Biodynamics of copper oxide nanoparticles and copper ions in an oligochaete - Part I: Relative importance of water and sediment as exposure routes.
Copper oxide (CuO) nanoparticles (NPs) are widely used, and likely released into the aquatic environment. Both aqueous (i.e., dissolved Cu) and particulate Cu can be taken up by organisms. However, how exposure routes influence the bioavailability and subsequent toxicity of Cu remains largely unknown. Here, we assess the importance of exposure routes (water and sediment) and Cu forms (aqueous and nanoparticulate) on Cu bioavailability and toxicity to the freshwater oligochaete, Lumbriculus variegatus, a head-down deposit-feeder. We characterize the bioaccumulation dynamics of Cu in L. variegatus across a range of exposure concentrations, covering both realistic and worst-case levels of Cu contamination in the environment. Both aqueous Cu (Cu-Aq; administered as Cu(NO3)2) and nanoparticulate Cu (CuO NPs), whether dispersed in artificial moderately hard freshwater or mixed into sediment, were weakly accumulated by L. variegatus. Once incorporated into tissues, Cu elimination was negligible, i.e., elimination rate constants were in general not different from zero for either exposure route or either Cu form. Toxicity was only observed after waterborne exposure to Cu-Aq at very high concentration (305μgL(-1)), where all worms died. There was no relationship between exposure route, Cu form or Cu exposure concentration on either worm survival or growth. Slow feeding rates and low Cu assimilation efficiency (approximately 30%) characterized the uptake of Cu from the sediment for both Cu forms. In nature, L. variegatus is potentially exposed to Cu via both water and sediment. However, sediment progressively becomes the predominant exposure route for Cu in L. variegatus as Cu partitioning to sediment increases.
Department of Environmental, Social and Spatial Change, Roskilde University, PO Box 260, Universitetsvej 1, DK-4000 Roskilde, Denmark; US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States. Electronic address: tramskov@hotmail.com.
Tina
T
Ramskov
Department of Environmental, Social and Spatial Change, Roskilde University, PO Box 260, Universitetsvej 1, DK-4000 Roskilde, Denmark. Electronic address: athitj@ruc.dk.
Amalie
A
Thit
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States. Electronic address: mcroteau@usgs.gov.
Marie-Noële
MN
Croteau
Department of Environmental, Social and Spatial Change, Roskilde University, PO Box 260, Universitetsvej 1, DK-4000 Roskilde, Denmark; US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States. Electronic address: selck@ruc.dk.
Henriette
H
Selck
D000818:Animals; D001682:Biological Availability; D003300:Copper / Q000378:metabolism* / Q000633:toxicity*; D004781:Environmental Exposure; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D007477:Ions / Q000633:toxicity; D053758:Nanoparticles / Q000378:metabolism* / Q000633:toxicity*; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity
D007477:Ions; D014874:Water Pollutants, Chemical; D003300:Copper; C000520:cuprous oxide
Biodynamic model; Freshwater; Lumbriculus variegatus; Metal; Nanoecotoxicity; Stable isotope tracer