Bioaccumulation and toxicity of uranium, arsenic, and nickel to juvenile and adult Hyalella azteca in spiked sediment bioassays
Environmental Toxicology and Chemistry
Uranium (U) mining and milling release arsenic (As), nickel (Ni) and U to receiving waters, which accumulate in sediments. The objective of the present study was to investigate if As, Ni, and U concentrations in tissue residue of Hyalella azteca, overlying water, sediment porewater, and solids could predict juvenile and adult survival and growth in conditions similar to lake sediments downstream of U mines and mills. We conducted 14-d static sediment toxicity tests spiked with U, As, and Ni
... h U, As, and Ni salts. For U, we spiked uranyl nitrate with sodium bicarbonate to limit U precipitation once in contact with circumneutral sediment. The median lethal concentrations for As, Ni, and U of juveniles and adults based on measured concentrations in sediments were 134 and 165 mg/g, 370 and 787 mg/g, and 48 and 214 mg/g, respectively. Adult survival and growth linearly decreased with increasing bioaccumulation. For juveniles, metal accumulation linearly predicted survival. We calculated median lethal body concentrations for juveniles and adults of 5 and 36 mg As/g, 14 and 49 mg Ni/g, and 0.4 and 1.0 mg U/g. The concentrations of As, Ni, and U in tissue residue leading to a 20% decrease in adult growth were 32 mg As/g, 44 mg Ni/g, and 1 mg U/g. Overall, the present study showed that U was the most toxic element, followed by As and Ni; that juveniles were more sensitive to the 3 metals tested than adults; and that threshold body concentrations can support assessment of benthic invertebrate community impairment.