Methylgermanium in natural waters

Abstract

Biological methylation of metallic elements¹ and the occurrence and cycling of organometals in the environment have been investigated in Japan during the 1950s and 1960s, where the ingestion of fish and shellfish contaminated with methylmercury compounds caused mercury poisoning^2,3. Biomethylation ability has been demonstrated in bacteria, fungi and algae for As, Cd, Hg, Pb, Se, Sn, Te and Tl^4–7. Naturally-occurring methylated species have been reported in estuaries and seawater for Sb⁸, As⁹, Ge^10–13 and Sn¹⁴, although recent evidence suggests that some reports of methyltin species result from interferences by Ge and volatile sulphur compounds¹⁵. With the exception of Sb⁸, As^9,12,16 and Ge^11,12, there are no consistent estuarine or oceanic profiles for methylmetal compounds in the literature from which to judge their biogeochemical behaviour. Early investigations^17–19 reported that methylgermanium species do not exist in the aquatic environment. Subsequently, we identified monomethylgermanium (MMGe) and dimethylgermanium (DMGe) in estuaries^10,12, the Baltic Sea¹¹ and the Bering and Sargasso seas¹³. We report here recent measurements of methylgermanium compounds in river water, estuaries, seawater and anoxic basins.