| Project Detail |
A novel approach to measure the speed of rock weathering and CO2 reduction
The natural conversion of rocks into soil by chemical weathering regulates atmospheric CO2. Although basalt and carbonate are particularly efficiently weathered, current rate measuring techniques are ineffective on these rock types. In a scientific first, the ERC-funded DEVENDRA project will create a universal erosion and weathering rate measuring system based on the comparison of beryllium isotopes. Using various soil and catchment samples, it will determine the laws governing lithologic weathering and CO2 reduction. This will allow refined quantification of the global carbon cycle over geological time scales and offer an extrapolation of the fate of man-made CO2 emissions over the next centuries. The project will also facilitate an evaluation of active CO2 reduction by artificially enhanced weathering using basalt.
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: as estimated from studies of the dissolved elements in rivers, basalt accounts for 20-35% of modern global silicate weathering and CO2 consumption flux, despite only covering 5% of Earth’s surface. 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. Currently, however, we lack the tools needed to decipher these controls, 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. |
