Lithium isotopes as a tracer for changes in interg.. (LITING)
Lithium isotopes as a tracer for changes in interglacial-glacial weathering processes
Start date: Sep 16, 2013,
End date: Jun 7, 2016
Silicate weathering is a long term CO2 sink and silicate weathering rates influence, and are influenced by, climate change. Understanding the environmental factors which control silicate weathering rates will enable a greater understanding of both past and future global climate. This project focuses on the effect of climate change (on glacial-interglacial timescales) on weathering rates which is currently poorly understood. This is important not only for CO2 consumption by silicate weathering but also nutrient supply to terrestrial and marine ecosystems. Weathering processes are expected to change during glacial-interglacial transitions and this project will quantify changes in weathering intensity over different time-scales using lithium isotope ratios. Lithium isotopes have been proposed as a sensitive tracer of weathering processes but a complete understanding of their behaviour in the weathering environment is still lacking. A three-pronged approach will be used which combines samples from lithologically identical glaciated and unglaciated catchments, laboratory experiments and a marine sediment core. All samples are derived from the high Arctic: a region which has witnessed repeated glaciation in the past and is the region on Earth most sensitive to modern climate change. The laboratory experiments will quantify lithium isotope fractionation as a result of specific weathering reactions, enabling differences in the lithium isotopic composition of field samples to be linked directly to specific weathering processes. Utilising the results of the field samples and laboratory experiments, the marine sediment core will be used to quantify how weathering intensity has changed in the past in response to well documented dramatic changes in climate. This will pave the way for the development of a new proxy of chemical weathering intensity applicable on a global scale and will serve to establish the European research area as a world leader in weathering processes.
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