Investigating the contribution of carotenoid degradation products to refractory dissolved organic matter (DOM)

研究类胡萝卜素降解产物对难溶有机物 (DOM) 的贡献

• 批准号: 1736656
• 负责人: Lihini Aluwihare
• 金额: $ 69.51万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736656&HistoricalAwards=false
• 关键词: Investigating; contribution; carotenoid; degradation; products

This research project will identify biological sources and chemical structures that are responsible for the long-term storage of carbon in the ocean. Each year, microscopic marine plants remove about as much carbon dioxide from the atmosphere as do land plants. Respiration returns much of this carbon to the ocean as carbon dioxide, but some is locked in the remnants of living organisms. These remaining compounds are modified by pathways that involve bacteria, sunlight, chemical reactions, and other processes that lead to storage of carbon for thousands to millions of years. Some compounds eventually contribute to the petroleum reservoir. Building on previous results, this project will study the reactions and oceanic lifetime of a particular set of biochemicals, called carotenoids, as a possible organic carbon storage pathway. Carotenoids are abundant in very many marine organisms, increasing the likelihood that they are part of this long-term carbon storage and petroleum formation. These compounds also have unique chemical properties that make them subject to specific chemical reactions. For this reason, they have been marketed as powerful antioxidants. Therefore, scientific outcomes from this research on carotenoid chemistry will not only inform ocean carbon cycles but could also benefit studies of their properties as antioxidants. The project will determine the lifetime of carotenoids and their degradation products in seawater to provide new insights into pathways that transfer carbon from the atmosphere through biota and into long-term storage reservoirs. Graduate students and underrepresented undergraduate students will be engaged in the research.Previous work has identified specific chemical backbones of compounds that are broadly distributed within the marine dissolved organic matter (DOM) reservoir. A high-resolution analytical approach that combines nuclear magnetic resonance (NMR) spectroscopy with comprehensive gas chromatography-mass spectrometry (GC-MS) has detected DOM compounds with unique structures closely related to carotenoids. Photochemical reactions of a representative carotenoid in laboratory experiments has further linked compounds detected in seawater to carotenoid degradation products (CDP). These preliminary studies show promise that the work funded here will be able to identify specific CDP structures and establish the quantitative significance, lifetimes, and timescales of CDP accumulation in seawater. The project will combine laboratory experiments, high resolution analyses, and chemical synthesis methods to determine the chemical composition of CDP and their abundance in seawater. The novel analytical methods developed through this research will be relevant for other carotenoid-focused studies in petroleum formation, soil chemistry, as well as food chemistry. Ramped pyrolysis oxidation (PyrOx) coupled to radiocarbon measurements will be used to determine the radiocarbon content of CDP-enriched DOM and seek to estimate the accumulation timescale of these dissolved molecules in the environment, and it is hypothesized that deeper, older ocean water will contain a relatively higher proportion of radiocarbon-depleted CDP. Collecting samples from different depths in the North Pacific Ocean where CDP-enriched DOM will be isolated following established sample processing methods will provide insights and new information on the mechanisms that control the amount and timescale of carbon redistribution among Earth?s various reservoirs.

该研究项目将确定负责在海洋中长期存储的生物学来源和化学结构。每年，微观海洋植物与陆地植物一样，从大气中清除大约二氧化碳。作为二氧化碳，呼吸将大部分碳返回到海洋中，但有些则锁定在活生物体的残留物中。这些剩余的化合物通过涉及细菌，阳光，化学反应的途径以及其他导致碳储存数千万到数百万年的途径。一些化合物最终有助于石油储层。基于先前的结果，该项目将研究一组称为类胡萝卜素的特定生化物的反应和海洋寿命，作为可能的有机碳储存途径。类胡萝卜素在许多海洋生物中都很丰富，增加了它们是这种长期碳储存和石油形成的可能性。这些化合物还具有独特的化学特性，使它们受到特定的化学反应的影响。因此，它们被销售为强大的抗氧化剂。因此，这项关于类胡萝卜素化学的研究的科学结果不仅会为海洋碳周期提供信息，而且还可以使对它们作为抗氧化剂的特性的研究受益。该项目将确定类胡萝卜素及其在海水中降解产物的寿命，以提供新的见解，以使途径从大气中通过生物群体转移到长期储存储层中。研究生和代表性不足的本科生将从事研究。预防工作已经确定了在海洋溶解有机物（DOM）储层中广泛分布的化合物的特定化学主链。一种将核磁共振（NMR）光谱与综合气相色谱 - 质量光谱法（GC-MS）结合的高分辨率分析方法，已检测到与类胡萝卜素密切相关的独特结构的DOM化合物。代表性类胡萝卜素在实验室实验中的光化学反应已进一步将海水中检测到的化合物与类胡萝卜素降解产物（CDP）联系起来。这些初步研究表明，这里资助的工作将能够识别特定的CDP结构，并确定CDP在海水中积累的定量意义，寿命和时间表。该项目将结合实验室实验，高分辨率分析和化学合成方法，以确定CDP的化学成分及其在海水中的丰度。通过这项研究开发的新型分析方法将与其他以类胡萝卜素形成，土壤化学和食物化学的研究有关。 Ramped pyrolysis oxidation (PyrOx) coupled to radiocarbon measurements will be used to determine the radiocarbon content of CDP-enriched DOM and seek to estimate the accumulation timescale of these dissolved molecules in the environment, and it is hypothesized that deeper, older ocean water will contain a relatively higher proportion of radiocarbon-depleted CDP.从既定的样品处理方法后将分离出富含CDP的DOM的不同深度的样品将提供有关控制地球各种储层中碳再分配的数量和时间表的机制的见解和新信息。