Geochemical and Isotopic Assessment of Groundwater Quality in the Alluvial Aquifer of the Eastern Mitidja Plain

Abstract

The Mitidja-plain is very important in size and role, it contains two important aquiferous tanks exploited to serve Algiers and the surrounding agglomerations, these resources used for the population, industry and the hydro agricultural needs are nowadays threatened by contamination. The Eastern region of this area is the most affected by this pollution. Groundwater from the alluvial aquifer have been analyzed in order to investigate the mineralization processes, water origin and to evaluate the levels of pollution. In addition principal component analysis was used to identify the sources of pollution. Groundwater from this aquifer fall into Cl–SO₄–Ca water type. Data inferred from ¹⁸O and ²H isotopes in groundwater samples indicated recharge with non-evaporated rainfall originating from Mediterranean air masses. Measurable tritium concentration allowed qualitative identification of modern recharge by recent precipitation. The groundwater quality is strongly influenced by the content of nitrates and heavy metals. The nitrates are certainly linked to pollution due to agricultural activities and the used of fertilizers. The concentrations of Fe, Mn, Pb and Cd were found higher than the prescribed limits defined by the World Health Organization. The application of principal component analysis for traces metals identified two sources of pollution—natural and anthropogenic sources.