Not tar balls but 'revolting' fatbergs invaded Sydney beaches: What are they?

Beaches in Sydney were left contaminated and closed after hundreds of mysterious black balls, initially thought to be tar balls from an oil spill, washed up onshore in mid-October.

This unusual sight set off a thorough investigation, ultimately revealing that these black blobs were not what they first appeared to be.

As authorities tested the substances extensively, it was discovered that these “tar balls” were actually large clumps of waste – a congealed mass of fats, oils, and chemicals more accurately described as “fatbergs.”

The investigation involved multiple agencies, including scientists from the University of New South Wales (UNSW), the New South Wales Environment Protection Authority (EPA), and the Department of Climate Change, Environment, Energy, and Water (DCCEEW).

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Their findings raised serious concerns about pollution levels on Sydney’s iconic beaches and have put the city’s urban waste management under a spotlight.

The discovery of the mysterious balls

On October 16, lifeguards at Sydney’s Coogee Beach reported clusters of strange black balls scattered across the sand. Further sightings quickly followed at Bondi, Bronte, Tamarama, and Maroubra beaches, leading to beach closures and intensive cleanup operations.

Workers equipped in hazmat suits collected the blobs, initially suspected to be tar balls, which typically result from oil spills. However, laboratory analysis has now uncovered a far more complex picture, with the balls comprising not just oil and debris but a highly varied composition of waste materials.

According to UNSW Associate Professor Jon Beves, “They are disgusting and they smell revolting,” describing the black balls as a “complex mixture of different things … but it looks consistent with human-generated waste.”

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Beves wrote in The Conversation, “Every ball was slightly different,” indicating the mixed origins of the waste, including domestic, industrial, and environmental sources.

What was the composition of the fatbergs?

Initial testing by UNSW and the EPA utilised techniques such as solid-state nuclear magnetic resonance spectroscopy, which indicated a composition rich in carbon but with a low fossil fuel content, ruling out an oil spill as the primary cause.

Further analysis using mass spectrometry and Fourier-transform infrared spectroscopy revealed a wide range of alarming components, including:

• Human waste: The blobs contained fatty acids, cholesterol byproducts like epicoprostanol, and traces of human fecal waste.

• Forever chemicals (PFAS): Scientists detected perfluoroalkyl substances (PFAS), known for their persistence in the environment and potential health risks.

• Recreational drugs: Methamphetamine and THC (the psychoactive compound in cannabis) were found within the fatbergs.

• Prescription medications: Traces of antihypertensive drugs like losartan and steroidal compounds, such as norgestrel, were present.

• Vehicle-grade fuels and grease: The analysis uncovered organic compounds and hydrocarbons typically found in motor oils, cooking oils, and industrial waste, indicating probable sources of urban runoff.

“These findings are consistent with contamination from sewage and industrial runoff,” noted Beves and William Donald of UNSW. “The question is, essentially, would you like to go and swim in the sewer?”

How do these fatbergs form?

With significant levels of oils, grease, and other solidified fats detected, the blobs closely resembled “fatbergs” – hard masses of accumulated waste, often found clogging sewers.

These fatbergs form when fats, oils, and grease (FOG) from domestic and commercial sources build up and solidify, mixing with other waste materials like food scraps, human hair, and even bits of plastic. FOG deposits are known to be extremely adhesive and resilient, creating stubborn blockages that are difficult to dissolve.

We repeated some extractions of samples of the balls, and found 30-50% of the mass of the balls were soluble in DCM. Some black stuff in there which is insoluble in either water or DCM, but it accounts for a relatively small proportion of the overall mass. pic.twitter.com/BIMHYP2CwJ

— Jon Beves (@JonBeves) November 7, 2024

“The disposal of used cooking oil in household and commercial sinks contributes to the formation of these adhesive and viscous deposits,” noted scientists at RMIT University in a related study last year. Such waste conglomerates in sewer systems can eventually discharge into the ocean, leading to pollution in coastal areas, especially after heavy rains.

The bigger problem in Sydney

The appearance of fatbergs on Sydney’s beaches highlights a serious pollution issue. Around 28 per cent of swimming sites in New South Wales receive poor water quality ratings, especially after rainfall, with areas like Gymea Bay and Malabar Beach flagged for contamination from human waste, reported ScienceAlert.

NSW Maritime’s analysis of ocean currents and Sydney Water’s inspection of treatment facilities have yet to identify the fatbergs’ exact origin. Researchers, including Beves, suggest the blobs may have formed “somewhere in a pipe … possibly through an overflow into stormwater.”

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These fatbergs have highlighted the need for improved waste disposal practices. Authorities are urging public awareness to prevent fat, oil, and grease (FOG) buildup in sewers. Better waste management policies could reduce such pollution events, protecting both marine ecosystems and public health.

The final results from the investigation are expected soon, and authorities hope to pinpoint the exact source of the blobs.

With inputs from agencies