CHENNAI: Experts in the Indian Institute of Technology (IIT) Madras, who are analysing the nature of the pollutant that wreaked havoc on city beaches, have concluded that it was bunker oil from the ship and was toxic, though it was unlikely to pose an immediate health hazard.
They say the authorities should lock down the Marina to prevent people from accessing it till the contaminated sandy soil is fully treated.
Although the tests have not yet been completed, IIT Madras sources told Express that it was residual fuel oil (RFO), which by navy specification is called Bunker C. It is a highly viscous residual oil produced by blending heavy residual oils with a lighter oil to meet the specifications for viscosity and pour point.
Indumathi M Nambi, associate professor, Department of Environmental and Water Resources Engineering, who is fingerprinting the pollutant, says the fuel oil is not acutely toxic, but coming in contact with it for long-time would cause skin ailments.
The shoreline cleanup can be very effective before the oil weathers and becomes very sticky and viscous. “Inhaling high viscosity residual oil odour would be harmful to children. The clean-up must be thorough. The affected sand must be scooped up and treated,” the associate professor said.
She also says the choice of dispersants must be made carefully. All dispersants may not work for high viscosity oil as the one in this case. The principal aim of dispersant application is to break up an oil slick into numerous small droplets which blends with the water column and are subsequently degraded by naturally occurring micro organisms. “The effectiveness of the dispersants depends on oil type. Laboratory tests must be conducted to assess the pairing of a particular oil type to the dispersant. Oils with a lower viscosity are more amenable to natural dispersion than those with a higher viscosity. We are voluntarily buying different types of dispersants and conducting lab tests to collate with the type of oil spilt here and suggest a most suitable dispersant,” she said and added that another key consideration should be the Material Safety Data Sheet (MSDS) that would state whether the dispersant was eco-friendly.