Project description:

The chemical weathering of rocks on the Earth’s surface draws down atmospheric CO₂, balancing emissions from volcanoes and maintaining habitable temperatures. Basalt and carbonate rocks are particularly crucial in this balance, because they are efficiently weathered. To formulate sensitivities and feedbacks between weathering of these rocks and climate, we need an accurate description of the exact processes that drive the conversion of rock to soil by weathering. Besides water flow, erosion rate and vegetation are thought to exercise significant control. The chemical composition of water flowing in rivers are commonly used to infer the weathering rates. Currently, however, we lack the tools needed to decipher the underlying controls when rock turns to soil, because the preferred approach used to quantify erosion and weathering rates – cosmogenic nuclides, produced in situ in quartz – does not work in basalt and carbonate lithologies.

The aim of DEVENDRA, dedicated to the pioneer of cosmogenic nuclide geochemistry Devendra Lal (1920 – 2012), is to eliminate this blind spot using a novel method never applied to basalt and carbonate lithologies: the ratio of cosmogenic beryllium-10 rained out from the atmosphere to stable beryllium-9 released by weathering. DEVENDRA will develop this system as a novel erosion and weathering rate meter for these rocks, and will use this new method to calibrate – using globally-distributed soil profiles and catchments of differing climate and erosion rate – the laws that govern weathering and CO₂ drawdown in these rocks. The outcomes from DEVENDRA will refine the global weathering models that are used to understand Earth’s carbon cycle on geological time scales, to predict the trajectory of anthropogenic CO₂ in coming centuries, and to estimate the potential for negative CO₂ emissions by artificially-enhanced weathering of basalts.

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