The testing would identify any hydrocarbons, he said, and this would narrow down the possibilities for the source.
Wright said there were three possibilities, two coming from a source on land and the third from oceangoing ships.
First, a discharge could come from the stormwater drain and make its way out to sea. For example, if someone was working with asphalt then the hot tar could travel down the drain, react with the water, congeal into balls and collect on the beach or the estuary waters.
A close-up of the black balls on the back of a truck as the clean-up operation progresses.Credit: Janie Barrett
Second, Wright said, it was possible it came from the sewage system because the big ocean outfalls at Malabar and Bondi were “not highly treated” and if people put oil or grease down the sink it could solidify and form “fatbergs” with solids in the wastewater.
The third possibility, Wright said, was discharge from a ship, which burn diesel or “an oilier, sludgier sort of fuel that’s more like asphalt”. That would be identified by the lab testing.
Australian Marine Conservation Society oil and gas campaign manager Louise Morris said oil pollution in the ocean came from both offshore oil rigs and ships. Some petroleum products formed tar balls, while others were more likely to dissipate, but in either form it was a toxic pollutant that harmed marine life.
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“We only see a small amount of what is going on because most of it will fall to the bottom of the ocean,” Morris said. “It’s out of sight, out of mind, but it’s being absorbed by marine life, some of which humans eat.”
On Wednesday morning, groups of walkers and swimmers were crowding around the barricades blocking access from the seawall to Coogee Beach. The closure interrupted daily swimmers and a PE class for Brigidine College Randwick.
Hans Visch, 76, is part of a group of swimmers who normally swim to Wedding Cake Island every morning. Visch saw news of the balls washing up last night, but tried his luck this morning hoping it had reopened.
Visch was horrified by the pollution, given the amount of wildlife, including whales, in the area.
“It makes me really sad to see this happening,” he said.
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