Quantification of CO 2 uptake by enhanced weathering of silicate minerals applied to acidic soils

• Published in: International Journal of Greenhouse Gas Control
• Main Authors: Dietzen, Christiana, Rosing, Minik T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Alkalinity; Carbon sequestration; Enhanced rock weathering; Glacial rock flour; Silicate minerals; Soil amendment; Carbonic acid; greenlandic
• Online Access: https://curis.ku.dk/portal/da/publications/quantification-of-co2-uptake-by-enhanced-weathering-of-silicate-minerals-applied-to-acidic-soils(71ba6d34-01c5-4c06-a467-50364eca8357).html; https://doi.org/10.1016/j.ijggc.2023.103872; https://curis.ku.dk/ws/files/346411070/1_s2.0_S1750583623000427_main.pdf

The application of ground silicate minerals to agricultural soils has been proposed as a method for taking up CO 2 by enhancing the weathering rate of these minerals through their exposure to soil acids. Alternatively, glacial rock flour, a finely grained material which is abundantly available without the need for energy-intensive grinding, could be used. However, simple and inexpensive methods for determining the amount of CO 2 taken up as a result of weathering of applied minerals are still needed, and the impact of non-carbonic acids on CO 2 uptake has yet to be accounted for. Here, we present a protocol for correcting estimates of CO 2 uptake due to enhanced mineral weathering to account for weathering by non-carbonic soil acids. We determine that soils with a pH below 6.3 need correction for weathering by other acids than carbonic acid and that, given the impact of non-carbonic acids, soils with a pH below 5.2 may not be ideal candidates for mineral applications aimed at CO 2 uptake, depending on the pCO 2 . We report an estimated CO 2 uptake of 728 kg CO 2 ha −1 after the application of 50 tons ha −1 of Greenlandic glacial rock flour to an acidic, sandy soil in Denmark over 3 years.