Calcite is an efficient and low-cost material to enhance benthic weathering in shelf sediments of the Baltic Sea

Abstract

Recent studies have proposed calcite and dunite as possible alkaline materials for enhanced benthic weathering in shallow depocenters of the Baltic Sea as a marine carbon dioxide removal strategy. In this study, insights on calcite and dunite weathering from laboratory incubations and long-term benthocosm experiments are combined with a numerical box-model to assess the carbon dioxide uptake potential of mineral addition to organic-rich sediments in the southwest Baltic Sea. The results reveal that calcite has an up to 10-fold higher carbon dioxide uptake efficiency and is therefore the preferable material for enhanced benthic weathering as a marine carbon dioxide removal method, with costs per tonne of sequestered carbon dioxide ranging between 82 and 462 euro for calcite while reaching 558–1920 euro for dunite. These findings could be applicable to other areas in the Baltic Sea and also globally to sediments in the wider coastal shelf with similar geochemical properties.