Publication
Title
Enhanced olivine dissolution in seawater through continuous grain collisions
Author
Abstract
Carbon dioxide removal (CDR) technologies at a gigaton scale need to be developed and implemented within the next decades to keep global warming below 1.5 °C. Coastal enhanced silicate weathering is one of the proposed CDR techniques that aims to accelerate the natural process of CO2-sequestration during marine chemical weathering of silicate minerals. To this end, finely ground rock containing olivine (MgxFe2-xSiO4) could be dispersed in dynamic coastal environments, where local biotic and abiotic factors potentially enhance the weathering process. However, accurate predictions of the olivine dissolution rate and the associated CO2 sequestration under in situ conditions are currently lacking and ecosystem impacts remain to be assessed. Previously, it has been hypothesized that in situ grain collisions, induced by bed load transport due to currents and waves, could accelerate the in situ chemical weathering of olivine particles. To examine this, we investigated the effects of continuous grain tumbling on olivine dissolution in natural seawater. A 70-day experiment was conducted in which forsterite olivine sand was continuously tumbled in filtered seawater at different rotation speeds, and dissolution rates were measured on a weekly basis. Results showed that continuously tumbled olivine dissolved 8 to 19 times faster compared to stagnant (no rotation) conditions. Olivine dissolution was complete and stoichiometric (except for Ni release), air-seawater CO2 exchange was not significantly rate limiting, and minimal particle fragmentation and secondary mineral formation were observed. Hence, we infer that olivine weathering was mainly enhanced via advective pore water flushing, which limits saturation effects at the grain scale. Overall, this study provides evidence that ambient physical stresses in coastal environments could enhance marine silicate weathering, which has implications for both the natural silicon cycle as well as the use of enhanced coastal weathering of silicates as a CDR technique.
Language
English
Source (journal)
Geochimica et cosmochimica acta. - Oxford, 1950, currens
Publication
Oxford : 2023
ISSN
0016-7037 [print]
1872-9533 [online]
DOI
10.1016/J.GCA.2023.09.002
Volume/pages
359 (2023) , p. 84-99
ISI
001081586000001
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Project info
Negative emissions through enhanced mineral weathering in the coastal zone.
Negative emissions through enhanced mineral weathering in the coastal zone.
Negative emissions through enhanced mineral weathering in the coastal zone.
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identifier
Creation 15.09.2023
Last edited 07.12.2023
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