Present pollution profile of Karachi coastal waters

Abstract

Natural and human interventions have posed serious threats to the sustainability and development of the coastal environment. This problem is more apparent in Karachi, a metropolitan city of Pakistan, which has a coastline extending up to about 30 km. The city, with more than 18 million people, generates around 472 million gallons per day of municipal and industrial wastewater. Out of which, about 80% is being discharged untreated into the Arabian Sea. The problem is more aggravated by oil spills from cargo ships, and oil tankers in the Harbor Area. This research study was focused to assess the level of pollution and its impact on the coastal environment. During the study, surface seawater samples were collected from six different locations in Manora Channel, the main pollution prone area. Significantly high volatile matter (42–65%) coupled with the measurable depletion of Dissolved Oxygen (DO) and a decrease in pH level was observed. Moreover, the distribution pattern of heavy metal pollution at the Karachi coast was found in the following descending order: Zn > Mn > Fe > Cu > Ni > Pb. Its concentration at several locations was not very critical. However, the trend indicated the likely increase in metal pollution. At Fish Harbor, the metal concentration was higher when compared with the sea water quality standard. Overall, the study suggested that the concerned authorities and industrialists should jointly take measures to reduce pollution and to achieve coastal ecosystem sustainability.