Journal Article

Coastal Supra‐Permafrost Aquifers of the Arctic and Their Significant Groundwater, Carbon, and Nitrogen Fluxes

Demir, Cansu, McClelland, James W., Bristol, Emily, Charette, Matthew A., Cardenas, M. Bayani

2024

Overview

Fresh submarine groundwater discharge (FSGD) can deliver significant fluxes of water and solutes from land to sea. In the Arctic, which accounts for ∼34% of coastlines globally, direct observations and knowledge of FSGD are scarce. Through integration of observations and process‐based models, we found that regardless of ice‐bonded permafrost depth at the shore, summer SGD flow dynamics along portions of the Beaufort Sea coast of Alaska are similar to those in lower latitudes. Calculated summer FSGD fluxes in the Arctic are generally higher relative to low latitudes. The FSGD organic carbon and nitrogen fluxes are likely larger than summer riverine input. The FSGD also has very high CO2 making it a potentially significant source of inorganic carbon. Thus, the biogeochemistry of Arctic coastal waters is potentially influenced by groundwater inputs during summer. These water and solute fluxes will likely increase as coastal permafrost across the Arctic thaws. Plain Language Summary Groundwater flows from land to sea, transporting freshwater, organic matter, nutrients, and other solutes that impact coastal ecosystems. However, along coasts of the rapidly‐warming Arctic, there is limited knowledge regarding how much fresh groundwater enters the ocean. Using field observations and numerical models, we show that groundwater flowing from tundra in northern coastal Alaska carries large amounts of freshwater, organic matter, and carbon dioxide to the Arctic lagoons during summer. These inputs are likely significant to coastal biogeochemical cycling and marine food webs. Groundwater discharge and the associated transport of dissolved materials are expected to increase due to longer periods of above‐zero temperatures that thaw frozen soils below the tundra. Key Points Summer fresh submarine groundwater discharge (FSGD) to the Alaskan Beaufort Sea is only 3%–7% of rivers but carries as much organic matter Summer FSGD delivers a median of 116 (interquartile range: 35–405) and 6 (2–21) kg/d per km dissolved organic carbon and nitrogen Fresh groundwater at the beach of Simpson Lagoon (SL) has a median PCO2 of ∼33,000 μatm implying substantial CO2 flux

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc
• Subject: Abrupt/Rapid Climate Change / Active Layer / Air/Sea Constituent Fluxes / Air/Sea Interactions / Aquifers / Asteroids / Atmospheric / Atmospheric Composition and Structure / Atmospheric Effects / Atmospheric Processes / Avalanches / Benefit‐cost Analysis / Biogeochemical cycles / Biogeochemical Cycles, Processes, and Modeling / Biogeochemical Kinetics and Reaction Modeling / Biogeochemistry / Biogeosciences / Carbon / Carbon cycle / Carbon dioxide / Climate and Interannual Variability / Climate Change and Variability / Climate Dynamics / Climate Impact / Climate Impacts / Climate Variability / Climatology / Coastal aquifers / coastal Arctic lagoons / Coastal ecosystems / Coastal plains / Coastal waters / Comets / Comets: Dust Tails and Trails / Computational Geophysics / Cryobiology / Cryohydrogeology / Cryosphere / Decadal Ocean Variability / Disaster Risk Analysis and Assessment / Earth System Modeling / Earthquake Ground Motions and Engineering Seismology / Effusive Volcanism / Explosive Volcanism / Fluxes / Food chains / Food webs / Freshwater / Freshwater ecosystems / Frozen food / Frozen ground / Frozen groundwater / General Circulation / Geodesy and Gravity / Geological / Global Change / Global Change from Geodesy / Gravity and Isostasy / Groundwater / Groundwater discharge / Groundwater flow / Groundwater/Surface Water Interaction / groundwater‐surface water interactions / Hydrological Cycles and Budgets / Hydrology / Impacts of Global Change / Informatics / Inland water environment / Inorganic carbon / Lagoons / Land/Atmosphere Interactions / Latitude / Marine Geology and Geophysics / Mass Balance / Mathematical models / Modeling / Mud Volcanism / Natural Hazards / Nitrogen / Numerical Modeling / Numerical models / Numerical Solutions / Nutrients / Ocean influence of Earth rotation / Ocean models / Ocean Monitoring with Geodetic Techniques / Ocean/Atmosphere Interactions / Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions / Oceanic / Oceanography: Biological and Chemical / Oceanography: General / Oceanography: Physical / Oceans / Organic carbon / Organic matter / Other / Paleoceanography / Permafrost / Permafrost depth / Permafrost, Cryosphere, and High‐latitude Processes / Physical Modeling / Planetary Sciences: Comets and Small Bodies / Planetary Sciences: Solar System Objects / Policy Sciences / Radio Oceanography / Radio Science / Regional Climate Change / Regional Modeling / Research Letter / Risk / Sea Level Change / Sea Level: Variations and Mean / Seismology / Solid Earth / Solutes / submarine groundwater discharge / Summer / Surface Waves and Tides / Thaws / Theoretical Modeling / Tsunamis and Storm Surges / Tundra / Volcanic Effects / Volcanic Hazards and Risks / Volcano Monitoring / Volcano Seismology / Volcano/Climate Interactions / Volcanology / Water Cycles / Water discharge