Fates of methane from different lake habitats:: Connecting whole-lake budgets and CH4 emissions
Fates of methane from different lake habitats:: Connecting whole-lake budgets and CH4 emissions
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DOI：
10.1029/2007jg000608
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发表时间：
2008-05-24
影响因子：
3.7
通讯作者：
Van de Bogert, Matthew C.
中科院分区：
文献类型：
--
作者：
Bastviken, David;Cole, Jonathan J.;Van de Bogert, Matthew C.
甲烷（CH 4）是湖泊中有机质分解的主要产物。甲烷一旦在沉积物中产生，就会被氧化或作为温室气体排放到大气中。湖泊是大气CH 4的一个重要来源，但导致CH 4排放的内部途径的相对大小尚不清楚。我们量化的内部循环和甲烷排放在三个湖泊在夏季分层。这些甲烷预算包括：沉积物在不同深度释放甲烷;水柱输送模式和甲烷氧化;水柱中的甲烷储存;以及通过扩散和沸腾向大气排放甲烷。还估计了甲烷氧化菌氧化甲烷对浮游食物网的贡献。尽管在地表沃茨中甲烷的浓度很低，但浅水表层沉积物是大气中甲烷的主要来源。深层沉积物中产生的CH 4有51 - 80%在水体中被氧化，而浅层沉积物中释放的CH 4大部分逃脱氧化而进入大气。在夏季分层过程中，表层沉积物排放的CH 4占100%，考虑到分层后湖泊环流过程中储存在深水层中的CH 4的释放，表层沉积物排放的CH 4占14 - 76%，扩散排放占26 - 48%，其余为沸腾排放。这些结果表明，它是重要的，以解决运输速率的甲烷从浅沉积物沿着的生产-消费过程时，试图了解甲烷动力学和调节湖泊甲烷排放。
Methane (CH4) represents a major product of organic matter decomposition in lakes. Once produced in the sediments, CH4 can be either oxidized or emitted as a greenhouse gas to the atmosphere. Lakes represent an important source of atmospheric CH4, but the relative magnitudes of the internal pathways that lead to CH4 emissions are not yet clear. We quantified internal cycling and methane emissions in three lakes during summer stratification. These methane budgets included: sediment release of CH4 at different depths; water column transport patterns and methane oxidation; methane storage in the water column; and methane emissions to the atmosphere by diffusion and ebullition. The contribution of CH4 carbon, via oxidation by methanotrophic bacteria, to pelagic food webs was also estimated. Despite the very low concentration of CH4 in surface waters, shallow, epilimnetic sediments were major contributors of CH4 to the atmosphere. While 51 - 80% of the CH4 produced in deep sediments was oxidized in the water column, most of the CH4 released from shallow sediment escaped oxidation and reached the atmosphere. Epilimnetic sediments accounted for 100% of CH4 emitted during summer stratification, and 14 - 76% considering the release of CH4 stored in deep water layers during lake circulation after the stratification period; diffusive emission accounted for 26 - 48% and ebullition the remainder. These results indicate that it is important to address transport rates of CH4 from the shallow sediment along with the production-consumption processes when trying to understand methane dynamics and the regulation of lake methane emissions.