Groundwater Discharge in the Arctic: A Review of Studies and Implications for Biogeochemistry

Abstract

Groundwater discharge, including submarine groundwater discharge, discharge to lakes and rivers, and subglacial discharge, affects freshwater and marine ecosystems across the globe. The implications for biogeochemistry include the transport of nutrients, metals, and gases to these systems. The Arctic is one region of the globe that has been understudied with respect to groundwater discharge until recently, when a handful of studies sought to understand the nature of groundwater discharge and its impacts on aquatic ecosystems. Those studies are summarized here, and the implications for biogeochemistry are synthesized. Carbon and nitrogen are the most frequently studied solutes with respect to groundwater discharge in the Arctic. The transport of carbon and nitrogen through groundwater discharge are discussed across study sites, and scientists expect their transport through this mechanism to significantly change with the onset of climate change. The Arctic is of special interest in terms of groundwater discharge, as climate change data predicts that it will warm faster than other environments. Lastly, the effects of climate change on the physical and biogeochemical aspects of groundwater discharge in the Arctic are discussed, as are research priorities.

Freshwater Seepage Into Sediments of the Shelf, Shelf Edge, and Continental Slope of the Canadian Beaufort Sea

“…Geochemistry, Geophysics, Geosystems suprapermafrost and subpermafrost groundwater flows (Clark et al, 2001;Deming, 1993;Deming et al, 1992;Kane et al, 2013;Lecher, 2017;Lemieux et al, 2016;Utting et al, 2013;Walvoord & Striegl, 2007). The Mackenzie River year-round flow with temperatures consistently above freezing suggests hydraulic connection between surface waters and a regional subsurface reservoir.…”

Evidence for Pathways of Concentrated Submarine Groundwater Discharge in East Antarctica from Helicopter-Borne Electrical Resistivity Measurements

“…While quantitative estimates of SGD flux now exist for the global ocean between 70N and 60S [5] observations at high latitudes remain very limited [6]. In the North, for example around the coast of Alaska, observed SGD is driven primarily by tidal pumping in areas with large tidal ranges and permafrost melting elsewhere where tidal effects are limited [7].…”

Synthesizing the Effects of Submarine Groundwater Discharge on Marine Biota

“…Submarine groundwater discharge (SGD) encompasses all manner of groundwater flow to the ocean, including point source discharge from springs, and diffuse seepage from coastal aquifers [1][2][3]. SGD may consist of seawater that has circulated through the coastal aquifer before returning to the ocean, fresh groundwater from inland sources, or a mixture of both of these waters [3][4][5].…”

“…Often hidden from the naked eye, SGD rivals river discharge globally in terms of volume discharge to the ocean, and it is known to occur in every ocean basin [1,9,10]. Not only a source of freshwater to the ocean, SGD also transports bioactive solutes to the coastal ocean when it discharges, including but not limited to nitrogen (N), phosphorous (P), silica (Si), iron (Fe), methane (CH 4 ), and mercury (Hg) [1,3,5,6,11,12]. The impacts of SGD can extend into society as well, as a freshwater resource and a process that exerts a positive influence on fisheries [13].…”