Seasonal cryogenic processes control supra-permafrost pore water chemistry in two contrasting Cryosols

Abstract Over the last decades, Arctic landscapes have experienced intense warming leading to permafrost degradation and rapid ecosystem changes. Active layer thickening, widespread melting of ground ice and thermo-erosion have affected the mobilization of organic and mineral elements. While the carbon and nitrogen cycles are intensively studied, the soil weathering has been less documented. In the present study, we monitored the chemistry of soil capillary and gravitational pore waters, rainfall and stream waters daily during the growing season in two experimental sites under tussock tundra vegetation in the low-Arctic region, in Salluit (Nunavik, Canada). We aimed to investigate the seasonal thaw controls on the evolution of concentrations of major organic and inorganic elements in the active layer (i.e., seasonally thawed surface layers) of two permafrost soils (Cryosols) differing in parental materials: an ombrotrophic bog (i.e., Histic Cryosol) and post-glacial marine sediments continuously waterlogged (i.e., Turbic Cryosol). In the Histic Cryosol, the electrical conductivity was