Mercury Strategy for the Bay-Delta Ecosystem - CALFED Bay-Delta ...

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limits, validation of data by third parties, and technical review of methods used for the handling,
preparation, and analyses of samples. Inter-laboratory comparisons, which are particularly
useful for documenting inter-laboratory precision, should be conducted annually or biannually
for the duration of the project. Blind Certified Reference Materials can be used in interlaboratory
comparisons to document and quantify both precision and accuracy (bias). An
effective, quality-assurance program enhances the confidence of participating research teams and
provides quantitative documentation of the precision, accuracy, comparability, and
representativeness of the data collected. About 5 to 10 percent of the annual analytical workload
in a project should be devoted to quality assurance at the programmatic level.
Project level. The effort devoted to quality control and quality assurance at the project level
should exceed that done at the program level. Quality control and quality assurance activities
should be designed to evaluate both field and laboratory methods. Project-level procedures or
material to be evaluated should include the collection, handling, preservation, and preparation of
samples, as well as chemical reagents, instrumentation, analyses, and documentation. About 25
to 35 percent of the total analytical workload in a project (including field replicates and
laboratory splits of samples) should be devoted to quality assurance at the project level.
REFERENCES
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California. U.S. Geological Survey Fact Sheet FS-061-00, Sacramento, California. 6 pp.
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phytoplankton biomass and production in an estuary. Limnology and Oceanography 37: 946-
955.
Atwater, B.F., Conrad, S.G., Dowden, J.N., Hedel, C.W., MacDonald, R.L., and Savage, W.
1979. History, landforms, and vegetation of the estuary's tidal marshes, in San Francisco
Bay: The Urbanized Estuary, Conomos, T.J. (Ed.), Pacific Division of the American
Association for the Advancement of Science, San Francisco, California, pp. 347-385.
Babiarz, C.L., Hurley, J.P., Hoffman, S.R., Andrew, A.W., Shafer, M.M., and Armstrong, D.E.
2001. Partitioning of total mercury and methylmercury to the colloidal phase in freshwaters.
Environmental Science and Technology 35: 4773-4782.
Bennett, W.A. and Moyle, P.B. 1996. Where have all the fishes gone? Interactive factors
producing fish declines in the Sacramento-San Joaquin estuary, in San Francisco Bay: The
Ecosystem, Hollibaugh, J.T. (Ed.), Pacific Division of the American Association for the
Advancement of Science, San Francisco, California, pp. 519-542.
Benoit, J., Gilmour, C., Heyes, A., Mason, R.P., and Miller, C. 2003. Geochemical and
biological controls over methylmercury production and degradation in aquatic ecosystems, in
Biogeochemistry of Environmentally Important Trace Elements, Chai, Y. and Braids, O.C.
(Eds.), American Chemical Society, Washington, DC, pp. 262-297.
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