EAGER: The camouflaging of terrigenous organic matter as marine organic matter through hydroxyl radical oxidation via the dark Fenton reaction

海洋中的有机碳由陆地和海洋来源的河流径流输送的物质组成。然而，尽管大量陆源有机碳从河流进入海洋，但海洋中的大部分碳似乎来自海洋来源。这使得科学家们得出结论，陆源碳并没有很远地输送到海洋中。这个急切的项目旨在检验这一假设。科学家团队将研究化学反应是否会改变陆源有机碳的组成，使其看起来像海洋有机碳。如果这被证明是真的，结果可能解释为什么海洋中很难识别陆源有机碳，并可能导致对目前的碳预算和模型的重新考虑。科学家们将使用从世界各地主要河流系统收集的陆源碳进行实验。在自然界存在的条件下，样品将在黑暗中被引入活性氧物种(主要是羟基自由基)和铁。在实验期间和之后，将监测反应速度和有机物组成的变化。这个热切的项目为没有接受过NSF支持的早期职业研究人员提供研究培训和宝贵的专业发展经验。在主要机构注册的STEM和REU项目的本科生将参与这项研究。这个热切的项目检验了在暗Fenton反应中产生的羟基自由基与陆源有机物反应产生的有机物在组成和同位素上与海洋有机物相似的假设。PIS将使用从几个大规模陆地河流系统收集的与环境相关的羟基自由基和陆地有机物样本来验证这一假设。PIS将使用多种方法来表征实验前、实验中和实验后的大量有机物质(红外/核磁共振光谱)、其分子组成(电喷雾电离傅立叶变换离子回旋共振质谱仪)以及碳和氮的稳定同位素值(δ13C、δ15N)。这项研究探索了一个未经检验但具有潜在变革性的假设，它可能会改变现有的关于海洋中陆地有机物命运的范式。这项研究的结果可能会修正人们对陆源有机物对海洋碳循环的贡献的理解。该项目将为早期职业调查员提供研究和专业发展机会，这些调查员之前没有接受过NSF的支持(共同担任Pi Goranov)。在私人投资机构的本土机构注册参加REU和STEM培训计划的本科生将参与研究。这一奖项反映了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。

Organic carbon in the ocean is made-up of materials delivered by riverine runoff from land and marine sources. However, even though a large amount of land-derived organic carbon enters the ocean from rivers, most carbon in the ocean appears to be from marine sources. This has led scientists to conclude that land-derived carbon is not transported far into the ocean. This EAGER project aims to test this assumption. The team of scientists will examine whether chemical reactions alter the composition of land-derived organic carbon in a way that makes it look like marine organic carbon. If this proves true, the results could explain why land-derived organic carbon is difficult to identify in the ocean and could lead to a reconsideration of present carbon budgets and models. The scientists will perform experiments using land-derived carbon collected from major river systems throughout the world. Samples will be introduced to reactive oxygen species (mainly hydroxyl radicals) and iron in the dark under conditions that occur in nature. Reaction rates and changes in the composition of the organic matter will be monitored during and following the experiments. This EAGER project provides research training and valuable professional development experience for an early career researcher who has not received prior support from NSF. Undergraduate students enrolled in STEM and REU programs at the lead institutions will participate in the research.This EAGER project examines the hypothesis that hydroxyl radicals generated during dark Fenton reactions react with terrigenous organic matter to produce organic matter that is compositionally and isotopically similar to marine organic matter. The PIs will test this hypothesis using environmentally relevant concentrations of hydroxyl radical and terrestrial organic matter samples collected from several large-scale terrestrial riverine systems. The PIs will use multiple methods to characterize bulk organic matter (infrared/nuclear magnetic resonance (NMR) spectroscopy), its molecular composition (electrospray ionization Fourier Transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), and stable isotope values of carbon and nitrogen (δ13C, δ15N) of dissolved and particulate organic matter pools before, during and following the experiments. This study explores an untested, but potentially transformative hypothesis that could alter existing paradigms about the fate of terrestrial organic matter in the ocean. Results from this study could revise understanding of the contributions of terrigenous organic matter to the ocean carbon cycle. The project would provide research and professional development opportunities for an early career investigator who has not received prior NSF support (co-PI Goranov). Undergraduates enrolled in REU and STEM training programs at the PIs’ home institutions would participate in the research.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.