Sydney’s famous Bondi Beach and other beaches around the Australian city were shut Thursday as authorities investigated mysterious tar balls that have washed ashore.
The dark, sticky, golf-ball-size blobs were first reported Tuesday on Coogee Beach, leading to a series of beach closures across the city’s shores. They also include Bronte, Tamarama, Gordons Bay and Clovelly and the northern end of Maroubra Beach, all of which are closed until further notice pending cleanup and removal of the material.
People have been advised not to swim near or touch the debris. The City Council of Randwick, a Sydney suburb that is home to four of the beaches, said preliminary test results showed that the blobs were tar balls, formed when oil comes into contact with debris and water.
“We don’t yet know what has happened to produce the debris washing up on our beaches,” Mayor Dylan Parker said in a statement Thursday. “But we will continue to work with relevant authorities to ensure the safety of the public and clean up our beaches.”
The Environment Protection Authority of New South Wales, the state that includes Sydney, said similar debris had also been found at Congong, Frenchmans, Little Bay and Malabar beaches. It said it was investigating the origin of the debris and whether it posed any risks to the community and environment.
“At this stage, the origin and contents of the balls remains a mystery. But the EPA is conducting extensive testing on a number of samples,” it said in a statement, adding that it could not confirm the presence of hydrocarbons, the chief components of petroleum-based products, as reported by the Randwick City Council.
The tar balls are “quite a chemical mystery,” William Alexander Donald, a chemistry professor at the University of New South Wales Sydney, told NBC News on Thursday.
Preliminary analysis by a team of UNSW researchers confirms that the tar balls originated from weathered oil, either from a crude oil spill or natural oil seeps from the ocean floor.
“They are formed from oil that’s been released into the ocean, and probably crude oil, based on our chemical analysis,” Donald said.
The tar balls are not just unsightly. They can hurt marine ecosystems and affect animals such as seabirds, turtles and fish by disrupting their movement and feeding. The toxic compounds inside them can also leach into the water, Donald said, potentially threatening marine biodiversity.
The tar balls’ appearance on the beaches “not only damages Australia’s pristine coastal reputation but also threatens the health of ecosystems that support industries like fishing and tourism,” he said in a news release.
Tar balls of this kind are “quite uncommon” in Australia, Donald said. But they have appeared elsewhere, including on beaches in California, as well as along coastlines in the Gulf of Mexico after the 2010 Deepwater Horizon oil spill.
“There’s still a lot of questions about what’s in these sticky blobs,” Donald said. “It’s quite an analytical challenge.”
