Assessment of heavy metal pollution in Lyari river and adjoining coastal areas of Karachi

The study objective was to determine the level and the distribution pattern of heavy metals in the coastal waters receiving a continuous discharge of untreated domestic and industrial effluent through Lyari river. In this research, the heavy metals in the surface water samples collected from Lyari river and adjoining coastal areas of Karachi namely; Fish Harbour, Netty Jetty, West Wharf, Naval Dockyard and Sandspit were analyzed using the atomic absorption spectrophotometer. The results of the analysis indicate that the mean concentrations of all metals (Cu, Fe, Mn, Ni, Pb & Zn) except for Cr, in Lyari river and Karachi fish harbor were significantly higher than the standard values. However, metal concentration decreased gradually as the distance from the discharged point increased and at the Sandspit point where no mixing of wastewater, the concentration was within safe limits. Moreover, the level of heavy metal concentration in the water samples were in following descending order Zn>Mn>Fe>Cu>Ni>Pb. Compare to other metal element, the Zn level was notably high and its main source of pollution could be the domestic and industrial waste as well as shipping activity. The study findings therefore suggest to incorporate quick remedial measures in order to combat pollution and to achieve socioeconomic sustainability in marine coastal environments