Brisbane's Bulimba Creek Tops Waterways for Hazardous Microplastics

A study of three creeks in Brisbane, Australia, has found that Bulimba Creek carries the highest load of hazardous microplastics among them. Researchers at Queensland University of Technology (QUT) developed a new risk-zoning framework to assess the ecological danger of microplastics in sediment from Kedron Brook, Bulimba Creek and Enoggera Creek, publishing their findings in the journal Marine Pollution Bulletin.

The framework combines three measures: how much microplastic is present in the sediment, how hazardous its polymer types are, and the ecological risk this combination poses. First author Heshani Mudalige, a PhD candidate at QUT's School of Chemistry and Physics, said the analysis showed that the hazard posed by specific polymer types influenced ecological risk more strongly than the sheer amount of microplastic present. Three polymer types — PVC (a widely used hard plastic), PMMA (an acrylic plastic) and polyester — scored highest for hazard and were the biggest contributors to ecological risk. Bulimba Creek scored highest for both hazardous microplastics and overall ecological risk, while Kedron Brook had the highest total microplastic load.

When PVC particles are eaten by organisms at the bottom of the food chain, the toxic chemicals in them can affect fish growth, reproduction and survival as the particles move up the food chain, Mudalige said. PMMA may cause physical stress, reduced feeding efficiency and energy loss in organisms that consume it. Microplastics can also absorb pollutants from the environment and release chemicals they already contain; they enter the human body mainly through seafood and are linked to potential harm to the circulatory and immune systems and to neurodegenerative disorders.

The researchers took sediment samples from six sites on each creek, four times over a year, to reflect the mix of industrial, commercial and residential land use each waterway flows through. The results show that land use plays an important role in how microplastic risk is distributed, which the team says can help environmental managers target cleanup and protection efforts where they are needed most.