Methane production as key to the greenhouse gas budget of thawing permafrost
Methane production as key to the greenhouse gas budget of thawing permafrost
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DOI：
10.1038/s41558-018-0095-z
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发表时间：
2018-04-01
影响因子：
30.7
通讯作者：
Pfeiffer, Eva-Maria
中科院分区：
文献类型：
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作者：
Knoblauch, Christian;Beer, Christian;Pfeiffer, Eva-Maria
永久冻土融化释放冻结的有机碳，这些有机碳被分解成二氧化碳(CO2)和甲烷(CH4)。这些温室气体(GHGs)的释放对大气中的CO2和CH4浓度形成正反馈，并加速气候变化(1，2)。目前的研究报告说，在水饱和(缺氧)的永久冻土(3-6)中CH4的产生是次要的，而排水(氧化)土壤(1，7)对永久冻土的碳-气候反馈更强。在这里，我们通过七年的实验室培养表明，在缺氧条件下融化的永久冻土中，在建立了稳定的产生甲烷的微生物群落后，形成了等量的二氧化碳和甲烷。考虑到甲烷较高的全球变暖潜势(GWP)，缺氧条件下的永久冻土碳矿化较少，但二氧化碳碳当量(CO2Ce)的形成多于氧气条件下(8)。根据观测到的分解数据校准的有机碳分解模型预测，到2100年，在氧气条件下(113+/-58g CO2-CKGC(-1)(KGC，碳千克))，永久冻土碳的损失会更大，但在缺氧条件下，CO2-Ce的产量(241+/-138g CO2-Ce KGC(-1))是前者的两倍。这些发现挑战了来自排水土壤的更强的永久冻土碳-气候反馈的观点1，7并强调了甲烷的产生在与气候相关的时间尺度上融化永久冻土的重要性。
Permafrost thaw liberates frozen organic carbon, which is decomposed into carbon dioxide (CO2) and methane (CH4). The release of these greenhouse gases (GHGs) forms a positive feedback to atmospheric CO2 and CH4 concentrations and accelerates climate change(1,2). Current studies report a minor importance of CH4 production in water-saturated (anoxic) permafrost soils(3-6) and a stronger permafrost carbon-climate feedback from drained (oxic) soils(1,7). Here we show through seven-year laboratory incubations that equal amounts of CO2 and CH4 are formed in thawing permafrost under anoxic conditions after stable CH4-producing microbial communities have established. Less permafrost carbon was mineralized under anoxic conditions but more CO2-carbon equivalents (CO2Ce) were formed than under oxic conditions when the higher global warming potential (GWP) of CH4 is taken into account(8). A model of organic carbon decomposition, calibrated with the observed decomposition data, predicts a higher loss of permafrost carbon under oxic conditions (113 +/- 58 g CO2-C kgC(-1) (kgC, kilograms of carbon)) by 2100, but a twice as high production of CO2-Ce (241 +/- 138 g CO2-Ce kgC(-1)) under anoxic conditions. These findings challenge the view of a stronger permafrost carbon-climate feedback from drained soils1,7 and emphasize the importance of CH4 production in thawing permafrost on climate-relevant timescales.