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

合作研究：草单宁——海洋发色溶解有机物的重要来源？

• 批准号: 1536927
• 负责人: Rossana Del Vecchio
• 金额: $ 14.53万
• 依托单位: University of Maryland, College Park
• 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 2019-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536927&HistoricalAwards=false
• 关键词: Collaborative; Research; Phlorotannins; Important; Source

Chromophoric 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.

发色溶解的有机物（CDOR）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很重要，因为它可用于追踪地表水的混合，作为碳循环的代理以及其他生物地球化学过程。尽管在过去的几十年中，它在海洋研究中的重要性已经牢固地确定，但海洋中CDOM的来源和结构性组成仍然不清楚，并且仍然是辩论的主题。 Sargassum是一种棕色藻类，广泛分布在温带和亚热带海水中，可能是萨尔加索（Sargassum）丰富的墨西哥萨尔加索海和墨西哥湾的重要来源。该项目将调查宏棕色藻类衍生化合物对海洋CDOM池的贡献。这项研究的结果将对海洋碳循环和海洋色的卫星遥感有影响，以评估地表水质量和生物地球化学过程的混合。该项目将为博士后学者，夏季本科实习提供教育机会（通过本地NSF赞助的本科生（REU）计划的研究经验），以及当地高中生的研讨会和研究机会。海洋cdom的源代码仍然有争议，并且对其起源，分布和命运的全面了解。有人建议海洋cdom，尤其是“腐殖样”的成分，起源于陆生源，主要是木质素。然而，最近的证据表明，宏棕色藻类产生的假霉素的渗出可能会对海洋c池产生重大贡献。菲洛丁蛋白是一类仅在sargassum等宏观棕色藻类中发现并连续散发出的多酚，强烈吸收了紫外线，并且可能被低估了它们对某些地理位置内部海洋库池的贡献。部分氧化后，这些特定化合物的光吸收在可见的可见光中延伸成更长的波长，从而产生了类似于木质素的吸收光谱。这些phlorotannins及其转化产物吸收的光线可能解释了在开阔的海洋环境中观察到的“腐殖样”标志。这项研究旨在表征萨尔加斯衍生的CDON的光学特性和分子组成，包括其有氧氧化和光化学行为，并量化了萨尔加斯姆衍生的CDOR，以更好地估计其对墨西哥萨尔加索海和墨西哥湾的CDOM池的可能贡献。