Connecting Hydrology, Biology, and Geochemistry in a Coastal Wetland: Feedbacks between Ecosystem Processes toward Predictive Understanding

沿海沼泽在碳循环中发挥着关键作用，因为它们储存了大量的碳，并调节了其在陆地，海洋和大气之间的运动。由于潮汐沼泽地位于陆海边缘，它们受到海平面上升、气候条件变化和人类压力的威胁，这可能会释放以前储存的碳，并降低它们未来储存碳的能力。对碳循环的影响将取决于沼泽水文学的变化如何影响碳的运动和化学形式，但这些影响目前尚不清楚。本研究探讨了不断变化的水文条件对沼泽水化学的影响，并将其与潮汐沼泽和沿海海洋之间碳运动的变化联系起来。该研究改进了对未来碳预算可能如何变化的预测，并使管理人员能够更好地保护这些脆弱的沿海生态系统的碳储存潜力。该项目还增加了本科生和研究生的教育机会，并使圣琼斯国家河口研究保护区的课程教学和公共宣传的发展，河口和沼泽是全球重要的碳库和陆地和海洋之间的相互作用的关键点，碳和养分循环。尽管它们的重要性，水文控制生物地球化学，反过来，这些生态系统的碳动力学研究相对不足，限制了预测反馈与气候变化和海平面上升，价值沼泽生态系统服务，并管理人类活动在这些脆弱的景观的能力。该项目结合了现场，实验室和建模方法，以阐明如何在沿海沼泽碳动态是由空间和时间复杂的水文物理和地球化学因素之间的相互作用。本研究（1）根据水文学、地下地球化学和生物活动描绘沼泽，（2）建立生物、地球化学和水文因素变化之间的机制联系，（3）将机制信息与水文建模相结合，以深入了解水文变化对氧化还原分带和相关碳动力学的长期影响。在多佛，特拉华州的圣琼斯国家河口研究保护区的中大西洋潮汐沼泽进行现场分析。这项工作填补了空白，了解湿地生态地球化学的水文影响，并确定具体的因素控制沼泽和沿海海洋之间的碳动态和通量。这项综合研究促进了新的概念和定量模型的发展，以预测沿海系统中地球化学和水文变化之间的反馈。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。

Coastal marshes play a critical role in the carbon cycle because they store vast amounts of carbon and regulate its movement between land, ocean, and atmosphere. Given their position at the land-sea margin, tidal marshes are threatened by rising seas, changing climatic conditions, and human pressures, which may release previously stored carbon and reduce their ability to store carbon in the future. The resulting impacts on the carbon cycle will depend on how changes in marsh hydrology affect the movement and chemical form of carbon, but these impacts are currently unknown. This study explores the impacts of changing hydrologic conditions on marsh water chemistry and links these to changes in carbon movement between tidal marshes and the coastal ocean. The research improves predictions of how carbon budgets may change in the future and enables managers to better protect the carbon storage potential of these fragile coastal ecosystems. The project also enhances education opportunities for undergraduate and graduate students, and enables the development of the St. Jones National Estuarine Research Reserve for course instruction and public outreach.Estuaries and marshes are globally important reservoirs of carbon and the critical points of interaction between land and oceans where carbon and nutrients are cycled. Despite their importance, the hydrological controls on biogeochemistry and, in turn, carbon dynamics of these ecosystems are relatively understudied, limiting the capacity to predict feedbacks with climate change and sea-level rise, to value marsh ecosystem services, and to manage human activities in these fragile landscapes. This project incorporates field, laboratory, and modeling approaches to elucidate how carbon dynamics in coastal marshes are driven by the spatially and temporally complex hydrology through interactions between physical and biogeochemical factors. This research (1) delineates the marsh based on hydrology, subsurface geochemistry, and biological activity, (2) establishes mechanistic linkages between changes in biological, geochemical, and hydrologic factors, and (3) combines mechanistic information with hydrological modeling to gain insights into longer timescale impacts of hydrologic change on redox zonations and associated carbon dynamics. Field analyses are conducted in a mid-Atlantic tidal marsh at the St. Jones National Estuarine Research Reserve in Dover, Delaware. This work fills gaps in the understanding of the hydrologic impacts on marsh biogeochemistry and identifies specific factors controlling carbon dynamics and fluxes between marshes and the coastal ocean. This integrated study promotes development of new conceptual and quantitative models to predict feedbacks between biogeochemistry and hydrologic change in coastal systems.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.