Norwegian Institute for Water Research, Oslo, Norway.
Department of Process Engineering, Swiss Federal Institute of Aquatic Science and Technology Eawag, Dübendorf, Switzerland.
Sci Total Environ. 2024 Nov 1;949:174768. doi: 10.1016/j.scitotenv.2024.174768. Epub 2024 Jul 14.
Wastewater Treatment Plants (WWTP) are a major repository and entrance path of nanoparticles (NP) in the environment and hence play a major role in the final NP fate and toxicity. Studies on silver nanoparticles (AgNP) transport via the WWTP system and uptake by aquatic organisms have so far been carried out using unrealistically high AgNP concentrations, unlikely to be encountered in the aquatic environment. The use of high AgNP concentrations is necessitated by both the low sensitivity of the detection methods used and the need to distinguish background Ag from spiked AgNP. In this study, isotopically enriched AgNP were synthesized to overcome these shortcomings and characterized by a broad range of methods including transmission electron microscopy, dynamic and electrophoretic light scattering. AgNP and gold NP (AuNP) were spiked to a pilot wastewater treatment plant fed with municipal wastewater for up to 21 days. AuNP were used as chemically less reactive tracer. The uptake of the pristine and transformed NP present in the effluent was assessed using the benthic amphipod Hyalella azteca in fresh- and brackish water exposures at environmentally relevant concentrations of 30 to 500 ng Au/L and 39 to 260 ng Ag/L. The unique isotopic signature of the AgNP allowed to detect the material at environmentally relevant concentrations in the presence of a much higher natural Ag background. The results show that the transformations reduce the NP uptake at environmentally relevant exposure concentrations. For Ag, lower accumulation factors (AF) were obtained after exposure to transformed NP (250-350) compared to the AF values obtained for pristine AgNP (750-840). The reduced AF values observed for H. azteca exposed to effluent from the AuNP-spiked WWTP indicate that biological transformation processes (e.g. eco-corona formation) seem to be involved in addition to chemical transformation.
污水处理厂（WWTP）是环境中纳米颗粒（NP）的主要储存库和进入途径，因此在 NP 的最终命运和毒性中起着重要作用。迄今为止，有关银纳米颗粒（AgNP）通过 WWTP 系统的传输和水生生物摄取的研究一直使用不切实际的高浓度 AgNP，而这些浓度在水生环境中不太可能遇到。使用高浓度的 AgNP 既是由于所使用的检测方法的灵敏度低，也是由于需要将背景 Ag 与添加的 AgNP 区分开来。在这项研究中，合成了同位素富集的 AgNP 来克服这些缺点，并通过一系列广泛的方法进行了表征，包括透射电子显微镜、动态和电泳光散射。将 AgNP 和金纳米颗粒（AuNP）添加到一个以城市废水为进水的中试污水处理厂中，持续 21 天。AuNP 被用作化学活性较低的示踪剂。在环境相关浓度为 30 至 500ng Au/L 和 39 至 260ng Ag/L 的新鲜水和微咸水中，使用底栖桡足类 Hyalella azteca 评估了废水中存在的原始和转化 NP 的摄取情况。AgNP 的独特同位素特征允许在存在更高天然 Ag 背景的情况下，在环境相关浓度下检测到该物质。结果表明，转化会降低 NP 在环境相关暴露浓度下的摄取量。对于 Ag，与原始 AgNP（750-840）相比，在暴露于转化后的 NP 后，获得的累积因子（AF）较低（250-350）。在暴露于 AuNP 污染的 WWTP 废水后，H. azteca 的 AF 值降低表明，除了化学转化之外，生物转化过程（例如生态冠形成）似乎也参与其中。
