iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany.
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Environ Sci Pollut Res Int. 2021 Mar;28(11):13991-13999. doi: 10.1007/s11356-020-11578-2. Epub 2020 Nov 17.
During its aquatic life cycle, nanosized titanium dioxide (nTiO) may interact with natural organic matter (NOM) ultimately altering the ecotoxicity of co-occurring chemical stressors such as heavy metals (e.g. copper (Cu)). In this context, the following hypotheses were tested: (1) aging of nTiO along with Cu reduces Cu toxicity, (2) nTiO agglomerates have a lower potential to reduce Cu toxicity and (3) aging of nTiO in presence of NOM reduces Cu toxicity further. A multifactorial test design crossing three nTiO levels (0.0, 0.6 and 3.0 mg/L) with two levels of NOM (0 versus 8 mg total organic carbon (TOC)/L) and seven nominal Cu concentrations (ranging from 0 to 1536 μg/L) aged in ASTM medium for 0, 1, 3 and 6 days was realised, while two aging scenarios were applied (type 1: nTiO jointly aged with Cu; type 2: Cu added after nTiO aging). Subsequently, Cu toxicity was assessed using the immobility of Daphnia magna after 48 h of exposure as response variable. The experiments revealed that neither aging duration nor the extent of agglomeration (type 1 vs. type 2 aging) has a substantial impact on Cu induced toxicity. Moreover, it was confirmed that the presence of NOM substantially reduced Cu induced toxicity, independent of the aging scenario and duration. More importantly, the data suggest the ingestion of Cu loaded nTiO as additional exposure pathway contributing to Cu toxicity. In conclusion, it seems unlikely that nTiO concentrations currently detected in or predicted for aquatic ecosystems, which are at least one order of magnitude below the concentration tested here, influence Cu toxicity meaningfully.
在水生生命周期中，纳米二氧化钛（nTiO）可能与天然有机物（NOM）相互作用，最终改变共存化学胁迫物（如铜（Cu））的生态毒性。在这种情况下，提出了以下假设：（1）nTiO 与 Cu 一起老化会降低 Cu 的毒性，（2）nTiO 团聚体降低 Cu 毒性的潜力较低，以及（3）NOM 存在下 nTiO 的老化会进一步降低 Cu 的毒性。采用多因素试验设计，交叉三个 nTiO 水平（0.0、0.6 和 3.0 mg/L）与两个 NOM 水平（0 与 8 mg 总有机碳（TOC）/L）和七个名义 Cu 浓度（0 至 1536μg/L），在 ASTM 培养基中老化 0、1、3 和 6 天，同时应用了两种老化方案（1 型：nTiO 与 Cu 共同老化；2 型：在 nTiO 老化后添加 Cu）。随后，使用 48 h 暴露后大型溞（Daphnia magna）的不活动作为响应变量评估 Cu 毒性。实验表明，老化时间和团聚程度（1 型与 2 型老化）都不会对 Cu 诱导的毒性产生实质性影响。此外，证实 NOM 的存在会大大降低 Cu 诱导的毒性，而与老化方案和持续时间无关。更重要的是，数据表明摄入负载 Cu 的 nTiO 是导致 Cu 毒性的另一种暴露途径。总之，目前在水生生态系统中检测到的或预测到的 nTiO 浓度（至少比这里测试的浓度低一个数量级）不太可能对 Cu 毒性产生有意义的影响。
