Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China.
Sci Total Environ. 2018 Mar 15;618:838-846. doi: 10.1016/j.scitotenv.2017.08.222. Epub 2017 Oct 18.
Toxicity of silver nanoparticles (AgNPs) has been studied in various culture media. However, these media notably differ from the natural aquatic system, thus the conclusions may be inapplicable for real environment condition. The toxicity and its underlying mechanism of AgNPs in surface waters warrant more investigations. This study investigated the acute toxicity, chronic toxicity, bioaccumulation, and alga-daphnia food chain transfer of citrate-coated AgNPs (C-AgNPs) and Ag (from AgNO) to D. magna in a culture medium (M4) and a surface water sample. Results show that the acute toxicity in the surface water was significantly lower than that in the M4 medium and the toxicity of Ag was greatly higher than that of C-AgNPs. The 48h median effect concentration (EC) of C-AgNPs to D. magna in the M4 medium and the surface water was 110±9.3μg/L and 270±26μg/L, respectively, while that of Ag was 1.8±0.7μg/L and 8.0±0.6μg/L, respectively. The released Ag contributed to but not dominated the acute toxicity of C-AgNPs. At the EC of C-AgNPs, the contribution of released Ag was 35.7% and 28.0% to the apparent nanotoxicity in the M4 medium and the surface water sample, respectively. The chronic toxicity of C-AgNPs and Ag was also lower in the surface water sample than in the M4 medium as indicated by the significantly higher survival of daphnia in the surface water during the 21d exposure. The daphnia took up less but depurated more Ag in the surface water than in the M4 medium, which could account for the lower toxicity in the surface water. Biological magnification of Ag through the alga-daphnia food chain was not observed. These findings will be helpful for assessing the environmental risk of AgNPs and understanding the mechanism of nanotoxcity.
纳米银（AgNPs）的毒性已在各种培养基中进行了研究。然而，这些培养基与天然水系统有明显的不同，因此得出的结论可能不适用于真实的环境条件。AgNPs 在地表水的毒性及其潜在机制仍需要进一步研究。本研究调查了在培养基（M4）和地表水中，柠檬酸包覆的 AgNPs（C-AgNPs）和 Ag（来自 AgNO3）对大型溞（Daphnia magna）的急性毒性、慢性毒性、生物累积和藻类-溞食物链传递。结果表明，地表水中的急性毒性明显低于 M4 培养基，Ag 的毒性大大高于 C-AgNPs。C-AgNPs 在 M4 培养基和地表水中对 D. magna 的 48 小时半数效应浓度（EC）分别为 110±9.3μg/L 和 270±26μg/L，而 Ag 的 EC 分别为 1.8±0.7μg/L 和 8.0±0.6μg/L。释放的 Ag 对 C-AgNPs 的急性毒性有贡献，但不是主要贡献。在 C-AgNPs 的 EC 下，释放的 Ag 对 M4 培养基和地表水中明显纳米毒性的贡献分别为 35.7%和 28.0%。C-AgNPs 和 Ag 的慢性毒性在地表水中也低于 M4 培养基，因为在 21d 的暴露期间，大型溞在地表水中的存活率明显更高。大型溞在地表水中的吸收量较少，但在地表水中的排泄量较多，这可能是地表水中毒性较低的原因。Ag 通过藻类-溞食物链的生物放大作用没有观察到。这些发现将有助于评估 AgNPs 的环境风险，以及理解纳米毒性的机制。
