Isotopic Tracers for Waste Fluid Tracking and Fluid-Soil Interactions: Hanford, Washington

The objective of this research is to develop and advance isotopic approaches for characterizing fluid flow and chemical transport through the vadose zone to groundwater. Previous research has been concentrated on developing and comparing different isotopic systems (e.g., hydrogen, oxygen and strontium isotopes) for determining fluid infiltration rates and pathways in the vadose zone (e.g., Maher et al., 2003; DePaolo et al., 2004; Singleton et al., in press). The results demonstrate the unique advantage of studies of multiple isotopic systems for distinguishing short-term versus long-term processes. The focus of our current efforts is on using the isotopic compositions of different chemical phases (e.g., uranium, nitrate) to track their movement through the vadose zone. Preliminary results indicate that this will be a powerful tool for assessing environmental risks associated with vadose zone contamination.