Sources and sinks of methane in Lake Baikal: A synthesis of measurements and modeling
Sources and sinks of methane in Lake Baikal: A synthesis of measurements and modeling
复制标题
贝加尔湖甲烷的来源和汇：测量和建模的综合
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
A. Wüest
中科院分区：
文献类型：
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作者：
Martin Schmid;M. Batist;N. Granin;V. Kapitanov;Daniel Frank Mcginnis;I. B. Mizandrontsev;Anatoly Obzhirov;A. Wüest
我们研究了贝加尔湖的甲烷(CH4)收支，贝加尔湖是世界上面积最大的湖泊，也是唯一已知的沉积物中存在甲烷水合物的淡水湖。在2002年10月至2004年6月期间进行的六次探险期间采集的水样中测量了甲烷浓度；这些探险覆盖了整个湖泊的体积。一维模式被用来(1)估计贝加尔湖南部盆地内的大尺度垂直CH4通量，(2)确定与大气的交换，(3)限制来自渗漏和泥火山的CH4输入到深水。通量通常比之前的估计低几个数量级。大洋表层混合层的甲烷年内部来源粗略估计为40毫克甲烷。这些输入的很大一部分向下扩散，并在水柱中消耗，甲烷的停留时间约为4年。来自深层气体渗漏和泥火山的甲烷输入不到10mgCH4yr−1，其中大部分在到达地表之前被氧化。大气和远离浅水区的主要水体之间的CH4净通量可以忽略不计，与零没有显着差异。然而，地表水和大气中的甲烷浓度偶尔很高，这表明塞伦加三角洲附近的地区是大气中甲烷的本地来源。中部盆地的CH4通量与南部盆地非常相似，而北部盆地的浅层CH4源较弱。
We studied the methane (CH4) budget of Lake Baikal, the most voluminous lake in the world and the only freshwater body with known occurrences of methane hydrates in the sediments. CH4 concentrations were measured in water samples taken during six expeditions between October 2002 and June 2004; these expeditions covered the entire lake volume. A one‐dimensional model was applied to (1) estimate the large‐scale vertical CH4 fluxes within the South Basin of Lake Baikal, (2) determine the exchange with the atmosphere, and (3) constrain the CH4 inputs from seeps and mud volcanoes to the deep water. Fluxes were generally several orders of magnitude below previous estimates. The annual internal source of CH4 to the pelagic surface mixed layer was roughly estimated to be 40 Mg CH4. A large part of this input diffuses downwards and is consumed in the water column, with a CH4 residence time of about 4 yr. The input of CH4 from deep gas seeps and mud volcanoes is less than a few 10 Mg CH4 yr−1, most of which is oxidized before reaching the surface. The net CH4 flux between the atmosphere and the main waterbody distant from shallow areas is negligible and not significantly different from zero. However, occasional high CH4 concentrations, both in the surface water and in the atmosphere, indicate that the region near the Selenga delta is a local CH4 source to the atmosphere. CH4 fluxes in the Central Basin are very similar to those in the South Basin, whereas in the North Basin, the shallow CH4 sources are weaker.