Northeastern Section - 49th Annual Meeting (23–25 March)

Paper No. 3
Presentation Time: 8:00 AM-12:00 PM


HEW, Melissa D.E., Environmental Science, Towson University, Towson, MD 21252, MOORE, Joel, Towson Univ, Towson, MD 21252-0001 and NAVARRE-SITCHLER, Alexis, Environmental Science & Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401,

Industrial development and activity over the past 100 years has resulted in a significant increase in atmospheric CO2 concentrations. Injection of supercritical CO2 into subsurface reservoirs, termed geologic carbon sequestration and storage, is emerging as a feasible method for reducing CO2 emissions. Potential storage sites include deep sedimentary basins, depleted oil reservoirs, or coal beds. While geologic storage represents a viable option for reducing carbon dioxide emissions, the possibility of a CO2 leak from deep storage sites into shallow aquifers is a concern. Leakage of can lead to acidification of ground water and subsequent geochemical reactions that have the potential to release trace metals as well as major elements such as Ca, K, Mg, and Na and degrade water quality. Early detection of CO2 leaks from subsurface storage sites will be key in mitigating any potential adverse affects associated with increased concentrations of CO2 in shallow drinking water aquifers.

In order to detect changes in aqueous chemistry driven by CO2 leaks, it is important to understand the natural variability of groundwater chemical parameters. Changes in ground water chemistry as a result of acidification only will be detectable if the variations resulting from CO2 leaks exceed natural variability of the groundwater chemistry. Comparing model results of CO2–driven changes in water chemistry to natural variability will allow us to determine the likelihood of early detection depending on the size and extent of CO2leaks from subsurface repositories.

To analyze natural variability, we analyzed the concentrations and ratios of major elements as well as trace metals from an existing dataset collected by the Ohio EPA to determine the natural variability of groundwater chemistry in wells from unconsolidated sediments, sandstone, and limestone wells. A key focus of our analysis was within-well variability across wells that have at least 15 years of data. Relationships between concentrations of major elements as well as trace metals were evaluated for significant correlations and should provide insight on the natural variability of major elements as well as trace metals. Reactive transport models will be used to quantify the size of CO2 fluxes needed to produce changes in groundwater chemistry that exceed natural variability.