Methane emission from Siberian arctic polygonal tundra: eddy covariance measurements and modeling
Methane emission from Siberian arctic polygonal tundra: eddy covariance measurements and modeling
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DOI：
10.1111/j.1365-2486.2008.01586.x
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发表时间：
2008-06
影响因子：
11.6
通讯作者：
C. Wille;L. Kutzbach;T. Sachs;D. Wagner;E. Pfeiffer
中科院分区：
文献类型：
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作者：
C. Wille;L. Kutzbach;T. Sachs;D. Wagner;E. Pfeiffer
在北纬72°N的Lena河三角洲中部的北极冻土带上进行了甲烷通量的涡动协方差测量，测量范围涵盖了2003年仲夏到初冬和2004年初春到仲夏的季节过程，包括春季融化和秋季冻结回升。研究地点的特点是非常寒冷和深度的永久冻土和大陆性气候，年平均气温为−14.7°C。地表以潮湿的多边形冻土带为特征，微起伏由隆起的中度干燥地点、凹陷的潮湿地点、多边形池塘和湖泊组成。我们发现盛夏期间典型的30 mg CH4 m−2天−1的通量相对较低，并确定土壤温度和近地表大气湍流是控制甲烷排放的因素。大气湍流的影响归因于冻土带开阔水面的高覆盖率。土壤融化深度和地下水位对甲烷通量没有明显影响。据估计，春季融化期间的过量排放约占6-10月测得的总排放的3%。冬季排放量是根据测量数据中发现的函数关系进行建模的。年甲烷排放量估计为3.15g m−2。与同类生态系统的报告数值相比，这一数值较低。其原因被认为是研究区域的永久冻土温度很低，沙质土壤质地和土壤中养分的生物有效性低，以及湿润到干燥的微型场地的表面覆盖率很高。甲烷排放量约占生态系统年碳平衡的14%。考虑到甲烷的全球变暖潜力，甲烷排放使冻土带成为有效的温室气体源。
Eddy covariance measurements of methane flux were carried out in an arctic tundra landscape in the central Lena River Delta at 72°N. The measurements covered the seasonal course of mid‐summer to early winter in 2003 and early spring to mid‐summer in 2004, including the periods of spring thaw and autumnal freeze back. The study site is characterized by very cold and deep permafrost and a continental climate with a mean annual air temperature of −14.7 °C. The surface is characterized by wet polygonal tundra, with a micro‐relief consisting of raised moderately dry sites, depressed wet sites, polygonal ponds, and lakes. We found relatively low fluxes of typically 30 mg CH4 m−2 day−1 during mid‐summer and identified soil temperature and near‐surface atmospheric turbulence as the factors controlling methane emission. The influence of atmospheric turbulence was attributed to the high coverage of open water surfaces in the tundra. The soil thaw depth and water table position were found to have no clear effect on methane fluxes. The excess emission during spring thaw was estimated to be about 3% of the total flux measured during June–October. Winter emissions were modeled based on the functional relationships found in the measured data. The annual methane emission was estimated to be 3.15 g m−2. This is low compared with values reported for similar ecosystems. Reason for this were thought to be the very low permafrost temperature in the study region, the sandy soil texture and low bio‐availability of nutrients in the soils, and the high surface coverage of moist to dry micro‐sites. The methane emission accounted for about 14% of the annual ecosystem carbon balance. Considering the global warming potential of methane, the methane emission turned the tundra into an effective greenhouse gas source.