【摘要】 反硝化型甲烷厌氧氧化（DAMO）是湿地生态系统中耦合碳氮循环的重要生物地球化学过程，对于削减湿地甲烷（CH₄）排放与缓和全球气候变暖具有重要意义。河流入湖口是流域碳、氮汇集场所，也是CH₄释放的热点区域，然而其DAMO及调控机制尚未明晰。本研究以鄱阳湖湿地为研究区域，于2021年2月（冬季）和6月（夏季）在赣江口、饶河口、抚河口、修水口、信江口和非河流入湖口采集表层（0～5 cm）沉积物样品，采用¹³C同位素示踪技术，量化不同河流入湖口DAMO过程的潜在速率。结果表明：（1）鄱阳湖湿地DAMO过程速率存在显著季节性与空间异质性（p<0.01）特征。夏季亚硝酸盐型（NO₂^--DAMO）和硝酸盐型（NO₃^--DAMO）平均速率分别为18.71和17.92 nmol/（g·d）（以CO₂计），显著高于冬季[5.66和5.72 nmol/（g·d）]。抚河口DAMO过程速率最高，其次为信江口，饶河口最低。（2）沉积物中mcrA基因丰度显著高于pmoA（p<0.05），夏季二者平均值分别为3.0×10⁷与2.9×10⁷ copies/g，冬季分别为2.3×10⁷与2.2×10⁷ copies/g,pmoA与mcrA基因丰度对DAMO过程速率的贡献度最高（p<0.01）。（3）湿地沉积物中TOC、Fe²⁺和Fe³⁺含量变化改变了mcrA和pmoA基因丰度，并成为影响DAMO过程速率的关键环境因子。（4）湿地沉积物每年通过DAMO可消耗1.39×104 t CH₄和3.3×10⁴ t NO_x^-，约占鄱阳湖年均CH₄排放通量的26.88%以及流域活性氮输入总量的2.76%。研究显示，鄱阳湖沉积物DAMO过程具有显著的时空变化，且受到多种环境因子的调控；DAMO过程具有增加CH₄氧化和减轻过量硝酸盐的双重作用，对于湖泊湿地生态系统CH₄和氮素削减具有重要意义。更多还原

【Abstract】 Denitrifying anaerobic oxidation of methane（DAMO） is a crucial biogeochemical process that couples the carbon and nitrogen cycles in wetland ecosystems and plays an important role in reducing wetland methane（CH₄） emissions and mitigating global warming.River-lake confluence zones act as convergence points for carbon and nitrogen within watersheds and are therefore hotspots for CH₄ emissions. However, DAMO processes and their regulatory mechanisms in these zones remain poorly understood. In this study, the Poyang Lake wetland was selected as the study area. Surface sediment samples（0-5 cm） were collected from the estuaries of the Gan River, Rao River, Fu River, Xiushui River, Xinjiang River, and non-river inflow areas during February（winter） and June（summer） 2021.13C isotope tracing technology were used to quantify potential DAMO rates at different river mouths. The results showed that:（1） DAMO rates exhibited pronounced seasonal and spatial heterogeneity. During summer, the average rates of the nitrite-mediated（NO₂^--DAMO）and nitrate-mediated（NO₃^--DAMO） processes were 18.71 and 17.92 nmol/（g·d）（expressed as 13 CO₂）, respectively, which were significantly higher than those observed in winter（5.66 and 5.72 nmol/（g·d））. The highest DAMO rates occurred at the Fu River estuary,followed by the Xinjiang River estuary, whereas the lowest rates were overserved at the Rao River estuary.（2） The abundance of the mcrA gene exceeded that of pmoA in Poyang Lake wetland sediments（p<0.05）, with summer averages of 3.0×10⁷ and 2.9×10⁷ copies/g,respectively, and winter averages of 2.3×10⁷ and 2.2×10⁷ copies/g. Both pmoA and mcrA gene showed significant positive contributions to DAMO rates（p<0.01）.（3） Variations in sediment total organic carbon（TOC）, Fe²⁺ and Fe³⁺ concentrations significantly influenced mcrA and pmoA gene abundances in the Poyang Lake wetlands, which become the key environmental factors influencing DAMO activity.（4） DAMO in Poyang Lake wetland sediments was estimated to consume 1.39×10⁴ t CH₄ and 3.3×10⁴ t NOx-annually, accounting for approximately 26.88% of the lake′s average annual CH₄ emission flux and 2.76% of the total reactive nitrogen input within the watershed.The research indicates that the DAMO process in the Poyang Lake wetland sediments exhibits significant spatiotemporal variation and is regulated by multiple environmental factors. By simultaneously enhancing CH₄ oxidation and removing excess nitrate, DAMO plays a crucial role in mitigating CH₄ emissions and nitrogen loading within lake wetland ecosystems.更多还原