L’ETUDE DE L’IMPACT DES LIXIVIATS DE L’ANCIENNE DECHARGE PUBLIQUE DE LA VILLE D’OUJDA (MAROC ORIENTAL) SUR LA QUALITE PHYSICOCHIMIQUE DES EAUX SOUTERRAINES ET SUPERFICIELLES

Abstract

To evaluate the impact of the leachate resulting from this landfill on groundwater and surface water quality, samples of leachate, groundwater and surface water were taken monthly during the year 2004 (seven samples of leachate inside the landfill) (three groundwater samples and 2 surface water samples were taken, respectively, of three wells located near the landfill and of a storage dam located on a temporary river circumventing the landfill).

The analyses of the sampled leachate revealed   strong content of biodegradable organic matter (DBO5 max = 13520 mg/l) and of mineral matter (conductivity: max = 170 ms/cm). The analysis of groundwater and surface revealed that NO3 presents an average concentration lower than 50 mg/l with temporal variations of a great amplitude (Standard suggested by WHO). The concentration of chloride exceeds 783 mg/l in water of the storage dam and remains lower than 400 mg/l in groundwater (Standard suggested by WHO is 600 mg/l for fresh waters). The concentrations of phosphates are very low; they are in agreement with the values found in the leachate. Concerning heavy metals, we note a total absence of Cu and Pb. The concentrations of Iron, Zn and Ni largely exceed the French values standards fixed for groundwater, while the Cd contents are in lower part of this standard.