Formation of methylmercury in the marine sediment under in vitro conditions

Abstract

The purpose of this study was to find out whether there is an appreciable conversion of inorganic mercury into methylmercury in the marine bottom sediment. Samples were taken from the Eastern Mediterranean coast, in the Haifa Bay area. HgCl 2 in various concentrations was added to flasks containing samples of sterile or nonsterile bottom sediment and growth medium, and the flasks were incubated under aerobic or anaerobic conditions, for different time intervals. We found that indeed methylmercury was formed, probably by microbial action (since no methylmercury was detected in any of the flasks containing sterile sediment samples). Several types of bacteria which could tolerate considerable concentrations of mercury were isolated, and each type was innoculated into flasks containing medium and a sterile sediment sample. Methylmercury was later found in the latter flasks also.