Reconstructing past and present chemical weathering conditions via lithium isotopes

Continental weathering processes not only shape the Earth’s surface but may also play a significant role in regulating global climate. Over geologic time scales, one of the major controls on atmospheric CO2 is continental silicate weathering, where carbon dioxide is consumed during weathering reactions. However, the coupling between CO2 consumption via silicate weathering and climate is still poorly understood. Even less is known how weathering-related CO2 consumption responds to climatic oscillations. Besides silicate weathering and its importance on the atmospheric CO2 cycle, weathering processes are directly related to soil formation. Soils are key environmental resource, which sustains most life on land. Understanding how soil formation responds to climatic oscillations and human impact via agricultural practises is of critical importance. To fully comprehend the environmental controls on chemical weathering, a reliable proxy is essential. In this PhD thesis, lithium (Li) isotopes, a non-traditional chemical weathering proxy, is applied to two contrasting environmental settings: a river basin and a lake catchment. These contrasting environments were chosen to test how Li isotopes evolve spatially and temporally in a relatively large-scale river in contrast to a small-scale lacustrine setting.