Isotope techniques in hydrology and sedimentology

Water is the foundation of all life on Earth. Although two thirds of the terrestrial surface are covered by water (estimated volume is 1.5 billion cubic meters), just 2% of this total are fresh water, most of it locked in glaciers, ice caps and in deep groundwater reservoirs. Only 2,000 cubic kilometers are estimated to be available for consumption. Water resources have become more and more scarce, and the utilization becomes increasingly costly, due to the impact caused by over-exploitation and by diversified fronts of pollution. Specialists have been working in the development and in the application of several techniques to face this problem and to produce sustainable solutions. Isotope techniques represent a group of widespread tools that have been used along many years, and have become outstanding in hydrological investigation. This paper introduces a comprehensive review of the isotope techniques, taking into account environmental isotopes (stable and radioactive), artificial tracers and the use of radioactive sealed sources. Potentialities and limitations, future perspectives, as well as risks and benefits are also discussed. (author)