Environmental experts have warned against possibility of oil pollution in Chilika lagoon, thanks to the large number of ill-equipped mechanised country boats that ply in the lagoon. Their analysis is based on petroleum hydrocarbon (PHC) concentration found in certain segments of the 1,100 sq km brackish water lake.
A scientific report that has appeared in the latest edition of Current Science says that PHC concentration was found in outer channel, central as well as in souther sectors of the lake. Samples collected during September were analysed.
The results showed that outer channel of the lagoon had the highest PHC concentration of 330 microgram per litre whereas northern sector had the lowest - 50 microgram per litre. Similarly, PHC concentration in central and southern sectors was 280 microgram and 130 microgram respectively.
The central sector and outer channel have higher concentration of traditional non-motorised and motorised fishing boats while these two zones are also heart of the tourism activities which could be the reason for the high PHC value compared to other sectors, the report said.
Interestingly, PHC values in Arabian Sea goes up to 305 microgram, reaches 123 microgram in Visakhapatnam harbour, 139 microgram at Chennai harbour and ranges between 14 and 1,771 microgram between Chennai and Nagapattinam.
The report said oil leaks from the motorised vessels may impact lagoon environment directly or indirectly in Chilika since petroleum oil contains volatile organic compounds which partially evaporate by losing 20 per cent to 30 per cent of their mass. These compounds become more viscous and dense which provide more resistance to oil flow. Though a small percentage of oil may dissolve, the residue can disperse invisibly to make a thick coating on the water surface posing problem for photosynthesis. Similarly, oil also mixes with suspended matter and sinks to the bottom affecting aquatic systems.
The experts, drawn from Department of Marine Sciences, Berhampur University, National Institute of Oceanography, Visakhapatnam and Indian National Centre for Ocean Information Services, felt that oil pollution can have an adverse impact on the birds and other wildlife. Irrawaddy Dolphins may also face health problems if the pollution level rises while outflux through outer channel to the Bay of Bengal could impact Olive Ridley turtles which nest on the State’s coast.
Over two lakh fishermen depend on Chilika for their livelihood. More than 5,000 non-motorised and 2,200-plus motorised boats are used for fishing in the lagoon.
The report has suggested that the problem can be solved by safer handling of fuel oil, awareness among boat owners and oil spill removal through bio-remedial and self-cleaning bacteria.