Environmental biochemistry of arsenic

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Reviews of Environmental Contamination and Toxicology; (United States)

DOI:https://doi.org/10.1007/978-1-4612-2864-6_4· OSTI ID:5752110

Tamaki, S; Frankenberger, Jr, W T ^[1]

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1. Department of Soil and Environmental Sciences, University of California, Riverside (United States)

Microorganisms are involved in the redistribution and global cycling of arsenic. Arsenic can accumulate and can be subject to various biotransformations including reduction, oxidation, and methylation. Bacterial methylation of inorganic arsenic is coupled to the methane biosynthetic pathway in methanogenic bacteria under anaerobic conditions and may be a mechanism for arsenic detoxification. The pathway proceeds by reduction of arsenate to arsenite followed by methylation to dimethylarsine. Fungi are also able to transform inorganic and organic arsenic compounds into volatile methylarsines. The pathway proceeds aerobically by arsenate reduction to arsenite followed by several methylation steps producing trimethylarsine. Volatile arsine gases are very toxic to mammals because they destroy red blood cells (LD50 in rats; 3.0 mg kg-1). Further studies are needed on dimethylarsine and trimethylarsine toxicity tests through inhalation of target animals. Marine algae transform arsenate into non-volatile methylated arsenic compounds (methanearsonic and dimethylarsinic acids) in seawater. This is considered to be a beneficial step not only to the primary producers, but also to the higher trophic levels, since non-volatile methylated arsenic is much less toxic to marine invertebrates. Freshwater algae like marine algae synthesize lipid-soluble arsenic compounds and do not produce volatile methylarsines. Aquatic plants also synthesize similar lipid-soluble arsenic compounds. In terrestrial plants, arsenate is preferentially taken up 3 to 4 times the rate of arsenite. In the presence of phosphate, arsenate uptake is inhibited while in the presence of arsenate, phosphate uptake is only slightly inhibited. There is a competitive interaction between arsenate and phosphate for the same uptake system in terrestrial plants.

• OSTI ID: 5752110
• Journal Information: Reviews of Environmental Contamination and Toxicology; (United States), Vol. 124; ISSN 0179-5953
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ARSENIC
BIODEGRADATION
ALGAE
AQUATIC ORGANISMS
ENVIRONMENTAL EXPOSURE PATHWAY
FRESH WATER
METHYLATION
MICROORGANISMS
PLANTS
REDOX REACTIONS
SEAWATER
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
SEMIMETALS
WATER
560300* - Chemicals Metabolism & Toxicology