Selenium from coal mining in the Elk River Valley Chapman, Peter M.
Coal mining in the Elk River Valley, B.C. enhances natural release of selenium (Se), resulting in elevated concentrations of selenium downstream of the mines. Studies to determine the extent and significance of Se in Valley waters began in 1996. Selenium concentrations downstream of the five coal mines have increased in some areas. However, the same magnitude of increases has not occurred in lotic (flowing water) fauna, and Se concentrations in fish from lotic areas have not increased from 1996 to 2003. Although Se concentrations in cutthroat trout and some of their eggs were above concentrations shown to be toxic in other areas with other fish species, a laboratory effects study found that fry hatched and developed normally. Both cutthroat and bull trout populations have increased since 1986. A study of two common waterfowl (American dippers and spotted sandpipers) living in lotic areas found no discernable adverse effects, and Se concentrations in eggs were below thresholds at which adverse effects have been documented in other areas. Although lotic areas are most common in the Elk River Valley, lentic (still water) areas may represent the worst case because there is more likelihood of inorganic Se being converted into the much more toxic organic Se. A reconnaissance study in 2002 examined lentic areas (a screening level sampling strategy) to identify “worst-case” lentic areas, to select appropriate reference areas comparable to key mine-exposed areas of interest and to identify receptor species that are at risk in these areas. For instance, the most contaminated lentic area was also the most productive area. However, more detailed studies are required before any definitive conclusions are reached. Ongoing and planned studies include determinations of aquatic food webs in both lentic and lotic areas, further monitoring in both areas, and fish and waterfowl effects studies in lentic areas. A human health risk assessment found that there was negligible risk to humans eating fish from the Valley, and benefits from consuming moderate quantities of fish.
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