Biodynamics and adverse effects of CuO nanoparticles and CuCl₂ in the oligochaete T. tubifex: Cu form influence biodynamics in water, but not sediment

Abstract

The use of copper oxide (CuO) NPs results in the release of these particles into the aquatic environment. Here, the particles settle out and accumulate in the sediment. However, little is known about the biodynamics of sediment-associated NPs in benthic organisms. We compared the toxicity and biodynamics of CuO NPs (7 nm) and dissolved Cu (CuCl₂) in the sediment-dwelling oligochaete, Tubifex tubifex, to gain insights into the relative importance of metal form (CuCl₂ vs CuO NPs) and exposure route (water vs sediment). Isotopically enriched ⁶⁵Cu was used as a tracer to distinguish background from newly accumulated ⁶⁵Cu in worms. For each exposure route, we conducted three experiments: one uptake, one elimination, and one longer-term net accumulation experiment to parameterize uptake and elimination of ⁶⁵CuCl₂ and ⁶⁵CuO NPs in T. tubifex. ⁶⁵Cu accumulation was detected for both ⁶⁵CuCl₂ and ⁶⁵CuO NPs regardless of whether T. tubifex were exposed in sediment- or water-only setups. Water exposures to ⁶⁵CuCl₂ resulted in tail trauma whereas limited effects were seen for sediment exposures or exposures to ⁶⁵CuO NPs via either exposure route. Uptake rate constants and accumulation of ⁶⁵Cu in T. tubifex were higher following ⁶⁵CuCl₂ exposure than ⁶⁵CuO NPs, in water, but not in sediment. Thus, the relative importance of exposure route and Cu form for uptake dynamics is not straightforward suggesting that findings on bioaccumulation and toxicity in water exposures cannot be directly extrapolated to sediment.

Keywords:

• Biodynamic model
• metal
• oligochaete
• stable isotope tracer
• uptake route

Acknowledgments

The authors are very grateful to Superb Misra for help with NP synthesis and Torben Brandt Knudsen and Mette Flodgaard for their help with ICP-MS measurements and assistance throughout. In addition, the authors want to thank Marie-Noële Croteau for training in the stable isotope labelling technique at the US Geological Survey and the NanoTransfer consortium for collaboration.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was financed by the Villum foundation [00010592]. ⁶⁵CuO NPs where synthesized at Natural History Museum, London, UK, receiving support from the QNano Project financed by the European Community Research Infrastructures under the FP7 Capacities Programme [INFRA-2010-262163], and its partner Natural History Museum, London.