Exploring the composition of macromolecular organic matter in Arctic Ocean sediments under a changing sea ice gradient
Exploring the composition of macromolecular organic matter in Arctic Ocean sediments under a changing sea ice gradient
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DOI：
10.1016/j.jaap.2019.02.006
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发表时间：
2019-06
影响因子：
6
通讯作者：
M. Stevenson;G. Abbott
中科院分区：
文献类型：
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作者：
M. Stevenson;G. Abbott
北极海冰受到气候变化的影响，导致过去几十年夏季海冰范围缩小，影响营养动态、海洋温度通量和海洋中的生物群落。海洋有机物是不同来源和不同时期的不同降解的陆地和海洋生物的复杂混合物。在这项研究中，热解-气相色谱-质谱（Py-GC-MS）被用来量化表面沉积物中海洋有机物的溶剂不溶性成分，以便更全面地了解斯瓦尔巴群岛东部北极巴伦支海（深度288-334m.b.s.l）沿南向北横断面的五个站点的大分子组成。比较两种方法以确定快速筛选的有效性，与对类似热解产品进行分组相比。使用这两种方法，整个南北横断面的海洋表面沉积物的大分子组成发生了变化，突出显示了极锋以北和变化的海冰边缘的不同底栖和中上层群落，对应于不同的生物群落（例如鱼类、浮游植物、冰藻、浮游动物）。变化的海冰样带上的所有五个站都被解释为主要具有海洋表面沉积物大分子特征，因为它们的位置远离主要陆地输入，并且与之前对东西伯利亚北极架的调查相比发生了更微妙的变化。横断面大分子组成的波动包括含氮化合物（包括吡啶）的增加以及来自平均冰盖最大的站点收集的沉积物的正烯烃/正烷烃双峰热解产物。如果极锋的未来位置向北移动，那么似乎得到有效处理的不稳定有机物的沉积将进一步向北移动，这意味着公海区域下有机碳的沉积量会更大。未来的研究需要了解这个有机碳将如何被掩埋，以及考虑到预期的分层减弱和巴伦支海北部受大西洋影响更大，它是否具有区域意义。
Arctic sea ice has been affected by climate change, leading to reductions in summer sea ice extent over the past few decades, impacting nutrient dynamics, ocean temperature fluxes and the biological communities present in the ocean. Marine organic matter is a complex mixture of differentially degraded terrestrial and marine organisms from a range of sources and time periods. In this study pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) has been used to quantify the solvent-insoluble component of marine organic matter in surface sediments to gain a more holistic understanding of the macromolecular composition at five stations along a south to north transect in the Arctic Barents Sea, east of Svalbard (depths 288–334 m.b.s.l). Two methods were compared to identify the effectiveness of rapid screening, in contrast to grouping similar pyrolysis products. There were changes in macromolecular composition of marine surface sediments across the S-N transect using both methods, highlighting the varying benthic and pelagic communities north of the Polar Front and across the variable sea ice margin, corresponding to differing biological communities (e.g. fish, phytoplankton, ice algae, zooplankton). All five stations across the changing sea ice transect were interpreted as having primarily marine surface sediment macromolecular signatures, given their locations far from major terrestrial inputs and the more subtle changes when compared with previous investigations on the East Siberian Artic shelf. Fluctuations in macromolecular compositions across the transect included increasing N-containing compounds (including pyridines) andn-alkene/n-alkane doublet pyrolysis products from sediments collected in stations with the greatest average ice cover. If the future position of the Polar Front moves northwards then deposition of labile organic matter which appears to be efficiently processed will move further north, meaning greater deposition of organic carbon under areas of open ocean. Future research needs to understand how this OC will be buried and if it is regionally significant, given anticipated weakening stratification and a more Atlantic influenced northern Barents Sea.