湖泊高温事件与"退养还湖"对太湖CH4排放的双重效应解析OA

Under global warming,the increasing frequency of high-temperature events in lakes,combined with the ecological resto-ration project"Cessation of Aquaculture and Return to Lake"implemented in east Lake Taihu since 2019,has created complex in-teractions that complicate the dynamics of lacustrine methane(CH4)emissions.This study aims to elucidate the impacts of these high-temperature events and ecological restoration on CH4 emissions in Lake Taihu and their underlying mechanisms.Using high-frequency observational data from the Dongtaihu site of the Taihu Eddy Flux Network(2018-2020),we employed the seasonal threshold method to identify high-temperature events and systematically analyzed their effects on CH4 fluxes alongside the regulatory influence of the restoration project.Results show that the seasonal threshold method effectively captured short-term high-tempera-ture processes that drive CH4 emissions,accommodating both seasonal water-temperature fluctuations and high-frequency temporal variations in emissions.From 2018 to 2020,23 high-temperature events were identified.Their promotive effect on CH4 emissions exhibited distinct seasonal differences,being stronger in spring and autumn than in summer and winter.During individual events,CH4 fluxes typically followed a three-phase pattern:stable in the pre-heatwave period,a sharp increase during the heatwave,and a decline in the post-heatwave period.The"Cessation of Aquaculture and Return to Lake"project effectively suppressed CH4 emis-sions during high-temperature periods.In the ecological restoration phase,the median CH4 fluxes before,during,and after high-temperature events were 0.05-0.17,0.07-0.25,and 0.04-0.15 μg/(m2·s),respectively,representing reductions of approxi-mately 72％-95％compared to the prior aquaculture phase(0.42-4.89,1.05-5.26,and 0.71-4.60 μg/(m2·s),respective-ly).This study provides a theoretical basis for understanding the response mechanisms of carbon cycling in shallow lakes to climate wanming and ecological management.