The trace element geochemistry upon carbon mineral storage in fresh and altered basalt: An experimental study at ambient temperature

Abstract

Industrial revolution and urbanization of modern society is causing a positive feedback on the global CO2 cycle and changes in climate patterns. In effort to reduce the effects of climate change, CO2 has to be synthetically removed from the atmosphere and stored long-term. The aim of this study is to understand the implication of CO2 sequestration in low temperature geothermal area in the Reykjanes peninsula of the Southwest Iceland through laboratory scale experiments mimicking water-rock interaction at the injection site. The experiments were performed using fresh basaltic glass (BG) and altered basalt (LTAB) at pH 3 and pH 5 at ambient temperature. Mineral composition of LTAB includes quartz, albite, K-feldspar, epidote, prehnite, saponite clay, zeolite, titanite, chlorite, epidote and calcite. The available divalent cation in the bulk rock composition in BG was 6.0 mol/kg and in LTAB was 5.8 mol/kg. As 1 mole of divalent cation is required to fix 1 mole of CO2, BG has slightly higher potential for CO2 fixation than LTAB. The leaching of elements were higher in pH 3 for both rock types, where BG has slightly higher elemental leaching than LTAB. Among the measured metals, Al, Fe, and Mn exceeded WHO 2017 safe drinking water guidelines and Cu exceeded Icelandic Ministry of Environment surface water category III regulation. Mobility of elements were higher in LTAB in both pH. Secondary precipitation of carbonates, oxyhydroxides, hydroxides, and oxides complexes can scavenge trace metals and cease their mobility in solution.