Detecting the Signature of Permafrost Thaw in Arctic Rivers

北极北方永久冻土区的大量（占全球的50%）还原有机碳库的全球变暖动员，以及向具有重要辐射意义的大气（温室）气体（如CO2和CH 4）的转化，呈现出潜在的相当大的强度的正变暖反馈。目前，人们还不了解这种储存的有机物质在北极流域和北极沿海系统内微生物转化的速度和程度。尽管有标记？老了？(14C耗尽）永久冻土碳的标签相比，当代有机质，比较缺乏一个？年龄？下游北极河流系统中的C信号提出了一个难题。此外，冻土还原碳的快速矿化是不一致的概念，还原（冻土）碳是crystalcitrant.This研究的目的是检查的分区，化学和同位素组成，和碳物种的年龄，包括有机和无机/溶解和颗粒碳，以及木质素/脂质生物标志物在三个亚北极/北极河流（Chena，豪猪，和Sagavanirktok）及其流域。这将使比较沿着纬度梯度覆盖零星的，不连续的和连续的永久冻土暴露，以及沿着时间尺度从最初的春季淡水到完整的夏季和秋季季节和冻结。

AbstractGlobal warming mobilization of the large (up to 50% of global) reservoirs of reduced organic carbon associated with northern permafrost regions of the Arctic, and conversion to radiatively important atmospheric (greenhouse) gases such as CO2 and CH4 presents a positive warming feed back of potentially considerable strength. Currently there is a lack of understanding of how fast and to what extent this stored organic matter is microbially transformed within Arctic watersheds and Arctic coastal systems. Despite the marked ?old? (14C depleted) label of permafrost carbon compared to contemporary organic matter, the comparitive lack of an ?aged? C signature in the downstream Arctic river systems presents something of a conundrum. Further, the rapid remineralization of permafrost reduced carbon is not consistent with the notion that reduced (permafrost) carbon is recalcitrant.This research aims to examine the partition, chemical and isotopic compositions, and ages of carbon species, including organic and inorganic/dissolved and particulate carbon, as well as lignin/lipid biomarkers in three subarctic/arctic rivers (Chena, Porcupine, and Sagavanirktok) and their basins. This will enable a comparison along a latitudinal gradient covering sporadic, discontinuous and continuous permafrost exposures, as well as along temporal scales from initial spring freshet to full summer and fall season and freeze-up.