Assessment of Physicochemical and Metallic Contamination (Cd, Zn, Cu) and 222 Rn Activity in Waters of the Doukkala Region, Morocco

Abstract

The present study aims to evaluate simultaneously, for the first time in the Doukkala region (Morocco), the degree of physicochemical and metallic contamination as well as the concentration of ²²²Rn radionuclides in freshwaters from the sources to the households. From March to June 2019, 23 water samples were collected from the Oum Er-Rbia River, wells located in the town of Ouled Ghanem, Sidi Abed, and El Oualidia, water treatment stations (before and after treatment), water towers, the irrigation canal of Sidi Bennour, and dwellings. Physicochemical parameters [temperature, conductivity, turbidity, pH, chlorides, alkalinity (TAC), total hardness (TH), oxidizability, nitrites, nitrates, ammoniums, and sulfates], heavy metal parameters [copper (Cu), zinc (Zn), and cadmium (Cd)], and radioactive measurements (²²²Rn) were determined for each sample. The results of the physicochemical analyzes of the water collected from the Oum Er-Rbia River showed that most of the values of the physicochemical parameters, namely conductivity (44,800 μS/cm), turbidity (17.41 NTU), sulfates (2,506.5 mg/L), and chlorides (18,105 mg/L), exceed the Moroccan and World Health Organization (WHO) standards. For the water collected from treatment stations and wells, the analyses showed that some parameters exceed the acceptable limits of drinking water in the towns of Ouled Ghanem, Sidi Abed, and Sidi Daoui station. In dwellings, almost all the water sampled is drinkable except a few ones in the towns of Ouled Ghanem and Sidi Abed. As for heavy metals, the concentrations of Cu, Zn, and Cd varied, respectively, from (0.002 to 0.061 mg/L), (0.02 to 7.5 mg/L), and (0.002 to 0.086 mg/L). These concentrations were within the national permissible limits for drinking water except for the water of Oum Er-Rbia River for Zn and the water in a dwelling of Sidi Abed for Cd. The mean volume activities of radon in the water samples ranged from 29.64 to 130.72 Bq/m³ and do not show any significant difference except for the water in the Ouled Ghanem dwellings. All the radon volume activities were within the admissible limit which is about 11.1 Bq/L set by WHO.