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

在这项奖励下，pi将检验这样一种假设，即在冰川消融期间，海洋的重组推翻了环流，释放了深海中的二氧化碳，从而在很大程度上解释了大气中二氧化碳的消融上升。他们发现，蛋白石埋藏率的峰值出现在冰消期的南大洋周围和赤道东太平洋。他们认为，这与此时深海重新恢复通风以及向地表水提供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更新是由南极洲周围的底部水形成驱动的。他们提出验证从这些发现中得出的两个假设：1：冰川时期深海分层的增加减少了赤道上升流地区溶解硅的供应；和H2：在每次海因里希事件期间，冰川边界条件的深海分层特征被破坏。为了验证这些假设，他们将重建南大洋沉积物中蛋白石的积累速率，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的生物标志物相对丰度的变化。他们预测，末次盛冰期赤道太平洋沉积物中的芥子甾醇（硅藻代物）/烯酮（球石斛代物）浓度比低于全新世。进一步的预测是，与冰川基线条件相比，油菜甾醇/烯酮比率，像蛋白石通量一样，在冰川消退期间和每次海因里希事件期间增加。他们将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明智的预测。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\Core Program\MG&amp；G May 2005\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