Olivine Dissolution in Seawater: Implications for CO^sub 2^ Sequestration through Enhanced Weathering in Coastal Environments

Enhanced weathering of (ultra)basic silicate rocks such as olivine-rich dunite has been proposed as a large-scale climate engineering approach. When implemented in coastal environments, olivine weathering is expected to increase seawater alkalinity, thus resulting in additional CO^sub 2^ uptake from...

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Bibliographic Details
Published in:Environmental science & technology 2017-04, Vol.51 (7), p.3960
Main Authors: Montserrat, Francesc, Renforth, Phil, Hartmann, Jens, Leermakers, Martine, Knops, Pol, Meysman, Filip J R
Format: Article
Language:English
Subjects:
Alkalinity
Carbon monoxide
Carbon sequestration
Climate change
Climate change mitigation
Coastal engineering
Coastal environments
Dissolution
Dunite
Emissions
Ocean floor
Olivine
Pore water
Seawater
Water pollution effects
Weathering
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Summary:Enhanced weathering of (ultra)basic silicate rocks such as olivine-rich dunite has been proposed as a large-scale climate engineering approach. When implemented in coastal environments, olivine weathering is expected to increase seawater alkalinity, thus resulting in additional CO^sub 2^ uptake from the atmosphere. However, the mechanisms of marine olivine weathering and its effect on seawater-carbonate chemistry remain poorly understood. Here, we present results from batch reaction experiments, in which forsteritic olivine was subjected to rotational agitation in different seawater media for periods of days to months. Olivine dissolution caused a significant increase in alkalinity of the seawater with a consequent DIC increase due to CO^sub 2^ invasion, thus confirming viability of the basic concept of enhanced silicate weathering. However, our experiments also identified several important challenges with respect to the detailed quantification of the CO^sub 2^ sequestration efficiency under field conditions, which include nonstoichiometric dissolution, potential pore water saturation in the seabed, and the potential occurrence of secondary reactions. Before enhanced weathering of olivine in coastal environments can be considered an option for realizing negative CO^sub 2^ emissions for climate mitigation purposes, these aspects need further experimental assessment.
ISSN:0013-936X