Microbial transformations of mercury in aquatic environments

Experiments were conducted to determine the fate of HgCl/sub 2/ and CH/sub 3/HgCl in lake sediments incubated under laboratory and field conditions. The results indicated that CH/sub 3/Hg/sup +/ is unstable in sediments and may be converted into dialkylmercury and possibly Hg/sup 2 +/. The necessity for microbial activity in mercury transformations was established using sediments sterilized with autoclaving or by exposure to gamma radiation. The rates of mercury conversions were enhanced by increasing temperatures, amending sediments with organic carbon, and increasing mercury concentrations. The field study indicated that monalkyl-mercury can be formed under natural conditions and that CH/sub 3/Hg/sup +/ introduced into sediments may be degraded. In general, the rates for mercury transformations were greater under laboratory conditions than during in situ incubation.