in: Isoscapes Understanding movement pattern and process on Earth through isotope mapping, J.B. West,G.J. Bowen,T.E. Dawson and K.P. Tu, Editor, Springer, London/Berlin , Heidelberg, pp.33-50, 2010
Environmental isotopes in water and other substances have been extensively used for almost five decades to improve our understanding of hydrologic, climatologic, oceanographic processes as well as other environmental processes involving several geochemical cycles. In case of the water cycle, oxygen-18, deuterium, tritium and carbon-14, among other isotopes, are considered excellent tracers of the water molecule and dissolved salts, providing information on processes in the hydrosphere or residence time indicators in water systems. Environmental isotopes have been used in hydrological studies for addressing issues such as recharge processes, origin of water, groundwater dynamics, vulnerability to pollution and interconnections among different water bodies.
Most applications of environmental isotopes rely on the analysis of temporal and/or spatial variability of isotope ratios in the different components of the water cycle, particularly precipitation, surface water and groundwater. In this chapter, we review the current status of isotope databases, operation of the monitoring networks and compilation and dissemination of isotope data on the global scale. Most of the databases mentioned in the chapter are maintained and updated by the IAEA, but other global isotope data sets, compiled by national or international organizations, are also decribed.