Riparian zones are recognized as major sources of greenhouse gas emissions, particularly methane (CH4). Denitrifying anaerobic methane oxidation (DAMO) has garnered growing attention due to its significant contribution to mitigating CH4 emissions in wetland environments. Nonetheless, the specific role and microbial mechanisms of DAMO in controlling CH4 release within riparian zones are still not well comprehended. This study employed isotopic labeling experiments to measure the nitrate-dependent anaerobic methane oxidation (NaDAMO) and nitrite-dependent anaerobic methane oxidation (NiDAMO) potential of soil samples from riparian zones that were collected during different hydrological cycles. Moreover, soil physicochemical properties, DAMO activity, and microbial abundance were integrated to analyze the key factors and mechanisms influencing DAMO in riparian zone soils. The isotope tracer results showed that NaDAMO activities (1.41–11.93 nmol 13CO2 g-1day-1) were significantly higher than NiDAMO activities (0.66–9.19 nmol 13CO2 g-1day-1) in the riparian zone (p < 0.05). NiDAMO activities were more strongly influenced by hydrological variations compared to NaDAMO activities, exhibiting higher levels during the discharge period (2.78–9.19 nmol 13CO2 g-1day-1) compared to the impoundment period (0.66–4.10 nmol 13CO2 g-1day-1). The qPCR analysis showed that the gene copies of NaDAMO archaeal mcrA (107 copies g-1) were approximately ten times greater than those of NiDAMO bacterial pmoA (106 copies g-1) in the majority of the sampling sites. Correlation analyses revealed that NiDAMO activity was influenced by soil pH (p < 0.05), while NaDAMO microbes were influenced by temperature, organic carbon, and ammonia nitrogen concentrations (p < 0.05). In summary, this research explored how hydrological changes in the riparian zone influence DAMO activities and their underlying mechanisms, providing a theoretical basis for mitigating CH4 emissions in riparian zones of reservoir regions.

中文翻译：

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三峡水库支流榆林河河岸带土壤中的反硝化厌氧甲烷氧化活性及微生物机制


河岸区被认为是温室气体排放的主要来源，尤其是甲烷 （CH4）。反硝化厌氧甲烷氧化 （DAMO） 因其对减少湿地环境中 CH4 排放的重大贡献而受到越来越多的关注。尽管如此，DAMO 在控制河岸带内 CH4 释放的具体作用和微生物机制仍未得到很好的理解。本研究采用同位素标记实验来测量在不同水文循环中收集的河岸区土壤样品的硝酸盐依赖性厌氧甲烷氧化 （NaDAMO） 和亚硝酸盐依赖性厌氧甲烷氧化 （NiDAMO） 电位。此外，结合土壤理化性质、DAMO 活性和微生物丰度，分析了影响河岸带土壤 DAMO 的关键因素和机制。同位素示踪剂结果表明，在河岸带，NaDAMO 活性 （1.41-11.93 nmol 13CO2 g-1day-1） 显著高于 NiDAMO 活性 （0.66-9.19 nmol 13CO2 g-1day-1） （p < 0.05）。与 NaDAMO 活动相比，NiDAMO 活性受水文变化的影响更大，与蓄水期 （0.66–4.10 nmol 13CO2 g-1day-1） 相比，在排放期间表现出更高的水平 （2.78–9.19 nmol 13CO2 g-1day-1）。qPCR 分析表明，在大多数采样点，NaDAMO 古细菌 mcrA 的基因拷贝 （107 拷贝 g-1） 大约是 NiDAMO 细菌 pmoA （106 拷贝 g-1） 的 10 倍。相关性分析显示，NiDAMO 活性受土壤 pH 值的影响 （p < 0.05），而 NaDAMO 微生物受温度、有机碳和氨氮浓度的影响 （p < 0.05）。 综上所述，本研究探讨了河岸带水文变化如何影响 DAMO 活动及其潜在机制，为减轻库区河岸带 CH4 排放提供了理论依据。