I conduct long-term investigations on the fate and geochemical effect of organic contaminants in subsurface environments. I use a combined field and laboratory approach in a variety of hydrogeologic environments in order to meet these objectives. The principal questions being addressed by this project are: 1. How do long-term changes in biogeochemical processes affect the fate of organic and inorganic constituents in aquatic environments? and 2. Does availability of electron acceptors and electron donors control the progress of degradation reactions? My overarching objective is to increase our understanding of the transformation of contaminants from hydrocarbon spills, wastewaters from oil and gas development, and landfill leachate, and how those transformation processes impact aquifer and wetland chemistry over the long-term. My research has been largely at Toxic Substances Hydrology sites and is highly interdisciplinary, focusing on the coupled hydrogeological, microbiological, and geochemical processes that control the redox potential of subsurface systems and are a fundamental issue in understanding nutrient and contaminant biogeochemical cycles and in protecting drinking water and ecosystem health.