云南小型高山湖泊沉积物产甲烷潜势及其驱动因素OA

Alpine lakes,rarely affected by human activities,are ideal for studying the mechanisms of lake methane(CH4)production and emission on natural environmental change.In this investigation,three small alpine lakes(Taiji Lake,Jiehu Lake and Sanxuan Lake)on Laoj unshan Mountain,Yunnan Province were selected for case study.Sediment CH4 production and primary driving factors were explored to bet-ter understand CH4 generation and emission.In the summer of 2022,we monitored routine water quality parameters,assessed sediment CH4 production and measured CH4 emission fluxes at the water-air inter-face.We also examined the influence of electron acceptors(SO42-,NO3-,Fe3+)and total Mn in sediment porewater,and the effect of sediment organic content on sediment CH4 production.Net CH4 emissions in all three lakes were low[0.12-1.21 mmol/(m2·d)],attributed primarily to low water temperatures(14.66-16.09 ℃)and high dissolved oxygen levels(78.40％-84.88％saturation).In all three lakes,CH4 produc-tion was relatively high in the top 5 cm of sediment and decreased as sediment depth increased.Anaero-bic oxidation of CH4 occurred in the sediment to varying degrees,with Fe3,SO42-,NO3-and total Mn po-tentially acting as electron acceptors in the oxidation process.Sediment organic content did not signifi-cantly affect sediment CH4 production,but there was nitrogen enrichment in the top 15 cm of sediments that could contribute to the higher CH4 production observed in the surface sediments.These results con-tribute to our understanding of CH4 dynamics in Alpine Lakes.