Collaborative Proposal: Mineral Ballast and Organic Matter Compositions as Determinants of Particle Settling Velocities and Fluxes in the Sea (MedFlux)

在这项资助的支持下，来自纽约州立大学石溪分校、斯基德威海洋研究所和华盛顿大学的MedFlux研究小组成员将完成他们对从海洋光带落下的生物颗粒命运的开创性研究的数据分析和信息合成。MedFlux项目于四年前在美国国家科学基金会的支持下启动，其中心重点是对“压载物假说”进行更好的机制理解，该假说认为，进入深海和沉积物的颗粒有机碳（POC）通量与生物（蛋白石或碳酸盐矿物）产生的“压载物矿物”的通量成正比（重量为3-7%），或通过物理过程引入表层海洋。早期的工作（Armstrong et al. 2002; Klaas & Archer 2002）表明，通过压载通量可以很好地预测深度有机碳通量（85-90%的解释方差）；因此，引入海洋表层的矿物压载物的类型和数量可能是海洋吸收和储存碳的能力的关键决定因素和预测因素。为了推进这些研究，研究小组还开发了专门的采样设备和方案，用于测量通量的两个基本组成部分：颗粒浓度C(z)和z深度的平均下沉速度w (z)。在此资助下，研究小组将能够充分评估项目的科学成果以及新的颗粒采样技术的性能。该研究对全球碳循环和环境变化问题具有广泛的影响。例如，由于海洋中人为二氧化碳的持续溶解，pH值降低，碳酸盐矿物可能优先溶解，从而影响海洋中POC的压舱和平均再矿化深度。这种情况需要对海洋中POC压舱有一个基于机理的理解。此外，MedFlux的工作将继续促进三所美国大学与摩纳哥、法国、西班牙和德国的同事之间的国际合作。该项目还为研究生提供支持和培训。

ABSTRACTOCE-0622754 / OCE-0622930 / OCE-0623271With support from this grant, the members of the MedFlux research team at SUNY-Stony Brook, Skidaway Institute of Oceanography, and University of Washington will complete data analysis and informational synthesis their pioneering study of the fate of biogenic particles falling from the oceanic euphotic zone. The central focus of the MedFlux, which began with NSF support four years ago, is to develop a better mechanistic understanding of the "ballast hypothesis," which states that Particulate Organic Carbon (POC) fluxes to the deep ocean and sediments are directly proportional (3-7% OC by weight) to fluxes of "ballast minerals" produced by organisms (opal or carbonate minerals) or introduced into the surface ocean by physical processes. Earlier work (Armstrong et al. 2002; Klaas & Archer 2002) showed that the flux of organic carbon at depth can be predicted extremely well (85-90% explained variance) by ballast flux; the types and amounts of mineral ballast introduced to the surface ocean may therefore be critical determinants and predictors of the ocean's ability to take up and store carbon. To advance these studies, the research team also developed specialized sampling devices and protocols for measuring the two fundamental components of flux: particle concentration C(z) and average sinking velocity w ( z) at depth z. With funding under this grant, the team will be able to evaluate fully both the scientific output of the project as well as the performance of the new particulate sampling technology.This research has a number of broader impacts for for global carbon cycle and environmental change issues. For example, as pH decreases in response to the continued dissolution of anthropogenic carbon dioxide in the ocean, carbonate minerals may dissolve preferentially, affecting both ballasting and the average remineralization depth of POC in the ocean. This situation would necessitate a mechanism-based understanding of POC ballasting in the ocean. Additionally, MedFlux work will continue to foster international collaborations among three U.S. universities and colleagues in Monaco, France, Spain, and Geermany. The project also provides for the support and training of graduate students.