ENVIRONMENTAL IMPACTS OF CO2 LEAKAGES FROM STORAGE SITES ON THE QUALITY OF POTABLE GROUNDWATER OF SHALLOW AQUIFERS

摘要

Leakages of CO2 from storage sites to shallow aquifers could have adverse impacts on the groundwater quality. A well-sorted silica sand is modified by the pH-controlled precipitation of eight metals(Cr,Mn,Fe,Co,Ni,Cu,Zn,Cd). Carbon dioxide and water are co-injected in a fixed-bed column packed with the modified sand,and the metal concentration in effluent is measured with atomic absorption spectroscopy(AAS). Mineralogical analysis of sand before and after the flow tests is done by Scanning Electron Microscopy – X-ray Energy Dispersive Spectroscopy(SEM-EDS),X-ray Photoelectron Spectroscopy(XPS),and AAS. Due to continuous CO2 dissolution,the release of Mn,Ni,Cu,Zn,Co is enhanced profoundly,the release of Cr increases moderately,the Cd dissolution accelerates,whereas Fe is strongly bonded as goethite and does not dissolve almost at all. The inverse modeling of the flow test results with a model coupling the mass-transfer with reactive processes enables us to quantify the dynamics of metal release in terms of equilibrium and kinetic desorption parameters,estimated under realistic flow conditions.