| This study quantified the natural mechanisms and rates of Hg release from Miocene epithermal Hg deposits in the Ivanhoe mining district, Elko County, Nevada. Sampling of groundwaters, rocks, soils, ephemeral stream sediments, and atmospheric Hg emissions was conducted to characterize Hg concentrations and distributions in each media.; Mercury concentrations in all Ivanhoe media were enriched relative to crustal averages. The correlation between Hg phases in rocks suggests that the vast majority of Hg in the rocks has not been mobilized since deposition. However, results from experimental and field observations showed that, despite the dry climate, some Hg in Ivanhoe rocks is mobilized during weathering and soil formation.; The largest loss of Hg from the district occurs by the emission of Hg from substrate to the atmosphere (90 kg/yr). Approximately 420 g of Hg is annually removed through groundwater flow leaving the district. Removal of Hg by surface waters is negligible. |
