Chromophoric DOM - A Photoactive Tracer of Biogeochemical Process.

有色溶解有机质(CDOM)是溶解有机质(DOM)池中的有色组分，在我们对公海生物地球化学的解释中起着重要的作用和影响。CDOM对光的吸收驱动光化学反应，影响许多具有辐射重要性的痕量气体(CO2、DMS、COS、CO等)。此外，CDOM对光的吸收常常模糊了我们从卫星海洋彩色图像诊断生物地球化学过程的能力。CDOM是一种光学特性；因此，它的浓度可以使用卫星传感器或从一系列自主平台上的现场同步量化到大的空间尺度上。尽管陆地-海洋交换是众所周知的海洋CDOM的来源，但最近的观测表明，开阔海洋的CDOM是通过原位生物地球化学过程产生的。加州大学圣巴巴拉分校的研究人员将利用这一NSF奖项的资金，继续他们在CDOM生物地球化学方面的研究，朝着第一次系统的海洋CDOM全球调查迈出下一步。他们将结合CLIVAR-REPEAT水文记录计划的数据，利用这些观测数据来描述公海中的CDOM。他们的具体目标是：(1)继续对太平洋、南大洋和印度洋CLIVAR重复水文航次上的CDOM和DOM质量指数进行全球调查；(2)利用荧光激发/发射矩阵和多光谱分析来表征CDOM的质量(使用新收集和存档的样本)；(3)通过高效液相色谱对可水解氨基酸池中的个别氨基酸进行量化，评估全球CDOM储量与DOM成岩状态之间的联系；(4)通过数据分析和数值模拟，发展和测试对公海CDOM循环的预测性理解。通过我们对CDOM储量的持续调查、化学和光谱表征以及分析和建模，研究小组希望对其来源、汇和在全球海洋中的分布有一个新的理解。CDOM的特征也应该打开一个新的维度，用来评估DOM在全球海洋中循环时的化学性质和稳定性的变化。这一项目预计将在学术海洋科学界内外产生一些更广泛的影响。这项研究将促进未来结合光学观测数据的全球海洋化学研究。特别是，收集的数据应有助于设计和实施未来的现场仪器和卫星飞行任务。所有数据将通过CLIVAR-REPEAT水文方案网站和NASA海洋光学数据库免费提供给感兴趣的各方。项目调查员是积极的课堂讲师，他们将把这项工作的结果纳入到本科生和研究生的课程中。这项研究还将支持UCSB的两名研究生完成学位论文。它还将帮助支持在实验室协助的本科生，以及将参加UCSB本科生研究会议的学生。

Chromophoric dissolved organic matter (CDOM), the colored fraction of the dissolved organic matter (DOM) pool, plays an important role in and affects our interpretation of the biogeochemistry of the open sea. Light absorption by CDOM drives photochemical reactions affecting many radiatively important trace gases (CO2, DMS, COS, CO, etc.). Further, light absorption by CDOM often obscures our ability to diagnose biogeochemical processes from satellite ocean color imagery. CDOM is an optical property; hence, its concentration can be quantified synoptically over large spatial scales using satellite sensors or in situ from a host of autonomous platforms. Although land-ocean exchanges are well known sources of ocean CDOM, recent observations have shown that open ocean CDOM is created through in situ biogeochemical processes. With funding through this NSF award, researchers at the University of California -- Santa Barbara will continue their research in CDOM biogeochemistry by making the next step towards the first systematic global survey of oceanic CDOM. They will use these observations in conjunction with data from the CLIVAR-Repeat Hydrography program to characterize CDOM in the open ocean. Their specific goals are to: (1) continue a global surveying of CDOM and DOM quality indices on CLIVAR-Repeat Hydrography cruises in the Pacific, Southern and Indian Oceans; (2) use spectrofluorometric excitation / emission matrix and multispectral analyses to characterize CDOM quality (using newly collected and archived samples); (3) assess the connections among global CDOM stocks and diagenetic state of DOM by HPLC quantification of the individual amino acids within the hydrolysable amino acid pool; and (4) develop and test predictive understanding of the open ocean CDOM cycle through data analyses and numerical modeling. Through our continued coupled investigation of CDOM stocks, chemical and spectral characterization, and analysis and modeling the research team expects to synthesize a new understanding of its sources, sinks and distributions within the global oceans. CDOM characterization should also open a new dimension with which to assess the changes in chemical nature and lability of DOM as it cycles through the global ocean.This project is expected to have a number of broader impacts within and beyond the world of academic ocean science. The study will facilitate future study of global marine chemistry that incorporates optical observables. In particular, the data collected should be useful in the design and implementation of future in situ instrumentation and satellite missions. All data will be freely available to interested parties via the CLIVAR-Repeat Hydrography Program website as well as the NASA SeaBASS ocean optics database. The project investigators are active classroom instructors who will incorporate results of this work in their course offerings at both the undergraduate and graduate levels. This research will also support the completion of the dissertations of two graduate students at UCSB. It will also help to support undergraduate students who are assisting in the laboratory and who will participate in undergraduate research conferences at UCSB.