Monitoring Water Pollution Levels in Wadi Hanifa, Riyadh, Saudi Arabia and its Public Health Implications.

This study was performed to evaluate the levels of metals in the fish caught from Wadi Hanifa's main basin over four seasons, determine the potential fitness of the fish for human consumption, and evaluate the overall water quality after enforcement of local standards. The physical and chemical parameters from a total of 192 water samples were tested using standard methods. Additionally, a total of 48 fish samples were analyzed for heavy metal concentrations. Mean values for basic water quality parameters of COD, PO4-3, NH3--N, and NO3--N exceeded Saudi standards in all seasons. Mean metal concentrations in water were consistently at their highest concentrations in samples collected during the summer, and the lowest in samples collected during the winter. Mean metal concentrations in fish muscle tissue exceeded Saudi standards for As and Cd, and United Nations FAO standards for Cr, Ni, Zn, Fe and Mn. Statistical analysis showed highly significant positive correlations between metal concentrations in water and metal concentrations in fish muscle for As-Fe, Pb-Cr, Pb-Ni, Cr-Cu, and Cu-Fe. This study highlights the urgent need for monitoring and controlling wastewater discharge in Wadi Hanifa to ensure public safety.

Evaluation of heavy metal pollution in water wells and soil using common leafy green plant indicators in the Al-Kharj region, Saudi Arabia.

This study was performed to determine the levels of eight heavy metals in irrigation well water and soil and to assess the suitability of some leafy green plants that are commonly cultivated in the Al-Kharj region, Saudi Arabia, for human consumption using an atomic absorption spectrometer. The mean concentrations of metals ranged from 0.0001 to 0.436 mg/L in well water and from 0.248 to 164.52 mg/kg in soil. The heavy metal concentrations showed significant differences among the different leafy green plants studied. Parsley (4.98 mg/kg) exhibited higher levels of Pb than other leafy green plants, whereas mallow (0.097 mg/kg) revealed greater amounts of Cd than other plants. All of the leafy green plants retained essential metals (Cu, Zn, Fe and Mn) more than the toxic metals (Pb and Cd). The levels of some of the metals in the leafy green plants were found to meet the FAO/WHO-recommended limits. The monitoring of heavy metals in leafy green plants must be continued because these plants are the main source of food for humans in many parts of the world and are considered to be bio-indicators for environmental pollution.

Quality of wastewater reuse in agricultural irrigation and its impact on public health.

This study is planned to perform a sanitary survey of the largest sewage treatment plant in Riyadh, KSA, fortnightly for 6 months to examine its effluent quality as an example for the growing dependence on reuse of treated municipal wastewater in agricultural irrigation purposes to cope with increasing water shortage. The biological and physico-chemical parameters of 12 wastewater samples from the plant were examined using standard methods. The physico-chemical analysis indicated that the surveyed municipal wastewater treatment plant contained some of the studied parameters, such as turbidity, total suspended solids, biochemical oxygen demand, chemical oxygen demand and residual chlorine above the maximum permissible wastewater limits set by the Saudi Standards. However, heavy metal concentrations in all samples were lower than the recommended standards. Total and faecal coliform counts were above the permissible limits indicating poor sanitation level. Fifty percent of all wastewater samples were contaminated with faecal coliforms but, surprisingly, Escherichia coli were only detected in 8.3 % of the samples. Regular monitoring and enhancement of microbial and physico-chemical parameters of the wastewater quality served by different wastewater treatment plants for reuse in agricultural irrigation is recommended to preserve the environment and public health.