Scientific tests of mysterious Sydney tar balls reveal

A team of scientists has run tests and investigated the mysterious black balls of oil that are washing up on Sydney’s eastern suburb beaches.

Testing of the mysterious black balls washing up on Sydney beaches has so far shone little light on what they are and where they have come from.

University of NSW scientists have done preliminary tests, finding the balls contain bituminous materials, and some biological matter like fatty acids.

Seven Sydney beaches have been closed to the public as the black tar balls wash up along the shore.

The “unusual” spheres were first discovered along Coogee Beach on Tuesday, prompting Randwick City Council to immediately shut the beach while testing was conducted.

UNSW researchers looked for clues on the tar balls by studying them under ultraviolet light. Picture: Associate Professor Vinh Nguyen / UNSW

Since then Gordons Bay, Clovelly Beach and Maroubra Beach have been closed to the public after tar balls also washed ashore.

Bondi, Tamarama and Bronte beaches were also closed “out of precaution”, Waverley council said.

The beaches will be closed until further notice.

UNSW chemist Alex Donald said the findings confirmed the tar balls originated from weathered oil.

“It is still unclear whether they resulted from natural seepage or a crude oil spill,” he said.

“Further chemical analysis is needed to pinpoint the source.”

The researchers also put the balls under UV radiation.

Thousands of the blobs have bobbed onto the beaches. Picture: NewsWire / Damian Shaw

Specks of the balls are fluorescent, indicating organic compounds.

The tar balls “likely originated from petroleum-based sources”.

“Whether caused by human activity or natural processes, solving the mystery of these sticky invaders requires ongoing scientific inquiry.”

“The source could be linked to oil spills, petrochemical processes, or environmental pollution involving hydrocarbons,” Professor Donald said.

The fluorescence points to marine algae becoming attached.

The tar balls are not rock hard, and their round shape indicates they have been at sea for at least weeks or months. Picture: Randwick City Council

Similar balls show up on Californian coasts from oil seeping out of the seafloor. Golden Beach in Queensland and Ninety Mile Beach in Gippsland have seen similar blobs, after oil spills or shipping discharges.

Professor Donald said figuring out whether the tar balls came from a spill or naturally from the seafloor was important in shaping the correct environmental response.

An industrial spill could spark legal action, and requires an immediate cleanup.

“The toxic compounds in tar balls can leach into the water, posing long-term threats to marine biodiversity,” he said.

“The appearance of tar balls on beaches such as Coogee not only damages Australia’s pristine coastal reputation but also threatens the health of ecosystems that support industries like fishing and tourism.”

The six UNSW scientists will continue to analyse the balls, being given samples by the Randwick City Council.

Coogee Beach has been closed until further after mysterious, black, ball-shaped debris was located washed along the length of the beach. Picture: NewsWire / Damian Shaw

Randwick Mayor Dylan Parker said the council would continue to remove the material across all beaches.

“The safety of the community is our first priority. That’s why Council has taken the precaution to close these beaches while we undertake the safe collection and disposal of this material.

“We don’t yet know what has happened to produce the debris washing up on our beaches, but we will continue to work with relevant authorities to ensure the safety of the public and clean up our beaches.”

Preliminary results showed the material of the “unusual” spheres were “hydrocarbon based pollutant which is consistent with the makeup of tar balls”.

Clean-up efforts were launched on Wednesday to remove and safely dispose the debris from the popular beaches. The Mayor said council staff had been working with the NSW Environment Protection Agency, Ports Authority and Transport for NSW to assist in the clean-up response.

Suspected tar balls that have washed up on Coogee Beach. Picture: NewsWire / Damian Shaw

The clean-up process is expected to continue into Thursday, Mayor Parker advised.

“Our community is rightfully very protective of our natural environment and this has been a very concerning incident,” he said.

“We have engaged an expert occupational hygienist and a specialist waste removal contractor who are currently systematically removing the debris from the beaches in accordance with an agreed safe work method statement developed with the NSW EPA.”

He thanked the public for remaining off the beach while the tests and clean-up efforts continue.

Originally published as Scientific tests of mysterious Sydney tar balls reveal