Selenium distribution in a lake system receiving effluent from a metal mining and milling operation in Northern Saskatchewan, Canada

Abstract

The release of selenium (Se) at relatively low concentrations into aquatic ecosystems over time can result in the accumulation and, if thresholds are exceeded, subsequent adverse effects in sensitive species, including higher trophic levels (such as fish). A milling operation in Northern Saskatchewan, Canada, releases treated effluent into a small stream system, and Se has accumulated in sediments and aquatic biota over time. The present study evaluated four small lakes downstream of the effluent discharge point, and one lake upstream, in order to describe and understand the distribution of Se in abiotic environmental compartments and the transfer of Se into benthic macroinvertebrates. The concentrations of Se in sampled sediments were highly variable but exceeded proposed thresholds for the protection of fish and aquatic birds in all study lakes downstream of the effluent discharge point. Selenium concentrations in surface water, whole-sediment, and sediment pore water revealed that whole-body Se concentrations in benthic invertebrates (chironomids) are best correlated with Se in pore water. It is proposed that Se accumulates in sediments through an association with the total organic carbon content of sediment and that Se is fixed from the surface water by micro-organisms and primary producers. The relationship between Se in pore water and Se in whole sediments appears to be influenced by the organic carbon content of each medium, and Se bioavailability in sediment and transfer to higher trophic levels via benthic macroinvertebrates is likely speciation dependent.

Impacts and prognosis of natural resource development on water and wetlands in Canada’s boreal zone

“…In a separate study from the same region, Muscatello and Janz (2009) reported selenium concentrations in water of a lake at the outflow of an effluent management system of approximately 20 times above reference levels. Wiramanaden et al (2010) found that although selenium concentrations in lakes downstream of uranium mining in their study area were fairly low some distance from the discharge point, they were above reference levels and accumulated in fish resulting in adverse effects.…”

The use of field-based mesocosm systems to assess the effects of uranium milling effluent on fathead minnow (Pimephales promelas) reproduction

“…For the water analyses since selenite was detected in samples collected from the EW treatments, we do know that transformation was occurring in the systems. As selenate is the released form of Se in the discharged effluent (Wiramanaden et al 2010a). …”

“…Increases of metals in the environment are a potential threat to the survival of organisms inhabiting the impacted area (Bervoets et al 2005). Selenium (Se) was recognized as an important environmental contaminant in the 1970s and 80s (Swift 2002) and its toxicity to fish from industrial activities in North America, Australia and New Zealand (SETAC Pellston Workshop 2009) has lead to an increase in the number of studies examining levels of Se in fish, sediment, and water at locations downstream of milling and mine operations (Pyle et al 2001;Klaverkamp et al 2002;Muscatello et al 2006;Wiramanaden et al 2010a).…”

“…This study is also one component of large interdisciplinary project to evaluate Se at the Key Lake site. Some of the initial site work has recently been reported by Wiramanaden et al (2010aWiramanaden et al ( , 2010b.…”

Selenium bioaccumulation and speciation in Chironomus dilutus exposed to water‐borne selenate, selenite, or seleno‐DL‐methionine

“…Analysis involved monitoring 80 Se and the use of collision cell technology as described previously [17]. Water samples collected for dissolved Se analyses were membrane filtered (0.45 mm polyethersulfone, Pall) and acidified to 2% nitric acid (omnitrace ultra, EM Science).…”