Understanding the Chemical Weathering Rate and Element Mobility of Soils: Using U-Series, Nd-Sr Isotopes Ree and Quantum Chemistry Computational Simulation

Soil played as the central role in the interaction of biosphere, hydrosphere, lithosphere and atmosphere and is the heart of earth’s critical zone study. The weathering and element mobility of soils have drawn considerable attention in soil studies since the complexity of these processes and the critical influence towards the earth and humanity, e.g., the global carbon cycles and fertilization. However, the interaction between soils and various factors including precipitation, bedrock ages, altitude is not well understood. Basse-Terre Island at French Guadeloupe, a small volcanic tropical island that has steep environmental gradients of bedrock ages, topography and precipitation, can be a great object to study soil weathering and development. This dissertation aims at contributing to the soil studies of Guadeloupe island as well as lesser Antilles by targeting at the chemical weathering rate of weathering clasts, the dust contribution and REE movement across the soil profiles. Tools we applied in this study including U-series dating technique, Sr-Nd isotopes as well as computational simulation. The dissertation helped answering several key questions including the relationship between soil weathering/element mobility and the environmental gradients, the scale discrepancy between weathering rate at different scale, and the uranium mobility at different pH condition