BIOACCUMULATION OF METHYLMERCURY AND TRANSFORMATION OF INORGANIC MERCURY BY MACROFUNGI

The terrestrial biogeochemical cycle of mercury between humus and fung i was investigated in a mercury-contaminated former mining area of Ger many. We used a variable volume extraction procedure and aqueous sodiu m boron tetraethyl derivatization to determine accurately and precisel y methylmercury bioconcentration factors for fungi. The methylmercury and total mercury content for fungi carpophores ranged from 0.08 to 7. 94 mu g/g of Hg as methylmercury and from 6.2 to 144.0 mu g/g of inorg anic Hg, respectively. The levels in humus material were between 0.01 and 0.09 mu g/g of Hg as methylmercury and 15.8 and 140.2 mu g/g of in organic Hg, respectively. The bioconcentration factors obtained are ge nerally lower than I for total mercury and between 3.0 and 199.0 for m ethylmercury. By an in vitro methylation experiment with two axenic cu ltures of Coprinus comatus and Coprinus radians, we could show for the first time that these saprophytic macromycetes are able to methylate mercury.