河道型水库溶解甲烷浓度的空间异质性研究

以河道型水库-西北口水库为研究对象，于2021年12月采用新型快速水-气平衡装置（FaRAGE）结合温室气体分析仪对其表层水体，垂向剖面溶解甲烷（CH₄）浓度进行监测，并采集代表性河段表层水体及库底沉积物，分别测定水体CH₄氧化速率与沉积物CH₄释放速率，初步探讨了河道型水库溶解CH₄浓度的空间异质性及其影响因素.结果表明，水库表层水体溶解CH₄浓度为0.02~0.42μmol/L （平均值为0.11±0.08μmol/L），从库首到库尾呈递增趋势；水体溶解CH₄浓度的空间异质性受水库内部CH₄产生，消耗及河道入流等多因素的综合作用，其中库尾水体因沉积物CH₄产生量大且低水深影响下CH₄消耗量较小而呈现高溶解浓度，库首水体则因为CH₄产生量相对较小且高水深影响下的CH₄消耗量较大而呈低溶解浓度；同时，河道入流可能是影响水体溶解CH₄浓度垂向分层的原因之一.

Spatial heterogeneity and influencing factors of dissolved methane in the channel-type reservoir

In this study, by connecting the newly fast-response automated gas equilibrator (FaRAGE) to a greenhouse gas analyzer, we investigated dissolved methane concentration (DMC) at the near-surface and its vertical profiles in the water column at a high resolution in channel-type reservoir-Xibeikou Reservoir in December 2021, together with measurements of water methane oxidation rate and sediment methane release rate on individual sampling sites, we preliminarily discussed the spatial heterogeneity and related influencing factors of DMC. The results showed that the DMC at the surface water ranged from 0.02 to 0.42μmol/L, with a mean of 0.11±0.08μmol/L and increased from the end to the head of the reservoir. The spatial heterogeneity of DMC in the water column within the reservoir was mainly attributed to CH₄ production in sediment, CH₄ consumption in the water column, and the inflow from the river; accordingly, high DMC in the water column of the reservoir tail resulted from the high CH₄ production and low CH₄ consumption due to shallow water, while low DMC in the water column of the reservoir head was caused by relatively low CH₄ production and high CH₄ consumption due to deep water; meanwhile, the inflow from the river may be one of the reasons for the vertical stratification of DMC.