Collaborative Research: Drivers and Biogeochemical Implications of Saltwater Intrusion Along Arctic Coastlines

海平面上升和风暴事件将盐水推向陆地（即盐水入侵），推动了陆地生态系统的化学、生态和温室气体通量的变化。目前关于盐水入侵的驱动因素和影响的知识是基于温带和热带环境的。人们对北极海岸线的盐水入侵知之甚少，那里的永久冻土是沿海生态系统的基础。在这项研究中，我们研究了北极沿海盐水入侵的驱动因素，以及盐水入侵对阿拉斯加波弗特海沿岸孔隙水化学和温室气体通量的影响。这项工作将为快速变化的北极海岸线上发生的物理、生物和化学过程提供基本的了解；将培训两名暑期实习生，一名研究助理和现场技术员；并将资助两位早期职业生涯的女性研究人员。研究结果将与科学界以及当地学校和公共论坛分享，将北极带到科德角社区。沿着世界各地的海岸线，海平面上升和风暴事件正在推动海水侵入陆地环境。目前对盐水入侵的驱动因素和生态系统影响的理解主要基于在温带和热带环境中进行的研究。盐水入侵对永久冻土层海岸线的物理和生物地球化学特性的影响的研究要少得多，在了解北极沿海生态系统对盐碱化的响应方面留下了明显的空白。这项研究将通过扩大对调节沿海孔隙水盐度分布过程的认识，以及北极冻土带盐碱化对大气温室气体通量和沿海海洋养分通量的影响，来填补这些空白。通过在阿拉斯加波弗特海岸进行的跨学科实地和实验室研究，我们将(1)表征地下温度、水位、融化深度和孔隙水盐度动态，(2)测量孔隙水营养物质浓度和温室气体通量，(3)评估健康和盐碱化苔原地区地下水位动态、地下水营养物质浓度和温室气体通量之间的联系。拟议的活动将通过揭示冻土带盐碱化与改变的物理和生物地球化学过程之间的联系来扩大对系统的理解，增强我们在气候变化中预测沿海生态系统功能的能力。该项目的更广泛影响包括早期职业指导，参与K-12教育，以及向科学界和更广泛的社区传播研究成果。具体而言，该项目将培训暑期实习生、一名研究助理和一名实地和实验室技术人员。通过与伍兹霍尔科学与技术教育计划的合作，项目成果将定期在当地学校和公共论坛上展示，pi将参加当地活动，包括在科学展览会上指导学生项目。最后，该项目的成果将通过期刊出版物和会议报告向科学界传播。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。

Sea-level rise and storm events push saltwater landward (i.e., saltwater intrusion), driving changes in the chemistry, ecology, and greenhouse gas fluxes of terrestrial ecosystems. Present knowledge of the drivers and impacts of saltwater intrusion is based on temperate and tropical environments. Little is known about saltwater intrusion along Arctic coastlines where permafrost underlies coastal ecosystems. In this study, we investigate the drivers of coastal Arctic saltwater intrusion and the impacts of saltwater intrusion on porewater chemistry and greenhouse gas fluxes along Alaska’s Beaufort Sea coast. This work will provide baseline understanding of the physical, biological, and chemical processes occurring along rapidly changing Arctic coastlines; will train two summer interns, a research assistant, and field technician; and will fund two early career, female researchers. Findings will be shared with the scientific community, as well as at local schools and public forums, bringing the Arctic to Cape Cod communities. Along coastlines worldwide, sea-level rise and storm events are driving saltwater intrusion into terrestrial environments. Present understanding of the drivers and ecosystem ramifications of saltwater intrusion is largely based on studies conducted in temperate and tropical environments. The influence of saltwater intrusion on the physical and biogeochemical properties of permafrost-bound coastlines has been investigated far less, leaving pronounced gaps in understanding of coastal Arctic ecosystem responses to salinization. This study will fill these gaps by expanding knowledge of the processes mediating distributions of coastal porewater salinity and the consequences of Arctic tundra salinization for greenhouse gas fluxes to the atmosphere and nutrient fluxes to the coastal ocean. Through an interdisciplinary field and laboratory study conducted along Alaska’s Beaufort Sea coast, we will (1) characterize subsurface temperature, water level, thaw depth, and porewater salinity dynamics, (2) measure porewater nutrient concentrations and greenhouse gas fluxes, and (3) assess links between water table dynamics, groundwater nutrient concentrations, and greenhouse gas fluxes across healthy and salinized tundra sites. The proposed activities will expand system understanding by uncovering links between tundra salinization and altered physical and biogeochemical processes, enhancing our ability to project coastal ecosystem function in a changing climate. The broader impacts of the project include early career mentorship, participation in K-12 education, and research dissemination to the scientific and broader community. Specifically, this project will train summer interns, a research assistant, and a technician both in the field and laboratory. Through partnerships with the Woods Hole Science and Technology Education Program, project outcomes will regularly be presented at local schools and public forums, and PIs will participate in local activities including mentoring student projects in science fairs. Lastly, results from this project will be disseminated to the scientific community through journal publications and conference presentations.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.