Magnitudes and Drivers of Greenhouse Gas Fluxes in Floodplain Ponds During Drawdown and Inundation by the Three Gorges Reservoir
Magnitudes and Drivers of Greenhouse Gas Fluxes in Floodplain Ponds During Drawdown and Inundation by the Three Gorges Reservoir
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DOI：
10.1029/2018jg004701
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发表时间：
2019-08
期刊：
影响因子：
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通讯作者：
B. Miller;Huai Chen;Yunkai He;Xingzhong Yuan;G. Holtgrieve
中科院分区：
文献类型：
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作者：
B. Miller;Huai Chen;Yunkai He;Xingzhong Yuan;G. Holtgrieve
水电站水库是众所周知的大气温室气体排放源。这部分是由于季节性的水位波动，将陆地C和N从洪泛区转移到水库。温室气体CH 4、CO 2和N2 O的分压和通量也是原位生物C和N循环以及整个生态系统代谢的函数，在内陆沃茨内，这些都是昼夜变化的。因此，在水电站水库的温室气体排放量可能会随着季节和昼夜时间尺度与当地水文和生态系统的新陈代谢。中国的三峡水库是世界上最大和最新的水库之一，其洪泛区约占库区面积的三分之一。本文对三峡漫滩池塘中温室气体的昼夜分压和通量进行了测定。我们在三峡水库淹没后的漫滩上重复了这些测量。在水库水位下降期间，CH 4沸腾占洪泛区池塘排放到大气中的60-68%。使用线性混合效应模型，我们表明，分压的CH 4和CO2和扩散CO2通量在河漫滩池塘的昼夜变化的基础上，在原地呼吸。三峡水库对洪泛区的淹没显著减缓了CH 4的扩散和沸腾。Diel pCO 2，pCH 4，pN 2 O，和CO2的扩散通量淹没漫滩也驱动原位呼吸。因此，三峡水库的水位下降/淹没周期的变化幅度的水生温室气体通量的洪泛区。
Hydropower reservoirs are well‐known emitters of greenhouse gases to the atmosphere. This is due in part to seasonal water level fluctuations that transfer terrestrial C and N from floodplains to reservoirs. Partial pressures and fluxes of the greenhouse gases CH4, CO2, and N2O are also a function of in situ biological C and N cycling and overall ecosystem metabolism, which varies on a diel basis within inland waters. Thus, greenhouse gas emissions in hydropower reservoirs likely vary over seasonal and diel time scales with local hydrology and ecosystem metabolism. China's Three Gorges Reservoir is among the largest and newest in the world, with a floodplain that encompasses approximately one third of the reservoir area. We measured diel partial pressures and fluxes of greenhouse gases in ponds on the Three Gorges Floodplain. We repeated these measurements on the submerged floodplain following inundation by the Three Gorges Reservoir. During reservoir drawdown, CH4 ebullition comprised 60–68% of emissions from floodplain ponds to the atmosphere. Using linear mixed effects modeling, we show that partial pressures of CH4 and CO2 and diffusive CO2 fluxes in floodplain ponds varied on a diel basis with in situ respiration. Floodplain inundation by the Three Gorges Reservoir significantly moderated areal CH4 diffusion and ebullition. Diel pCO2, pCH4, pN2O, and diffusive fluxes of CO2 on the submerged floodplain were also driven by in situ respiration. The drawdown/inundation cycle of the Three Gorges Reservoir therefore changes the magnitudes of aquatic greenhouse gas fluxes on its floodplain.