Ecotoxicology of arsenic in the marine environment
- Battelle Ocean Sciences Lab., Duxbury, MA (United States)
Arsenic has a complex marine biogeochemistry that has important implications for its toxicity to marine organisms and their consumers. The average concentration of total arsenic in the ocean is about 1.7 {micro}g/L, about two orders of magnitude higher than the US Environmental Protection Agency`s human health criterion value of 0.0175 {micro}g/L. The dominant form of arsenic in oxygenated marine and brackish waters in arsenate (As V). The more toxic and potentially carcinogenic arsenite (As III) rarely accounts for more than 20% of total arsenic in seawater. Uncontaminated marine sediments contain from 5 to about 40 {micro}g/g dry weight total arsenic. Arsenate dominates in oxidized sediments and is associated primarily with iron oxyhydroxides. In reducing marine sediments, arsenate is reduced to arsenite and is associated primarily with sulfide minerals. Marine algae accumulate arsenate from seawater, reduce it to arsenite, and then oxidize the arsenite to a large number of organoarsenic compounds. The algae release arsenite, methylarsonic acid, and dimethylarsinic acid to seawater. Dissolved arsenite and arsenate are more toxic to marine phytoplankton than to marine invertebrates and fish. This may be due to the fact that marine animals have a limited ability to bioconcentrate inorganic arsenic from seawater but can bioaccumulate organoarsenic compounds from their food. Tissues of marine invertebrates and fish contain high concentrations of arsenic, usually in the range of about 1 to 100 {micro}g/g dry weight, most of it in the form of organoarsenic compounds, particularly arsenobetaine. Organoarsenic compounds are bioaccumulated by human consumers of seafood products, but the arsenic is excreted rapidly, mostly as organoarsenic compounds. Arsenobetaine, the most abundant organoarsenic compound in seafoods, is not toxic or carcinogenic to mammals. Little of the organoarsenic accumulated by humans from seafood is converted to toxic inorganic arsenite.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 514533
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 16, Issue 5; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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