SHORT-TERM EFFECTS OF VARIABLE SNOWPACK ON SOIL CHEMICAL AND BIOPHYSICAL WEATHERING

Climate and snowpack variability regulate hydrologic conditions that affect the physical and chemical processes in underlying soils. Weathering processes are often anticipated to occur over millennial temporal scales, however, relatively little is quantitatively known about how snowpack influences chemical weathering, nutrient release, and general soil evolution on shorter time scales. Here we use a 47-year snowpack manipulation experiment located in the Greater Yellowstone Ecosystem (GYE) in order to quantify soil evolution as affected by snowpack over decadal temporal scales. We use fallout radiogenic nuclide (¹³⁷Cs and ²¹⁰Pb) concentrations within soil profiles to quantify biogenic soil mixing and hydrologically-driven redistribution over these time scales. Preliminary data from over 200 samples across nine soil cores suggest that snowpack manipulation (4X and 2X ambient levels) significantly impacts the isotopic character of soil profiles, with fallout-nuclide profiles in enhanced snowpack sites indicative of significant redistribution of soil. Coupling these measurements with numerical advection-diffusion models, we find notable differences in the physical weathering of soils associated with decadal changes in snowpack. Isotopic data will be supplemented by lab-based analysis of soil texture, soil carbon, and elemental chemistry to determine whether short-term snowpack variability also influences chemical weathering mechanisms. This research provides new insights into snowpack variation effects on chemical and biophysical weathering, with important implications on how weathering processes are influenced by climate.