Isotopes in chemical analysis for water management

The concepts of origin, sources, processes and balances often call on common tools and reasoning, among which the use of geochemical tracers plays a predominant role. The tracers used enable the identification of material sources, the conditions and processes of their formation or transformation, the quantification of fluxes, the estimation of element transfer processes between different reservoirs, and the identification of sources of elements of natural or anthropogenic origin. These tracers are often selected for their specific characteristics, and the ultimate aim of their use is to integrate all the data into a hydrochemical model designed to determine water flows, material flows (erosion rates, transfer balances, etc.) in the various compartments of the basin.

The circulations and interactions of water, whether surface or groundwater, with the surrounding rocks, are increasingly documented by the use of geochemistry, and particularly by the application of isotope tracings. For each of the systems studied, isotope tracings make it possible to define the natural or anthropogenic origin of chemical elements, their behavior, their transport in different compartments (e.g., dissolved and/or particulate form for rivers), the circulation patterns of deep waters and fluids, and the interactions between waters and different types of host rock.

This dossier is based on scientific studies and publications carried out by the author and isotope geochemists from the BRGM geological and mining research bureau, in the field of the application of isotope methods to improve knowledge of the water cycle within research programs. This dossier is by no means exhaustive, and includes only a selection of the work carried out.