Oxygen depletion in subarctic peatland thaw lakes
Oxygen depletion in subarctic peatland thaw lakes
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DOI：
10.1139/as-2016-0048
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发表时间：
2017-06-01
期刊：
影响因子：
3.3
通讯作者：
Vincent, Warwick F.
中科院分区：
文献类型：
--
作者：
Deshpande, Bethany N.;Maps, Frederic;Vincent, Warwick F.
多年冻土融化和侵蚀导致土壤有机质在北方湖泊中富集。这些外来输入有利于细菌分解，并可能导致溶解氧下降到缺氧条件下，促进甲烷生成。在本研究中，我们的目标是确定溶解氧的季节性变化，在一组永久冻土泥炭地湖泊在亚北极魁北克，加拿大，并将这些变化与代谢率，冰盖，和混合。湖泊溶解有机碳浓度高，其表面沃茨在夏季的温室气体浓度高达一个（CO2）至三个（CH4）的数量级以上的空气平衡值，表明其强烈的异养特性。与这些观察结果相一致，泥炭地湖泊的细菌生产和氧气消耗率升高。通过现场传感器对氧气的连续测量和通过自动化现场摄像机对冰盖的连续测量表明，湖泊在冻结后不久就完全缺氧了。沃茨在春季和秋季的混合事件中部分地重新充氧，但在一个湖泊中，底部沃茨全年保持缺氧状态。这些观测结果为泥炭地解冻湖作为北极淡水生态系统的一个丰富类别的后续生物地球化学和建模研究提供了基础。
Permafrost thawing and erosion results in the enrichment of northern lakes by soil organic matter. These allochthonous inputs favour bacterial decomposition and may cause the draw-down of dissolved oxygen to anoxic conditions that promote methanogenesis. Our objective in the present study was to determine the seasonal variations in dissolved oxygen in a set of permafrost peatland lakes in subarctic Quebec, Canada, and to relate these changes to metabolic rates, ice cover, and mixing. The lakes had high dissolved organic carbon concentrations, and their surface waters in summer had greenhouse gas concentrations that were up to one (CO2) to three (CH4) orders of magnitude above air-equilibrium values, indicating their strongly heterotrophic character. Consistent with these observations, the peatland lakes had elevated rates of bacterial production and oxygen consumption. Continuous measurements of oxygen by in situ sensors and of ice cover by automated field cameras showed that the lakes became fully anoxic shortly after freeze-up. The waters were partially re-oxygenated by mixing events in spring and fall, but in one lake, the bottom waters remained anoxic throughout the year. These observations provide a foundation for subsequent bio-geochemical and modelling studies of peatland thaw lakes as an abundant class of Arctic freshwater ecosystems.