A former mercury plant, where mercury salts and organomercurials for pesticide use were produced, caused soil contamination in high concentrations. Typical organomercurial products included ethylmercury, phenylmercury, methoxyethylmercury and ethoxyethylmercury compounds. Risk assessment of these sites must be carried out before any major clean-up processes can be planned. A sensitive speciation technique for the various organomercury species in environmental matrices is a prerequisite for toxicity investigations. In this connection, a high-performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) technique has been developed to differentiate between and determine the presence of eight organomercury compounds in environmental samples. Using this technique, methylmercury, ethylmercury and phenylmercury and some unknown organomercury species were found in soil samples collected from the sites of an old mercury products producing plant. With regard to risk assessment, it is necessary to assess the toxicity of the organomercurials. As different microbial metabolic pathways react differently to mercury and its compounds, batteries of bioassays are, therefore, useful to evaluate the toxicity of pollutants. To describe the toxicity and genotoxicity of MeHg+, MeOEtHg+, EtHg+, EtOEtHg+ and PhHg+, p-tolymercury chloride, nitromersol and Hg2+ six bioassays were used: resazurin reduction method, Spirillum volutans test, nematode toxicity assay Panagrellus redivivus, Toxi-Chromotest and SOS-Chromotest. A ranking of the toxicity of the organomercurial is shown. The SOS-Chromotest indicated genotoxicity for 5-7 organomercurials.

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A simple and sensitive method for the determination of submicrogram amounts of mercury in lake water was developed by combination of concentration by dithizone extraction and gas-phase atomic absorption. The mercury was first extracted by dithizone, back extracted by hydrochloric acid, and then converted to vapor by a reduction-aeration reaction. Hg, Hg(I), Hg(II), and some organomercuric compounds were extracted by the present procedure. A sensitivity of 0.008 µg. per liter (0.008 p.p.b.) was achieved for water analysis. Standard deviations of 0.0087 and 0.0042 were found for lake water samples containing 0.478 and 0.048 µg. per liter of Hg, respectively.

Sediment and water samples were taken from five sites in Thunder Bay, one upstream (control) and four downstream locations from a bleached kraft pulp mill. Biochemical effects were examined by estimating the carbohydrate content and enzymatic activities of alkaline phosphatase, cellulase, and dehydrogenase in the sediment. Genotoxicity and toxicity of sediment and water were assessed by the SOS Chromotest, although liver microsomal samples were not used to screen for progenotoxic substances. Sediment and water samples were also analyzed for resin and fatty acids, which indicate the degree of effluent contamination. Significant differences in enzyme activity and carbohydrate content were found between sites. Genotoxic values were obtained for downstream water samples for most of the sampling months, however, the sediment only showed genotoxic activity in the July and October samples. The study showed that there are substances causing genotoxic and biochemical effects in the Kaministiquia River, Ontario. 0 7994 by John Wiley & Sons, Inc.

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