Collaborative Proposal: Phlorotannins - An Important Source of Marine Chromophoric Dissolved Organic Matter?

合作提案：草单宁 - 海洋发色溶解有机物的重要来源？

• 批准号: 1536888
• 负责人: Michael Gonsior
• 金额: $ 37.05万
• 依托单位: University of Maryland Center for Environmental Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-10-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536888&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Phlorotannins; Important; Source

Collaborative Proposal: Phlorotannins - An Important Source of Marine Chromophoric Dissolved Organic Matter?Michael GonsiorID: 1536888Chromophoric dissolved organic matter (CDOM), the sunlight absorbing components in filtered water, is important in the study of marine and freshwater ecosystems as it can be used to trace the mixing of surface waters, as a proxy for carbon cycles, and other biogeochemical processes. Although its importance in ocean studies has been firmly established over the last several decades, sources and structural composition of CDOM within the oceans remains unclear and continues to be a subject of debate. Sargassum, a brown alga, is widely distributed in temperate and subtropical marine waters and may be important source of CDOM to the Sargasso Sea and Gulf of Mexico where Sargassum is abundant. This project will investigate the contribution of macro brown algae-derived compounds to the marine CDOM pool. Results from this study will have implications for the marine carbon cycle and satellite remote sensing of ocean color to assess mixing of surface water masses and biogeochemical processes. The project will provide educational opportunities for a postdoctoral scholar, summertime undergraduate internships (through a local NSF-sponsored Research Experiences for Undergraduates (REU) program), and workshop and research opportunities for local high schools students. Sources of marine CDOM remain debatable and a comprehensive understanding of its origins, distribution and fate have been difficult. Marine CDOM, and in particular the "humic-like" component, have been suggested to originate from terrestrial sources, primarily lignins. However, recent evidence indicates that the exudation of phlorotannins produced by macro brown algae may contribute significantly to the marine CDOM pool. Phlorotannins, a class of polyphenols that are only found in, and continuously exuded by macro brown algae such as Sargassum, strongly absorb ultraviolet light and may have been underestimated in their contribution to the marine CDOM pool within certain geographic locales. Upon partial oxidation, light absorption by these specific compounds extends into longer wavelengths in the visible creating an absorption spectrum similar to that of lignin. These phlorotannins and their transformation products absorb light that might explain in part the "humic-like" signatures observed in open ocean environments. This study aims to characterize the optical properties and molecular composition of Sargassum-derived CDOM including its aerobic oxidation and photochemical behavior, as well as quantify Sargassum-derived CDOM to better estimate its possible contribution to the CDOM pool in the Sargasso Sea and Gulf of Mexico.

合作提案：根皮单宁-海洋有色溶解有机物的重要来源？Michael GonsiorID：1536888有色溶解有机物（CDOM）是过滤水中吸收阳光的成分，在海洋和淡水生态系统的研究中非常重要，因为它可用于追踪表层沃茨的混合，作为碳循环和其他地球化学过程的替代物。虽然在过去几十年中，CDOM在海洋研究中的重要性已得到牢固确立，但其在海洋中的来源和结构组成仍不清楚，并继续成为辩论的主题。马尾藻属（Sargassum）广泛分布于温带和亚热带海洋沃茨，是马尾藻属（Sargassum）资源丰富的海洋环境中CDOM的重要来源。本计画将探讨大型褐藻衍生化合物对海洋CDOM的贡献。这项研究的结果将对海洋碳循环和海洋颜色的卫星遥感产生影响，以评估地表水质量和海洋地球化学过程的混合。该项目将为博士后学者提供教育机会，夏季本科生实习（通过当地NSF赞助的本科生研究经验（REU）计划），并为当地高中学生提供研讨会和研究机会。海洋CDOM的来源仍有争议，全面了解其起源，分布和命运一直很困难。海洋CDOM，特别是“腐殖类”成分，已被认为是来自陆地来源，主要是木质素。然而，最近的证据表明，由大型褐藻产生的根皮单宁的分泌物可能对海洋CDOM池有显着贡献。根皮单宁，一类多酚，只发现，并不断渗出的大型褐藻，如马尾藻，强烈吸收紫外线，并可能被低估，在某些地理区域内的海洋CDOM池的贡献。在部分氧化时，这些特定化合物的光吸收延伸到可见光中的较长波长，产生类似于木质素的吸收光谱。这些根皮单宁及其转化产物吸收光，这可能部分解释了在开阔海洋环境中观察到的“类腐殖酸”特征。本研究旨在表征马尾藻衍生的CDOM的光学性质和分子组成，包括其好氧氧化和光化学行为，并量化马尾藻衍生的CDOM，以更好地估计其对马尾藻海和墨西哥湾CDOM池的可能贡献。

项目成果

Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum

• DOI: 10.3389/fmars.2020.588287
• 发表时间: 2020-11
• 作者: L. Powers;Rossana Del Vecchio;N. Blough;N. McDonald;P. Schmitt‐Kopplin;M. Gonsior