Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw
Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw
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DOI：
10.1073/pnas.1511705112
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发表时间：
2015-11-10
影响因子：
11.1
通讯作者：
Striegl, Robert G.
中科院分区：
文献类型：
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作者：
Drake, Travis W.;Wickland, Kimberly P.;Striegl, Robert G.
北方的永久冻土储存了大量的碳，几乎是现在大气的两倍。目前和预计的气候变暖威胁着这些冰冻的、富含有机碳（OC）的土壤的广泛解冻。解冻后，流动的永久冻土有机碳以溶解和颗粒形式进入溪流和河流，这是有机碳的重要处理器和二氧化碳（CO2）排放到大气中的管道。在这里，我们证明了古老的溶解有机碳（DOC）从35,800年B. P.永冻土浸出迅速矿化为CO2。在一种新型的高时间分辨率生物反应器中进行的200小时实验中，DOC浓度平均下降了53%，使溶解无机碳（DIC）浓度增加了7倍以上。87%的DOC损失的微生物吸收来自低分子量（LMW）的有机酸乙酸和丁酸。据我们所知，我们的研究是第一个直接量化高二氧化碳生产率从永冻层衍生的低分子量DOC矿化。所观察到的DOC损失率是最高的报告为冻土碳，并证明了潜在的重要性，低分子量DOC在驱动更新世时代的冻土碳的快速代谢后解冻和CO2释放到大气中的土壤和附近的内陆沃茨。
Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high-temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low-molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thawand the outgassing of CO2 to the atmosphere by soils and nearby inland waters.