Raudsepp et al. (2025): The fate of CO₂, Ca, and Mg after terrestrial rock weathering
Maija J. Raudsepp, Sasha Wilson and Benjamin M. Tutolo, IN: Geology, https://doi.org/10.1130/G53354.1
The silicate−carbonate cycle controls atmospheric CO₂ concentrations and moderates Earth’s climate over geologic time scales. Chemical weathering of silicate minerals by CO₂ results in the release of cations and the neutralization of CO₂ to HCO₃⁻ or CO₃²⁻. The precipitation of Ca- and Mg-carbonate minerals is expected once waters are supersaturated. However, quantifying the magnitude of supersaturation required, particularly for Mg-carbonates, has remained challenging. Here the authors present a database of 854 water samples from the Central Plateau, British Columbia, Canada, representing a wide range of salinities, including both Na−(SO₄)−HCO₃−CO₃ and Mg−Na−SO₄ hypersaline lakes, to determine the geochemical thresholds for Ca- and Mg-carbonate formation.