Collaborative Research: Changes in Ocean Circulation, Productivity & Carbon Cycling during Heinrich Events

根据这一奖项，PIS将测试这样的假设：在冰川消融期间，海洋的重组颠覆了环流，释放了深海中的二氧化碳，从而解释了大气二氧化碳消融上升的很大一部分原因。他们发现，在消冰期间，蛋白石埋藏率的峰值出现在南大洋周围和赤道东太平洋。他们认为，这与此时深水通风重新活跃以及向地表水供应溶解硅的相应增加是一致的。因为这发生在海因里希事件1期间，当时北大西洋深水地层被认为已经崩溃，他们推断深水通风的恢复是由南极洲周围的底水地层驱动的。他们建议检验从这些发现中得出的两个假设：H1：冰川时期深海分层的增加减少了对赤道上升流地区的溶解硅的供应；以及H2：冰川边界条件在每次海因里希事件期间破裂的深海分层特征。为了验证这些假设，他们将重建南大洋沉积物中的蛋白石累积速率，并评估蛋白石通量以及赤道太平洋沉积物中某些浮游植物分类群生物标志物相对丰度的变化。他们预测，在最后一次冰盛期，赤道太平洋沉积物中的油菜籽甾醇(硅藻替代品)/烯酮(球藻替代品)的浓度比在全新世要低。进一步的预测是，与冰川基线条件相比，油菜籽甾醇/烯酮比率在冰川消融期间和每次海因里希事件期间都会增加，就像蛋白石通量一样。他们将使用常规的古海洋学方法来检验这些预测。他们希望这项工作将导致对未来海洋吸收人为二氧化碳的更有见地的预测。这项工作将支持一名年轻的阿富汗裔美国女性的博士研究。P：\MGG\IPAS\核心计划\MG&amp；G 2005年5月\摘要

Under this award the PIs will test the hypotheses that reorganization of the oceans overturning circulation during deglaciation released CO2 from the deep sea, thereby accounting for a large part of the deglacial rise of atmospheric CO2.They found that peak opal burial rates occurred around the Southern Ocean and in the eastern equatorial Pacific Ocean during deglaciation. They believe that this is consistent with a reinvigorated ventilation of deep waters at this time and a corresponding increase in supply of dissolved Si to surface waters. Because this occurred during Heinrich Event 1, when North Atlantic Deep Water formation is believed to have collapsed, they infer that the renewal of deep water ventilation was driven by bottom water formation around Antarctica. They propose to test two hypotheses derived from these findings: H1: Increased stratification of the deep ocean during glacial times reduced the supply of dissolved Si to equatorial upwelling regions; and H2: Deep ocean stratification characteristic of glacial boundary conditions broke down during each Heinrich Event. In order to test these hypotheses they will reconstruct opal accumulation rates in Southern Ocean sediments, and evaluate opal fluxes together with changes in the relative abundance of biomarkers diagnostic of certain phytoplankton taxa in equatorial Pacific sediments. They predict that brassicasterol (diatom proxy)/alkenone (coccolithophorid proxy) concentration ratios were lower during the Last Glacial Maximum than during the Holocene in equatorial Pacific sediments. A further prediction is that brassicasterol/alkenone ratios, like opal fluxes, increased during deglaciation, and during each Heinrich event, relative to glacial baseline conditions. They will test these predictions using routine paleoceanographic methods. They hope that this work will lead to more informed predictions about the oceans uptake of anthropogenic CO2 in the future. The work will support the PhD research of a young female Afghani-American. P:\MGG\IPAs\Core Program\MG&G May 2005\Abstracts