Uptake and depuration rates of bulk ZnO powder, ZnCl2, and ZnO nanoparticles by Eisenia fetida before and after soil weathering: the potential for trophic transfer
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x, 61 pages
ProgramTowson University. Environmental Science and Studies Program
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The earthworm Eisenia fetida was exposed to three treatments of isotopically-labeled zinc (68ZnCl2, bulk 68ZnO, and 68ZnO nanoparticles (NPs) at 148 mg/kg Zn) amended to topsoil for 21 days followed by 21 days in a "clean" topsoil to assess uptake and elimination rates (Initial). The exposure was repeated following a 21 day soil-aging period (Aged). All Zn treatments followed the same two-compartment elimination pattern. During the Initial experiment, bulk 68ZnO demonstrated slower uptake in compartment one than 68ZnCl2 and 68ZnO NPs, then matched the rates of other treatments during the Aged experiment. A significant difference was observed in compartment two of the 68ZnO NP treatment in both experiments. We saw no evidence of ZnO NP retention in E. fetida to suggest the potential for trophic transfer of ZnO NPs in a terrestrial food web. These data benefit risk assessment as ZnO NP (5-30nm) mimics ZnCl2 in E. fetida.