Bai Zhuoan, Zhang Yu, Cheng Luman, Zhou Xiaoping, Wang Minghua
Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies/College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China.
Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies/College of the Environment & Ecology, Xiamen University, Xiamen, 361102, China.
Chemosphere. 2023 Jun;325:138371. doi: 10.1016/j.chemosphere.2023.138371. Epub 2023 Mar 9.
Due to human activities, high abundances of nano/microplastics (N/MPs) concurrent with metal pollution have become a serious problem in the global marine environment. Because of displaying a high surface-area-to-volume ratio, N/MPs can serve as the carriers of metals and thus increase their accumulation/toxicity in marine biota. As one of the most toxic metals, mercury (Hg) causes adverse effects on marine organisms but whether environmentally relevant N/MPs can play a vector role of this metal in marine biota, as well as their interaction, is poorly known. To evaluate the vector role of N/MPs in Hg toxicity, we first performed the adsorption kinetics and isotherms of N/MPs and Hg in seawater, as well as ingestion/egestion of N/MPs by marine copepod Tigriopus japonicus, and second, the copepod T. japonicus was exposed to polystyrene (PS) N/MPs (500-nm, 6-μm) and Hg in isolation, combined, and incubated forms at environmentally relevant concentrations for 48 h. Also, the physiological and defense performance including antioxidant response, detoxification/stress, energy metabolism, and development-related genes were assessed after exposure. The results indicated N/MPs significantly increased Hg accumulation and thus its toxicity effects in T. japonicus as exemplified by decreased transcription of genes related to development and energy metabolism and increased transcriptional levels of genes functioning in antioxidant and detoxification/stress defense. More importantly, NPs were superimposed onto MPs and produced the most vector effect in Hg toxicity to T. japonicus, especially in the incubated forms. Overall, this study highlighted the role of N/MPs as a potential risk factor for increasing the adverse effects of Hg pollution, and emphasized the adsorption forms of contaminants by N/MPs should doubly be considered in the continuing researches.
由于人类活动，高丰度的纳米/微塑料（N/MPs）与金属污染同时出现已成为全球海洋环境中的一个严重问题。由于N/MPs具有高的表面积与体积比，它们可以作为金属的载体，从而增加金属在海洋生物群中的积累/毒性。作为毒性最强的金属之一，汞（Hg）会对海洋生物造成不利影响，但环境相关的N/MPs是否能在海洋生物群中充当这种金属的载体以及它们之间的相互作用，目前还知之甚少。为了评估N/MPs在汞毒性中的载体作用，我们首先进行了N/MPs与汞在海水中的吸附动力学和等温线研究，以及海洋桡足类日本虎斑猛水蚤对N/MPs的摄食/排泄研究，其次，将日本虎斑猛水蚤暴露于环境相关浓度的聚苯乙烯（PS）N/MPs（500纳米、6微米）和汞的单独、组合及孵育形式中48小时。此外，在暴露后评估了包括抗氧化反应、解毒/应激、能量代谢和发育相关基因在内的生理和防御性能。结果表明，N/MPs显著增加了汞在日本虎斑猛水蚤中的积累，从而增强了其毒性作用，例如与发育和能量代谢相关基因的转录减少，以及在抗氧化和解毒/应激防御中起作用的基因转录水平增加。更重要的是，纳米塑料叠加在微塑料上，对日本虎斑猛水蚤的汞毒性产生了最大的载体效应，尤其是在孵育形式中。总体而言，本研究强调了N/MPs作为增加汞污染不利影响的潜在风险因素的作用，并强调在后续研究中应加倍考虑N/MPs对污染物的吸附形式。
