Zhou Yun, Cun Deshou, Wang Yiting, Wang Yuan, Li Yanye, Jeppesen Erik, Chang Junjun
Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650500, China.
Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650500, China; Yunnan Field Scientific Station for Restoration of Ecological Function in Central Yunnan of China, Yunnan University, Kunming 650091, China.
Water Res. 2025 Sep 1;283:123822. doi: 10.1016/j.watres.2025.123822. Epub 2025 May 13.
Per- and polyfluoroalkyl substances (PFASs), typical groups of emerging contaminants (ECs), can accumulate in wetland systems and adsorb onto the surface of microplastics (MPs), resulting in composite pollution. However, the effects of PFASs and their composite pollution with MPs on the ecological processes and functions of wetlands remain largely unknown. We studied the effects of perfluorooctanoic acid (PFOA) and its combined pollution with two types of MPs (polylactic acid (PLA) and polyethylene (PE)) at low and high concentration levels on nitrogen elimination processes and NO emissions in wetlands as well as the associated microbial mechanisms over three months. The results showed that PFOA inhibited nitrification in wetland sediment (P < 0.05), most pronouncedly with the composite pollution of PFOA and MPs. NO₃⁻ isotope tracing analysis showed that anammox and denitrification rates were both significantly inhibited by PFOA contamination, especially at high concentrations, while co-presence of MPs, especially PLA, weakened the inhibitory effect of PFOA on anammox and denitrification rates. The contribution of anammox to nitrogen elimination declined under PFOA and its composite pollution with high concentrations of MPs. Overall, PFOA and its composite pollution with MPs weakened the nitrogen removal capability of the wetlands. PFOA presence increased N₂O emissions (by 43.4-343 %) from the wetlands, and its composite pollution with MPs, particularly with PLA, further exacerbated N₂O emissions (by 35.6-197 %), evidencing a concentration- dependent effect. The increases were primarily attributed to that PFOA and MPs contamination regulated the community structure of the functional microbiome and reduced the abundance of ammonia-oxidizing and N₂O-reducing bacteria. DO, nitrogen (NH-N or NO-N) and dissolved organic carbon (DOC) concentrations were the key environmental factors influencing nitrogen loss rates in the wetlands. PFOA and its composite pollution with MPs regulated the nitrogen loss processes and NO emission in the wetlands following distinct pathways. This study provides new insights into the impacts of PFASs and their composite pollution with MPs on nitrogen transformation and N₂O emissions in wetlands and the indispensable management of wetlands under continuous inputs of ECs.
全氟和多氟烷基物质（PFASs）是典型的新兴污染物（ECs），可在湿地系统中积累并吸附到微塑料（MPs）表面，导致复合污染。然而，PFASs及其与MPs的复合污染对湿地生态过程和功能的影响仍 largely未知。我们研究了全氟辛酸（PFOA）及其与两种类型的MPs（聚乳酸（PLA）和聚乙烯（PE））在低浓度和高浓度水平下的复合污染对湿地氮去除过程和一氧化二氮（N₂O）排放以及相关微生物机制的影响，为期三个月。结果表明，PFOA抑制了湿地沉积物中的硝化作用（P < 0.05），在PFOA与MPs的复合污染情况下最为明显。硝酸根（NO₃⁻）同位素示踪分析表明，厌氧氨氧化和反硝化速率均受到PFOA污染的显著抑制，尤其是在高浓度时，而MPs的共存，特别是PLA，削弱了PFOA对厌氧氨氧化和反硝化速率的抑制作用。在PFOA及其与高浓度MPs的复合污染下，厌氧氨氧化对氮去除的贡献下降。总体而言，PFOA及其与MPs的复合污染削弱了湿地的氮去除能力。PFOA的存在增加了湿地的N₂O排放（增加了43.4 - 343%），其与MPs的复合污染，特别是与PLA的复合污染，进一步加剧了N₂O排放（增加了35.6 - 197%），显示出浓度依赖性效应。增加主要归因于PFOA和MPs污染调节了功能微生物群落结构并降低了氨氧化和N₂O还原细菌的丰度。溶解氧（DO）、氮（NH-N或NO-N）和溶解有机碳（DOC）浓度是影响湿地氮损失率的关键环境因素。PFOA及其与MPs的复合污染通过不同途径调节了湿地的氮损失过程和N₂O排放。本研究为PFASs及其与MPs的复合污染对湿地氮转化和N₂O排放的影响以及在持续输入ECs情况下湿地的必要管理提供了新的见解。
