| Summary: | In general, bacteria are capable of biotransforming inorganic arsenic
into methylarsenic acids and arsines. The microbial activity of lake
sediments was examined with respect to the mobilization of mine tailings
that have a high arsenic content. Aerobic and anaerobic mixed microbial
populations were isolated from Kam Lake, Yellowknife, N.W.T.
An aerobic microbial population from 5 cm sediment depth, the layer
immediately above the contaminated mine tailings, was capable of
transforming arsenicals. Speciation of arsenicals in the culture medium,
determined by using hydride generation - gas chromatography - atomic
absorption spectrometry (HG-GC-AAS) shows that this bacterial population
is able to methylate arsenicals and subsequently demethylate the product.
However, only methylation was observed in media containing
dimethylarsinic acid.
Anaerobic microbial populations, from all depths, produce a yellow
precipitate upon incubation with arsenate for 10-14 days. The precipitate
was identified as AS₂S₃ by microanalysis and scanning electron microscope +
energy dispersive x-ray (SEM + EDX). The anaerobic microbial population,
which should not contain sulfate-reducing organisms, appears to be arsenic
tolerant; there is no evidence of methylation of arsenic. === Science, Faculty of === Chemistry, Department of === Graduate
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