The role of sediments in the carbon budget of a small boreal lake
The role of sediments in the carbon budget of a small boreal lake
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DOI：
10.1002/lno.10336
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发表时间：
2016-09-01
影响因子：
4.5
通讯作者：
Sobek, Sebastian
中科院分区：
文献类型：
--
作者：
Chmiel, Hannah E.;Kokic, Jovana;Sobek, Sebastian
我们调查了湖泊沉积物作为碳（C）源和汇的作用，在一个小的（0.07公里（2））和浅（平均深度，3.4米），在瑞典北部腐殖型湖泊的年度碳预算。沉积物中的有机碳（OC）埋藏和矿化定量Pb-210定年的沉积物和实验室沉积物培养实验，分别。埋藏和矿化率，然后放大到整个盆地和一整年的沉积物厚度来自底层剖面，盆地形态，以及温度和氧浓度的水柱监测数据。此外，集水区碳进口，开放水域代谢，光化学矿化以及二氧化碳（CO2）和甲烷（CH 4）排放到大气中进行了量化的沉积过程与其他湖泊碳通量。我们发现，在全流域和年度尺度上，沉积物有机碳矿化是三倍大的有机碳埋藏，并贡献了约16%的年CO2排放量。二氧化碳排放的其他贡献是水柱代谢（31%），光化学矿化（6%），集水进口通过进口河流和流入的浅层地下水（22%）。其余的（25%）不能用我们的通量计算来解释，但最有可能是由于低估了地下水流入。结果表明，在全年和全流域尺度上，沉积物有机碳矿化作用大于有机碳埋藏作用，水体有机碳矿化作用对湖泊CO2排放的贡献大于沉积物有机碳矿化作用，流域碳输入大于湖泊内部碳循环。
We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km(2)) and shallow (mean depth, 3.4 m), humic lake in boreal Sweden. Organic carbon (OC) burial and mineralization in the sediments were quantified from Pb-210-dated sediment and laboratory sediment incubation experiments, respectively. Burial and mineralization rates were then upscaled to the entire basin and to one whole year using sediment thickness derived from sub-bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere were quantified to relate sediment processes to other lake C fluxes. We found that on a whole-basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16% to the annual CO2 emission. Other contributions to CO2 emission were water column metabolism (31%), photochemical mineralization (6%), and catchment imports via inlet streams and inflow of shallow groundwater (22%). The remainder (25%) could not be explained by our flux calculations, but was most likely attributed to an underestimation in groundwater inflow. We conclude that on an annual and whole-basin scale (1) sediment OC mineralization dominated over OC burial, (2) water column OC mineralization contributed more to lake CO2 emission than sediment OC mineralization, and (3) catchment import of C to the lake was greater than lake-internal C cycling.