Basic Research Needs for Geosciences - Energetics Meetings and ...

PANEL REPORT: CHEMICAL MIGRATION PROCESSES IN GEOLOGIC MEDIACHEMICAL MIGRATION PROCESSES IN GEOLOGIC MEDIACURRENT STATUSThe ability to predict the transport of energy byproducts and related contaminants in geologicalsystems over long times is one of the most important and daunting challenges facing theDepartment of Energy (DOE). For example, in the geological disposal of nuclear waste, the mainscenario in which radionuclides could reach the biosphere and expose humans to unacceptablyhigh radiation doses is through groundwater transport (Macfarlane and Ewing 2006).Groundwater may contact and corrode waste containers, leach radionuclides from wasteforms,and transport radionuclides as dissolved species or colloids (e.g., Kersting et al. 1999; Santschi etal. 2002) to wells used to extract drinking or irrigation water (Figure 4). As a second example,one mode of sequestering CO 2 in the earth is by injection into subsurface rock units. Evaluatingthe long-term integrity of these rock units, and therefore their ability to retain the CO 2 , willdepend on the chemical and physical interactions that occur among minerals, in-place pore fluid,and the CO 2 . In all cases, forecasting how chemical byproducts and related contaminants maymigrate through deep subsurface regions of the earth must be accurate and scientificallydefendable. This requires that we understand the key chemical and transport processes that occurin geological systems.Figure 4. Illustration of possible contaminant migration pathways in the geologic system at Yucca Mountain,Nevada (CRWMS M&O 2000).Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems 23