Detecting the Signature of Permafrost Thaw in Arctic Rivers

摘要全球变暖动员了与北极北部永久冻土层相关的大型（高达全球50%）还原有机碳库，并将其转化为具有重要辐射意义的大气（温室）气体，如CO2和CH4，呈现出潜在强度相当大的正变暖反馈。目前，人们对这些储存的有机物质在北极流域和北极海岸系统内微生物转化的速度和程度缺乏了解。尽管标着？old？（14C枯竭）标签的永久冻土碳与当代有机质相比，比较缺乏和？北极下游河流系统的C特征提出了一个难题。此外，永冻层还原碳的快速再矿化与还原（永冻层）碳是顽固性的概念不一致。本研究旨在研究三条亚北极/北极河流（Chena、Porcupine和Sagavanirktok）及其盆地中有机碳、无机碳、溶解碳和颗粒碳的分布、化学和同位素组成、年龄以及木质素/脂质生物标志物。这将能够沿着纬度梯度进行比较，包括零星的、不连续的和连续的永久冻土暴露，以及沿着从春季初新鲜到整个夏秋季节和冻结的时间尺度进行比较。

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.