This study aimed to assess the contamination of sediments in Wadi Djedra and its tributaries by seven trace elements. The average concentrations of Mn, Pb, Zn, Cu, Ni, Cd, and Cr in the sediments ranged from 31.4 to 59.2, 1.2 to 18.4, 15.1 to 54.7, 11.2 to 19.7, 1.1 to 14.7, 0.1 to 0.3, and 0.1 to 4.3 mg/kg, respectively. Sediment contamination was evaluated using the enrichment factor (EF), geoaccumulation index (Igeo), and potential ecological risk index (Eri). The Igeo values for Cd indicated moderate contamination at sites S2, S4, S5, and S7, while for other sites and elements, the values were negative, indicating no contamination. The results revealed very high enrichment of Cd and Cu in the analyzed sediments, attributed to human activities. In contrast, chromium and manganese concentrations were comparable to those observed in the Earth's crust, suggesting even a depletion of metals in the sediments (EF < 2). The Eri index measurements showed that the sediments in the Djedra basin exhibited moderate to high pollution levels for Cd at most study sites. Lithogenic sources, urban discharges, and agricultural activities were the main factors affecting the concentrations of Cd, Cu, Zn, and Pb in the studied sediments. Although the current contamination is not alarming in the short term, it should be considered in future monitoring and management efforts.
Adjili et al. (Sun,) studied this question.