The Adsorption and Release of Sulfur in Mineral and Organic Soils of the Athabasca Oil Sands Region, Alberta, Canada

Mineral soil and fibric peat from acid-sensitive western boreal catchments in the Arhabasca Oil Sands Region of Alberta, Canada were evaluated for their ability to adsorb and release SO42-. Laboratory batch studies indicated that SO42- adsorption in mineral soil from both the A and B horizons exhibits a limited response to elevated SO42-. concentrations, with the slope of initial mass isotherms <0 2 for all sods, likely due to low iron and aluminum oxide content Although S retention is the dominant process in pear soils in the region, drought simulations in the lab using fibric peat collected from a pool fen exhibited as much as a five-fold increase in SO42- concentration after drying and rewetting. Given the limited SO42- adsorption capacity of mineral soils and the potential drought-induced S release from peatlands in this region where increased S deposition is expected, further investigation of acidification impacts is warranted