Linke et al. (2024): Direct evidence of CO2 drawdown through enhanced weathering in soils

T. Linke, E.H. Oelkers, S.C. Möckel, S.R. Gislason IN: Geochemical Perspectives Letters, https://doi.org/10.7185/geochemlet.2415

Here the authors report the carbon balance in an Icelandic Histic/Gleyic Andosol that has received large quantities of basaltic dust over 3300 years, providing opportunity to quantify the rates and long term consequences of enhanced weathering. The added basaltic dust has dissolved continuously since its deposition. The alkalinity of the soil waters is more than 10 times higher than in equivalent basalt dust-free soils. After accounting for oxidation and degassing when the soil waters are exposed to the atmosphere, the annual CO₂ drawdown due to alkalinity generation is 0.17 t C ha⁻¹ yr⁻¹. This study validates the ability of fine grained mafic mineral addition to soils to attenuate increasing atmospheric CO₂ by alkalinity export. Induced changes in soil organic carbon storage, however, likely dominate the net CO₂ drawdown of enhanced weathering efforts.

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