Evaluating enhanced mineral weathering of olivine as a carbon dioxide removal method in coastal wetland sediments of New South Wales, Australia

The silicate mineral olivine naturally weathers, reacting with carbon dioxide and water to produce alkalinity, dissolved silica, and base cations. Due to this weathering effect, olivine is a candidate for developing methods of carbon dioxide removal. Olivine dissolution can be enhanced by grinding the mineral to a powder and subjecting it to conditions that are conducive to faster weathering. To determine whether olivine weathering is effective as carbon dioxide removal in coastal marine ecosystems, sediment cores from three different types of sediment collected from a New South Wales wetland were incubated with and without olivine. Different sediment types included benthic mud from a mangrove creek, sediment from a salt marsh, and inert sand that was used as a control. These cores were placed in saltwater mesocosms that simulated natural conditions with LED aquarium lights and temperature controllers. Experimental cores had olivine dust applied, whereas control cores were not treated. Intermittent sampling was done over a three-week period to determine changes in alkalinity, pH, dissolved oxygen, and nickel and chromium, which are trace products of olivine weathering. Fluxes of alkalinity, dissolved inorganic carbon and dissolved oxygen were calculated for six 24-hour periods within the experimental timeline. Higher alkalinity fluxes were recorded in cores containing olivine dust, suggesting weathering occurred under these conditions, however, there were differences between the different sediment types.

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Primary Presenter: James Westphalen, Georgia Southern University (westphalenjames@gmail.com)

Authors:

James Westphalen, Georgia Southern University  (westphalenjames@gmail.com)