The Study of the Groundwater by Using the 34S and 18O of the Sulphates-S18O4 Isotopes

The stable isotope of the sulphur atom (34S) and the 18O of the sulphates (S18O4) give information about the type of the mineralisation of the groundwater existing during the water seepage. The decrease of the concentrations in dissolved SO42− (meq/L) versus the increase of δ18O (‰ vs. SMOW) of the sulphates (S18O42−) confirms a partial reduction of the dissolved sulphates in the water. The Under-saturated waters versus the gypsum do not cause the precipitations of the sulphates. The study of δ34S (‰ CD) vs. Cl− (mg/L) indicates high variations in δ34S (‰ CD) for weak difference in the Cl− (mg/L) content, this is due to the reduction of the dissolved sulphates. Concerning the Jurassic water in Lebanon, an oxidation of the sulphide can take place.