Monitoring dynamic changes and process in eco-environment by applying hydrogen and oxygen isotopes: a review

The hydrological cycle, or water cycle, embraces and connects all forms of water-related processes in the atmosphere and geosphere, which include water as vapour in, and precipitation from, the atmosphere, and in rivers, lakes, runoff, soil water, and groundwater. Better understanding of the interactions among various water bodies is necessary to sustainably manage and utilise precious resource. As the concentrations of the stable deuterium and oxygen-18 are relatively conservative during the change from one state to the other, and the radioactive isotope tritium provides a measure of the circulation time, isotopes have been widely applied as ideal tools of water environment management. This review briefly surveys the development of applications of hydrogen and oxygen isotopes in hydrological studies in order to report progress in the field. It begins with some fundamental isotopic concepts, and then recollects theoretical and practical hydrogen and oxygen isotopes, especially stable deuterium and oxygen- 18 applications in the study of precipitation, soil water, runoff, groundwater, and plants. Finally, the review provides some perspectives for further research based on the viewpoints of active researchers in isotopic hydrology.