Formed out of dumped oil and ballast from seafaring vessels, tar balls in the beaches of Goa are presenting an environmental and health hazard
As the monsoons mark an end to the tourist season in Goa, tar balls begin to make their annual appearance on the beaches. Since the 1970s, several stretches of Goa’s shoreline have seen the deposits of brownish-black, oily, sticky residue brought yearly by the high tides from May till the end of October.
“It is very smelly and sticks to your shoes when you walk on the beach. I see this every year, so I know it is the season for it now,” said a Cavelossim beach goer. Citizens have become so accustomed to this they now consider it a natural phenomenon.
Despite appearing for decades, tar balls have only recently begun to be examined for their contents and effects, several of which are yet to be discovered. Scientists from the state-based National Institute of Oceanography (NIO) – a constituent laboratory of the Council of Scientific and Industrial Research (CSIR) – have undertaken studies in studying the trajectories, bacterial degradation and genetic material of the tar balls by sampling seawater and its sediments.
The hydrocarbons present in the tar balls are same as those present in crude oil and petroleum, linking the source to oil spills and dumps from ships and oil rigs in the Arabian Sea. Several microbes present in the tar balls aid in degrading the hydrocarbons. Polycyclic Aromatic Hydrocarbons (PAHs) found in them contain pollutants like fluorine, naphthalene, acenaphthene and 13 others.
“There is sufficient evidence to conclude that PAHs like benzo(a)pyrene and chrysene are carcinogenic even at very low concentrations,” said Suneel Vasimalla of the Physical Oceanography Department at NIO, Goa. He specialises in marine pollution and coastal processes.
“As tar balls float in the water over a period of time, there is a chance of leaching of these PAHs into the marine environment and this can produce harmful impacts on marine life,” said Rakhee Khandeparker, a senior scientist in the NIO’s Biological Oceanography Department, who specialises in microbiology, ecology and ecosystem functioning.
The two scientists said studies into the PAHs show they can accumulate at various levels in the food chain. Due to long-term exposure, some of the compounds can get added to genetic materials and ultimately cause genetic disorders. “It is difficult to specify what organisms are affected, but in the case of oil spills, generally, sessile organisms with limited or no mobility have a higher chance of being impacted,” Khandeparker said.
A recent study by Khandeparker and colleagues at NIO, Goa and at a CSIR laboratory in Visakhapatnam found that tar balls cause an unusual surge of Vibrionaceae or vibrio species of bacteria which can cause vibriosis – an infection that arises from consuming raw or undercooked shellfish that contains the bacteria or even by exposing a wound to the bacteria. Local guards warn beachgoers about this every monsoon.
Eating contaminated sea food like oysters and shrimp is the commonest way people are exposed to the pathogens, which may increase the risk of cancer.
“I warn people about the presence of tar balls because it is quite annoying to clean off the shoes and even causes irritation of the eyes and skin in case they accidentally step on it, and it is worse if people are allergic to it,” said a guard at Varca beach.
Tar balls have been appearing in Juhu beach of Mumbai and the coast of South Gujarat from last year and have also caused the death of some turtles and dolphins in Mangalore. Internationally, Los Angeles county and Florida Keys have also reported lumps of oil being deposited on their beaches because of oil spills nearby.
For environmentalists all over the world, tar balls are a cause of great concern. It may get worse, because there is so much yet to be discovered about their impact on marine life, land-based animals and plants, and human health.