Characteristics of methane emission of thermokarst lakes and ponds and its influencing factors in the Arctic region
Significant warming in the Arctic has led to the rapid degradation of permafrost,resulting in the devel-opment of a large number of thermokarst lakes and ponds,which are hotspots for greenhouse gas emissions.Based on the published results of methane(CH4)in Arctic thermokarst lakes and ponds from 1992 to March 2022,this paper systematically investigated the CH4 emission characteristics,carbon dynamics process,and the microbial mechanism of thermokarst lakes and ponds in the Arctic.The results showed that the annual CH4 emis-sion flux in the Arctic was about(7.78±19.60)g CH4·m-2·a-1,with significant differences among sub-regions.High CH4 emission[(23.40±26.50)g CH4·m-2·a-1 to(11.00±26.40)g CH4·m-2·a-1]were recorded in Eastern Siberia and Alaska.Bubble emission was the main pathway of CH4 emission from Arctic thermokarst lakes and ponds,with an annual emission flux of about(13.80±27.80)g CH4·m-2·a-1,accounting for 52.02%of the total CH4 emissions.The type of lake sediment significantly influences CH4 emissions from thermokarst lakes and ponds.Emissions from yedoma-type permafrost areas are(17.90±32.90)g CH4·m-2·a-1,which is 3.24 times that of non-yedoma permafrost areas.However,the main pathways and changes of CH4 emissions from peatland thermokarst lakes and ponds remain highly uncertain.The expansion and drainage trends of thermokarst lakes and ponds and the production and oxidation processes of CH4 also have important impacts on the potential CH4 emissions.There is still a lack of systematic observation for multiple CH4 emissions pathways from thermokarst lakes and ponds in the Arctic,especially in understanding the microbial process of CH4 production and oxida-tion.This study improved our understanding of the emission characteristics and mechanisms of CH4 from thermo-karst lakes and ponds in the Arctic,providing valuable insights into the potential impact of CH4 emissions from this region and its impacts on climate change.
thermokarst lakes and pondsmethaneArcticpermafrostclimate change
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