Chromophoric DOM: An Ignored Photoactive Tracer of Geochemical Process

有色溶解有机物质(CDOM)是溶解有机物质(DOM)池中的有色部分，是一种在整个开阔海洋中发现的高度动态的性质。CDOM是一种光学特性；因此，可以使用星载传感器或从一系列自主平台上就地定量地在大空间尺度上对其浓度进行量化。最近的工作表明，CDOM的净产生与异养细菌的循环过程有关，而其损失是由于光漂白。因此，CDOM的垂直分布，特别是其表面特征，受到垂直混合过程如何重新分布CDOM循环的基本过程的调节。这表明CDOM可能是一种很好的上层海洋交换示踪剂。在这项研究中，加州大学圣巴巴拉分校的研究人员将对CDOM循环进行过程级描述，以测试其作为地球化学示踪剂的效用。具体地说，研究小组将：(1)阐明在CO2/CLIVAR重复水文调查的几个子午面上一系列大洋区域的CDOM分布；(2)量化CDOM的产生和销毁过程并将其参数化，目的是在数学上限制CDOM的循环；(3)通过与重复水文调查中的重合示踪剂分布进行比较，评估CDOM作为上层海洋年龄示踪剂的用途；以及(4)开发CDOM动力学的一维模型，用于广泛的大洋区域，目的是诊断混合层-温跃层交换。拟议的项目具有超出海洋科学学术界的广泛影响。该项目的三名主要调查人员都是积极的指导者，这项拟议工作的结果(以及所获得的经验)将用于他们在本科生和研究生两级提供的课程。这项研究将支持UCSB一名研究生的论文。所有数据将通过UCSB的网站和CO2/CLIVAR重复水文测量计划免费提供给所有感兴趣的各方。最后，如果他们的科学假设被证明是正确的，这项研究可能导致从卫星轨道远程估计混合层和下面的水之间的水团交换。对这些交换的预见性理解对于理解排放到大气中的人为化合物的海洋命运至关重要。

ABSTRACTOCE-0241614Chromophoric dissolved organic material (CDOM), the colored fraction of the dissolved organic material (DOM) pool, is a highly dynamic property found throughout the open ocean. CDOM is an optical property; hence, its concentration can be quantified synoptically over large spatial scales using satellite-borne sensors or in situ from a host of autonomous platforms. Recent work demonstrates that net CDOM production is related to heterotrophic bacterial cycling processes while its losses are due to photobleaching. Vertical distributions of CDOM and in particular its surface signature are therefore regulated by how vertical mixing processes redistribute the basic processes of CDOM cycling. This suggests that CDOM may be an excellent tracer of upper ocean exchanges. In this study, researchers at the University of California - Santa Barbara will apply a process-level description of CDOM cycling to test its utility as a geochemical tracer. Specifically the research team will: (1) elucidate CDOM distributions over a range of oceanic regimes on several meridional sections of the CO2/CLIVAR Repeat Hydrography survey; (2) quantify and parameterize CDOM production & destruction processes with the goal of mathematically constraining the cycling of CDOM; (3) evaluate the utility of CDOM as an upper ocean age tracer by comparing with coincident tracer distributions from the Repeat Hydrography survey; and (4) develop a one-dimensional model of CDOM dynamics for use across a wide range of oceanic regimes with the goal of diagnosing mixed layer - thermocline exchanges.The proposed project has broad impacts beyond the world of academic ocean science. The three principal investigators on the project are active instructors, and results of this proposed work (and experiences gained) will be used in their course offerings at both the undergraduate and graduate levels. This research will support a dissertation of a graduate student at UCSB. All data will be freely available to all interested parties via a website at UCSB and the CO2/CLIVAR Repeat Hydrography Program. Finally, tf their scientific hypotheses prove correct, this research could lead to the remote estimation of water mass exchanges between the mixed layer and underlying waters from satellite orbit. A predictive understanding of these exchanges is critical for understanding the oceanic fate of anthropogenic compounds discharged to the atmosphere.