Yao Li,Wenhong Fan,Xiaolong Yang,Shu Liu,Ying Wang,Wen-Xiong Wang
Cosmetics and personal care products containing titanium dioxide nanoparticles (TiO 2 NPs) may enter aquatic environments, where the surface coatings of TiO 2 NPs may change with aging due to environmental factors such as light, and potentially affect their bioaccumulation and toxicity. This study examined how aging impacted the physicochemical properties of three commercially available TiO 2 NPs and subsequent influence on the bioaccumulation and toxicity of copper (Cu) in Daphnia magna ( D. magna ). We demonstrated that aging significantly affected the hydrophobicity of TiO 2 NPs, which affected their binding to water molecules and adsorption of Cu. Changes of bioaccumulation of TiO 2 NPs and Cu in D. magna ultimately affected the activities of intracellular antioxidant enzymes such as SOD, CAT, GSH-Px, and the transmembrane protein Na + /K + –ATPase. Molecular docking calculations demonstrated that changes of activities of these biological enzymes were due to the interaction between TiO 2 NPs, Cu, and amino acid residues near the sites with the lowest binding energy and active center of the enzyme. Such effect was closely related to the hydrophobicity of TiO 2 NPs. Our study demonstrated the close relationship between surface properties of TiO 2 NPs and their biological effects, providing important evidence for understanding the behavior of nanomaterials in aquatic environments.
Multiple water chemistry parameters influence metal toxicity in natural waters and accurate quantification of those influences may accelerate the development of site-specific water quality criteria (WQC) and further execute metal risk assessment for better protection of aquatic biota. Here, we investigated the effects of water chemistry parameters on copper (Cu) toxicity of larval zebrafish ( Danio rerio ) and then incorporated the effects of key parameters in a Toxicokinetic and Toxicodynamic (TK-TD) model. Further, the proposed TK-TD model was used to predict Cu toxicity in laboratory artificial waters as well as natural water samples. The predictive performance of the TK-TD model was evaluated in comparison to the biotic ligand model (BLM). The results showed that increasing Ca, Mg, pH, and fulvic acid (FA) levels significantly mitigated Cu toxicity in larvae, while K and Na levels had no significant effect on Cu toxicity. A predictive TK-TD model based on these data described 91 % of Cu accumulation and 87 % of survival of larvae exposed to Cu under 0, 2.5, 5, 10 mg/L FA. Compared with BLM, TK-TD model predicted better Cu accumulation and toxicity for an independent dataset in low DOC concentration (<10.95 mg L −1 ) of 9 sites in Haihe river (Tianjin, China) media during 96 h exposure. The BLM under-predicted the acute Cu toxicity to larvae when compared with observed values. In high DOC concentration (13.12–17.78 mg L −1 ) among three field sites, BLM and TK-TD model both under-predicted the acute Cu toxicity to larvae when compared with observed values. Our research provides a TK-TD approach for predicting Cu toxicity under complex water chemistry conditions and deriving Cu-WQC in different scenarios where there exist limits for using the BLM.
危险品化学品经营许可证（带存储）