Skip to main content Skip to secondary navigation
Journal Article

Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers

Authors: Little MG, RB Jackson


Future Carbon Capture and Storage (CCS) deployment is likely to use deep saline aquifers for CO2 storage. Small CO2 leakage (<0.1%/yr) could pose a risk to overlying fresh groundwater resources. We performed laboratory incubations of CO2 infiltration under oxidizing conditions and atmospheric pressure on freshwater aquifer samples from Aquia (MD), Virginia Beach (VA), Mahomet (IL), and Ogallala (TX) for > 300 days with three goals: 1) understand how CO2 leakage affects shallow freshwater quality; 2) develop selection criteria for sequestration sites based on inorganic metal contamination caused by CO2 leaks; and 3) identify geochemical signatures for early-detection criteria. After exposure to CO2, water pH declines of 1-2 units were apparent in all aquifer samples. CO2 caused concentrations of the alkali and alkaline earths and some transition metals (Mn, Co, Ni, and Fe) to increase by more than 2 orders of magnitude. Potentially dangerous elements U and Ba continued to increase over the entire 300 days of monitoring in some samples. Mobility of solid phase metals, carbonate buffering capacity, and redox state of the shallow overlying aquifer all control the impact on groundwater quality and should be considered when selecting deep, underlying sequestration sites. Mn, Fe, Ca, and pH should be used as geochemical markers of a CO2 leak because they respond substantially within 2 weeks of exposure to CO2.
est2010.pdf
Journal Name
Environmental Science and Technology, in press
Publication Date
2010
DOI
doi:10.1021/es102235w