Estuary is the promising site for olivine-dissolution engineering: Insight from olivine mineralogy

Published 22 January 2024 Science Leave a Comment
Tags: mitigation

To keep global warming below 1.5 °C to address the threats posed by global climate change, various geoengineering strategies based on increasing the negative carbon emissions in oceans have been proposed, considering the ocean the largest reservoir of carbon [1, 2]. Dissolution of silicate minerals, such as olivine, is one promising engineering that not only depletes carbon dioxide (CO2) but reduces ocean acidification. Olivine is the most abundant mineral in the earth’s upper mantle [3]. Olivine consists of a hexagonal close-packed array of oxygen atoms from Si-O tetrahedrons lying parallel to (100) (Figure 1) [4]. Olivine is a magnesium iron silicate with the formula (Mg2+, Fe2+)2SiO4 and has an orthorhombic crystal system. In olivine, the Mg2+ and Fe2+ ions form a complete isomorphic series, and forsterite and fayalite are the two end-member minerals of the olivine group. The Mg-O and Fe-O bonds in olivine have a much lower bond energy than thatof Si-O bonds [4]. Moreover, bridging oxygen atoms lack between Si and Mg, and thus Mg2+ is more easily released from the olivine’s surface during dissolution [5]. The dissolution reaction of olivine depends on H+ ions, which form an activated complex with Mg2+ and enhance its removal from the olivine’s surface, damaging its structures [5]. Therefore, the dissolution of olivine led to a significant increase in seawater alkalinity. And meanwhile, olivine dissolution also consumes CO2.

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Liu D., Yu R. & Yuan P., 2023. Estuary is the promising site for olivine-dissolution engineering: Insight from olivine mineralogy. Ocean-Land-Atmosphere Research: 0039. doi: 10.34133/olar.0039. Article.

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