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RMP NewsVolume 5, Issue 1
Regional Monitoring News, Spring 1999
Contents
Calculation of TMDLs for Copper and Nickel in South
San Francisco Bay
Tom Grieb, Tetra Tech, Inc. and Adam Olivieri, EOA, Inc.
The emergence of the TMDL process as an important planning and regulatory
decision-making tool is a recent development in national, regional, and
local efforts to achieve continued improvement in the quality of the nation's
surface waters. The TMDL, or total maximum daily load, establishes the
allowable loadings of a pollutant that a water body can receive without
violating applicable water quality standards or harming beneficial uses.
Although identified in Section 303(d) of the federal Clean Water Act (CWA)
over 20 years ago, it is only since 1996 that the TMDL has become an important
process for developing state water quality standards.
The development of TMDLs for copper and nickel is required because South
San Francisco Bay (South Bay) has been designated an impaired water body
under Section 303(d) of the CWA. Although this is a requirement, there
is also optimism that these TMDLs will provide a unique opportunity to
address the many complex issues associated with setting water quality standards
for the South Bay. Stefan Lorenzato, the TMDL coordinator at the State
Water Resources Control Board, notes that the collaborative approach that
is being taken to prepare these TMDLs is likely to be more successful than
the programmatic approach that has traditionally been used by state and
local regulatory agencies.
These copper and nickel TMDLs are noteworthy for several reasons. Foremost
among them is the fact that they are being independently funded by the
City of San Jose. David Tucker and Dan Bruinsma, the City of San Jose's
co-project managers, note that this is one of the most comprehensive, chemical-specific,
environmental assessments ever conducted in San Francisco Bay. A total
of $3.5 million has been allocated by the City for this 4-year effort.
The copper and nickel TMDLs are also being integrated into the ongoing
Santa Clara Basin Watershed Management Initiative (WMI), and a major emphasis
is being placed on establishing and maintaining public and industry involvement.
One indication of the collaborative aspect of this effort, referred to
above by Stefan Lorenzato, is the formation of a TMDL Work Group (TWG).
The TWG is made up of stakeholders from wastewater and stormwater dischargers,
environmental groups, industry, regulatory agencies, and other involved
citizens, and it has been formed as part of the WMI's Bay Modeling and
Monitoring Subgroup. The charter of this group is to guide the TMDL process
and to develop new and preferred ways to make the process understandable
and equitable. A Technical Review Committee (TRC) has also been formed
to review the technical products of the TMDL effort. The TRC is made up
of nationally recognized technical experts in such areas as the behavior
of metals in aquatic systems, hydrodynamics, estuarine modeling, ecological
effects of trace metals, sediment transport processes, and atmospheric
modeling.
The focus of the copper and nickel TMDL efforts during the first year
of activity has been in the following five primary areas of investigation:
Data Collection and Analysis
One of the first efforts has been to create an extensive database that
is available to both technical and stakeholder personnel involved in the
project. The database is unique in that it brings together different types
and large volumes of information (over 1.5 million records have been entered
so far) focused on the specific issues of TMDL development for copper and
nickel in the lower South San Francisco Bay. Many investigators in the
area have contributed to the development of a database that consists of
water quality data, sediment quality data, sediment core data, point and
nonpoint source loading data, basemap information, bathymetric data, hydrodynamic
data, suspended solids data, air quality data, and photographic/satellite
imagery.
Additional data will continually be entered, as they become available
during the project. To facilitate use and understanding of the data, the
database has been created in a Geographic Information System (GIS).
Conceptual Model Development
A conceptual model that depicts the current understanding of the processes
that influence copper and nickel cycling in Lower South San Francisco Bay
and adjacent Bay waters was recently produced. To communicate the information
that has been developed on loadings, sediment transport and copper and
nickel cycling, the conceptual model makes extensive use of graphics. The
objective of this effort was to develop a tool for effectively communicating
the existing information to a wide audience of interested stakeholders.
Diagrams such as the one shown can be used to facilitate the discussions
of upcoming TMDL issues such as source characterization, beneficial-use
impairment, simulation model development, and the design of special studies.
The conceptual model was the topic of one of the poster sessions at the
recent State of the Estuary Conference.
Source Characterization. The major sources of copper and nickel that
enter the South Bay are being quantified. The loadings have been divided
into four major source categories: wastewater discharges, tributary loads,
atmospheric deposition to the surface water, and sediment exchange with
the water column within the Bay. This effort is the first step in identifying
the major contributors of copper and nickel loading so that appropriate
control measures can be developed if necessary. It is also the purpose
of this work to identify limitations and uncertainties in the existing
loading data so that additional efforts to improve these estimates can
be focused in the appropriate areas.
Assessment of Beneficial Use Impairment
In January of this year, over 50 individuals from local regulatory agencies,
municipal dischargers, stormwater management groups, environmental groups,
and other South Bay stakeholder groups participated in an impairment assessment
workshop held at the San Francisco Bay Regional Water Quality Control Board.
Information was presented on progress made in developing indicators for
assessing impairment to beneficial uses. The results of the workshop were
also presented at the recent State of the Estuary Conference. Later this
spring, an Impairment Assessment Report will be completed. The purpose
of the impairment assessment is to determine if, when and how the beneficial
uses of the South Bay are adversely affected by copper and nickel, and
what concentrations cause these problems. The results of this assessment
will determine the course of all further activities associated with these
TMDLs.
Simulation Model Development
The first of several technical reports that will be produced in the evaluation
of existing two- and three-dimensional numerical simulation models was
completed in December 1998. This document identifies models that could
be used in the calculation of TMDLs for copper and nickel in South San
Francisco Bay. This evaluation process is important because numerical models
will be the primary tool used to evaluate the responses of the South Bay
to copper and nickel loading. This initial report identifies the model
components that are necessary to simulate and predict the transport and
fate of copper and nickel in South San Francisco Bay. Twenty potentially
applicable models were identified and classified according to type and
functionality, and a subset of 10 models was recommended for further evaluation.
Comments on the TMDL Process
Numerous individuals in the copper and nickel TWG have already made significant
time commitments to this process. Tom Mumley of the California Regional
Water Quality Control Board and the TWG's co-chairman suggests that this
is because many people recognize that the up-front involvement of the stakeholders
and the level of funding available offers a unique opportunity to achieve
resolution of issues that are acknowledged to be both politically contentious
and technically complex.
Rainer Hoenicke, the other TWG co-chairman and the Program Manager for
the RMP, also points out that "The information synthesis effort that is
part of the problem characterization is particularly relevant, because
for most of the stakeholders, this is an invaluable opportunity to become
educated about the complex issues surrounding these two metals." Also,
as the program manager for the RMP, he is personally excited about the
TMDL effort because it demonstrates that the monitoring activities conducted
in the Estuary will have an impact on environmental decision-making. He
is also hopeful that the conceptual model and the other problem definition
efforts of the TMDL will help to focus future data collection efforts.
Michael Stanley-Jones of the Silicon Valley Toxics Coalition and CLEAN
South Bay's environmental coordinator for the Copper-Nickel TMDL has expressed
optimism that the tools that are being developed for these TMDLs will provide
a strong technical foundation for future TMDL efforts in the San Francisco
Bay/Estuary.
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The ABCs of TIEs
Jeffrey Cotsifas and Scott Ogle, Pacific Eco-Risk Laboratories
For any monitoring program investigating water and/or sediment toxicity,
there are two fundamental questions: (1) when and where is toxicity occurring,
and (2) what is causing the toxicity? The RMP currently assesses when and
where water toxicity is occurring in San Francisco Bay by performing ambient
water toxicity tests (bioassays) with Mysidopsis bahia (an estuarine
shrimp test) and sediment toxicity tests with Eohaustorius estuarius
(estuarine amphipod) and sediment elutriate tests with bivalves. However,
it is equally as important to answer the question of what is causing the
toxicity if the RMP is to achieve the goal of providing information to
the Regional Board which will help improve water and sediment quality within
the Bay.
When toxicity is present in ambient waters, effluent discharges or sediments,
it is often difficult, or even impossible, to identify the cause(s) of
toxicity by looking for specific chemicals via analysis of the traditional
set of priority pollutants. This conventional approach to identifying potential
suspects has many difficulties: it assumes that the culprit can be measured
by the analytical methodology being used, that the toxicity of the identified
chemical is known, that the synergistic and antagonist effects of multiple
compounds are known, and that the effects of the sample matrix on the toxicity
of these compounds is understood.
One alternative to this conventional approach is the use of toxicity
identification evaluations (TIEs), which have been successfully used to
identify the causes of toxicity in ambient waters and effluents, and more
recently, sediments.
What is a TIE?
A TIE is a process that allows for determination of the compound(s) responsible
for toxicity in ambient waters, effluents, and sediments.
How does a TIE Work?
A TIE works by performing physical and chemical manipulations on a toxic
sample which typically removes, and in subsequent phases recovers, toxicity.
Toxicity removal and recovery is tracked though the use of toxicity tests
performed on the physically and chemically manipulated samples. For example,
if the addition of ethylene diamine tetracetic acid (EDTA) to a sample
removes toxicity, then the cause of the toxicity was likely a divalent
cationic metal. Similarly, if aeration of the sample removes toxicity,
then volatile compounds are suspect. The resulting patterns of toxicity
removal and recovery provide clues that direct the investigator to the
chemical(s) responsible for the toxicity.
TIEs have three major parts (or phases): Phase I (Characterization),
Phase II (Identification), and Phase III (Confirmation).
Phase I : Characterization
Phase I procedures are aimed at characterizing the physical and chemical
properties of the toxicants present in a water or sediment sample through
a variety of manipulations that include (but are not limited to): pH adjustment,
filtration, aeration, reverse phase SPE column extraction, graduated pH,
EDTA addition, sodium thiosulfate addition, and PBO addition (see flow
chart). Each of these manipulations is designed to alter generic classes
of compounds in such a way that they are rendered unavailable to the bioassay
test organism. Below is a description of each treatment and how each affects
the sample.
For pH adjustment fractionations, the pH of aliquots of the sample are
adjusted down (to pH3) and up (to pH11) and then subjected to aeration,
filtration, and SPE manipulations (the samples are re-adjusted back to
the initial pH prior to testing). The pH of the sample can determine the
ionization, or polarity, of constituent chemicals, thereby making them
more or less amenable to removal by aeration, filtration, or SPE. Again,
the greater the removal of a toxic compound from the sample, the less toxicity
will be present in the subsequent toxicity test.
Aeration manipulations are designed to determine whether the observed
toxicity is due to volatile, oxidizable, or sublatable compounds. If this
treatment is effective in removing toxicity, then further differentiation
between oxidizable and volatile compounds may be required (this can be
accomplished by sparging the sample with nitrogen rather than air).
Filtration manipulations help determine whether or not the toxicity
is associated with filterable compounds whereas reverse-phase SPE is geared
towards the removal of relatively non-polar compounds such as organophosphate
pesticides (e.g., diazinon and chlorpyrifos). As with the aeration manipulation,
the ionization, or polarity, of the compound will strongly effect the ability
of these filtration and reverse-phase SPE manipulations to remove toxicity.
EDTA is a strong chelating agent and will bind with many cationic metals,
creating a nontoxic complex. Another chelating agent that is used in the
TIE process to identify metals is sodium thiosulfate (STS). Some metals
are amenable to removal by both EDTA and STS whereas others can be removed
by one or the other, but not both. The pattern of removal by EDTA and STS
manipulations can allow the investigator greater resolution in identifying
causative metals. STS is also a strong reducing agent, and is also used
in the TIE process to identify oxidants such as chlorine, bromine and iodine.
Piperonal butoxide (PBO) additions to the sample result in inactivation
of the Cytochrome P-450 enzyme system of the test organisms. PBO removal
of toxicity indicates that metabolically activated compounds (e.g., organophosphate
pesticides such as diazinon and chlorpyrifos), are suspect.
Some Examples of Phase I (characterization) results and interpretations:
-
If EDTA addition removes toxicity, then cationic metals are a likely cause
of toxicity.
-
If reverse phase SPE column extraction removes toxicity, then non-polar
organics are a likely cause of toxicity.
-
If the addition of PBO removes toxicity, then compounds that are activated
by the Cytochrome P450 enzyme system are suspect (e.g., organophosphate
pesticides, such as diazinon and chlorpyrifos).
It is important to note that, in general, Phase I TIEs are limited to identifying
the class of compound(s) responsible for toxicity. If further resolution
of the cause(s) of toxicity is desired, Phase II identification procedures
are implemented.
Phase II: Identification
The primary goal of the Phase II identification procedures is the isolation
of toxicants through the use of chemical fractionation procedures followed
by identification of the specific compound(s) responsible for the toxicity.
The method selected to identify the toxicant(s) will depend on the results
of the Phase I characterization tests.
Selected Methods to identify suspect chemicals in toxic samples
Non-polar organics |
SPE => HPLC => GC/MS, MS-MS |
Cationic metals |
AA, ICP, ICP-MS |
Volatiles |
Purge-and-Trap => GC/MS |
Ammonia, sulfide |
ion specific electrodes |
Polar organics |
LC-MS |
Anionic Metals |
AA, ICP, ICP-MS |
Once specific suspects have been identified in the Phase II portion
of the TIE process, confirmation of these compounds as the responsible
toxic agents is investigated. Confirmation of the specific cause(s) of
toxicity constitutes Phase III of the TIE.
Phase III: Confirmation
Confirmation is one of the most important steps of the TIE process when
specific toxicant identification is the primary goal. Some routinely used
Phase III procedures include:
-
Mass balance (tracking concentrations and toxicity as a result of removal
and amendment of suspect toxicant in the sample.
-
Toxicity recovery via sample spiking with the suspect toxicants.
-
Correlation of toxicity and chemical concentrations.
TIEs and the RMP
RMP monitoring has revealed both ambient water and sediment toxicity in
San Francisco Bay. The next step is to identify the causes of the toxicity
being observed. Sediment TIEs have been part of the RMP for several years,
whereas ambient water TIEs are just getting underway.
Sediment TIEs have been performed on sediment elutriates which have
been demonstrated to be toxic to bivalve embryo development. These TIEs
have strongly implicated metals as the cause of toxicity in sediments in
the Rivers and North Bay (Grizzly Bay, Suisun Bay) stations. TIE investigations
are also being implemented to investigate toxicity observed in South Bay
sediment samples.
Ambient water toxicity has been observed primarily during and after
storm events. As a result, monitoring of stormwater runoff has become a
primary focus for toxicity testing. Based on studies performed in the Central
Valley watershed, pesticides (particularly OP-pesticides) are a primary
suspect as the cause of the observed ambient water toxicity, although other
chemicals may, in fact, be responsible).
The RMP is currently initiating simplified "scaled down" TIEs on toxic
water samples to help identify the cause(s) of the toxicity. As pesticides
are a primary suspect, the TIE fractionations initially being used are
C18SPE (to remove organics) and PBO additions (to identify OP-pesticides
as a potential cause of toxicity). The results of these efforts will be
reported as they become available.
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Tale of Two Watersheds: Chlorinated Hydrocarbons in the
South Bay
Ted Daum and Rainer Hoenicke, SFEI
Introduction
After the first three years of pollutant characterization conducted by
the Regional Monitoring Program for Trace Substances (RMP) throughout the
Estuary, it became evident that sampling stations at the Estuary margins
generally exhibited higher concentrations of chlorinated hydrocarbons (CHCs)
in water and sediment than those in the deeper parts of the Bay. CHCs include
many synthetic compounds that were used as pesticides and in industrial
applications, such as DDT, chlordane, and polychlorinated biphenyl (PCB),
among many others. Because of their persistence, their tendency to accumulate
in the food web, and their toxic properties, their production and use in
the U.S. was either banned or restricted many years ago.
At the time the RMP data revealed higher concentrations at the Estuary
margins, it was not clear which factors were primarily responsible for
this phenomenon. In order to determine the role of CHC inputs from adjacent
watersheds, the RMP decided that sampling at the interface between the
Bay and uplands had to be conducted. The Estuary Interface Pilot Study
(EIP) began in 1996. Initially, the Standish Dam station at the upper end
of the tidal prism of Coyote Creek was selected. In 1997 sampling was expanded
to include the mouth of the Guadalupe River, also known as Alviso Slough
(see map).
Objectives
The overall goals of the Estuary Interface Pilot Study are to:
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Link pollutant patterns found in the Estuary with those in adjacent watersheds
to test if runoff and sediment taken at the lower end of Coyote Creek and
the Guadalupe River differ from each other and from water and sediment
in the South Bay, including the Local Effects Monitoring (LEM) stations
maintained by the San Jose-Santa Clara Wastewater Treatment Plant and the
Sunnyvale Treatment Plant.
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Explore what kinds of ancillary water quality parameters and watershed
characteristics should be measured or described to explain some of the
patterns found, improve sampling design, and fine-tune testing methodology.
Monitoring sites for the Estuary Interface Pilot Study.
Sampling Plan
In 1997, a second sampling station was selected in an adjacent watershed.
The Alviso Slough station is on the lower reach of the Guadalupe River
at the South Bay Yacht Club. Both sampling locations are within the tidal
prisms. During the wet season, runoff amounts are large enough to dominate
the pollutant signal, while during the dry season, water sampled at both
stations was a brackish mix of both freshwater runoff and Bay water. Both
sites were selected for their accessibility, location in the brackish transitional
zone, and the fact that sediment deposition and accumulation was likely
to occur.
The same parameters in water and sediment were measured here as in the
RMP base program stations and sampling occurred at approximately the same
times (late February/early March, late April, and early August).
Sampling methodology for water was similar to that employed by the RMP.
Sediment was sampled from the creek bank at low tide from an area approximately
the same size as that sampled from the van Veen sediment grab used in the
RMP Base Program sampling.
Specific Questions for the Second Year of Sampling
With the completion of the second year of sampling, the following questions
have arisen:
-
Is the CHC concentration gradient that was observed in 1996 for Coyote
Creek also applicable for the Guadalupe River?
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Are there pronounced differences in the CHC profiles between the two interface
stations?
-
Are there pronounced differences in CHC concentrations between high- and
low-flow periods between the interface stations and those in the Estuary?
-
Which factors may influence the findings?
Highlights of Monitoring Results
Water Organics
1997 monitoring results show that concentrations of CHCs in the dissolved
and total water fractions were oftentimes higher at the Estuary Interface
Pilot Study stations than at the RMP Base Program stations, averaged by
reach.
Concentrations of total organics in water at the EIP sites compared with
RMP stations averaged by Bay reach, 1997. All concentrations are in parts
per quadrillion (ppq).
Sediment Organics
1997 monitoring results show that CHCs in sediments were oftentimes higher
at the Estuary Interface Pilot and Southern Slough reach stations than
at the remaining RMP Base Program reaches.
Concentrations of organics on sediments for the Standish Dam and Guadalupe
Slough sites compared with RMP stations averaged by Bay reach, 1997. All
concentrations in parts per billion (ppb). ND = below detection limit.
Because dieldrin was below the detection limit at most stations, it was
not included.
PCB Fingerprinting
In order to discern source, fate and transport patterns, analysis of the
congener spectrum (also called a fingerprint) may be conducted.
PCB fingerprints were generated from samples collected at the Estuary Interface
Pilot Study stations and representative stations in all reaches of the
Bay, for the dissolved and particulate fractions of water and for sediments,
for all cruises. These PCB fingerprints showed similar patterns of higher
molecular weight congeners dominated the EIP and representative South Bay
stations from the base program in both the water fractions and sediments.
These patterns were distinctly different from those measured in the rest
of the Bayconsisting of higher percentages of the lower weight congeners,
and lower overall concentrations. This suggests a possible ongoing source
load near the EIP stations, and a mixing of the PCB congener signal away
from the watersheds. Similar gradient patterns are seen in other localized
watershed sampling efforts in the Bay. Preliminary data from the San Leandro
Bay Project (conducted by the San Francisco Estuary Institute) strongly
suggests localized inputs of PCBs, as well as PAHs, and some trace metals.
A Simplified Evaluation of PCB Loadings to the South Bay
In 1998, RMP staff and outside experts reviewed the current approach to
monitoring CHCs and focused on PCBs due to their consistent and widespread
exceedances of water quality objectives throughout the Estuary. Although
chlorinated pesticides and PCBs have been banned or their use restricted
for decades, the long-term database on mussel tissue concentrations seems
to indicate that, after initial steep declines, PCB concentrations have
remained steady for the past 15 years. A more limited database on water
concentrations parallels the tissue findings of no further declines in
concentrations. If the Estuary is at steady-state as suggested by the long-term
datasets, new inputs must be approximately equal to total losses from the
Bay due to outflows of PCBs through the Golden Gate, volatilization, sediment
burial, and degradation.
Institute scientists and collaborators developed a preliminary mass
budget for PCBs for the Estuary based on a simple box model. This preliminary
budget indicates that approximately 60 kg of new inputs into the Estuary
are possible. Many of the assumptions underlying this estimate need to
be tested, and therefore this estimate has significant uncertainties associated
with it. Based on preliminary data from this study, it is quite probable
that the PCB load from the two South Bay watersheds contributes significantly
to the estimated total input to the Estuary.
To verify and quantify this, the monitoring program may take water samples
during hydrographic events i.e., storms and high river flow periods. These
are the times when the majority of the suspended sediments, and the CHCs
and other pollutants which sorb to them, make their way from the watersheds
into the Bay. Our investigations at the bottom of these two watersheds
indicate the importance of linking upstream monitoring with that of the
RMP. A new study element is under consideration that deals with investigating
pollutant sources, pathways, and loadings to better address where the best
control points may be found.
The information generated by the Estuary Interface Pilot Study in its
first two years has both enhanced our understanding of the contributions
of localized pollutant inputs to the Estuary, and underscored the data
gaps which remain to be filled in order to improve this understanding.
Specific questions for the second year of sampling were addressed. Similarities
in CHC concentrations between the two EIP stations occur in both water
and sediments, and these are in general enriched above the levels found
in the RMP stations in the Estuary. Pronounced differences between high
and low flow periods were also found at the EIP stations. These findings
indicate localized CHC inputs from the watersheds. The next task of the
EIP will be to quantify and verify these findings.
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Highlights from the RMP Annual Report
Lauren Gravitz, SFEI
The RMP will soon be releasing the 1997 Annual Report. This
year's report, as in previous years, includes results from the Base
Program (water, sediment, and bivalve monitoring), as well as from Pilot
and Special Studies completed in 1997, and an update on the RMP 5-year
review implementation. The report also includes papers contributed by
RMP investigators and other scientists which address other related monitoring
activities, such as the Sacramento River Watershed Program.
The 1997 monitoring year proved to be a strange one; it was the year
of the Big Storm, which resulted in record-setting precipitation in the
watershed in December and January, but was then followed by unusually dry
weather in February and March. These weather patterns had a visible effect
on RMP results and frequently created a sharp contrast between the first
two sampling cruises of the year as well as higher than normal contaminant
concentrations at many RMP sampling sites. For example, water sampling
revealed that mercury, chromium, and lead concentrations were at an all-time,
baywide high, with the north bay concentrations appearing to be particularly
elevated due to unusually high flow from nearby rivers. Sediment contaminant
concentrations were especially high as well, with many contaminants exceeding
their conventional guidelines. Also notable was a special study on contaminant
concentrations in San Francisco Bay fish, which showed that toxic chemicals
in Bay fish remained at concentrations of potential human health concern.
Additional highlights from the 1997 Annual Report are described
below; for a copy of the Executive Summary and/or the full report, please
contact Gabriele Marek at (510) 231-5713, or visit our web site at: http://www.sfei.org.
Water
Due to the Big Storm of 1997, which resulted in a combination of high flows
and elevated contaminant concentrations, the mass loading of many contaminants
to the Bay was higher than in previous years. The extreme hydrologic variation
at the beginning of the year created a distinct contrast in conventional
water quality parameters between the first two sampling cruises of the
year. During January sampling, salinity in the Bay's surface waters was
extremely low and the baywide mean of total suspended solids (TSS) was
the highest ever recorded in RMP history; in April salinity had increased
to almost twice its January value, while the mean TSS was less than half
of its January mean.
This contrast between sampling periods was also visible in dissolved
trace element concentrations. In January, dissolved concentrations of trace
elements (e.g., metals) were relatively high throughout the Estuary, with
chromium, mercury, and lead exhibiting the highest baywide average concentrations
for any cruise since the beginning of the RMP. These dissolved trace element
concentrations were especially high in the Northern Estuary and Rivers
monitoring stations, while concentrations in the South Bay appeared to
be unaffected by the Big Storm. Total (dissolved + particulate) concentrations
of some trace elements that are transported primarily in the particulate
phasechromium, copper, mercury, nickel, lead, and zincwere also sharply
elevated in January and mirrored the declines seen in TSS from January
to April.
Organochlorine pesticides also exhibited high concentrations in January,
with dissolved and total (dissolved + particulate) chlordanes and DDTs
at high levels in the Northern Estuary, although no clear seasonal variation
was visible in the southern reach. Dissolved diazinon, however, exhibited
seasonal variability in both northern and southern portions of the Bay.
The high dissolved + particulate concentrations of DDTs, chlordanes, and
dieldrin in the Northern Estuary suggest that contaminated sediment particles
from the Central Valley were transported during January's high flows. Total
polychlorinated biphenyl (PCB) concentrations, however, did not increase
as a result of the Big Storm, suggesting that sediment particles washed
down from the Central Valley were not elevated in PCBs.
Aquatic toxicity testing revealed toxicity to mysids (Mysidopsis)
in January at many of the Northern Estuary sites: Grizzly Bay, Napa River,
and both Rivers stations in January. In August, however, mysid toxicity
was concentrated in the southern reach of the Bay, with all four South
Bay stations showing low to zero percent survival. A separate toxicity
study, with emphasis on episodic toxicity, was also performed during the
winters of 1996-1997 and 1997-1998. Episodic toxicity is an important concern,
because contaminant concentrations can vary as a result of runoff following
large rainstorms or agricultural pesticide applications. Scientists have
found that toxicity coincides with this runoff, and results from this year's
study indicate that northern Bay waters may be toxic for as long as a week
following such events.
Sediment
As in previous years, most contaminant concentrations were highest in the
Southern Sloughs and South Bay, although the flood flows of January did
seem to have an effect on contaminant concentrations in the northern reach
of the Bay. Mercury concentrations were higher throughout the Estuary in
February, and several contaminants, such as copper, lead, selenium, and
polycyclic aromatic hydrocarbons (PAHs) had obviously elevated concentrations
at the San Joaquin River site in the Northern Estuary. When compared to
previous years, both copper and PAHs were higher than in the past at both
Rivers sites in the North Bay, while cadmium, chromium, nickel, chlordanes,
and DDTs were higher in the South Bay.
Sediment contaminant concentrations in the San Francisco Estuary were
frequently above levels known to cause effects at most of the RMP sites.
The highest concentrations of most contaminants were at the Estuary Interface
sites, the Southern Sloughs, and in the South Bay. Two different sets of
guidelines were used to help interpret RMP results: the Effects-Range guidelines
developed by the National Oceanic and Atmospheric Association, and the
Ambient Sediment Concentration (ASC) guidelines, developed by the San Francisco
Bay Regional Water Quality Control Board. The Effects-Range guidelines
can be used to predict the potential for biological effects, while ASC
guidelines are based on the ambient or "background" concentrations of contaminants
in the Bay and can indicate sites where contaminants exceed those background
levels. Most of the 1997 RMP sediment samples had multiple Effects-Range
exceedances, suggesting potential harm to resident species. ASC guideline
exceedances appeared most frequently in nickel and chromium concentrations,
as well as some individual PAH compounds. Both Effects-Range and ASC guidelines
had more exceedances in February than in August, suggesting that January's
flood flows increased sediment contaminant concentrations, therefore potentially
increasing toxicity.
Toxicity to bivalve embryos or amphipods was most pronounced and occurred
most frequently in the South Bay, where more of the samples were toxic
than in previous years, and at the Suisun Bay and Rivers. RMP investigators
are searching for the causes of the observed toxicity, especially at the
RMP Rivers stations, which have exhibited consistent toxicity to bivalves
and intermittent toxicity to amphipods over the past five years. In most
of the samples, it appears that a mixture of different contaminants, especially
metals, was the cause of the observed sediment toxicity.
Bivalves
In 1997, certain trends within the Estuary were definitely visible. By
combining the databases of the RMP and the State Mussel Watch Program,
thus increasing the size of the dataset, scientists found statistically
significant declines in silver in both the Central and South Bay reaches,
and less pronounced declines in mercury and lead concentrations. They also
found that lipid normalization of chlorinated hydrocarbon (CHC) concentrations
in bivalves reveals patterns that are otherwise not apparent, such as dramatic
declines in CHC concentrations soon after use restrictions were established.
Unlike previous years, the 1997 bivalve component of the RMP focused
more on evaluating the effectiveness of bivalve monitoring and how it might
be improved, in addition to simply examining contaminant concentrations
trends. The reasons for this were many; while bivalves are good trend indicators
for many contaminants, they do not bioaccumulate all contaminants in the
same manner. Additionally, water quality parameters such as TSS, temperature,
salinity, and dissolved oxygen can affect bivalve species' growth and condition,
making it difficult to compare trends both within and among different species.
Thus, special attention was given to assessing the use of bivalve monitoring
within the context of the RMP, and to finding methods of normalizing data
that might prove helpful in uncovering contaminant trends within the Estuary.
After extensive evaluation, RMP scientists concluded that while bivalves
are effective as a tool for monitoring spatial and temporal trends, they
are of limited use when applied to trace elements such as arsenic and mercuryelements
that do not accumulate appreciably above background levels in bivalve tissues.
They can, however, provide valuable insight into contaminant concentrations
in the Estuary, for while water and sediment sampling only provides a brief
snapshot of contamination, bivalve bioaccumulation studies provide an integrative
measure of water contamination over a three-month period.
Fish Tissue
As a followup to a 1994 Regional Board Study, a Special Study of contaminant
concentrations in San Francisco Bay fish was performed in 1997. RMP fish
sampling in 1997 targeted seven species frequently caught and eaten by
Bay fishers at seven popular fishing areas around the Bay. The results
revealed that persistent toxic chemicals in Bay fish remained at concentrations
of potential human health concern. For instance, mercury exceeded a human
health screening value in 44 of 84 Bay samples, with all leopard shark
and striped bass samples exceeding the screening value. PCBs and other
trace organics were highest in white croaker and shiner surfperch, the
two species with the highest fat content in their muscle tissue. PCBs exceeded
the human health screening value in more than two-thirds of the Bay samples,
while dieldrin, DDT, and chlordane had fewer samples above screening values.
Dioxins and dibenzofurans exceeded their screening values in all seven
of the samples that were analyzed.
There was significant variation in contaminant concentrations among
Bay locations. Oakland Harbor had significantly elevated concentrations
of mercury, PCBs, DDTs, and chlordanes compared to other Bay locations.
Mercury concentrations in 1997 were not significantly different from 1994.
Statistically significant declines in concentrations from 1994 to 1997
were observed for PCBs, DDTs, chlordanes, and dieldrin. However, continued
monitoring is required in order to establish whether these observed declines
are true indications of declining contaminant masses in the Bay instead
of variation due to other factors.
Conclusions
The original goals of the RMP are being met, and the program continues
to collect high quality baseline data, examine Estuary trends, and collaborate
with other local and regional monitoring programs. In addition, new and
continuing studies which complement RMP research and/or use RMP data have
proven to be extremely valuable. Some of the studies not mentioned above
but which are described fully in this year's Annual Report include:
the Bay Protection and Toxic Cleanup Program's study to identify toxic
hot spots; a Pilot Study examining pollutant patterns where Bay and upland
waters converge; and a study of benthic foraminifers (small protozoans)
and their response to environmental contaminants in the San Francisco Bay.
back to contents
RMP Calendar
Tuesday, May 11th
Technical Review Committee meeting, 9:30-2:30, at SFEI offices on the
Richmond Field Station.
Monday, July 19th
Steering Committee meeting, 9:30-12:00, at SFEI offices, Richmond Field
Station.
Announcements
New Reports in Print
Contaminant Concentrations in Fish from San Francisco Bay 1997 presents
the results of the RMP's 1997 Fish Contamination Pilot Study. to request
a copy of this 60-page report, please contact Gabriele Marek at (510) 231-5713.
Baylands Ecosystem Habitat Goals is a report of recommendations
on the types, amounts, and distribution of wetlands and related habitats
needed to sustain healthy and diverse populations of fish and wildlife
in the San Francisco Estuary is now available. A PDF version is available
to download from http:
//www.sfei.org/sfbaygoals/index.html. To order a hard copy of this
report call (510) 622-2465.
The 1997 RMP Annual Report will be available in June. This year
the report will be available as both hard copy and on CD-ROM as a PDF file.
To request your copy, please call (510) 231-5713. Please specify which
version you prefer.
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