Department of Physical Geography and Ecosystem Science, Lund University, Sweden.
Département de sciences biologiques, Université de Montréal, Canada.
Sci Rep. 2017 Apr 5;7:45811. doi: 10.1038/srep45811.
Global warming can substantially affect the export of dissolved organic carbon (DOC) from peat-permafrost to aquatic systems. The direct degradability of such peat-derived DOC, however, is poorly constrained because previous permafrost thaw studies have mainly addressed mineral soil catchments or DOC pools that have already been processed in surface waters. We incubated peat cores from a palsa mire to compare an active layer and an experimentally thawed permafrost layer with regard to DOC composition and degradation potentials of pore water DOC. Our results show that DOC from the thawed permafrost layer had high initial degradation potentials compared with DOC from the active layer. In fact, the DOC that showed the highest bio- and photo-degradability, respectively, originated in the thawed permafrost layer. Our study sheds new light on the DOC composition of peat-permafrost directly upon thaw and suggests that past estimates of carbon-dioxide emissions from thawed peat permafrost may be biased as they have overlooked the initial mineralization potential of the exported DOC.
全球变暖会极大地影响泥炭-永冻层向水生系统输出溶解有机碳 (DOC)。然而，由于先前的永冻土融化研究主要针对已经在地表水中经过处理的矿物质土壤汇或 DOC 池，因此这种泥炭衍生的 DOC 的直接可降解性受到很大限制。我们对来自冰楔泥炭沼泽的泥炭芯进行了培养，以比较活动层和实验性融化的永冻层在孔隙水中 DOC 的组成和降解潜力方面的差异。我们的研究结果表明，与活动层的 DOC 相比，融化的永冻层的 DOC 具有较高的初始降解潜力。事实上，分别具有最高生物和光降解能力的 DOC 均源自融化的永冻层。我们的研究揭示了永冻土融化后直接产生的 DOC 组成，并表明过去对融化泥炭永冻土排放二氧化碳的估计可能存在偏差，因为它们忽略了已输出 DOC 的初始矿化潜力。
