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

海平面上升和风暴事件将咸水推向陆地(即咸水入侵)，促使陆地生态系统的化学、生态和温室气体通量发生变化。目前关于咸水入侵的驱动因素和影响的知识建立在温带和热带环境的基础上。人们对北极海岸线的咸水入侵知之甚少，那里的永冻层是沿海生态系统的底层。在这项研究中，我们调查了北极沿岸咸水入侵的驱动因素，以及咸水入侵对阿拉斯加波弗特海沿岸的孔隙水化学和温室气体通量的影响。这项工作将提供对快速变化的北极海岸线上发生的物理、生物和化学过程的基线了解；将培训两名暑期实习生、一名研究助理和现场技术员；并将为两名职业生涯早期的女性研究人员提供资金。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。在世界各地的海岸线上，海平面上升和风暴事件正在推动咸水入侵陆地环境。目前对咸水入侵的驱动因素和生态系统影响的了解主要是基于在温带和热带环境中进行的研究。咸水入侵对永久冻土边界海岸线的物理和生物地球化学性质的影响的研究要少得多，这在理解北极沿海生态系统对盐碱化的反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水盐度分布的过程以及北极冻土带盐碱化对温室气体向大气的通量和对沿海海洋的营养通量的影响的知识来填补这些空白。通过阿拉斯加波弗特海沿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、融化深度和淡水盐分动态，(2)测量孔隙水营养物质浓度和温室气体通量，以及(3)评估健康和盐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了解，增强我们在不断变化的气候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。具体地说，该项目将培训暑期实习生、一名研究助理和一名现场和实验室技术人员。通过与伍兹霍尔科技教育计划的合作，项目成果将定期在当地学校和公共论坛上展示，私人投资机构将参与当地的活动，包括在科学博览会上指导学生项目。最后，这个项目的结果将通过期刊出版物和会议报告向科学界传播。这个奖项反映了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。

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.