Detecting the Signature of Permafrost Thaw in Arctic Rivers

摘要全球变暖动员了北极北部永久冻土区大量(高达全球50%)的还原有机碳储藏库，并将其转化为具有辐射重要性的大气(温室)气体，如CO2和CH4，提供了潜在相当大的正向变暖反馈。目前，人们对这些储存的有机物质在北极流域和北极沿海系统内微生物转化的速度和程度缺乏了解。尽管与当代有机质相比，永久冻土层的碳有标记的老的(14C耗尽)的标签，但相对缺乏一个老的？C在北极河下游水系中的签名是一个难题。此外，多年冻土还原碳的快速再矿化与(永久冻土层)还原碳是顽固的概念不一致。本研究旨在研究三条亚北极/北极河流(切纳河、波丘派恩河和萨加瓦尼尔克托克河)及其盆地中碳物种的分配、化学和同位素组成、年龄，包括有机碳、无机碳/溶解碳和颗粒碳，以及木质素/脂肪生物标志物。这将使得能够沿着纬度梯度进行比较，包括零星、不连续和连续的永久冻土暴露，以及从最初的春季淡水到整个夏季和秋季以及冰冻的时间尺度。

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.