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

海洋中的有机碳是由陆地和海洋来源的河流径流输送的物质组成的。然而，尽管大量陆源有机碳从河流进入海洋，但海洋中的大多数碳似乎来自海洋。这使科学家得出结论，陆地来源的碳不会被输送到海洋深处。EAGER项目旨在验证这一假设。科学家团队将研究化学反应是否会改变陆地来源的有机碳的组成，使其看起来像海洋有机碳。如果这被证明是真的，那么研究结果就可以解释为什么海洋中的陆源有机碳很难识别，并可能导致重新考虑目前的碳预算和模型。科学家们将利用从世界各地主要河流系统收集的陆地来源的碳进行实验。在自然条件下，在黑暗中将样品引入活性氧（主要是羟基自由基）和铁。在实验期间和之后将监测反应速率和有机物组成的变化。这个EAGER项目为没有得到NSF事先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。本研究以STEM和REU专业的本科生为研究对象，探讨暗芬顿反应中产生的羟基自由基与陆源有机物发生反应，生成与海洋有机物在组成和同位素上相似的有机物的假说。研究所将使用从几个大规模陆地河流系统收集的与环境有关的羟基自由基和陆地有机物样本浓度来检验这一假设。在实验之前、期间和之后，主要研究者将使用多种方法来表征大量有机物（红外/核磁共振光谱法）、其分子组成（电喷雾电离傅里叶变换离子回旋共振质谱法）以及溶解和颗粒有机物池的碳和氮的稳定同位素值（δ 13 C、δ 15 N）。这项研究探索了一个未经检验但可能具有变革性的假设，该假设可能会改变有关海洋中陆地有机物命运的现有范式。该研究的结果可以修正对陆源有机质对海洋碳循环贡献的认识。该项目将提供研究和专业发展的机会，为早期的职业调查谁没有收到之前的NSF支持（共同PI戈拉诺夫）。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.