Surface water quality in a water run-off canal system: A case study in Jubail Industrial City, Kingdom of Saudi Arabia

Water quality in a run-off canal system in an industrial area was evaluated for a range of physical and chemical properties comprising trace metals (including mercury (Hg), chromium (Cr), iron (Fe), manganese (Mn), salinity, pH, turbidity, total dissolved solids, total suspended solids, chemical oxygen demand (COD), and dissolved oxygen). High concentrations of potassium (K) (1.260-2.345 mg/l) and calcium (Ca) (19.170-35510 mg/l) demonstrated that the salinity in the water was high, which indicates that industrial effluents from fertilizer manufacturing and Chlor-alkali units are being discharged into the canal system. Almost all the metal concentrations in water and sediment were within the thresholds established by the local regulatory body. Concentrations of Cr (0.0154-0.0184 mg/l), Mn (0.0608-0.199 mg/l), Fe (0.023-0.035 mg/l), COD (807-916 mg/l), and turbidity (633 ± 15-783 ± 22 NTU) were high where the canal discharges into the Persian Gulf; these discharges may compromise the health of the aquatic ecosystem. There is concern about the levels of Hg in water (0.00135-0.0084 mg/l), suspended sediment (0.00308-0.0096 mg/l), and bed sediment (0.00172-0.00442 mg/l) because of the bio-accumulative nature of Hg. We also compared the total Hg concentrations in fish from Jubail, and two nearby cities. Hg contents were highest in fish tissues from Jubail. This is the first time that heavy metal pollution has been assessed in this water run-off canal system; information about Hg is of particular interest and will form the basis of an Hg database for the area that will be useful for future investigations.