C. Marjorie Aelion is dean of the School of Public Health and Health Sciences at the University of Massachusetts, Amherst. She worked for the U.S. Geological Survey, Water Resources Division, as a hydrologist for three years before beginning her academic career at the University of South Carolina in Columbia as an assistant professor, associate professor, professor, and associate dean for research. Her research interests lie in the assessment of biodegradation and bioremediation of organic contaminants, and associations between soil metals and negative childhood health outcomes. Ramon Aravena is a research professor in the Department of Earth and Environmental Sciences at the University of Waterloo, Ontario, Canada. Dr. Aravena's research has focused on the application of environmental isotopes in hydrology, geochemistry, and quaternary geology. He has been involved in numerous groundwater studies in Latin America, Canada, the United States, and Europe related to evaluation of groundwater resources and groundwater contamination. Patrick Hohener is a professor in hydrogeochemistry at the University of Provence, Marseille. He obtained a Ph.D in environmental sciences in 1990 from the Swiss Federal Institute of Technology, where he later had a position as lecturer at Zurich and Lausanne. His research interests lie in the management and remediation of soils and aquifers contaminated with organic chemicals. Daniel Hunkeler is professor for groundwater quality at the Centre for Hydrogeology of the University of Neuchatel, Switzerland and adjunct professor at the University of Waterloo, Canada. He obtained a Ph.D from the Swiss Federal Institute for Technology, Zurich. His research focuses on the development of stable isotope methods and their application to gain insight into the contaminant behavior at the field scale.