LEVELS OF CHEMICAL VERSUS BIOLOGICAL METHYLATION OF MERCURY IN SEDIMENTS

Conversion to methylmercury in soils and sediments amplifies the environmental hazards of inorganic mercury (Hg) pollutants. For the purpose of this discussion chemical Hg methylation is defined as the portion of the total that occurs also in the absence of a metabolically active microbial community. Two approaches were used in comparing the contributions of biochemical versus chemical Hg methylation: its level in anoxic saltmarsh sediments incubated at favorable pH and temperature was compared to methylation at pH and temperature values hostile to life. Hg methylation in normal sediment was also compared to that in steam-sterilized sediment incubated either at normal or elevated temperatures. Refs.