ABSTRACT
An oil tanker, Tasman Spirit, carrying 67000 tons crude oil, got damaged near the Clifton Beach of Karachi, Pakistan and approx. 31,000 ton oil spilled into the sea. The distribution of aliphatic and aromatic hydrocarbons was determined in deep sea and surface sediment collected at 12 stations along the Clifton beach of Karachi, following the oil spill. Sampling was performed during 2003-2006, starting just after the accident of the oil tanker. Concentrations of PAHs [116 parent components] and aliphatics were in the range of 0.09-560 ng/kg dw and 0.12-685 |ug/kg dw, respectively, since the date of accident and after bioremedial measures. The highest concentrations were found within the radius of 50 km around the site, the area most heavily impacted by the spill, whereas at the stations, away from the ship, the concentrations were in the lower range without alkylated compounds. Addition of increasing amounts of ship fuel oil [taken from a Pakistani ship] to a representative sediment sample showed that measurable concentration of the Tasman Spirit oil was > 1 g/kg of sediment. The toxicity of selected samples of surface sediment from the coastal area near oil spill showed higher PAH concentrations; the average number of dead fauna was 90-95% within 3 days of oil spill which gradually decreased with the time