Environmental Isotopes

Abstract

Environmental isotopes are useful tools for evaluating the source and time of precipitation of groundwater and geochemical reactions during groundwater flow (i.e., fluid–rock interactions). Such data can be used to estimate recharge rates, regional groundwater flow rates, and the time of emplacement of fossil groundwater. Isotopic analyses are not a routine element of water resources investigations largely because of their costs and the nature of the information they can provide. Environmental isotopic analyses have been typically applied to large (basin) scale investigations. Some of the applications of environmental isotopes have been of more academic than applied hydrogeological interest. For example, determination of the age of non-renewable groundwater resources usually does not have much bearing on current water management, so long as it is recognized that the groundwater is in fact non-renewable on a human time scale. From a practical perspective, it matters little if water is 10,000 years old or 1,000,000 years old.