Microplastics (<5mm) are now recognised as ubiquitous in aquatic environments, despite having only been defined in the early 2000’s. These have become pervasive in Australia’s waterways, and yet, our understanding of their concentration and distribution remains in its infancy. In 2018, the Australian Microplastic Assessment Project (AUSMAP) was created to address this shortfall. This citizen science program allows the collection of rigorous data along marine and freshwater shorelines around the country.
This study sought to add to the current knowledge base by offering the largest single dataset of microplastic concentrations from aquatic environments in South Australia. Over 50 estuarine and coastal sediment samples were analysed between 2019 and 2024. Microplastics were found in over 70% of samples, with significantly higher loads reported in the estuaries. An analysis of the typology of the microplastics also highlighted that industrial and commercial activities were the main sources. Analysis of environmental samples also demonstrated the presence of chemicals of concern potentially leaching from these plastics. These findings reiterate the significance of long-term monitoring over broad spatial and temporal scales to determine key microplastic hotspots. Their concentration in estuarine environments highlights land-based pollution as a consistent source and the potential for environmental harm.