Sydney beaches shut over mysterious tar balls washing ashore

“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.”