In-field carbon dioxide removal via weathering of crushed basalt applied to acidic tropical agricultural soil.

Autor: Holden FJ; College of Science and Engineering, James Cook University, Cairns, Australia; Leverhulme Centre for Climate Change Mitigation, University of Sheffield, Sheffield, United Kingdom. Electronic address: fredrick.holden@jcu.edu.au., Davies K; College of Science and Engineering, James Cook University, Cairns, Australia; Leverhulme Centre for Climate Change Mitigation, University of Sheffield, Sheffield, United Kingdom., Bird MI; College of Science and Engineering, James Cook University, Cairns, Australia; Leverhulme Centre for Climate Change Mitigation, University of Sheffield, Sheffield, United Kingdom., Hume R; Department for Environment and Water, Adelaide, Australia., Green H; College of Science and Engineering, James Cook University, Townsville, Australia., Beerling DJ; Leverhulme Centre for Climate Change Mitigation, University of Sheffield, Sheffield, United Kingdom., Nelson PN; College of Science and Engineering, James Cook University, Cairns, Australia; Leverhulme Centre for Climate Change Mitigation, University of Sheffield, Sheffield, United Kingdom.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Dec 10; Vol. 955, pp. 176568. Date of Electronic Publication: 2024 Oct 09.
DOI: 10.1016/j.scitotenv.2024.176568
Abstrakt: Enhanced weathering (EW) of silicate rocks such as basalt provides a potential carbon dioxide removal (CDR) technology for combatting climate change. Modelling and mesocosm studies suggest significant CDR via EW but there are few field studies. This study aimed to directly measure in-field CDR via EW of basalt applied to sugarcane on acidic (pH 5.8, 0-0.25 m) Ultisol in tropical northeastern Australia, where weathering potential is high. Coarsely crushed basalt produced as a byproduct of gravel manufacture (<5 mm) was applied annually from 2018 to 2022 at 0 or 50 t ha -1 a -1 , incorporated into the soil in 2018 but not in subsequent years. Measurements in 2022 show increased soil pH and extractable Mg and Si at 0-0.25 m depth, indicating significant weathering of the basalt, but showed no increase in crop yield. Soil inorganic carbon content and bicarbonate (HCO 3 - ) flux to deep drainage (1.25 m depth) were measured to quantify CDR in the 2022-2023 wet season (i.e. one year). Soil inorganic carbon was below detection limits. Mean HCO 3 - flux was 3.15 kmol ha -1 a -1 (±0.40) in the basalt-treated plots and 2.56 kmol ha -1 a -1 (±0.18) in the untreated plots but the difference (0.59 kmol ha -1 a -1 or 0.026 t CO 2 ha -1 a -1 ) was not significant (p = 0.082). Most weathering of the basalt was attributed to acids stronger than carbonic acid. These were, in decreasing order of contribution, surface-bound protons (inherent soil acidity), nitric acid (from nitrification), organic acids, and acids associated with cation uptake by plants. These results indicate in-field CDR via EW of basalt is low where soil and regolith pH is well below the pK a1 of 6.4 for H 2 CO 3 . However, increased soil pH, and the consumption of strong acids by weathering will eventually lead to reduced CO 2 emission from soil or evasion from rivers, with continued basalt addition.
Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. D.J.B. has a minority equity stake in Future Forest/UNDO, is a member of the Advisory Board of The Carbon Community, a UK carbon removal charity, and the Scientific Advisory Council of the non-profit Carbon Technology Research Foundation. P.N.N., F.J.H., M.I.B. and H.G. receive funding for EW research from UNDO Carbon, Consolidated Pastoral Company and Sugar Research Australia.
(Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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