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研究报告

The transformation process of CuO nanoparticles in aqueous environment and its toxicity effects on Daphnia magna

摘要：为探究纳米CuO颗粒（CuO NP）在水体中的环境暴露风险，考察了腐殖酸（SRHA）和酸根离子对CuO NP转化行为的影响，探讨了CuO NP在不同条件下转化对大型溞的毒性效应差异.结果表明，与单独水体中CuO NP的转化行为相比，H₂PO₄^-显著促进了CuO NP释放Cu²⁺，Cl^-、NO₃^-、SO₄^2-对CuO NP的转化行为没有显著影响，而CO₃^2-、HCO₃^-、PO₄^3-、HPO₄^2-抑制了CuO NP中Cu²⁺的释放；SRHA显著促进了CuO NP释放Cu²⁺，但HCO₃^-、PO₄^3-的存在可以明显抑制SRHA促进CuO NP中Cu²⁺释放的进程.CuO NP在单独水体中，以及在Cl^-、PO₄^3-和SRHA+PO₄^3-存在的水体中转化后对大型溞的致死中浓度为16~32 mg·L^-1，而在SRHA与SRHA+Cl^-存在的水体中转化后对大型溞的致死中浓度分别降到0.8和2.5 mg·L^-1，说明SRHA促进了CuO NP释放Cu²⁺，提高了CuO NP颗粒分散性，使其易于被大型溞体内细胞组织摄取，增加了CuO NP对大型溞的毒性效应，因此，环境转化对CuO NP的环境暴露风险有重要影响.

Abstract：To evaluate the risk of CuO nanoparticles (CuO NP) exposure in aquatic environment, the dissolving behavior of CuO NP in aqueous solution containing humic acid (SRHA) or acidic ions was investigated, and the toxicity to Daphnia magna after its transformation in aqueous media was also measured. The presence of acidic ions, such as Cl^-, NO₃^-, and SO₄^2-, had little effect on their dissolving behavior, compared with that of water, whereas CO₃^2-, HCO₃^-, PO₄^3- and HPO₄^2- greatly inhibited the dissolving process of CuO NP. Although SRHA could significantly increase the dissolving rate of CuO NP, HCO₃^- and PO₄^3- exhibited great inhibitory effects on the process. The measured Median Lethal Concentrations (LC₅₀) of CuO NP in Daphnia magna after transformation in water alone、Cl^-、PO₄^3- and SRHA+PO₄^3- were 16~32 mg·L^-1, but they decreased to 0.8 and 2.5 mg·L^-1 CuO NP in SRHA and SRHA+Cl^- solution, respectively, suggesting that the dissolved Cu²⁺ rather than nanoparticles was the major source of toxicity. These results imply that including the transformation of CuO NP is critical to the evaluation of their risk of environmental exposure.

Key words：CuO NP humic acid acid radical ion environmental transformation biotoxicity