Significance of one and two carbon photoproducts in the photolysis of marine dissolved organic matter

一碳和二碳光产物在海洋溶解有机物光解中的意义

• 批准号: 2242014
• 负责人: Leanne Powers
• 金额: $ 68.38万
• 依托单位: SUNY College of Environmental Science and Forestry
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-15 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2242014&HistoricalAwards=false
• 关键词: Significance; two; carbon; photoproducts; photolysis

Marine dissolved organic carbon (DOC) is one of Earth’s major carbon reservoirs, but despite many years of study, the pathways and rates of DOC production and removal are poorly constrained. It is important to identify major pathways and determine rates in the oceans to better predict how DOC cycling will change in the future, and how these changes will alter the global carbon cycle. One potentially important process that affects marine DOC is photochemistry, the breakdown of organic molecules by sunlight. This project will investigate photochemical destruction of DOC. Findings from the work will be of interest to biologists, chemists, ecologists, climate scientists, and ocean-atmosphere modelers. The project will foster research and educational opportunities for one postdoctoral scholar, a graduate student, and several undergraduates. The project team will engage in public outreach and education through a project website, videoconferencing, online discussion forums, and an interactive blog in partnership with the State University of New York, College of Environmental Science and Forestry’s Louis Stokes Alliance of Minority Participation Program and the local American Chemical Society’s Project SEED for economically-disadvantaged high school students. The research plan is to re-evaluate two long-held assumptions: that dissolved inorganic carbon (i.e., carbon dioxide) is the main product produced from the photochemical breakdown of marine DOC, and that sunlight-driven chemistry is an important process in the removal of DOC from the oceans. The project will investigate three interrelated questions: (1) Are coastal-to-offshore transects in production rates of acetone, pyruvate and C1- and C2-carbon photoproducts nonlinear functions of CDOM absorption, as observed for DIC? (2) Is DIC the main carbon photoproduct produced from the photolysis of DOC in the open ocean? (3) Is the production of C1- and C2-carbon photoproducts, together with acetone and pyruvate, collectively a significant removal mechanism for DOC in the oceans on an annual basis? To address these questions, the project will combine laboratory experiments and a 19-day research cruise. The project will focus on low molecular weight carbon compounds because these are the main products produced from the photolysis of DOC, and yet no one has co-measured photochemical production rates of these compounds in seawater. Compounds to be considered include carbon monoxide, dissolved inorganic carbon, formaldehyde, acetaldehyde, acetone, glyoxal, glyoxylate, pyruvate, formate, and acetate. The team will measure photochemical production rates and determine wavelength- and temperature-dependent apparent quantum yields (AQY) for the production of these compounds. Using AQY data, they will model depth-resolved photochemical carbon fluxes using remotely sensed ocean color to determine the impact of this process in the marine DOC cycle.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海洋溶解有机碳(DOC)是地球上主要的碳库之一，但尽管进行了多年的研究，但DOC的产生和去除的途径和速率受到的限制很少。重要的是要确定海洋中的主要路径和速率，以便更好地预测DOC循环在未来将如何变化，以及这些变化将如何改变全球碳循环。影响海洋DOC的一个潜在重要过程是光化学，即阳光对有机分子的分解。该项目将研究DOC的光化学破坏。生物学家、化学家、生态学家、气候学家和海洋-大气模型师将对这项工作的发现感兴趣。该项目将为一名博士后学者、一名研究生和几名本科生提供研究和教育机会。项目团队将通过项目网站、视频会议、在线讨论论坛和互动博客，与纽约州立大学、环境科学和林业学院的路易斯·斯托克斯少数群体参与计划和当地美国化学协会针对经济困难高中生的项目种子合作，参与公共宣传和教育。研究计划将重新评估两个长期持有的假设：溶解的无机碳(即二氧化碳)是海洋DOC光化学分解产生的主要产物，以及阳光驱动的化学是从海洋中去除DOC的重要过程。该项目将调查三个相互关联的问题：(1)沿海到近海横断面的丙酮、丙酮酸以及C1和C2碳光产物的生产率是否像DIC一样具有CDOM吸收的非线性函数？(2)DIC是DOC在公海中光解产生的主要碳光产物吗？(3)C1和C2碳光产品的生产与丙酮和丙酮酸一起，是海洋中DOC每年显著清除的机制吗？为了解决这些问题，该项目将结合实验室实验和19天的研究巡航。该项目将专注于低分子碳化合物，因为这些是DOC光解产生的主要产物，但还没有人共同测量这些化合物在海水中的光化学产生率。考虑的化合物包括一氧化碳、溶解的无机碳、甲醛、乙醛、丙酮、乙二醛、乙醛、丙酮酸、甲酸盐和醋酸盐。该团队将测量光化学产生率，并确定这些化合物的生产与波长和温度相关的表观量子产率(AQY)。使用AQY数据，他们将利用遥感海洋颜色模拟深度分辨的光化学碳通量，以确定这一过程在海洋DOC循环中的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。