Selenium in a Wyoming Grassland Community Receiving Wastewater from

Water, soil, vegetation, grasshoppers (Family Acrididae), bird eggs and bird livers collected at a 23.5 hectare (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. Bird surveys were conducted at the irrigated grassland at the in situ uranium mine to determine species use, relative abundance and behavior. We observed 23 species of birds using the Study Area. Western meadowlarks (Sturnella neglecta), red-winged blackbirds (Agelaius phoeniceus), lark buntings (Calamospiza melanocorys) and horned larks (Eremophila alpestris) were the most common avian species using the Study Area and were observed feeding and drinking at this site. Meadowlarks, red-winged blackbirds and lark buntings were observed nesting at the Study Area. Selenium concentrations in the uranium mine wastewater applied onto the grassland ranged from 340 to 450 µg/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 µg/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 µg/g and 11 to 20 µg/g dw, respectively. Selenium in red-winge