Abstract
Wadi Hanifah, one of the most important valleys within the city of Riyadh - Saudi Arabia, has served as a natural wastewater drainage system for the city. For the past 20 years, however, this valley has been treated as a dumping site. Many industries are dumping their waste to the Wadi, which is causing major environmental degradation and posing health hazards; therefore, the present study was planned to analyze the physico-chemical and heavy metal status of wastewater and sediments of Wadi Hanifah to assess their quality. The analyses showed that the wastewater collected from all sites possessed high levels of Cd (0.004-0.026 mg/L), Ni (0.006-0.034 mg/L), Pb (0.018-0.137 mg/L), Zn (0.013-0.026 mg/L), a neutral to alkaline pH (7.46-8.37), and had high BOD (15.77-22.37 mg/L). The sediment of Wadi Hanifah also showed high concentrations of some metals: Cd (15.40-57.95 mg/kg), Ni (20.47-68.80 mg/kg), Pb (135-296 mg/kg), and Zn (24.55-203.80 mg/kg), which may pose long-term problems for the wadi environment.