Bioaccumulation

Bioaccumulation is a general term for the accumulation of substances, such as pesticides (DDT is an example), methylmercury, or other organic chemicals in an organism or part of an organism. The accumulation process involves the biological sequestering of substances that enter the organism through respiration, food intake, epidermal (skin) contact with the substance, and/or other means. The sequestering results in the organism having a higher concentration of the substance than the concentration in the organism’s surrounding environment. The level at which a given substance is bioaccumulated depends on the rate of uptake, the mode of uptake (through the gills of a fish, ingested along with food, contact with epidermis (skin), …), how quickly the substance is eliminated from the organism, transformation of the substance by metabolic processes, the lipid (fat) content of the organism, the hydrophobicity of the substance, environmental factors, and other biological and physical factors. As a general rule the more hydrophobic a substance is the more likely it is to bioaccumulate in organisms, such as fish. Another way of saying this is that bioaccumulation of a substance is correlated to the octanol-water partition coefficient (K_OW) of the substance. Increasing hydrophobicity (lipophilicity) leads to an increasing propensity to bioaccumulate. Some substances do not conform to this relationship, such as methlymercury. Methlymercury accumulates in fish to a much greater degree than methlymercury’s K_OW would indicate.

A related term is bioconcentration. Bioconcentration differs from bioaccumulation because it refers only to the uptake of substances into the organism from water alone. Bioaccumlation is the more general term because it includes all means of uptake into the organism.

More Information

• Biodynamic Model is Unraveling the Complexities of Metal Bioaccumulation from Contaminated Sediments
• National Assessment of Mercury in Aquatic Ecosystems, Includes information on the bioaccumulation of mercury in fish.
• New Method for Assessing Bed Sediment Contamination
• Bioaccumulation of Mercury by Fish and Fish-Forage Organisms in Camp Far West Reservoir, Yuba and Placer Counties, California
• Mercury Bioaccumulation in Fish in a Region Affected by Historic Gold Mining: The South Yuba River, Deer Creek, and Bear River Watersheds, California, 1999, Open-File Report 00-367
• The Virtual Fish: Semipermeable Membrane Device (SPMD) basics, A paper on the use of a semipermeable membrane device (SPMD) to measure contaminants in water by mimicking the parts of fish that cause concentration of specific chemicals in fish tissues
• Research on Bioaccumulation and Toxicity of Contaminants
• Integrated Geochemical Studies in the Everglades - Mercury Cycling and Bioaccumulation
• Mercury Bioaccumulation through an Everglades Aquatic Food Web
• The Countering Contamination: Data and DDE, A teaching curriculum that introduces high school students to the basics of ecotoxicology, bioaccumulation, and biomagnification

References

• Barron, M.G., 1990, Bioconcentration--Will water-borne organic chemicals accumulate in aquatic animals?: Environmental Science & Technology, v. 24, no. 11, p. 1612-1618.
• Spacie, A., McCarty, L.S., and Rand, G.M., 1995, Bioaccumulation and bioavailability in multiphase systems, chapter 16 in Rand, G.M., ed., Fundamentals of Aquatic Toxicology, 2d ed.: Washington, D.C., Taylor and Francis, p. 493-521.
• Nowell, L.H., Capel, P.D., and Dileanis, P.D., 1999, Pesticides in stream sediment and aquatic biota--distribution, trends, and governing factors: Boca Raton, Fla., Lewis Publishers, 1001 p.
• International Union of Pure And Applied Chemistry (IUPAC), 1993, Glossary For Chemists Of Terms Used In Toxicology: Pure and Applied Chemistry, v. 65, no. 9, p. 2003-2122 (on-line version posted by the U.S. National Library of Medicine).
• USGS National Water-Quality Assessment Glossary
• The American Heritage Dictionary of the English Language, 2000: Houghton Mifflin Company, Fourth Edition.

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