Large uncertainties in estimates of methane (CH 4 ) emissions from tropical inland waters reflect the paucity of information at appropriate temporal and spatial scales. CH 4 concentrations, diffusive and ebullitive fluxes, and environmental parameters in contrasting aquatic habitats of Lake Janauacá, an Amazon floodplain lake, measured for two years revealed patterns in temporal and spatial variability related to different aquatic habitats and environmental conditions. CH 4 concentrations ranged from below detection to 96 µM, CH 4 diffusive fluxes from below detection to 2342 µmol m −2 h −1 , and CH 4 ebullitive fluxes from 0 to 190 mmol m −2 d −1 . Vegetated aquatic habitats had higher surface CH 4 concentrations than open water habitats, and no significant differences in diffusive CH 4 fluxes, likely due to higher k values measured in open water habitats. CH 4 emissions were enhanced after a prolonged low water period, when the exposed sediments were colonized by herbaceous plants that decomposed after water levels rose, possibly fueling CH 4 production. Statistical models indicated the importance of variables related to CH 4 production (temperature, dissolved organic carbon) and consumption (dissolved nitrogen, oxygenated water column), as well as maximum depth, in controlling surface water CH 4 concentrations.

中文翻译：

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从热带泛滥平原湖到大气的溶解甲烷浓度和通量

热带内陆水域甲烷 (CH 4 ) 排放量估计值的巨大不确定性反映了适当时空尺度上的信息缺乏。对亚马逊洪泛区湖泊 Janauacá 湖的对比水生栖息地的 CH 4 浓度、扩散和沸腾通量以及环境参数进行了两年的测量，揭示了与不同水生栖息地和环境条件相关的时空变异模式。CH 4 浓度范围从低于检测到96 µM，CH 4 扩散通量从低于检测到2342 µmol m -2 h -1 ，CH 4 沸腾通量从0 到190 mmol m -2 d -1 。植被水生栖息地的地表 CH 4 浓度高于开放水域栖息地，并且扩散 CH 4 通量没有显着差异，可能是由于在开阔水域栖息地测量的 k 值较高。CH 4 排放量在长时间的低水期之后增加，当时暴露的沉积物被草本植物定殖，在水位上升后分解，可能会促进 CH 4 的产生。统计模型表明与 CH 4 生产（温度、溶解有机碳）和消耗（溶解氮、含氧水柱）以及最大深度相关的变量在控制地表水 CH 4 浓度方面的重要性。