647 / 2024-09-18 19:48:42

Impact of Particle Size on Olivine Weathering and Alkalinity Enhancement in Coastal Areas

olivine weathering; coastal areas; particle size

       The continuous rise in atmospheric CO2 levels due to the burning of fossil fuels and other human activities has led to global warming. Controlling the atmospheric CO2 level and mitigating global warming have thus become a priority of global action. Currently, the natural weathering of rocks consumes approximately 1.1 Gt CO2 annualy from the atmosphere. The deployment of olivine mineral particles in coastal marine areas has been shown the potential to not only sequester atmospheric CO2 but also to alleviate ocean acidification. Previous studies have shown that coastal wave action can wear down mineral particles and increase the dissolution rate of olivine minerals. The particle size has been identified as a key factor affecting the dissolution rate of olivine, with smaller particles more readily to dissolve. However, it is also suggested that there may be a potential negative impact of overly small olivine particles on the abrasive effects of wave action, which is not yet fully understood.

        This study utilizes a laboratory setting to simulate the wave processes in coastal areas and to explore the dissolution differences between two sizes of olivine particles (ie., coarse with D50=100~150 μm and fine with D50=30~45 μm) under vibration and static conditions. We reveal that the dissolution rate of fine olivine particles do not significantly differ between the two conditions, both exhibiting strong negative reactions, with the static experiments showing a more intense negative response. In contrast, the dissolution rate of coarse olivine particles under vibration conditions was found to be 1~2 times higher, indicating a weaker negative reaction.