Change at the margin of the North Water Polynya, Baffin Bay, inferred from organic matter records in dated sediment cores
Change at the margin of the North Water Polynya, Baffin Bay, inferred from organic matter records in dated sediment cores
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DOI：
10.1016/j.margeo.2013.04.017
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发表时间：
2013-07-01
期刊：
影响因子：
2.9
通讯作者：
Stern, Gary A.
中科院分区：
文献类型：
--
作者：
Bailey, Joscelyn N. -L.;Macdonald, Robie W.;Stern, Gary A.
北水Polynya（NOW）是北极最具生产力的海洋环境之一。由于北极海冰覆盖是海洋有机物（OM）生产的主要控制因素，冰穴很可能是最近冰气候变化影响的哨兵。我们从NOW收集了六个沉积物岩心，尽可能使用与Cs-137相证实的Pb-210对它们进行测年，并分析了OM干酪根（Rock-Eval 6分析）、总有机碳（TOC）、总有机氮（TON）、δ C-13和δ N-15的岩心剖面。近150年来沉积物有机质总浓度（TOC和TON）随水深呈指数下降，反映了水体矿化过程。使用一个模型来解释沉积速率和沉积物表面混合，我们发现，从内部的NOW的核心没有显着的变化之间的前1900年的沉积物和后1900年的沉积物，和核心之间的差异很小。与此相反，从该地区的西北边界的核心海洋有机碳输入增加的证据，从东南边界的两个核心显示减少陆源碳输入的证据。此外，在东南边界的核心，在格陵兰岛的斜坡上，目睹了在同一时间间隔的沉积速率显着下降。我们解释OM的变化在边界核心的区域冰气候和径流的变化的背景下。我们的研究结果表明，这个冰间湖的边缘比内部更容易受到变化的影响，因此是一个更好的位置来寻找变化的证据。此外，NOW内的环境多样性表明，必须在次区域范围内理解变化。皇冠版权所有2013年（C）出版的爱思唯尔B. V.保留所有权利。
The North Water Polynya (NOW) is one of the most productive marine environments in the Arctic. With Arctic sea-ice cover a prominent control in the production of marine organic matter (OM), polynyas are likely to be sentinels of the effects of recent change in ice climate. We collected six sediment cores from the NOW, dated them using Pb-210 corroborated with Cs-137 where possible, and analysed down-core profiles of OM kerogen (Rock-Eval 6 analysis), total organic carbon (TOC), total organic nitrogen (TON), delta C-13 and delta N-15. The down-core records were examined for evidence of recent (past 150 years) change.Sediment OM bulk concentrations (TOC and TON) displayed exponential decreases with water depth reflecting water-column remineralization processes. Using a model to account for sedimentation rate and sediment surface mixing, we found that cores from the interior of the NOW showed no significant change between pre-1900 sediments and post-1900 sediments, and little variance among cores. In contrast, a core from the northwest boundary of the region showed evidence of increased marine organic carbon input, and two cores from the southeast boundary showed evidence of decreased terrigenous carbon input. In addition, the cores at the southeast boundary, on the slope off Greenland, witnessed a significant decline in sedimentation rate during the same time interval. We interpret the change in OM in the boundary cores in the context of change in regional ice climate and runoff. Our results suggest that the margin of this polynya is more vulnerable to change than the interior, and thus is a better location to seek evidence of change. Furthermore, the diversity of settings within NOW indicates that change must be understood at sub-regional scales. Crown Copyright 2013 (C) Published by Elsevier B.V. All rights reserved.