Collaborative Research: A Quantitative Assessment of Mineral Ballasts in Carbon Export and Remineralization

沉降性颗粒物是将碳从海面输送到海洋内部的主要载体。在向海底转移的过程中，大多数颗粒有机碳(POC)以无机形式返回并重新分布在水柱中。这种再分配决定了溶解的二氧化碳的表面浓度，从而决定了海洋从大气中吸收二氧化碳的速度。因此，定量预测再矿化深度分布的能力对于预测全球碳循环对环境变化的反应至关重要。在这项研究中，纽约州立大学石溪分校、华盛顿大学和斯基德韦海洋研究所的研究人员将与摩纳哥和法国的同事合作，测试生物产生的矿物或通过风进入表层海洋的矿物对深海和沉积物的碳出口产生关键影响的假设。他们将采用多种示踪方法，明确考虑不同的矿物“压舱物”类型，以及相关的有机物和放射性同位素。他们的第一个假设是，压载矿物在物理上保护了与其相关的总有机物质的一小部分，在水柱较低的部分(1000米)，有机物质继续占据主导地位，而不是没有保护的部分。要了解这类过程的机理基础，就需要了解特定化合物层面上的有机-矿物相互作用。他们的第二个假设是，有机碳与压舱物的比率是预测使用放射性示踪剂估计的有机碳出口通量和下沉速度变化的关键。总体目标是对整个水柱中的碳通量和相关的矿物压载通量进行无缝描述。为了实现这一目标，研究小组将同时测量一组被认为指示通量的属性。他们将使用各种建模和统计技术综合从水柱顶部到沉积物的这些测量结果。该战略将联合几个学科的力量：(1)有机地球化学，用于确定受保护和未受保护形式的有机质的特征并确定其退化状态；(2)放射化学，用于评估颗粒动力学和迁移所涉及的过程和时间尺度；(3)浮游动物生态学，用于评估放射性同位素分配和有机生物标志物的变化；(4)微生物学，其在有机物分解中的作用；(5)模拟和统计分析，以提供从真光带向海底迁移的基于过程的模型。

ABSTRACTOCE-0136370 / OCE-0136387 / OCE-0136318Sinking particulate matter is the major vehicle for exporting carbon from the sea surface to the ocean interior. During its transit towards the sea floor, most particulate organic carbon (POC) is returned to inorganic form and redistributed in the water column. This redistribution determines the surface concentration of dissolved CO2 , and hence the rate at which the ocean can absorb CO2 from the atmosphere. The ability to predict quantitatively the depth profile of remineralization is therefore critical to predicting the response of the global carbon cycle to environmental change. In this study, researchers at the State University of New York at Stony Brook, the University of Washington, and the Skidaway Institute of Oceanography will collaborate with colleagues in Monaco and France to test the hypothesis that minerals produced by organisms, or introduced into the surface ocean by winds, critically influence carbon export to the deep ocean and sediments. They will carry out a multi-tracer approach to explicitly consider different mineral "ballast" types, along with the associated organic matter and radioisotopes. Their first hypothesis is that ballast minerals physically protect a fraction of their associated total organic matter, which persists to predominate over the unprotected fraction in the lower (1000 m) part of the water column. Understanding the mechanistic basis of such processes will require an understanding of organic-mineral interaction at the compound-specific level. They hypothesize secondly that the ratio of organic carbon to ballast is key to predicting variability in the export fluxes and sinking velocities of organic carbon as estimated using radiotracers. The overall goal is to develop a seamless description of carbon fluxes and associated mineral ballast fluxes throughout the water column. To achieve this goal, the research team will measure simultaneously a suite of properties that are thought to be indicative of fluxes. They will synthesize these measurements from the top of the water column to the sediments using a variety of modeling and statistical techniques. The strategy is to unite the power of several disciplines: (i) organic geochemistry for characterizing organic matter in protected and unprotected forms and determining its degradation state; (ii) radiochemistry for assessing processes and time-scales involved in particle dynamics and transport; (iii) zooplankton ecology for assessing radioisotope partitioning and organic biomarker alteration; and (iv) microbiology for its role in organic matter decomposition, and (v) modeling and statistical analyses to provide a process-based model of flux out of the euphotic zone to the sea floor.