What are the mysterious 'tar balls' that have led to the closure of Sydney beaches?

Seven beaches in Sydney, Australia, including the popular Bondi, were closed after hundreds of mysterious golf ball-sized black masses washed up on the city’s shores. These black solid masses were confirmed to be “tar balls” and are suspected to be toxic after they were first spotted on Coogee Beach on Tuesday.

Waverley Council announced that it had shut down Bondi, Bronte, and Tamarama beaches for safety reasons, while Randwick Council closed an additional four beaches to the south. Bondi and Maroubra beaches were later reopened.

In a statement, Waverley Mayor Will Nemesh said, “The wellbeing of our community is paramount. That’s why Council has taken the precaution to close our beaches.”

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Photos and videos showed workers in hazmat suits gathering the tar balls into plastic bags as the beaches remained closed.

Authorities have urged the public to avoid contact with the tar balls until further notice.

What are these mysterious “tar balls”?

For several days, thousands of black spheres - ranging from the size of peas to tennis balls - have washed up on Sydney’s shores, leaving both locals and tourists puzzled.

Now, chemical testing has identified these spheres as hydrocarbon-based “tar balls” - lumps of oil and debris, local officials confirmed.

Monica O’Connell, a resident of Coogee, said, “We’ve got so many pollutants in the atmosphere, so many pollutants on the boats, so many pollutants, plastic, it’s going to come to our beaches, it’s everywhere else in the world unfortunately.”

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Notably, tar balls form when slicks of spilled oil mix with wind and waves, creating a sticky emulsion with seawater. Over time, this mixture breaks apart into smaller sticky pieces, known as “tar balls.”

Scientia Professor Matthew England, UNSW Centre for Marine Science and Innovation, said that the surface matter may include sand or small-scale biota, Radio New Zealand reported.

“Those tar balls are spherical due to the action of wind, waves, and weathering,” he explained.

The Environment Protection Authority (EPA), which is leading the investigation, said in a statement that these tar balls had been observed at Congwong, Frenchmans, Little Bay, and Malabar beaches.

“At this stage, the origin and contents of the tar balls remain a mystery,” the EPA said on Thursday.

“While we understand that initial Randwick City Council testing suggests the presence of hydrocarbons, the EPA’s tests have not yet confirmed the contents.”

Where did these balls come from?

The source of these “tar balls” remains unknown.

The New South Wales Maritime and the Australian Maritime Safety Authority stated that they are currently researching to find out the potential origins of the tar balls.

Speaking to ABC Radio Sydney, NSW Maritime director Darren Wood said, “[The Australian Maritime Safety Authority] will do reverse modelling and drift modelling, take into account the currents and the wind, for [NSW Maritime] to be able to work out whether it’s come from the south, north or east off the coast of New South Wales.”

How dangerous are tar balls?

Professor England told Radio New Zealand that contact with tar balls is generally safe, as long as you wash your hands afterwards. However, he warned that they can be seriously harmful if ingested.

“It’s like crude oil, it’s toxic, it’s carcinogenic to ingest, but to touch, you just go wash your hands and you’ll be fine.”

England informed that the “real danger is through the food chain”.

“Humans eating fish, for example, that have ingested this. It’s incredibly toxic stuff,” he said.

Dr Sharon Hook, CSIRO’s principal research scientist, said that while any oil spill can be harmful to marine life, Sydney’s beaches would be safe for people once the tar balls are collected and removed.

They “are filled with carcinogenic compounds so you wouldn’t want people to come in contact with them,” she told ABC radio.

When will the beaches reopen?

Beaches are expected to reopen once the council has cleared debris from all affected areas, but with more tar balls appearing, the process may take some time.

Although the beaches are officially closed, access has not been forcibly restricted, and some surfers and swimmers have still been spotted in the water.

It is quite common for authorities to close beaches during large swells.

Sydney, known for its more than 100 harbour and oceanfront beaches, attracts millions of tourists and locals each year.

With inputs from Reuters, AFP