Controlling factors of methane dynamics in tropical lakes of different depths
Controlling factors of methane dynamics in tropical lakes of different depths
复制标题
不同深度热带湖泊甲烷动态控制因素
DOI：
10.1029/2020jg005828
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
N.
中科院分区：
文献类型：
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作者：
Mendoza-Pascual;M. U.;Itoh;M.;Aguilar;J. I.;Padilla;K.S.A.R.;Papa;R. D. S.;Okuda;N.
为了了解热带湖泊中甲烷（CH4）的动态并描述其在CH4总排放中的重要性，我们观察了菲律宾不同深度（浅、中深和深）湖泊水柱中CH4储存的时间趋势。我们在更深的湖泊的深层缺氧层中检测到更高的ch4。逐月监测的平均表层和深层ch4浓度分别为：浅湖0.27±0.07和421±189 μmol l - 1，中深湖0.48±0.37和1121±125 μmol l - 1，深湖0.34±0.23和943±119 μmol l - 1。由于不同的分层和混合制度，ch4在水柱中储存的命运与深度有关。分析了ch4与日天气和理化参数的时间关系，揭示了它们通过控制全年的频率和混合强度对ch4动力学的影响。只有浅水湖泊ch4浓度随大气压力的降低而升高。这允许垂直混合和从较深的层向较浅的层输送ch4。在中深湖和深湖中，日天气参数对最深层（30 m以下）ch4浓度的影响不明显。这表明，为了精确估算热带湖泊的ch4排放，应考虑湖泊深度和分层。与不同气候条件下的湖泊比较，揭示了热带湖泊由于地表ch4浓度较高，对地表ch4排放的重要性。水温变化是控制深层ch4产生、储存及其向浅层输送的因素之一。
To understand methane (CH4) dynamics in tropical lakes and describe their importance in overall CH4emissions, we observed temporal trends of CH4stored in the water columns of Philippine lakes of different depths (shallow, moderately deep, and deep). We detected higher CH4stored in profundal anoxic layers of deeper lakes. The average surface and profundal CH4concentrations throughout our monthly monitoring were 0.27 ± 0.07 and 421 ± 189 μmol L–1in the shallow lake, 0.48 ± 0.37 and 1,121 ± 125 μmol L–1in the moderately deep lake, and 0.34 ± 0.23 and 943 ± 119 μmol L–1in the deep lake. The fate of CH4stored in the water column was related to depth, owing to different stratification and mixing regimes. Analyses of temporal relationships of CH4with daily weather and physicochemical parameters revealed their impact on CH4dynamics by controlling the frequency and mixing intensity throughout the year. Only shallow lake exhibited increase in CH4concentrations with lowering atmospheric pressure. This allows vertical mixing and transport of CH4from deeper to shallower layers. In moderately deep, and deep lakes, effects of daily weather parameters were not apparent on CH4concentrations in the deepest layers (below 30 m depth). This suggests that lake depth and stratification should be considered for precise estimation of tropical lakes' CH4emissions. Comparison with lakes under different climate conditions revealed the importance of tropical lakes for surface CH4emission due to higher surface CH4concentrations. Changes in water temperature is one of the factors controlling profundal CH4production, storage, and its transport to shallower layer.