Methane emissions from a wetland region within the Hudson Bay Lowland: An atmospheric approach
Methane emissions from a wetland region within the Hudson Bay Lowland: An atmospheric approach
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哈德逊湾低地湿地区域的甲烷排放：大气方法
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
I. Levin
中科院分区：
文献类型：
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作者：
A. Kuhlmann;D. Worthy;N. Trivett;I. Levin
在安大略弗拉斯代尔（49°53′N，81°34′W）的一个偏远的中陆监测站，利用甲烷（CH 4）混合比、大气222 Rn活度和大气CH 4中碳和氢的稳定同位素比的连续观测，对哈德逊湾低地（HBL）的区域CH 4排放进行了表征和定量。在夏季，这是由于地面源的排放积累在强烈的夜间逆温大的昼夜变化中观察到的痕量物质。利用Fraserdale大气CH 4稳定同位素组成的日变化，确定该区域湿地CH 4源的同位素特征为δ 13 CVPDB =（−60.0±3.2）‰和δDVSMOW =（−442±142）‰。这些综合值被认为是几百平方公里的代表。1994-1996年9月和10月期间进行的大气222 Rn子体观测被用来估计Fraserdale地区的总CH 4排放率。9月和10月的CH 4通量分别为（11.5±1.2）mg CH 4 m−2 d−1和（4.7±2.7）mg CH 4 m−2 d−1，估计绝对不确定度为± 30%。这些值与1990年NOWES活动期间使用静态室进行的夏季通量测量结果具有很好的可比性[Roulet等人，1994]以及使用在高塔上进行的涡流相关测量[Edwards等人，1994年]。
Continuous observations of methane (CH4) mixing ratios in combination with the atmospheric 222Rn activity and stable isotope ratios of carbon and hydrogen in atmospheric CH4 at a remote midcontinental monitoring station at Fraserdale, Ontario (49°53′N, 81°34′W) are used to characterize and quantify the regional CH4 emissions from the Hudson Bay Lowland (HBL). Large diurnal variations are observed in both trace substances during the summer which are due to emissions from ground level sources accumulating during strong nocturnal inversions. Diurnal changes of the stable isotopic composition of atmospheric CH4 at Fraserdale were used to determine the isotopic signature of the regional wetland CH4 source to be δ13CVPDB = (−60.0±3.2)‰ and δDVSMOW = (−442±142)‰. These integrated values are regarded as representative of several hundred square kilometers. The atmospheric 222Rn daughter observations made during the months of September and October 1994–1996 were used to estimate total CH4 emission rates in the region of Fraserdale. The fluxes of CH4 for September and October were (11.5±1.2) mg CH4 m−2 d−1 and (4.7±2.7) mg CH4 m−2 d−1, respectively, with an estimated absolute uncertainty of ±30%. These values are well comparable with summer flux measurements performed during the 1990 NOWES campaign using static chambers [Roulet et al., 1994] as well as using eddy correlation measurements performed on a tall tower [Edwards et al., 1994].