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

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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.