College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Res. 2023 Feb 15;219:115074. doi: 10.1016/j.envres.2022.115074. Epub 2022 Dec 14.
Silver nanoparticles (AgNPs) has been widely detected in the substrates of constructed wetlands (CWs), posing threaten to pollutants removal efficiency of CWs. However, the way to alleviate the toxicity of AgNPs on CWs is unclear. In this study, the gravel (GR), biochar (BC), pyrite (PY) and pyrite coupled with biochar matrix (PYBC) were selected as substrates to restore the pollutants removal efficiency of CWs under the exposure to the environment (0.2 mg/L) and accumulation (10 mg/L) concentration of AgNPs. Results showed that the BC and PY showed limited mitigation effects, while the PYBC alleviated the toxicity significantly. Especially in the exposure to the accumulation concentration of AgNPs, the removal of NH-N, TN, COD and TP in the PYBC were 10.2%, 8.3%, 9.4% and 10.7% higher than that in the GR, respectively. Mechanism analysis verified that AgNPs were transformed into Ag-Fe-S core shell aggregates (size >200 nm) decreasing bioavailability and the damage to cytomembrane. The PYBC restored the nitrogen removal efficiency by increasing the abundance of Nitrospira and Geothrix, which these bacteria were defined as nitrifiers and Feammox bacteria. This study provides a promising strategy to mitigate AgNPs' toxicity on the pollutant removal efficiency in CWs.
银纳米颗粒（AgNPs）已广泛存在于人工湿地（CWs）的基质中，对 CWs 的污染物去除效率构成威胁。然而，减轻 AgNPs 对 CWs 的毒性的方法尚不清楚。在这项研究中，砾石（GR）、生物炭（BC）、黄铁矿（PY）和黄铁矿耦合生物炭基质（PYBC）被选为基质，以恢复 CWs 在暴露于环境（0.2 mg/L）和积累（10 mg/L）浓度的 AgNPs 下的污染物去除效率。结果表明，BC 和 PY 表现出有限的缓解效果，而 PYBC 则显著减轻了毒性。特别是在暴露于积累浓度的 AgNPs 时，PYBC 对 NH-N、TN、COD 和 TP 的去除率分别比 GR 高 10.2%、8.3%、9.4%和 10.7%。机制分析验证了 AgNPs 转化为 Ag-Fe-S 核壳状聚集体（尺寸>200nm），降低了生物利用度和细胞膜损伤。PYBC 通过增加硝化菌和亚铁氧化菌（定义为硝化菌和 Feammox 菌）的丰度来恢复氮去除效率。本研究为减轻 AgNPs 对 CWs 中污染物去除效率的毒性提供了一种有前景的策略。
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