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ensure accuracy. Earth Materials and Health: Research Priorities
for Earth Science and Public Health can use arsenate as a
terminal electron acceptor to reduce As+5 to As+3 (Jackson and
Dugas; 2003), conserving energy from the oxidation of organic
carbon in anaerobic environments but producing the more toxic
form of arsenic. Other microbes (or even the same organism,
e.g., Thermus HR-1: see Gihring and Banfield, 2001) oxidize
arsenite to arsenate, sometimes using arsenite as substrate and
conserving energy as a chemoautotroph (e.g., Oremland et al.,
2002). Oxidized arsenic (arsenate) is accidentally taken up by
micro-organisms as part of the phosphate transport system, due
to the similarity of the As+5 oxyanion species to inorganic
ortho-phosphate, and the effects of arsenic toxicity can be
increased or decreased by pH, temperatu