OPP-PRF: Organic Matter Export, Processes, and Transformations Drive Carbon Cycling Patterns in the Arctic Ocean

全球碳循环支持着地球上的生命，并影响着海洋、陆地和大气生态系统。人类活动通过向当代大气中添加化石碳，从而改变了这种自然循环的平衡，从而改变了我们的气候。随着气候变暖，海冰覆盖的减少和北极河流碳输出的增加极大地改变了海洋中的微观有机分子。这些化合物在地球的自然元素循环中发挥着重要作用，有助于在海洋中储存大气温室气体（如二氧化碳、CO2），并支持海洋生物。因此，随着北极地区大规模生态系统的变化，现在是时候更好地了解北冰洋中的微观物质将塑造地球上所有其他海洋的组成和功能。关于北冰洋将在20-50年后无冰的预测，本研究旨在了解北冰洋碳循环过程和影响，如进一步的生物和化学反馈回路，以及在矿化过程中改变的微观碳基物质（如溶解有机物（DOM））的CO2释出。从北极出口的大部分DOM都是河流，通过弗拉姆海峡输送，这是一个相对较小的水域，连接着北冰洋和全球传送带。这很重要，因为弗拉姆海峡代表了北极陆地碳与其他海洋环境的联系。研究人员将测量海洋中导致大气中二氧化碳浓度增加的最大变化的DOM的数量和类型。在全球变化的背景下，需要提供基本的分子级化学数据来理解DOM签名，并将为科学界提供明确的DOM数据。研究人员还认为这项工作是一个理想的机会，可以在不同的北极科学研究人员之间带头开展碳化学倡议，从而实现更安全、更健康的碳表征实践。全球环境变化影响北极冰盖、海冰、海洋和环流，影响生态系统功能和海水碳循环。随着气候变暖，海冰减少，格陵兰岛冰盖损失增加，北极河流碳(C)输出增加，使北冰洋成为多种有机物质（OM）的混合区，这些有机物质在全球循环之前通过弗拉姆海峡。因此，弗拉姆海峡将通过自然过程对海洋表面和底部水域产生巨大影响，从而导致二氧化碳（CO2）的排放。海洋碳矿化过程取决于溶解的DOM （DOM）组成、微生物、养分有效性和阳光照射，所有这些都决定了转化DOM释放二氧化碳的机制。总体假设是，拉姆海峡DOM的微生物和光化学矿化到CO2之间的分子组成差异是由北冰洋不同来源的异质性驱动的。DOM的先进分析化学测量（超高分辨率质谱，C同位素组成和核磁共振波谱）将用于破译弗拉姆海峡发生的生物和非生物降解机制的分子组成和独特的C标记。因此，DOM组成与CO2脱气的联系将被建立起来。这项工作的目标是DOM如何在快速和长时间的时间尺度上在海峡中持续存在和转换。绘制Fram海峡微生物和光化学dom相互作用图的进展将解决看似不同领域的知识差距，最终更好地了解北极的C循环。这些数据将为社区提供明确的DOM组成标记，可用于更好地了解北极海水，并在气候变暖和海平面上升的情况下帮助执行健康的环境政策。分析和绿色化学专业知识将结合起来，以确定对下一代北极研究人员至关重要的北极C研究的改进。该奖项反映了美国国家科学基金会的法定使命，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。

Global carbon cycling supports life on Earth and affects marine, terrestrial, and atmospheric ecosystems. Human activities alter the balance of this natural cycle by adding fossil carbon to the contemporary atmosphere, thereby changing our climate. As the climate warms, reduced sea ice cover and increased Arctic river carbon export dramatically change the microscopic organic molecules in the oceans. These compounds play essential roles in Earth’s natural elemental cycles, contribute to the storage of atmospheric greenhouse gasses (e.g., carbon dioxide, CO2) in the ocean, and support marine organisms. Therefore, with large-scale ecosystem changes across the Arctic, the time is now to better understand what microscopic materials in the Arctic Ocean will shape the composition and function of all other Earth’s oceans. Concerning the prediction that the Arctic Ocean will be ice-free around 20–50 years from now, this research is designed to understand Arctic Ocean carbon cycling processes and impacts, such as further biological and chemical feedback loops as well as CO2 outgassing from microscopic carbon-based materials, such as dissolved organic matter (DOM), altered in mineralization processes. Much of the DOM exported from the Arctic is riverine and is funneled through the Fram Strait, a relatively small body of water that connects the Arctic Ocean to the global conveyor belts. This is important because Fram Strait represents a linkage of Arctic terrestrial carbon to other ocean environments. The researchers will measure the amount and type of DOM responsible for the largest transformations in the ocean resulting in increased concentrations of CO2 in the atmosphere. Providing essential molecular-level chemical data is needed to understand DOM signatures within the context of global change and will provide the scientific community with definitive DOM data. The researchers also embrace this work as an ideal opportunity to spearhead a carbon chemistry initiative across diverse Arctic science researchers to lead to safer and healthier carbon characterization practices. Global environmental change impacts Arctic ice sheets, sea ice, ocean, and circulation, affecting ecosystem function and carbon cycling in marine waters. As the climate warms, sea ice diminishes, ice sheet loss from Greenland increases, and Arctic river-carbon (C) outputs increase, making the Arctic Ocean a mixing zone of diverse organic material (OM) that gets funneled through the Fram Strait before circulating globally. Thus, the Fram Strait is poised to dramatically impact marine surface and bottom waters resulting in carbon dioxide (CO2) emissions upon OM mineralization through natural processes. Marine C mineralization processes depend on dissolved OM (DOM) composition, microbes, nutrient availability, and sunlight exposure, all of which shape the mechanisms for CO2 outgassing from transformed DOM. The overarching hypothesis is DOM molecular composition distinctions between microbial and photochemical mineralization of DOM to CO2 in Fram Strait are driven by the heterogeneous nature of diverse Arctic Ocean sources. Advanced analytical chemistry measurements of DOM (ultrahigh resolution mass spectrometry, C isotopic composition, and nuclear magnetic resonance spectroscopy) will be used to decipher molecular composition and unique C markers from biotic and abiotic degradation mechanisms occurring in the Fram Strait. As a result, linkages of DOM composition and CO2 outgassing will be made. This work will target how DOM can persist and be transformed in the Fram Strait across rapid and prolonged time scales. Progress in mapping microbe- and photochemical-DOM interactions in the Fram Strait will address knowledge gaps across seemingly disparate fields, culminating in better understandings of C cycling in the Arctic. The data will provide the community with definitive DOM compositional markers that can be used to better understand Arctic marine waters and help enforce healthy environmental policy as the climate warms and sea levels rise. Analytical and green chemistry expertise will be combined to identify improvements in Arctic C research which will be essential for the next generation of Arctic researchers.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.