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

oce -0136370 / OCE-0136387 / oce -0136318下沉颗粒物是从海面向海洋内部输出碳的主要载体。在向海底迁移的过程中，大多数颗粒有机碳（POC）返回到无机形式并重新分布在水柱中。这种再分配决定了溶解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率。因此，定量预测再矿化深度剖面的能力对于预测全球碳循环对环境变化的响应至关重要。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威海洋学研究所的研究人员将与摩纳哥和法国的同事合作，验证一个假设，即生物体产生的矿物质，或被风引入海洋表层的矿物质，对向深海和沉积物的碳输出有重要影响。他们将采用多示踪剂方法，明确考虑不同的矿物“压载物”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，压舱物矿物在物理上保护了与其相关的总有机物质的一部分，这些有机物质在水柱较低（1000米）部分的未受保护的部分中仍然占主导地位。要理解这些过程的机理基础，就需要在特定化合物的水平上理解有机-矿物的相互作用。其次，他们假设有机碳与压载物的比例是预测有机碳出口通量和下沉速度变异性的关键，正如使用放射性示踪剂估计的那样。总体目标是对整个水柱的碳通量和相关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系列被认为是通量指标的特性。他们将利用各种建模和统计技术综合从水柱顶部到沉积物的测量结果。该战略是要联合几个学科的力量：(i)有机地球化学，以确定受保护和不受保护形式的有机物的特征，并确定其退化状况；（ii）用于评估粒子动力学和输运过程和时间尺度的放射化学；（iii）用于评估放射性同位素分配和有机生物标志物变化的浮游动物生态学；（iv）微生物学在有机物分解中的作用，(v)建模和统计分析，以提供从光带到海底的通量的基于过程的模型。

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.