SEDIMENT TOXICITY AND BIOACCUMULATION OF NANO AND MICRON-SIZED ALUMINUM OXIDE

摘要

Nano-aluminum oxide (Al_2O_3) is used commercially in coatings and abrasives. Nano-Al_2O_3 can also be generated through the oxidation of nano-aluminum in military propellants and energetics. The purpose of the present study was to assess toxicity and bioaccumulation of nano-Al_2O_3 to a variety of sediment organisms (Tubifex tubifex, Hyalella azteca, Lumbriculus variegatus, and Corbicula fluminea). The bioaccumulation and toxicity of nano-Al_2O_3 was compared with that of micron-sized Al_O_3 to investigate potential size-related effects. Results of the present study show species-specific differences in relative bioaccumulation of nano- and micron-sized Al_2O_3. Significant toxic effects (survival and growth) were observed in H. azteca testing, but only at high concentrations unlikely to be found in the environment. Nano-Al_2O_3 was found to be more toxic than micron-sized Al_2O_3 to H. azteca survival in a 14-d study in which organisms were in direct contact with a thin layer of 625 or 2,500 mg of Al_2O_3 dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron-sized Al_2O_3 at the highest treatment level tested (100 g/kg A12O3) in a 10-d H. azteca bioassay in which A_2O_3 was homogenized with sediment. However, differences in measured sediment Al concentrations (micron-sized = 55.1 [±0.6] g/kg Al; nano-sized = 66.2 [±0.6] g/kg Al) in the nano and micron-sized Al_2O_3 preclude direct comparison of the toxicity of these two treatments based on particle size.