Yu Chenhui, He Qiang, Nie Wen-Bo, Zhang Tanglong, Wu Hao, Yang Yulong, Fu Shibo, Tan Xin, Chen Yi
College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
Water Res. 2025 Jun 15;278:123415. doi: 10.1016/j.watres.2025.123415. Epub 2025 Feb 28.
Effluent organic matter (EfOM) from wastewater treatment plants (WWTPs) contains humic-like substances that function as electron shuttles, thereby facilitating microbially-mediated redox reactions. However, the mechanisms governing the coupled processes of anaerobic oxidation of methane (CH) (AOM) and nitrous oxide (NO) reduction in river sediments, which receive WWTPs effluents, remain poorly understood. In this study, an incubation experiment with anoxic river sediments was conducted to assess the impacts of EfOM on AOM and nitrous oxide reduction using different effluent dilution ratios. The results showed that EfOM significantly enhanced both processes. Specifically, the AOM rate increased from 8.1 to 14.3 μg g d, while the NO reduction rate increased from 29.2 to 56.5 μg g d. The results of batch tests demonstrated that AOM process enhanced NO reduction in the presence of EfOM, highlighting the critical role of EfOM in linking these processes. Nitrate-dependent anaerobic methane oxidation (n-DAMO) archaea and denitrifying bacteria dominated the sediment incubated with EfOM. Metagenomic and metatranscriptomic analyses revealed that the denitrifying bacteria exclusively reduce NO, confirming the role of EfOM in facilitating electron transfer between n-DAMO archaea and NO reducers. This indicates that effluent discharge could be a potential factor driving the concurrent sinks of methane and nitrous oxide, offering a perspective for investigating the impacts of WWTPs effluent on greenhouse gas sinks in freshwater ecosystems.
污水处理厂（WWTPs）的出水有机物（EfOM）含有类似腐殖质的物质，这些物质作为电子穿梭体，从而促进微生物介导的氧化还原反应。然而，对于接收污水处理厂出水的河流沉积物中甲烷（CH）厌氧氧化（AOM）和氧化亚氮（NO）还原耦合过程的控制机制，人们仍知之甚少。在本研究中，进行了一项缺氧河流沉积物的培养实验，以评估不同出水稀释比例下EfOM对AOM和氧化亚氮还原的影响。结果表明，EfOM显著增强了这两个过程。具体而言，AOM速率从8.1增加到14.3μg g d，而NO还原速率从29.2增加到56.5μg g d。批次试验结果表明，在EfOM存在的情况下，AOM过程增强了NO还原，突出了EfOM在连接这些过程中的关键作用。硝酸盐依赖型厌氧甲烷氧化（n-DAMO）古菌和反硝化细菌在与EfOM一起培养的沉积物中占主导地位。宏基因组和宏转录组分析表明，反硝化细菌专门还原NO，证实了EfOM在促进n-DAMO古菌和NO还原菌之间电子转移中的作用。这表明废水排放可能是驱动甲烷和氧化亚氮同时汇的一个潜在因素，为研究污水处理厂出水对淡水生态系统中温室气体汇的影响提供了一个视角。
