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Australian scientists have solved a mystery which has gripped Sydney: what were the sticky dark blobs which washed up on some of the city’s famed beaches last month?<\/p>\n
Initially believed to be tar balls, they were in fact a “disgusting” combination of human faeces, cooking oil, chemicals and illicit drugs, researchers say.<\/p>\n
Eight beaches including Bondi were closed for several days and a massive clean-up ordered after thousands of the black deposits started appearing from 16 October. <\/p>\n
Testing by chemists has determined the balls were most likely the result of a sewage spill, though their exact origin remains unknown.<\/p>\n<\/div>\n
Last month authorities in New South Wales (NSW) said they suspected the objects were a mixture of fatty acids, fuel oil and chemicals found in cleaning and cosmetic products.<\/p>\n
But further testing found the material is unlikely to have originated solely from an oil spill or waste from a ship, as some had thought.<\/p>\n
Each ball was slightly different but had a firm surface – hardened partially by accumulating sand and minerals like calcium – and a soft core.<\/p>\n
Inside was everything from cooking oil and soap scum molecules, to blood pressure medication, pesticides, hair, methamphetamine and veterinary drugs.<\/p>\n
“They smell absolutely disgusting, they smell worse than anything you’ve ever smelt,” lead investigator Associate Professor Jon Beves, from the University of NSW, told 9News.<\/p>\n
Professor William Alexander Donald said they resembled fat, oil, and grease blobs – often called fatbergs – which are commonly formed in sewerage systems. <\/p>\n
Detecting this along with recreational drugs and and industrial chemicals had “pointed us to sewage and other sources of urban effluent”, he explained.<\/p>\n
The researchers said they had received unconfirmed reports of smaller but otherwise similar balls washing up over the past two years.<\/p>\n
Sydney Water has reported that there are no known issues with waste systems in the city.<\/p>\n<\/div>\n