Use of the Br/Cl ratio to determine the origin of the salinity of groundwater: an example from the Souss plain (Morocco)

The use of bromide anion contents is an essential complement to chloride me asurements in order to explain the salinity anomalies in groundwaters. Than ks to the relationship Br = f(Cl) and to the molar ratio Br/Cl, it allows m arine influence areas (the Ocean, precipitation, aerosols, sedimentary pale osalinity) to be distinguished from evaporitic or anthropogenic influence a reas, which are impoverished in Br as opposed to the oceanic domain. Applie d to the Souss alluvial plain, and thanks to this methodology, we can inter pret phenomena which are responsible for conductivity anomalies in groundwa ters: present salt encroachment, sedimentary paleosalinity or wastewaters d ownstream; evaporites, recycling of irrigation waters in the mean Souss. (( C) Academie des sciences, Elsevier, Paris.)