Ice Cover Influences Redox Dynamics in Prairie Pothole Wetland Sediments

Abstract

The Prairie Pothole Region (PPR) of North America encompasses nearly 750,000 km 2 of the Upper Great Plains that straddle the United States and Canada. This region is composed of a heavily glaciated landscape densely populated by depressional wetlands connected hydrologically by groundwater with little surface water connectivity. Thus, wetland surface area varies greatly with annual precipitation patterns (Liu & Schwartz, 2011). These wetlands also exhibit a salinity gradient ranging from <800 to >60,000 µS/cm that mirrors groundwater flow from higher elevation freshwater "recharge" (output only) wetlands to increasingly saline and sulfidic lower elevation "flow though" (input and output) and ultimately "discharge" (input only) water bodies (Mushet et al., 2015;Winter & Rosenberry, 1998). In contrast pothole surface waters are either saturated or super-saturated with respect to calcite and occupy a narrow pH range (8-9+) relative to lower alkalinity surface waters (Mushet et al., 2015).Prairie pothole wetlands provide significant ecosystem services ranging from important waterfowl habitats to pesticide attenuation and carbon sequestration (Euliss et al., 2006;Zeng et al., 2011Zeng et al., , 2012. However, landscape alterations caused by increased agricultural activity in the PPR (e.g., loss of wetlands, tilling of soils) may negatively impact these important ecosystem functions. For example, 90% of wetlands in the Des Moines Lobe of the Iowa PPR have been lost to anthropogenic activity, with a disproportionate loss of small upland wetlands and a resulting increased mean distance between wetlands (Van Meter & Basu, 2015). Others have observed accelerating rates of wetland loss in North and South Dakota with a higher proportion of central wetlands (i.e., those in the same region as the Cottonwood Lakes Study Area) being lost to row

Spatial distribution and biogeochemistry of redox active species in arctic sedimentary porewaters and seeps

“…75 Although our measurements captured only the icefree summer behavior of redox-active solutes, it is highly likely that they are inuenced by winter hydrodynamics. 74,76,77 Future studies will be paramount in linking winter hydrodynamics, mixing, and hydrology to biogeochemical cycling in order to determine the effect of decreasing ice cover on methane production within Arctic lake sediments. Previous studies have linked methane transport from active layers of permafrost thaw and ground water into near shore, shallow areas of Toolik Lake.…”

Whither Winter: The Altered Role of Winter for Freshwaters as the Climate Changes

“…McAdams et al. (2021) observed the migration of reduced sulfur species from several centimeters below the sediment‐water interface when no ice was present in shallow Prairie Pothole lakes to at or above the sediment‐water interface under the ice. Another study found a relationship between methane oxidation and P content among different lakes (Sawakuchi et al., 2021), which could also be a redox‐related relationship given that phosphate is released from sediments at higher rates under lowered redox states (Mortimer, 1942).…”