Br-Li and stable isotopes to induce groundwater salinity in crystalline and detrital aquifers: Oriental Haouz Morocco

Abstract

Paleozoic, Triassic and Quaternary lateral aquifers have been the subject of detailed geochemistry study, in Oriental Haouz, Morocco. Interpretations are based on the combination of major elements, Br, Li, and stable isotopes. In order to identify the origin of salinization, hydrochemical analysis were applied on forty groundwater samples, twenty of them are used for stable isotope measurement, three rivers, a sample from the natural spring in the south-western part and one rain water. High values of Li are considered with regard to micaschists and evaporite formations. This is roughly consistent with Lithium’s origin from saline dissolution. Cl/Br ratios show that the initial sedimentary rocks which give the present micaschists were relatively rich in evaporitic minerals and the beginning with of metamorphism during the hercynian orogeny, the major elements originally present in low-grade phases, would preserved in medium-grade phases such as evaporite minerals. Consequently, these minerals were easily liberated via alteration of alterated Paleozoic micaschist strata. NO 3 2- does not only come from agricultural pollution but also from septic waste. Stable isotopes are segregated into two groups: Group1 coexists with high hydraulic parameters and is depleted of δ 18 O and δ 2 H; Group2 coexists with low hydraulic parameters, and is enriched with δ 18 O and δ 2 H. Thus, during precipitation events, waters infiltrate safely/sparingly, and evaporation did not/or occur following hydraulic parameters. • Groundwater salinity was assessed by chemical elements and stable isotopes. • Based on Li+ , increasing salinity was linked to advanced minerals dissolution. • Dissimilarity in Cl/Br ratio indicates heterogeneous lateral minerals distribution. • Salinity and low hydraulic parameters coexist in crystalline and detrital aquifers. • Stable isotopes values were affected by orographic and local climatic conditions.