Volatilisation of methylmercuric chloride by hydrogen sulphide

Abstract

THE interconversion of mercury compounds in the environment has attracted considerable interest, especially the synthesis and breakdown of the highly toxic methyl-mercury. The alkylmercurial can be formed and degraded by microorganisms in lakes, rivers, soil and the mammalian intestinal tract^1–6, although the ecological significance of these processes is difficult to assess. We describe here a further reaction which may be important with respect to the fate of mercury in the biosphere—the interaction of methylmercuric chloride (CH₃HgCl) with hydrogen sulphide. Hydrogen sulphide is produced by many bacteria in anaerobic conditions such as are found in the sediments of lakes and rivers, and it has been shown that trimethyllead salts can be converted to the volatile tetramethyllead by reaction with H₂S (ref. 7).