A B S T R A C TThe aim of this study is to assess the spatial and temporal water quality variation and to determine the main contamination sources in the Oum Er Rbia River and its main tributary, El Abid River. The water quality data were collected during 2000-2012 from fourteen sampling stations distributed along the river. The water quality indicators used were TEMP, pH, EC, turbidity, TSS, DO, NH 4 + , NH 3 -, TP, BOD 5 , COD and F. coli. The water quality data was analyzed using multivariate statistical methods including Pearson's correlation, PCA, and CA. The results showed that in some stations the water quality parameters were over Moroccan water standards. PCA applied to compare the compositional patterns among the analyzed water samples, identified and four factors accounting for almost 63% of the total variation in the data. This suggests that the variations in water compounds' concentration are mainly related to point source contamination (domestic and industrial wastewater), non-point source contamination (agriculture activities), as well as natural processes (weathering of soil and rock). CA showed relatively spatial and seasonal changes in surface water quality, which are usually indicators of contamination with rainfalls or other sources. Overall, this study showed that the water was potentially hazardous to health of the consumers and highlighted the need to treat industrial and municipal wastewater and to encourage sustainable agricultural practices to prevent adverse health effects. We therefore suggest wise management of anthropogenic activities in the catchment of Oum Er Bia River and their tributaries.

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The present study investigated the potentially toxic heavy metal (Cu, Pb, Zn, Cr, and Cd) contamination and its ecological impact in the agricultural soil in the northeast part of Tadla plain (Morocco). A total of 60 subsurface composite samples were collected and analyzed to determine pH, soil organic matter (SOM) and texture, and heavy metal concentrations. Pollution levels were assessed by adopting enrichment factor (ef), geoaccumulation index (I geo), contamination factor (CF), pollution load index (PLI), and ecological risk index (RI). The results showed that the average concentrations of Cd, Cr, Cu, Pb, and Zn in the collected 60 topsoil samples were 0.92, 32.72, 138.10, 31.72, and 162.11 mg/kg, respectively, and followed the order Zn > Cu > Cr > Pb > Cd. These concentrations exceeded acceptable thresholds of the World Health Organization (WHO) and Food and Agriculture Organization (FAO) and local background. From the Principal Component Analysis (PCA) results showing no correlation between the soil properties and heavy metal contents, suggesting that the metal elements were of different sources, especially anthropogenic. The mean RI values of 65.68 indicated a low ecological risk and indicate that the study area is moderately to strongly pollute in the case of Zn and Cu and partly influenced by human activities. Nevertheless, this study provided important information for policymakers to propose an appropriate plan for pollution control in the agricultural Tadla plain.

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