Influence of a CO2 long term exposure on the mobilisation and speciation of metals in soils

Abstract This study investigates the potential risks associated with high levels and long term exposure of carbon dioxide (CO 2 ) on the mobility and speciation of exchangeable metals in soils. CO 2 incubation batch experiments at high pressure and temperature coupled with geochemical modelling were carried out to elucidate the behaviour and mobilisation of metals and the response of soil chemical parameters as a result of long term CO 2 exposure. A t -Student analysis was performed to ascertain whether differences in the mean concentration of exchangeable metals in soils before and after CO 2 -incubations are attributable to increase of metal molibilisation because of the long term CO 2 exposure. The t -Student revealed the CO 2 long term incubation was statistically significant ( p  2 -soil incubation induces the acidification of the pore water of soils via CO 2 hydrolysis and as a consequence, it increases the exchangeable concentration of Ni, Zn, and Pb in the soils. As, Al, Cr, Cu, and Fe show a different mobilisation pattern depending on the moisture content in soils. Al 3+ , Fe 2+ , Cr 3+ , and Cu 2+ as free cations, As as HAsO 2 , Pb 2+ and PbHCO 3 − , Zn 2+ and ZnHCO 3 − , are predicted to be the predominant aqueous complexes in the pore water of the incubated soils.