Selenium in a Wyoming Grassland Community Receiving Wastewater from an In Situ Uranium Mine

Abstract

Water, soil, vegetation, grasshoppers, bird eggs, and bird livers collected at a 23.5-ha (58 acres) grassland irrigated with wastewater from an in situ uranium mine (study area) and a reference site in 1998 were analyzed for selenium and other trace elements. Selenium concentrations in the uranium mine wastewater applied onto the grassland ranged from 340 to 450 microg/L. Selenium in the upper 15 cm (6 in) of soil from the irrigated grassland at the mine ranged from 2.6 to 4.2 microg/g dry weight (DW). Mean selenium concentrations in soil and water were 5 and 15 times higher at the study area than at the reference site. Selenium concentrations in grasses and grasshoppers ranged from 6.8 to 24 microg/g and 11 to 20 microg/g DW, respectively. Selenium in red-winged blackbird eggs and livers collected from the study area ranged from 13.2 to 22 microg/g and 33 to 53 microg/g DW, respectively, and concentrations were well in excess of toxic thresholds. Mean selenium concentrations in grasses, grasshoppers, and bird eggs and livers were 5.8 to 30 times higher at the study area than at the reference site. Elevated selenium concentrations in water, soil, grasshoppers, and red-winged blackbird eggs and livers collected from the study area demonstrate that selenium is being mobilized and is bioaccumulating in the food chain.

Stage susceptibility of Japanese medaka (Oryzias latipes) to selenomethionine and hypersaline developmental toxicity

“…Selenium (Se) is an essential micronutrient that can be toxic to oviparous animals in excess . Present naturally in soils, Se is released into waterways following anthropogenic activity, such as irrigation of arid soils; coal, phosphate and uranium mining; and coal burning in power plants . Free Se is often present in water in its inorganic forms of selenate and selenite and can be taken up by microorganisms and converted into various organic forms, including selenomethionine (SeMet) .…”

Se Isotopes as Groundwater Redox Indicators: Detecting Natural Attenuation of Se at an in Situ Recovery U Mine

“…At the study site, a progression from nitrate-reducing to Fe(III)reducing and then to U(VI)-reducing conditions along the hydraulic gradient is inferred from concentrations of the redox species (e.g., NO 3 − , Fe(II), and U(VI)), Eh values, and isotopic measurements (e.g, δ 15 N, and δ 238 U) of groundwater samples. 20 Briefly, a general decrease in NO 3 − concentrations along the hydraulic gradient and a linear relation between the δ 18 O-nitrate and δ 15 N-nitrate (r 2 = 0.77, n = 11) with a slope (Δδ 18 O/Δδ 15 N) of 0.73 ± 0.13 is indicative of microbial denitrification. In addition, localized zones of Fe(III) and Mn(IV) reduction is suggested by elevated dissolved Mn (>0.05 mg/L) and Fe (>0.1 mg/L) concentrations in groundwater samples from PAA 1, PAA 2, and PAA 3.…”

“…16,17 Despite several advantages such as the lack of mill tailings and radioactive dust, and its low CO 2 emission footprint, this mining method releases Se as toxic, mobile Se oxyanions along with U(VI) directly into groundwater. 18 Current strategies to mitigate Se(VI) in the groundwater after the completion of mining include groundwater sweep and occasionally active remediation by biostimulation or injection of abiotic reductants. 19 Understanding naturally occurring reduction of Se oxyanions is critical for designing efficient remediation−restoration strategies at ISR sites.…”

Selenium and Other Trace Element Mobility in Waste Products and Weathered Sediments at Parys Mountain Copper Mine, Anglesey, UK

“…A well-known concern to former and operational mining sites worldwide is contamination of soils and groundwaters from Se, particularly in U mining sites [11,81,82]. The release of Se during extraction can have environmental ramifications, affecting livestock [3,4,7,10,[83][84][85]. Elevated water-soluble trace elements such as Cd, Co, Cu and Pb at Parys Mountain are also typically higher than previously determined maximum permitted levels by various studies and governing bodies [86,87].…”