L’étude des caractéristiques physico-chimiques des eaux souterraines de la communauté Mzamza, soumises aux rejets liquides de la ville de Settat à partir de l’oued Boummoussa, montre que la qualité des eaux des différents puits est variable et dépend d’un certain nombre de facteurs tels que l’emplacement des puits par rapport aux eaux usées et l’activité agricole. L’interprétation des données d’analyse, la corrélation existante entre eaux usées et eaux de puits, et la répartition des eaux souterraines en groupes sont réalisées en utilisant l’Analyse en Composante Principale Normée. L’étude a révélé des origines différentes de la contamination des eaux souterraines, à savoir, la contamination par la matière organique due essentiellement à l’utilisation des eaux usées à des fins d’irrigation et à leur infiltration continue, et finalement le retour des eaux d’irrigation (chargées en engrais azotés) qui est considéré comme étant la principale origine de la minéralisation et de la pollution des eaux.Plusieurs facteurs conditionnent la progression de cette pollution : les concentrations des polluants dans les eaux usées, la nature des sols, la lithologie, la perméabilité de l’aquifère exploité et la profondeur de la nappe.Les résultats acquis dans cette étude font ressortir également l’influence primordiale des variations saisonnières, ainsi que le rôle bénéfique des précipitations.The study of the physical-chemical characteristics of groundwater of the Mzamza community, subjected to domestic and industrial wastes from Settat City (Morocco) via the Boummoussa river, shows that the quality of water of the various wells is variable and depends on a certain number of factors such as the location of the wells in relation to waste water and agricultural activity. The interpretation of analyzed data, the correlation between waste water and well water, and the distribution of groundwater sites into groups was carried out using Normalized Principal Components Analysis. The study revealed several sources of groundwater contamination, namely, the contamination by organic matter due primarily to the infiltration of waste waters used for irrigation, and the return of irrigation water (loaded with nitrate fertilizers), which is regarded as being the principal source of dissolved solids and inorganic nitrogen in the groundwater. Several factors influence the progression of this pollution: the concentrations of the pollutants in the waste waters, the nature of the soil, the lithology, the permeability of the aquifer in use and the depth of the water table. The results achieved in this study also revealed the paramount influence of seasonal variability and the beneficial role of atmospheric precipitation

Several determining factors were highlighted in the contamination of ground waters by these pollutants, namely: the contribution of nitrogenized fertilizers, the nature of soil, the lithology, the permeability of the aquifer and the outdistances well compared to the sources of pollution which are waste waters.

In recent years, the town of Settat has seen a considerable industrial growth, which has resulted in increased environmental pollution. This includes pollution by household and industrial wastewaters, which are released into the Boumoussa River without any preliminary treatment. The river valley crosses the community of Mzamza 8 km to the north of the town. Years of drought forced members of the community to use this polluted ground water for irrigation and put themselves and the environment at risk. The aim of this study was to determine the physicochemical and metal profi le of Settat wastewaters and to assess their impact on the water table. The second objective was to investigate the genotoxic potential of wastewater on human peripheral blood lymphocytes in vitro, using the micronucleus test and cellular proliferation index. This study demonstrated signifi cant pollution of Boumoussa valley groundwater and of the local wells. Sampled water induced a clear increase in the frequency of micronucleated cells and a lower cell proliferation in human peripheral blood lymphocytes in vitro.

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