ABSTRACT
Karst groundwaters can be characterized by natural or anthropogenic tracers including isotopes (this chapter), hydrochemical constituents (chapter 6), and artificial tracers such as fluorescent dyes (chapter 8). Isotopic data elucidate the origin and age of karst waters and the rocks that enclose them, and show that mixing and carbonate reactivity are major variables. Many isotopic systems are useful, but those highlighted here offer particularly important insights into the nature of karst systems. In our experience the most reliable approach that leads to predictions useful for groundwater management is high frequency time series analysis of stable isotopes, followed by a modest number of isotopic age-dating measurements for residence time verification. We review both types of isotopic systems and introduce interpretive methods that factor in dispersion and reactivity in order to delineate sources and residence times.
