College of Earth Sciences, Chengdu University of Technology, Chengdu, 610059, China.
Institute of Geophysical & Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, 065000, China.
Sci Rep. 2020 May 5;10(1):7520. doi: 10.1038/s41598-020-63054-z.
In this study, systematic soil methane cycle geochemical monitoring was carried out in a typical gas hydrate region in the Qinghai-Tibet Plateau. Soil gas samples were collected for hydrocarbon components and carbon isotope analysis. Meanwhile, soil-methane fluxes from the upper active layer (20-30 cm) were monitored during six months of one year. The results of this research provide evidence of a new source of methane emission from wetland soils in permafrost regions: gas hydrate release. Sites with large methane emissions were found using flux monitoring, the characteristics of thermogenic methane were identified using carbon isotope tracing, and the relationship between emission by soils and effusion from gas hydrates was determined through correlation analyses of soil-adsorbed hydrocarbons. Seasonal variation of methane emissions are also discussed by considering the emission of bacterial methane, thermogenic methane, and the absorption of methane from the soil active layer. These comprehensive findings provide valuable information for carbon cycle research of wetlands in permafrost regions.
本研究在青藏高原典型天然气水合物区进行了系统的土壤甲烷循环地球化学监测。采集了土壤气体样品进行烃类成分和碳同位素分析。同时，在一年中的六个月内监测了上活跃层（20-30 厘米）的土壤甲烷通量。该研究结果为冻土区湿地土壤甲烷排放的新来源提供了证据：天然气水合物释放。通过通量监测找到了甲烷排放量较大的地点，通过碳同位素示踪确定了热成因甲烷的特征，并通过土壤吸附烃的相关分析确定了土壤排放和天然气水合物渗出之间的关系。通过考虑细菌甲烷、热成因甲烷和土壤活跃层甲烷的吸收，还讨论了甲烷排放的季节性变化。这些综合发现为冻土区湿地碳循环研究提供了有价值的信息。
