There remains a lack of understanding of environmental isotopes and their use; students and practitioners typically find the concepts of isotope concentrations and partitioning to be more complicated than for geochemistry. However, this need not be so, if the basics are presented together with geochemistry, using case studies and examples to make the point. This new book presents the basics of environmental isotopes and geochemistry together, with case studies and simple examples that build a real understanding of their use in natural and contaminated groundwater.