Wetlands were found to be important sources of methyl mercury to the boreal forest ecosystem. Yields of methyl mercury were about 26–79 times higher from wetland portions of catchments (1.84–5.55 mg∙ha−1∙yr−1) than from purely upland areas (0.07 mg∙ha−1∙yr−1). Mass-balance estimates using methyl mercury inputs in wet deposition and outputs in runoff water indicated that purely upland catchments and lakes were sites of methyl mercury retention or demethylation, while catchments with wetland areas were sites of net methyl mercury production. These observations may explain the high concentrations of mercury in fish taken from lakes that are high in colour because they receive water from wetlands. There was no relationship between the concentration of total mercury and the concentration of methyl mercury in runoff water. Total mercury yields were low from a wetland-dominated catchment, higher from a combination upland/riparian wetland catchment, and highest from a purely upland catchment. The opposite was true for methyl mercury yields from these same catchments. This indicates that environmental factors other than total mercury concentration are controlling the production and loss of methyl mercury from catchments.

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Raw petroleum and natural gas often contain high concentrations of mercury, which can be damaging to the metal components of production facilities, as well as to the environment. Various Hg species have different properties in terms of mobility, reactivity and bioavailability. Thus, for cost-effective decisions regarding plant design, Hg extraction, and pollution control, speciation information must be available at the production facility. In this paper, a simple, wet chemical speciation method, which provides data on Hg(o), dissolved and particulate total Hg, Hg(II), and methyl Hg is presented. The method incorporates species-specific extraction and separation procedures, followed by cold vapor atomic fluorescence spectrometry (CVAFS). For each species, detection limits of approximately 0.1 ng/g were obtained. Storage experiments in various containers showed that organo-mercury species were stable for at least 30 days in all containers except those made of polyethylene; and Hg(o) was stable in all containers except those made of stainless steel or polyethylene. Hg(II) was rapidly lost from all containers except those made of aluminum, which rapidly converted it to Hg(o), which was stable. In general, most of the total Hg in petroleum products was particulate Hg, followed by dissolved Hg(II) and Hg(o). Sub-ng/g concentrations of methyl-Hg were observed in most samples.

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