Kedron Brook, Bulimba and Enoggera creeks found to contain thousands of plastic particles
More than 4000 small pieces of plastic per kilogram of sediment are found in two popular Brisbane streams, posing a serious health threat, a new study has found.
Queensland University of Technology researchers dredged mud from Kedron Brook, Enoggera and Bulimba streams four times a year in 2024 and found approximately 4400 plastic particles in one kilogram of Kedron Brook sediment.
Bulimba Creek mud contained approximately 4100 particles, while Enoggera was the cleanest, with 2800 particles of plastic per kilogram.
Microplastics are ubiquitous and can be found in water, soil and air. As a result, fragmented plastics have been discovered in every human tissue type and have been linked to colon and lung cancer, although the health threats are not fully understood.
PhD candidate Heshani Mudalige said the amount of plastic found in three streams in Brisbane depended on the slope, seasons and where the stream flowed.
“Kedron Brook’s microplastic load is strongly influenced by its passage through commercial and industrial areas, including the Brisbane Airport area,” he said, noting that the stream’s peak load was in March following heavy summer rains.
Mudalige said impervious areas in the Kedron catchment likely introduced more microplastics into the stream.
He said Enoggera probably had the lowest load because the stream’s flow was regulated by the dam.
Mudalige said a 2021 survey of the Brisbane River found about 500 pieces of plastic per kilo of sediment.
He said this was the first time Kedron Brook sediment had been tested for microplastics.
Associate Professor Prasanna Egodawatta said the study would provide impetus for future research into how microplastics are transported in Brisbane’s urban water systems.
“This study is the first step towards quantifying land-based microplastic inputs into Moreton Bay via the stormwater pathway,” Egodawatta said.
Although the three streams do not flow into water treatment plants that could lead to human consumption, Mudalige said plastics could still pose a danger if they reached the sea.
The findings of the QUT study were published in the journal Environmental pollution.
Mudalige is also working to track the amount of PFAS “forever chemicals” and heavy metals in the three streams, with papers to be published in the near future.
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