Influence of microbes on the mobilization, toxicity and biomethylation of arsenic in soil

To understand the effects of microbial activity on the mobilization and spe ciation of arsenic in soil, the cycling of arsenic was studied in microcosm experiments under laboratory conditions. Particular attention was paid to the biomethylation of arsenic and to the toxicity of inorganic and organic arsenic species for microbes. Microbes enhanced mobilization of arsenic fro m soil by 19-24% compared to formaldehyde inhibited controls. Formation of dissolved methylated arsenic species by microbes was low (< 0.1%) during th e 5-day incubation. Even though methylation may function as a detoxificatio n method, it was of minor importance in the soil tested. (C) 1999 Elsevier Science B.V. All rights reserved.