Influence of permafrost thaw on an extreme geologic methane seep
Influence of permafrost thaw on an extreme geologic methane seep
复制标题
DOI：
10.1002/ppp.2114
复制
发表时间：
2021-05
影响因子：
5
通讯作者：
Taylor D. Sullivan;A. Parsekian;Jane Sharp;P. Hanke;F. Thalasso;M. Shapley;M. Engram;K. W. Walter Anthony
中科院分区：
文献类型：
--
作者：
Taylor D. Sullivan;A. Parsekian;Jane Sharp;P. Hanke;F. Thalasso;M. Shapley;M. Engram;K. W. Walter Anthony
北极地区天然化石甲烷（CH4）排放的发生情况及其排放量鲜为人知。源于永久冻土之下的地质成因甲烷（一种强效温室气体）的排放尤其令人关注，因为它可能对气候变暖产生正反馈，即未来气候变暖加速永久冻土融化，从而释放出被困在永久冻土中的甲烷。北极地区覆盖油气藏的湖泊中贯穿性融区的形成是释放地质来源的永久冻土下甲烷的一种机制。在此，我们利用新颖的气体通量测量、地下地球物理观测、浅层沉积物取芯、高分辨率测深测量以及湖水化学测量，对埃西埃湖（阿拉斯加西北部一个地质甲烷渗漏排放量极大的湖泊）的气体排放系统进行了一次综合调查。我们发现，微生物产生的化石甲烷正通过埃西埃湖下的一个狭窄融化通道，经由湖底的麻坑排放出来。这是陆地环境中已知的通量最高的地质甲烷渗漏区域之一，可能也是通量最高的单一甲烷渗漏点。连续永久冻土向极地退缩可能意味着随着永久冻土融化加剧，更多的盖层下甲烷会被释放出来。
The occurrence and magnitude of natural fossil methane (CH4) emissions in the Arctic are poorly known. Emission of geologic CH4, a potent greenhouse gas, originating beneath permafrost is of particular interest due to the potential for positive feedback to climate warming, whereby accelerated permafrost thaw releases permafrost‐trapped CH4 in a future warmer climate. The development of through‐going taliks in Arctic lakes overlying hydrocarbon reservoirs is one mechanism of releasing geologically sourced, subpermafrost CH4. Here we use novel gas flux measurements, geophysical observations of the subsurface, shallow sediment coring, high‐resolution bathymetry measurements, and lake water chemistry measurements to produce a synoptic survey of the gas vent system in Esieh Lake, a northwest Alaska lake with exceedingly large geologic CH4 seep emissions. We find that microbially produced fossil CH4 is being vented though a narrow thaw conduit below Esieh Lake through pockmarks on the lake bottom. This is one of the highest flux geologic CH4 seep fields known in the terrestrial environment and potentially the highest flux single methane seep. The poleward retreat of continuous permafrost may have implications for more subcap CH4 release with increased permafrost thaw.