Hydrochemical and Isotopic Study of Water Downstream of the City of Marrakech after the Installation of the Sewage Treatment Plant

Abstract

The objective of this work is to gauge the impact of the installation of the treatment plant on the water quality of El Azzouzia aquifer. The aquifer of El Azzouzia is located downstream of the Haouz aquifer. The water of this area was threatened by the pollution resulting from the mushrooming houses that proliferated in the region, which culminated in the degradation of the environment. According to hydrochemical analyses, electric conductivity is high in that it varies between 400 and 3200µs/cm. There is also a decrease in the majority of chemical elements in which the rates are inferior or equal to the quality standards, except for chlorides and sodium which can reach a maximum of 2300 mg/l and 1000 mg/l respectively. Another type of study that has been conducted is the isotopic study. This kind of study aims to determine the source of the elements that still mark the waters of this area. The results show that the 18O contents range from -7.89 to -5.21‰ while the 2H contents range from -52.49 to -37.05‰ indicating that the recharge area is located on an altitude that varies between 840 and 1900m, which corresponds to the Permo-Triassic evaporite formations. The degradation of the water quality sources is either from natural pollution (i.e. from the geological contributions of the aquifer recharge basin) or is anthropogenic (i.e. from the seepage of wastewater).

Keywords: Pollution; El Azzouzia groundwater; Haouz; Sewage Treatment Plant; wastewater; isotopic; hydrochemistry; recharge.