| Summary: | Climate change is having a direct impact on hydrological connectivity in permafrost environments1. In this work, we combine soil physics and silicon isotope geochemistry to locate pathways of hydrological connectivity in permafrost soils at Eight Mile Lake, Alaska. Silicon in soil pore waters (< 0.2 µm) can be a colloidal fraction (~ 0.2 µm to ~ 1 nm) and a truly dissolved fraction of silicic acid (~ < 1 nm), with an isotope fractionation associated with colloidal amorphous Si formation. Here we propose that soil pore waters contain different proportions of these Si pools during freezing and thawing, and apply this conceptual framework to detect the freezing and thawing conditions in permafrost soils during winter months. We propose that this approach could be applied in other cold, extreme environments to detect changes in water and nutrient flow paths. 1 Walvoord, M.A. and Kurylyk, B.L., 2016. Hydrologic impacts of thawing permafrost—A review. Vadose Zone Journal, 15(6).
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