Geochemical Assessment of the Heavy Metal Pollution in Superficial Sediments along Wadi As-Sir Stream, Jordan

Abstract

The concentrations of Cu, Mn, Cd, Pb, and Zn in superficial sediment samples from the Wadi As-Sir area were analyzed to evaluate pollution levels. A total of seventeen samples were collected between April and July 2019, including nine from Wadi As-Sir, six from Wadi Al-Sheta, and two from Al-Kafrain Dam. Sediment contamination was assessed using standard indices, namely the Pollution Index (PI), Pollution Load Index (PLI), and Geoaccumulation Index (Igeo). The Igeo results indicate that Mn, Cu, Cd, and Pb concentrations in Wadi As-Sir stream sediments and Al-Kafrain Dam sediments fall within safe limits, whereas Zn concentrations exceed average background values. In contrast, Wadi Al-Sheta sediments show safe levels of Mn, Cu, and Pb, but elevated concentrations of Zn and Cd. PI results reveal high levels of Zn and Cd in Wadi As-Sir, while Wadi Al-Sheta exhibits elevated Zn, Mn, and Cd concentrations. In Al-Kafrain Dam, Zn is the only element showing high concentration levels. The elevated Zn, Mn, and Cd are primarily attributed to anthropogenic inputs, including irrigation return flows and the weathering of surrounding rock formations. Despite these localized enrichments, PLI values suggest an overall absence of significant pollution across the study area, as indicated by generally low index values. Correlation analysis demonstrates variable relationships among the studied metals, reflecting differences in their sources and geochemical behavior. To mitigate future contamination, continuous monitoring and effective management of anthropogenic discharges are strongly recommended.