Post-glacial variability of sea ice cover, river run-off and biological production in the western Laptev Sea (Arctic Ocean) - A high-resolution biomarker study
Post-glacial variability of sea ice cover, river run-off and biological production in the western Laptev Sea (Arctic Ocean) - A high-resolution biomarker study
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DOI：
10.1016/j.quascirev.2016.04.011
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发表时间：
2016-07-01
影响因子：
4
通讯作者：
Birgel, D.
中科院分区：
文献类型：
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作者：
Hoerner, T.;Stein, R.;Birgel, D.
对两个沉积物岩心（PS51/154、PS51/159）应用多代理生物标志物测量，以前所未有的时间分辨率重建拉普捷夫海西部近 17ka 的海冰覆盖（IP25）、生物生产（菜籽甾醇、地甾醇）和河流径流（菜油甾醇、β-谷甾醇）。 17.2 至 15.5 ka 期间不存在 IP25，再加上浮游植物生物标志物浓度最低，表明拉普捷夫海陆架西部大部分被永久海冰覆盖。在此寒冷时期，河流径流非常少，生物生产也受到限制。从大约16ka到7.5ka，陆源（河流）有机质的长期减少和海洋有机质的同期增加反映了由于冰后海侵的开始，拉普捷夫海西部逐渐建立了完全海洋条件。 15.2 至 12.9 ka 之间的时间间隔为河流径流增强和海冰覆盖减少，其中包括 Bolling/Allerod 暖期（14.7-12.9 ka）。 DIP25 指数的突出峰值与副极地有孔虫的最大丰度一致，被解释为拉普捷夫海陆架西部大西洋水流入的脉冲。温暖期过后，11.9 至 11 ka 期间突然恢复严重海冰条件，冰覆盖最强，恰逢新仙女木期（12.9-11.6 ka）。新仙女木期开始时，发现了生态系统的明显变化（反映在陆源和浮游植物生物标志物的明显下降）。在过去 7 ka 中，海冰代理反映了拉普捷夫海春/夏季的变冷。这种冷却趋势叠加了海冰覆盖范围的短期变化，可能代表与太阳活动变化相关的邦德周期（1500+/-500ka）。因此，在现代海平面条件下，大气环流的变化显然能够影响拉普捷夫海陆架的海冰状况。 (C) 2016 Elsevier Ltd. 保留所有权利。
Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), biological production (brassicasterol, dinosterol) and river run-off (campesterol, beta-sitosterol) in the western Laptev Sea over the last similar to 17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted biological production occurred during this cold interval. From similar to 16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bolling/Allerod warm period (14.7-12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9-11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 +/- 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level conditions. (C) 2016 Elsevier Ltd. All rights reserved.