Testing the Silicic Acid Leakage Hypothesis: A Study of Opal in the Atlantic

检验硅酸泄漏假说：大西洋蛋白石的研究

• 批准号: 1029986
• 负责人: Laura Robinson
• 金额: $ 24.62万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1029986&HistoricalAwards=false
• 关键词: Testing; Silicic; Acid; Leakage; Hypothesis

Intellectual merit: The circulation and supply of nutrients from deep and intermediate waters to the surface ocean plays a key role in controlling global biological productivity. Silicon is an essential nutrient for diatoms: photosynthetic algae that are responsible for nearly half of the export of organic carbon to the seafloor. Reconstructing past changes in the distribution of dissolved silicon in the oceans is therefore needed for testing hypotheses that link biological drawdown of carbon and climate change.The skeletons (spicules) of deep-sea sponges are composed of amorphous silica (or opal). We have previously demonstrated that sponge-spicule silicon isotope compositions reflect the concentration of dissolved silicon in which they grew and can, therefore, be used to reconstruct past seawater silicic acidconcentrations. Combined with the isotopic and trace element composition of surface dwelling diatoms, which are largely controlled by surface water productivity, the coupling of surface and deep silicon cycles in the past can be constrained. In this proposal we aim to reconstruct the distribution and biogeochemical cycling of silicon in the Atlantic Ocean during the last ice age and the subsequent the deglaciation. Deglacial warming waspunctuated by periods of rapid climate change accompanied with shifts in ocean biological productivity and physical circulation and atmospheric pCO2. To investigate the role of silicon in the ocean during this dynamic period, we will extract and analyze biogenic opal from existing well-dated sediment cores from the western Atlantic. The isotopic and trace metal composition of these skeletal remains will be used to reconstruct deep, intermediate and surface dissolved silicon concentrations and surface productivity. Our results will be interpreted in conjunction with existing proxy data, and in the framework of box-modeling the silica cycle. The direct output of this proposal will include: 1) record of the silicon isotope composition of sponge spicules in intermediate and deep waters of both the South and North Atlantic basins since the last glacial maximum; 2) silicon isotope compositions and trace metal compositions of diatoms from the North Atlantic; 3) box-models of silicon cycling in the Atlantic, to aid interpretation of the experimental results. The data from this project will form the first comprehensive study of deep-water silicon cycling in the mid-latitudes and the North Atlantic.Broader impacts: An understanding of the link between nutrient supply and the biological drawdown of carbon is important and timely given the public concern with climate change and interest in geoengineering and ocean. We propose to carry out novel research to advance our understanding of the role in biological productivity of one of the major nutrients in seawater, silicon. Although our work will focus on past changes over the last twenty thousand years, it may provide useful insights into the linkages between silicon cycling and related carbon drawdown relevant when considering the impact of future changes in Atlantic Ocean circulation. The project will fund the research of postdoctoral investigator Katharine Hendry, and will be instrumental in the development of her scientific career. Mentoring will be provided to Dr Hendry through personal interaction with WHOI Scientists, and through activities co-coordinated at Departmental and Institutionwide levels. For example, the department has a mentoring committee that meets biannually to provide formal and informal feedback to their postdoctoral researchers. Both PIs foresee participation in many outreach activities, including media calls, interviews, inclusion of undergraduate students anddemonstrations of our research. All data will be archived electronically and made available to the community through WHOI. Education and public outreach activities will continue to be an integral part of all our ongoing studies and we believe that our past records attest to our commitment to continue theseactivities.

智力优点：从深水和中间水到地面海洋的循环和供应在控制全球生物生产力方面起着关键作用。硅是硅藻的必不可少的营养素：光合藻类，其造成了将近一半的有机碳出口到海底的藻类。因此，需要重构海洋中溶解硅在海洋中分布的变化，以测试将碳和气候变化的生物学缩减的假设进行测试。深海海绵的骨骼（SPICULES）由无定形硅（或Opal）组成。我们以前已经证明，海绵硅硅同位素组成反映了它们生长的溶解硅的浓度，因此可以用于重建过去的海水硅酸酸浓度。结合表面住宅硅藻的同位素和痕量元素组成，这些硅在很大程度上由地表水生产率控制，过去可以限制地表水生产率和深层硅周期的耦合。在该提案中，我们旨在重建在最后一个冰河时代和随后的脱胶化期间，硅在大西洋中的分布和生物地球化学循环。冰川变暖是由快速气候变化的时期伴随着海洋生物生产力和物理循环和大气PCO2的变化的。为了研究在这个动态时期内硅在海洋中的作用，我们将从西大洋西部现有的良好日期岩心核心提取和分析生物蛋白石。这些骨骼残留物的同位素和痕量金属组成将用于重建深，中间和表面溶解的硅浓度和表面生产力。我们的结果将与现有的代理数据以及盒子调制二氧化硅周期的框架一起解释。该提案的直接输出将包括：1）自上次冰川最大值以来，南大西洋盆地中间和北大西洋盆地的海绵spicules的硅同位素组成记录； 2）来自北大西洋的硅藻的硅同位素组成和痕量金属成分； 3）大西洋硅循环的盒子模型，以帮助解释实验结果。该项目的数据将构成对中期和北大西洋中深水硅循环的首次全面研究。BRODARE的影响：鉴于对碳的生物供应与碳的生物学缩减之间的联系非常重要，而且鉴于对气候变化和对地球工程和海洋的气候变化和兴趣的关注，这是很重要的。我们建议进行新的研究，以促进我们对硅海水之一的主要营养物质之一生物生产力中的作用的理解。尽管我们的工作将集中在过去的两万年中的过去变化上，但在考虑大西洋循环未来变化的影响时，它可能会提供有关硅自行车与相关碳累积相关的联系的有用见解。该项目将资助博士后研究员Katharine Hendry的研究，并将在她的科学生涯的发展中发挥作用。通过与WHOI科学家的个人互动以及在部门和机构范围内协调的活动，将向Hendry博士提供指导。例如，该部门有一个指导委员会，每两年开会，向其博士后研究人员提供正式和非正式的反馈。 PIS都预见到许多外展活动，包括媒体电话，访谈，包括本科生的介绍以及我们研究的示意。所有数据将以电子方式存档，并通过WHOI提供给社区。教育和公共宣传活动将继续成为我们正在进行的所有研究中不可或缺的一部分，我们相信我们过去的记录证明了我们继续进行这种反应的承诺。