnows, was reported at both Potomac
River sites with the presence of elevated levels of toxic substances.
5. REVIEW OF BAY WATER COLUMN METALS CONCENTRATIONS
Fritz Riedel, Benedict Estuarine Research Laboratory, presented an overview of the ranges
of metal concentrations observed in Bay waters during the past decade, including data from ongoing
work supported by the Chesapeake Bay Toxics Research Program. Most of the data presented were
collected in the mainstem Bay, with some data available for the tidal tributaries.
From the data collected in the Bay mainstem, it appears that observed copper and lead
concentrations most closely approach EPA water quality criteria (Table 7). For lead, this reflects
a single sample which was probably contaminated. However, copper has often been seen at these
levels in a variety of habitats in the Chesapeake Bay, primarily the upstream estuarine portions of
tributaries. A few very high concentrations of iron and manganese, probably caused by flux from
sediment into anoxic bottom waters, were reported.
Table 7. Dissolved metals concentration ranges reported in the Chesapeake Bay
mainstem.
Metal
Arsenic
Cadmium
Cobalt
Chromium
Copper
Iron
Lead
Mercury
Manganese
Molybdenum
Nickel
Range of Dissolved
Concentrations
(ug/L)
0.1 -2
0.001 - .09
0.002 - .2
0.02- 1.5
0.08 - 2.0
0.09 - 100
0.01 - 1.5
0.00005 - 0.0005
0.4 - 400
0.6-7
0.8-3
EPA Chronic
Freshwater
Criteria
190
1.0 *
150*
10 *
2.0
0.012
100
EPA Marine
Criteria
36
9.3
50
2.9
8.5
0.025
8.3
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Metal
Tin
Selenium
Zinc
Range of Dissolved
Concentrations
(ug/L)
0.01 - 1.5
0.02-0.1
0.1 - 10
EPA Chronic
Freshwater
Criteria
5.0
70 ,
EPA Marine
Criteria
71
86
* Actual value depends on water hardness, value shown fits within expected hardness range
for Chesapeake Bay.
In discussing levels of trace metals, Fritz Riedel explained that it is important to determine
whether the source is natural or anthropogenic in origin. Sources of trace metals might include
"natural" weathering and runoff, wastewater treatment plants and industrial discharges, agriculture,
and seawater. Air inputs could come from dry deposition, wet deposition, or gas phase metals, such
as mercury. Sediment related sources of metals entering the water column include anoxic reduction
and release of iron, manganese, and arsenic, and oxidation of organics and diagenesis resulting in
the release of copper and chromium.
Several metals have different chemical forms which may be present simultaneously, although
with different geochemical behavior and toxicity. Several examples are given below.
Arsenic
Arsenate
Arsenite
Monomethyl arsenate
Dimethyl arsenite
Chromium
Hexavalent Chromium
Trivalent Chromium
More toxic to plants
More toxic to animals
Highly toxic
Less toxic
Soluble, highly toxic
Particle reactive, less toxic
Copper, Cadmium, Zinc (maybe others)
Organically complexed
Free ion
Mercury
Inorganic Mercury
Methyl mercury
Not biologically available
Biologically available
Highly toxic
Very highly toxic, biomagnifying
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Selenium
Selenate Toxic, bioaccumulative
Selenite More toxic, bioaccumulative, more toxic to animals
Organic Selenium Less toxic, bioaccumulative?
The monomethyl and dimethyl forms of arsenic are produced by organisms. Over 99% of
copper is originally complexed, as is 50% of cadmium and zinc. Mercury is toxic in very low
concentrations; methyl mercury is a neurotoxic, and is truly biomagnified (i.e. concentrations in
tissue tend to increase with each step in the food chain).
In presenting data for arsenic speciation in the Patuxent River estuary, Fritz Reidel stated that
dinoflagelates and other algae metabolize arsenate to the dimethyl arsenite form. Arsenate has been
shown to have effects on phytoplankton species composition at concentrations approaching those
found in the Bay. The effect generally consists of a shift of species from larger diatoms to smaller
diatoms and other small algae, such as flagellates. Such shifts have the potential of altering trophic
relationships, probably in a deleterious manner, by shifting carbon away from the "standard" food
chain model (e.g. algae, copepod, fish) and toward the "microbial loop" (alga, microzooplankton,
bacteria).
Data for dissolved arsenic in the Patuxent River from July 1992 were presented. Differences
in bottom versus surface samples show a benthic flux in arsenic. Copper was measured at 0.5-3
ug/L in the Patuxent River. These values were high, but do not reflect gross contamination. High
levels of copper, silver, and cadmium in Patuxent River oysters may be due to a low salinity regime.
Oysters have the tendency to uptake much higher levels of metals at low salinities than at higher
salinities, at a constant metal exposure, unlike some other shellfish such as mussels. This presents
a problem in using oysters as an indicator of toxic metal contamination. Although mercury levels
in water were found to be 3 or 4 orders of magnitude less than other metals, this may represent a
problem due to mercury's extreme toxicity and tendency bioaccumulate.
In addressing the forum questions, Fritz Riedel offered the following analysis.
Have we defined the relative magnitude and extent of water column contamination in the Chesapeake
Bay System ?
"Yes, no, and maybe, depending on the metal and the site. By and large the data
suggest that there is not serious widespread contamination in the mainstem Bay.
Clearly, some metals are elevated in some tributaries, and industrial areas. However,
for many elements at many sites it is unclear whether present concentrations are
'natural' or 'contaminant'."
Does this give us reason to believe that toxic trace elements are causing or can cause an impact
(bioaccumulation or toxicity) on any scale?
"Yes, bioaccumulation of several metals (cadmium, copper, mercury and silver)
23
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occurs in selected sites and organisms around the Bay. However, it is very difficult
to demonstrate that trace elements are having a deleterious effect (toxic?) on
organisms."
What additional data or research are needed to answer questions the above questions better ?
"Analytical methods have improved since 1979 (when the majority of the data
discussed were collected) both in sensitivity and specificity (form of the element).
We are at a stage where detailed attempts to examine the behavior of trace elements
seasonally and over specific areas will better tell us whether the levels present are
'contaminants' or 'natural'. The costs will not be trivial. Improved biological
techniques will be required to test for and detect toxicity at 'ambient' levels."
6. REVIEW OF BAY WATER COLUMN ORGANICS/TBT CONCENTRATIONS
Mike Unger, Virginia Institute of Marine Science, presented an overview of organic
contaminant concentrations observed in Bay waters during the past decade. Findings from past and
continuing water column monitoring of tributyltin concentrations were also discussed.
Several problems associated with making water column measurements of organic
contaminants were outlined:
• Hydrophobic compounds readily partition to sediments and biota.
• Most organic compounds exist at concentrations below conventional analytical detection limits
(i.e. sub ppb level).
• Reported laboratory toxicity values often exceed the solubility of the organic compound
because of the use of solubility enhancers to introduce the compound into the toxicity test
vessel.
The available water column for organic contaminants for the Chesapeake Bay, above detection limits,
was so limited an effective summary of the information could not be presented.
Tributvltin
Because of the extreme toxicity of tributyltin (TBT), analytical capabilities to measure
concentrations down to 1 part per trillion were developed. This enhanced analytical capability lead
to TBT monitoring programs in the mid 1980s and the subsequent enactment of legislation limiting
TBT use (1987-1988).
Recent data show an obvious decrease in TBT concentrations over time. For some areas,
however, such as Old Point Comfort and Sarah Creek in the York River, TBT levels have remained
fairly constant. One explanation for these stable concentrations is that TBT sorbs to sediments, then
later desorbs, reentering the water column. In this way, sediments can act as a source of TBT.
24
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Mike Unger discussed laboratory data which show the absorption isotherm for TBT. These
data showed that TBT reestablished equilibrium concentrations after only 2 hours. The half life of
TBT in water is 7-14 days. In sediments, however, the half life is much longer.
There are areas in the Chesapeake Bay, near marinas and drydocks, where TBT
concentrations approach levels which have been shown to be toxic to estuarine organisms in acute
and chronic laboratory studies, but these concentrations have been decreasing. Summarizing six
years of TBT monitoring data, Mike Unger concluded the following:
• TBT concentrations are highest near marinas.
• Concentrations have declined in Chesapeake Bay since legislation for TBT has been enacted.
• Concentrations may be leveling off in some areas.
• In-place sediments may be important sources of TBT.
• Legal use (painting of large vessels) of TBT may increase, however, new paints have lower
leaching rates than paints used prior to legislation in 1988.
7. DISCUSSION
The four critical issue forum questions were addressed by the participants as part of the effort
to define the extent and magnitude water column contamination in the Chesapeake Bay basin. Two
major points were made and reiterated throughout the discussion: 1) existing data are insufficient (i.e.
spatially, temporally, and geochemically limited) to determine the nature, magnitude, and extent of
water column contamination in the Chesapeake Bay basin; and 2) because the analysis of water
column samples is expensive and available resources are limited, the focus of future monitoring or
assessment of Bay basin water column contamination needs to be determined. At present, water
column metals data for Bay tidal waters are limited; water column organic for Bay tidal waters are
very limited or rare.
Another important point raised throughout the discussion was that there are two different
purposes for collecting water column contaminants data: 1) to understand processes and transport of
chemicals in the water column and their relative bioavailability; and 2) as a basis for states to
determine if water quality standards are being met. When water column contaminants data are
collected for these two distinctly different purposes, further issues arise. Water column metals data
are often collected and reported in two different forms - dissolved for understanding processes and
total recoverable for assessing violations of water quality standards - which cannot be directly
compared.
Water column data routinely collected and analyzed for regulatory purposes is often analyzed
using methods with very high detection limits, yielding many nondetect values. Contamination of
the samples during sample collection and handling is also an inherent problem.
Water column data collected for the purpose of understanding processes is often of better
25
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quality (lower detection limits, use of collection and handling procedures resulting in less sample
contamination), leading to a better general understanding of the geochemistry of trace elements and
organics in the water column. Forum participants suggested that it may be beneficial to utilize water
column processes directed research for this purpose, rather than rely on basinwide monitoring efforts
to addresses these needs.
Several forum participants pointed out there is little chance that more sensitive analytical
methods for detecting contaminants in the water column will be developed without some impetus to
drive the resource intensive methods development process. In the past, efforts to develop and refine
analytical methods that can detect small concentrations of substances have been chemical specific.
For example, large investments of time and resources were to improve the methods for
detecting small quantities of tributyltin (TBT). These efforts stemmed from the extreme toxicity of
this compound, as was evidenced by the fact that toxicity was observed when the concentrations of
TBT were below the existing detection limits. Researchers had to develop more sensitive analytical
methods to detect TBT in the parts per trillion range, the concentration range TBT was determined
to be toxic to estuarine and marine organisms. This work, however, was mostly funded by the U.S.
Navy, and driven by the extreme toxicity of TBT. This type of intensive methods development
might be difficult to replicate for other substances.
Very few routine monitoring programs target repeated sampling of water column
contaminants, particularly in the Bay's tidal waters. The result is there are few areas with a
sufficient temporal record to show larger scale patterns and trends.
With limited resources available, forum participants recommended a determination be made
as to whether and how resources should be directed towards further studying metals and organics
contamination in the water column. Copper and arsenic were suggested as priority elements for
more intensive assessment. Copper has been seen repeatedly in high concentrations and exhibits
toxic effects. According to work done by Jim Sanders, chronic low levels of arsenic killed some
species of Bay phytoplankton and has been incorporated into higher trophic levels through
consumption of contaminated phytoplankton.
It was suggested as selenium contamination has had serious consequences in other systems
at relatively low concentrations, due to its bioaccumulative nature, it should be further investigated
in Chesapeake Bay. Because water column testing is so expensive, and many areas do not appear
to have problems, specific substances, such as mercury, or processes, such as sediment fluxes,
should be targeted because there is concern or evidence that there could be a problem in Chesapeake
Bay. There was general consensus that water column processes do need to be understood, and that
perhaps the focus should be on both a chemical and regional basis, rather than on maintaining broad
monitoring programs.
The general question of the usefulness of water column contaminants data, as opposed to
sediment or fish tissue contaminants data, was raised. Water column analysis of contaminants is
expensive and, therefore, the need for it must be well substantiated. Several supporting reasons to
do water column work were: 1) for metals, comparisons cannot be made between water column and
sediment concentrations; 2) bioavailability cannot be determined from sediment concentrations; and
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3) at this time, fish tissue residue data only reflect human health issues, therefore, water column
testing is also needed to look at ecosystem health.
ft was generally agreed that the data are spatially and temporally limited, and that the extent
and magnitude of the problem cannot be characterized based on this data. Although limited, existing
data do suggest problems, substances, or areas where there is a need to focus water column sampling
efforts.
When asked whether a level of concern can be derived from a review of the available data,
relative to the water column habitat, the general consensus of the forum participants was that the
available data were too limited to answer this question. Several additional points emerged in
response to this discussion:
• Long term chronic levels of water column contaminants may have adverse effects.
• More information is needed concerning low levels of contamination over longer periods of
time.
• Water quality criteria are not always sufficient to prevent effects.
• A concerted effort is needed to establish water quality criteria specific to the Chesapeake
Bay.
• There is a great need to focus research on a chemical specific and region specific basis.
• There is a need to determine what constitutes a problem for water column habitats.
• Over the past several years, there has been a reduction in point source effluent toxiciry as
evidenced by Maryland's effluent toxicity testing program.
• Nonpoint sources of water column contamination remain largely unknown.
The question of whether the Toxics Subcommittee should recommend specific sampling,
handling, and analytical methodologies protocols for future water column contaminants monitoring
throughout the Bay basin was raised for further consideration during the reevaluation of the
Basinwide Toxics Reduction Strategy.
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NAME
Roster of Participants
Chesapeake Bay Water Column Contaminants
Critical Issue Forum
April 14, 1993
AFFILIATION
Richard Batiuk (Forum Chair)
Greg Baier
Dean Baudler
Tim Cohn
Betsy Dobler
Rich Eskin
Marianne Fisher
Dana Frye
Adil Godrej
Lenwood Hall
Ian Hartwell
Jessica Landman
John Kennedy
Rod Kime
Deirdre Murphy
Adrienne Nemura
Harriette Phelps
Scott Phillips
Harold Post
Chuck Prorok
Fritz Riedel
James Sanders
Jackie Savitz
David Sirois
Gary Speiran
Peter Tinsley
Nathalie Valette-Silver
David Velinsky
Linda Zynjuk
U.S. EPA Chesapeake Bay Program Office
U.S. Geological Survey
Computer Science Corporation/CBPO
U.S. Geological Survey - Reston
Maryland Department of the Environment
Maryland Department of the Environment
Chesapeake Research Consortium/STAC
Chesapeake Research Consortium/CBPO
Virginia Tech/Occoquan Laboratory
University of Maryland - Wye
Maryland Department of Natural Resources
Natural Resources Defense Council
Virginia Department of Environmental Quality
Pennsylvania Department of Natural Resources
Maryland Department of the Environment
Metropolitan Washington Council of Governments
University of the District of Columbia
U.S. Geological Survey - Towson
Virginia Tech/Occoquan Laboratory
Computer Science Corporation/CBPO
Academy of Natural Sciences, Benedict
Academy of Natural Sciences, Benedict
Chesapeake Bay Foundation
Virginia Tech/Occoquan Laboratory
U.S. Geological Survey - Richmond
Maryland Department of the Environment
National Oceanic and Atmos. Administration
Interstate Commission for the Potomac River Basin
U.S. Geological Survey - Towson
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