Occurrence and transport of pharmaceuticals along the water reuse supply chain for irrigation in the Jordan Valley, Jordan

Graphical abstract showing the summation of pharmaceutical compounds concentrations at each sampling point of the study. Water scarcity in semi-arid regions has driven the reuse of treated wastewater for irrigation, which is raising concerns about the accumulation of pharmaceutical residues in agroecosystems. A multicampaign sampling was conducted to investigate the occurrence and transport of selected pharmaceuticals from As-Samra Wastewater Treatment Plant (WWTP) through Zarqa River, King Talal Dam (KTD), and farm irrigation ponds into irrigated soils and crops in the Jordan Valley. The results show that 21 pharmaceutical compounds were detected at the WWTP influent with a total of 8,083 ng/L, dominated by carbamazepine, diclofenac, and some antibiotics. As-Samra WWTP was unable to completely remove all pharmaceuticals resulting high concentrations in the effluent. Natural attenuation in the Zarqa River and KTD further reduced pharmaceutical loads but exhibited compound-specific variability. Further reduction was observed in the PVC distribution network resulting from pharmaceuticals at irrigation ponds (374 ng/L). The highest concentrations of carbamazepine, diclofenac, and sulfamethoxazole were detected in the irrigation water, which was transported to soil at three farms ranging from 1.1 to 6.4 μg/kg. Thus, diclofenac (32 μg/kg) and carbamazepine (14 μg/kg) were detected in lettuce. These findings demonstrate that wastewater reuse can facilitate the transport and accumulation of persistent pharmaceuticals in agricultural systems, highlighting potential long-term risks to soil quality and human exposure.