Application of environmental isotopes in the study of groundwater resources in arid zones

In Algeria, the issue of water availability is a major concern, and great efforts are made in order to ensure water allocation to people as the resource becomes scarcer with time. In this socio-economic and climatic context, groundwater resources in the Saharan Atlas remain poorly understood, particularly with regard to the processes controlling mineralization, the identification of recharge areas, the origin of groundwater, and timing of recharge. Environmental isotopes and hydrochemistry are combined for the sake of identifying the mechanisms controlling hydrochemistry. Moreover, it is sought to identify natural or anthropogenic processes affecting groundwater quality, as well as the source, the origin, and the timing of recharge. 18O, 2H, and 3H are constituents of the water molecule and have a great significance in isotope hydrology as ideal tracers for describing the water cycle phenomena. Environmental tritium is widely used in hydrology as an age indicator for groundwaters. In our study, special emphasis is given to tritium as a radioactive tracer, given its significance for groundwater dating and its relevance to environmental radiation monitoring. Tritium concentrations are determined using electrolytic enrichment followed by liquid scintillation counting, with detection limits appropriate for assessing low-level environmental radioactivity.