Methane efflux from bubbles suspended in ice-covered lakes in Syowa Oasis, East Antarctica
Methane efflux from bubbles suspended in ice-covered lakes in Syowa Oasis, East Antarctica
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DOI：
10.1029/2009jd011849
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发表时间：
2009-09
影响因子：
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通讯作者：
M. Sasaki;S. Imura;S. Kudoh;T. Yamanouchi;S. Morimoto;G. Hashida
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文献类型：
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作者：
M. Sasaki;S. Imura;S. Kudoh;T. Yamanouchi;S. Morimoto;G. Hashida
[1]这是第一次估计南极洲湖冰气泡中的甲烷流出量。2004年，作为第45次日本南极研究考察的一部分，在东南极洲Lutzow-Holm湾（Syowa绿洲）东海岸沿着无冰岩石区，观察到20个湖泊的浅冰中悬浮的气泡。在湖冰中悬浮气泡的甲烷浓度和湖水中溶解甲烷浓度的异常现象时有发生，气泡中甲烷浓度的变化范围为1.9ppmv ~ 18%vol/vol，变化幅度达5个数量级。通过数字照片观察到的亮度和气泡中的甲烷浓度。这种程序适用于Skarvsnes地区的Oyako Ike湖，在那里观察到最大的甲烷浓度，表明总气泡体积约为冰体积的0.6%，湖中气泡中甲烷的质量约为74公斤。几乎所有气泡中的气体都在冰融季节早期（12月和1月的几周时间）释放到大气中。通过将面积分数频率分布应用于调查的20个湖泊的甲烷浓度范围，外推到包括110个湖泊在内的整个Syowa绿洲，将得出约2吨甲烷/年的总排放量的临时估计。
[1] This is the first estimation of methane efflux from bubbles in lake ice in Antarctica. Bubbles suspended in shallow ice in 20 lakes were observed as part of the operations of the 45th Japanese Antarctic Research Expedition in ice-free rocky areas along the eastern coast of Lutzow-Holm Bay (Syowa Oasis) in East Antarctica in 2004. Anomalous methane concentrations in bubbles suspended in lake ice and anomalous dissolved methane concentrations in lake water were frequently found. Methane concentrations in bubbles varied of 5 orders of magnitude, from 1.9 ppmv to 18% vol/vol. A procedure that makes estimations of methane flux from ice bubbles possible has been developed, on the basis of a relationship between bubble-density distribution, brightness observed by digital photographs, and methane concentration in bubbles. Such a procedure applied to Lake Oyako Ike in the Skarvsnes area, where the maximum methane concentration was observed, suggests that total bubble volume is about 0.6% of ice volume and the mass of methane in bubbles in the lake is about 74 kg. Almost all gases in bubbles are released to the atmosphere in the early ice melt season (a period of a few weeks in December and January). By applying area fraction frequency distributions to methane concentration ranges for 20 lakes surveyed, extrapolation to the whole Syowa Oasis, including 110 lakes, would give a provisional estimate of total emission of about 2 tons-CH4/yr.