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.

摘要

使用氧化铜 (CuO) NP 会导致这些颗粒释放到水生环境中。在这里，颗粒沉淀并积聚在沉积物中。然而，对底栖生物中沉积物相关纳米颗粒的生物动力学知之甚少。我们比较了栖息在沉积物的寡毛动物Tubifex tubifex中 CuO NPs (7 nm) 和溶解 Cu (CuCl ₂ )的毒性和生物动力学，以深入了解金属形式 (CuCl ₂与 CuO NPs) 和暴露途径的相对重要性（水与沉积物）。同位素富集的⁶⁵ Cu 用作示踪剂以区分背景与新积累的⁶⁵蠕虫中的铜。对于每个暴露途径，我们进行了三个实验：一个吸收、一个消除和一个长期净积累实验，以参数化T. tubifex中⁶⁵ CuCl ₂和⁶⁵ CuO NPs 的吸收和消除。⁶⁵为两个检测到的Cu累积⁶⁵的CuCl ₂和^65层的CuO的NP无论T.水丝蚓是在sediment-或仅水设置露出。水暴露于⁶⁵ CuCl ₂导致尾部损伤，而沉积物暴露或暴露于⁶⁵CuO NPs 通过任一暴露途径。在⁶⁵ CuCl ₂暴露后，T. tubifex中⁶⁵ Cu 的吸收速率常数和积累高于⁶⁵ CuO NPs，在水中，但不是在沉积物中。因此，暴露途径和铜形式对吸收动力学的相对重要性并不简单，这表明水暴露中的生物积累和毒性的发现不能直接外推到沉积物。