Studies on short term weathering of spilled oil along Chennai coast in South India

This paper discusses about the results of a short term monitoring study of sea coast contaminated with oil spill. Collision of two oil-cargo ships, namely BW Maple and MT Dawn Kanchipuram near the Ennore Port, Chennai had released an approximately 200 tonnes of heavy fuel oil. We analyzed four different oil spill samples collected from Chennai beaches for different time intervals (1st, 3rd, 6th, 10th day of oil spill) from 1 km away from the source of the off shore spill location. The physicochemical characteristics of spilled oil sludge, concentration of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) present in the spilled oil were investigated. The variations in pH, moisture content and volatile hydrocarbon content, viscosity and density of the spilled oil were in the range of 7 ± 0.2, 255–575 g/kg, 118 to 850 PaS and 1.04 to 0.98 g/cm3 respectively. Elemental analysis showed that C, H, N and S were in the range of 9.9–13.3 (%), 0.63 to 1.76 (%), 1.88 to 1.02 (%) and 0.29 to 0.27 (%) respectively. Analysis of oil spill samples using gas chromatography and mass spectrometry (GCMS) shows the presence of recalcitrant and hazardous PAHs such as fluoranthene and pyrene. Ocean sediments were collected at different locations along the coast line from Ennore to Cooum after 60 days of oil spill and analyzed for TPH in GCMS. The results showed that the residual concentrations of TPH varied from 0.19 to 3.43 mg/g. The presence of heavy PAHs, which are highly toxic and recalcitrant, could pose a severe threat to the marine environment and ecology.The long term effects of these compounds were unexplored on marine environment. This environmental monitoring study gives an overview about the post oil spill activities and steps taken to remediate the sludge along the coastline.