Do interactions between vertically and horizontally transported particles measurably affect particle composition and flux to the sediments? A mechanistic approach.

许多元素从表层海洋向深海的出口是由下沉颗粒的通量调节的；例如，下沉颗粒占通过中层带的有机碳垂直输送的50%-80%。开放海洋中颗粒有机碳(POC)的异养再矿化通常是非常有效的，因为在地表水中产生的POC的90%在真光区或在通过上层水柱时返回到无机形式。然而，在地表水中产生的有机物中，有一小部分幸存到深海或海底。同样，无机材料在输送到海底的过程中，其通量和组成也会发生变化。也许这种修饰最明显的例子是碳酸盐和生物成因二氧化硅在水柱中下沉时的溶解。然而，到达深海和沉积物的颗粒有机和无机物的通量和组成不仅取决于它们在表层水中的来源，而且还取决于垂直运输过程中发生的改变、补充和选择性清除。在一些地区，特别是靠近边缘的地区，横向运输也可能是广泛的。沉降物与悬浮颗粒或溶解有机质之间通过聚集/解聚和溶解/溶解进行的交换也会影响组成。在这个项目中，纽约州立大学石溪分校的一个研究小组着手从机制上更好地理解海洋？S在全球碳循环中的作用以及影响沉积记录的因素。他们的工作围绕五个相互关联的假设展开，这些假设围绕以下主题展开：颗粒下沉到海底时的再矿化和交换，对下沉颗粒的潜在水平影响，以及垂直和水平运输如何潜在地影响沉积物记录的解释。他们将应用最近MedFlux计划期间开发的一些工具，通过纳入对压载矿物(包括天青石和重晶石)的明确考虑，产生更好的下沉通量定量模型，并更好地定义颗粒下沉时的相互作用。他们还将比较捕集器和水泵采集的颗粒物的无机、有机和放射化学分析结果，与我们建议的百慕大海隆海底沉积物的结果进行比较。虽然这是一项现代过程研究，但预计将具有重大的古海洋学意义。量化关键古海洋学指标的相对垂直和水平通量，结合季节通量的特征，将极大地增强我们对百慕大隆起现有沉积物记录的了解，并提高未来重建的质量，以及从其他具有重要横向输入的站点获得更可靠的解释。更广泛的影响。以PIs(有机地球化学、放射化学、古海洋学、建模)为代表的背景的多样性为培训下一代海洋科学家提供了独特的机会。四名研究生将参与这个项目。所有人都将在海上、实验室和现代数据分析方面接受培训。除了研究生，一名博士后学者将参与本项目，而国家科学基金会不承担额外费用。专业人员还参加外展活动，包括向非专业人士和其他社区团体介绍研究成果。

The export of many elements from the surface ocean to the deep sea is mediated by the flux of sinking particles; for example, sinking particles account for 50-80% of the vertical transport of organic carbon through the mesopelagic zone. Heterotrophic remineralization of particulate organic carbon (POC) in the open ocean is usually very efficient, as 90% of the POC produced in surface waters is returned to inorganic form in the euphotic zone or during transit through the upper water column. However, a small fraction of the organic matter produced in surface waters survives transit to the deep ocean or seafloor. Similarly, the flux and composition of inorganic material also vary during transport to the sea floor. Perhaps the most obvious example of such modification is the dissolution of carbonate and biogenic silica as they sink through the water column. However, the flux and composition of particulate organic and inorganic matter that reaches the deep sea and sediments depend not just on their source in the surface waters, but also on alteration, supplementation, and selective removal that occurs during vertical transit. In some regions, particularly near margins, lateral transport can also be extensive. Exchange between sinking material and suspended particles or dissolved organic matter via aggregation/disaggregation and solution/dissolution can also influence composition. In this project, a research team at the State University of New York at Stony Brook set out to develop a better mechanistic understanding of the ocean?s role in the global carbon cycle and the factors that influence the sedimentary record. Their work is developed around five interrelated hypotheses revolving around the themes of remineralization and exchange as particles sink to the sea floor, potential horizontal influences on sinking particles, and how vertical and horizontal transport potentially influence the interpretation of the sediment record. They will apply some of the tools developed during the recent MedFlux program to produce better quantitative models of sinking fluxes by incorporating explicit consideration of ballast minerals (including celestite and barite) and to define better the interactions among particles as they sink. They will also compare results of inorganic, organic and radiochemical analyses of particles sampled by traps and pumps with those of bottom sediments at our proposed site on the Bermuda Rise. While this is a modern process study, it is expected to have significant paleoceanographic implications. Quantifying the relative vertical and horizontal fluxes of key paleoceanographic proxies in combination with characterization of the seasonal fluxes will greatly enhance our understanding of the existing sediment record at the Bermuda Rise, and improve the quality of future reconstructions as well as lead to more robust interpretations from other sites with significant lateral input. Broader Impacts. The diversity of backgrounds represented by the PIs (organic geochemistry, radiochemistry, palaeoceanography, modeling) offers unique opportunities to train the next generation of marine scientists. Four graduate students will be involved in this project. All will receive training at sea, in the laboratory, and in modern data analysis. In addition to graduate students, a postdoctoral scholar will be involved in the present project at no additional cost to NSF. The PIs also participate in outreach activities that will include presentations of research results to lay persons and other community groups.