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The terrestrial biogeochemical cycle of mercury between humus and fungi was investigated in a mercury-contaminated former mining area of Germany. We used a variable volume extraction procedure and aqueous sodium boron tetraethyl derivatization to determine accurately and precisely methylmercury bioconcentration factors for fungi. The methylmercury and total mercury content for fungi carpophores ranged from 0.08 to 7.94 μg/g of Hg as methylmercury and from 6.2 to 144.0 μg/g of inorganic Hg, respectively. The levels in humus material were between 0.01 and 0.09 μg/g of Hg as methylmercury and 15.8 and 140.2 μg/g of inorganic Hg, respectively. The bioconcentration factors obtained are generally lower than 1 for total mercury and between 3.0 and 199.0 for methylmercury. By an in vitro methylation experiment with two axenic cultures of Coprinus comatus and Coprinus radians, we could show for the first time that these saprophytic macromycetes are able to methyl ate mercury.

We report a novel aqueous derivatization of methylmercury chloride by NaBH 4 to mehtymercury hydride (CH 3 HgH), a volatile and unexpectedly stable species which we determined has a half-life of approximately 2 h. The analytical apparatus consisted of a purge and trap (PT) unit linked to a gas chromatograph (GC), in line with a Fourier transform infrared spectrometer (FTIR). The sample was purged with nitrogen, and volatile compounds were concentrated in a cold trap

A new method is suggested for determining methylmercury in biological samples. The determination is based on the use of whole cells of a broad-spectrum mercury-resistant bacterium, Pseudomonas putida, strain FB1, which is induced to produce the enzymes organomercurial lyase and mercuric reductase. These biocatalysts convert organomercurials to elemental mercury and their derivative hydrocarbons. The extraction procedure for methylmercury in biological samples follows the conventional toluene extraction method, which is retained until methylmercury is concentrated in an aqueous phase containing 0.01 M Na{sub 2}S{sub 2}O{sub 3}. This solution is mixed with bacterial cells in exponential growth phase and then incubated in microreaction vessels. A complete biological degradation of methylmercury to methane occurs. The efficiency of derivatization depends on the organomercurial concentration, the incubation time, and the cell density. The detection limit is 15 ng of methylmercury in 1 g of biological tissue and the coefficient of variation is 1.9% in 10 replicate samples with 100 ng/mL.