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Anaerobic biotransformation of roxarsone and related N-substituted phenylarsonic acids

January 1, 2006

Large quantities of arsenic are introduced into the environment through land application of poultry litter containing the organoarsenical feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid). The objective of this study was to evaluate the bioconversion of roxarsone and related N-substituted phenylarsonic acid derivatives under anaerobic conditions. The results demonstrate that roxarsone is rapidly transformed in the absence of oxygen to the corresponding aromatic amine, 4-hydroxy-3-aminophenylarsonic acid (HAPA). The formation of HAPA is attributable to the facile reduction of the nitro group. Electron-donating substrates, such as hydrogen gas, glucose, and lactate, stimulated the rate of nitro group reduction, indicating a microbial role. During long-term incubations, HAPA and the closely related 4-aminophenylarsonic acid (4-APA) were slowly biologically eliminated by up to 99% under methanogenic and sulfate-reducing conditions, whereas little or no removal occurred in heat-killed inoculum controls. Arsenite and, to a lesser extent, arsenate were observed as products of the degradation. Freely soluble forms of the inorganic arsenical species accounted for 19-28% of the amino-substituted phenylarsonic acids removed. This constitutes the first report of a biologically catalyzed rupture of the phenylarsonic group under anaerobic conditions. ?? 2006 American Chemical Society.

Publication Year 2006
Title Anaerobic biotransformation of roxarsone and related N-substituted phenylarsonic acids
DOI 10.1021/es051981o
Authors I. Cortinas, J.A. Field, M. Kopplin, J.R. Garbarino, A.J. Gandolfi, R. Sierra-Alvarez
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Index ID 70030534
Record Source USGS Publications Warehouse