Tar ball deposition on Goa's beaches, a regular phenomena from June to October every year, is affecting the marine life in the coastal waters of the state, says a new study.
Scientists at the National Institute of Oceanography (NIO) in Goa initially thought that the tar ball deposition was due to off-shore oil exploration, oil tanker accidents, oil-well blow-outs, accident or deliberate release of bilge and ballast water from ships.
However, when there were depositions on the Goan beaches, even though no cases of oil spills or accidents were reported in 2010 and 2011, the NIO decided to conduct further study on this.
To carry out the study the NIO also collected samples from Baga, Candolim, Calungute and Mandrem beaches from North Goa and Velsao, Betalbatim, Colva and Benaulim from South Goa.
"There were no reports of oil spills in the Arabian Sea or on the Western coastal belt. We assume that some unknown spills or tanker routes might be the cause for the formation of present tar balls," the study said.
The study states that after the oil spill, weathering process also cause half of the oil to disperse within 24 hours. After 24 hours, depending on the sea state, water-in-oil emulsion is formed and this increases with the salinity of water.
The winds, waves and turbulence at sea surface cause the emulsion to break into smaller pieces, which eventually become tar balls.
