Boron Isotope Fractionation in Soils at Shale Hills CZO

Isotope fractionation of many elements can fingerprint the biogeochemical, weathering and erosion processes that govern the evolution of the Critical Zone (CZ). This study investigates boron isotope fractionation in two soil profiles developed on the same shale bedrock at Shale Hills Critical Zone Observatory. The first soil profile, located at the valley floor, is isotopically similar to the bedrock and appears to have lost boron mostly through the loss of fine particles matter (clays) with no isotopic fractionation. The second soil profile, located at the ridge top appears to be more depleted in boron concentration and isotopically fractionated toward lower values, as expected from mineral dissolution followed by adsorption/co-precipitation processes.