A screening study was carried out on bottom sediments of five Jordanian dams namely Wadi ElArab, King Talal, Karamah, Mujib and Tannur, to assess the polychlorinated biphenyls (PCBs) concentrations using GC/MS. King Talal dam had highest concentrations of all studied pollutants followed by Wadi ElArab. Both dams are considered most polluted dams, the total PCBs concentrations (£PCBs) were found for both dams 324.90, and 104.14 ng/g dry weight (dw) respectively. Also £pg TEQ/g values were found to be for both dams 497.47 and 3339.26 respectively. PCBs 118 (TEF=0.00003), 126 (TEF=0.1), and 189 (TEF=0.0001) were detected in all sites with the higher concentrations in King Talal, and Wadi ElArab dams. Where Wadi ElArab dam contained 33.35 ng/g of PCB-126 compared to King Talal dam with 4.81 ng/g. The maximum levels of PCBs congeners in the dams are in the decreased order of 114 >189 >156 >118 > 126 >123 >77 >81 >167 >169 >157 >105. It was found that Tannur, Mujib, and Karamah dams are relatively clean with low pollution level compared to King Talal and Wadi ElArab dams. This is because there are no industrial activities in their surroundings; while King Talal is connected to Zarqa polluted river and Kherbet Al-Samra Waste Water Treatment Plant (WWTP), and Wadi ElArab dam is connected to anthropogenic activities from nearby Irbid city. This environmental study provides a snapshot of the PCBs contamination status in Jordanian dams and up to date data for comparison among ecosystems worldwide.
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