Winter Soil Processes in Transition

PI: Fereidoun Rezanezhad, University of Waterloo

Co-I's: Philippe Van Cappellen; David Rudolph, Laura Hug; Scott Smith, University of Waterloo

In an uncertain future climate, both the quantity and quality of water supplied by headwater wetland source areas in cold regions are expected to change significantly. However, our knowledge of how climate change will impact the biogeochemical functioning and hydrochemistry of these source areas remains limited. We propose to elucidate the role of winter soil processes on the export of carbon (C) and nutrients (N, P, S, Fe) to the river network under changing climate conditions. The project builds on the hypothesis that spring pulses of dissolved organic and inorganic C and nutrients by these headwaters reflect the cumulative effects of microbial and geochemical processing of redox sensitive elements during the non-growing season. The project will advance the predictive understanding of C and nutrient cycling in soils of headwater source areas under seasonal snow and ice cover. The project specifically aims to improve our conceptual and quantitative understanding of changes in C and nutrient stocks, speciation and fluxes driven by variations in snow cover and freeze-thaw cycles. The data collected in laboratory experiments will be integrated into reactive transport and bioenergetic modeling to simulate the biogeochemical transformations of C and nutrients in winter soils under changing climate conditions. The data and insights gained through the proposed laboratory-controlled experimental and modeling activities will yield a better conceptual understanding of shallow subsurface biogeochemical processes and strengthen their representation in coupled biogeochemical-hydrological catchment models. Overall, the proposed project will enhance our ability to evaluate the impact of different potential climatic scenarios on C and nutrient export and speciation along the aquatic continuum.