Microplastics contamination detection in Swan-Canning Estuary via Raman spectroscopy: Insights from shoreline sampling

Plastic pollution along the shores of Swan-Canning Estuary (Swan and Canning Rivers) in Perth, Australia is an increasing concern, with a survey by the Western Australian Government reporting an average of 151 plastic pieces per square meter in the Swan-Canning Estuary. This study examines the origins, distribution, and concentrations of microplastics (MPs) in the Swan-Canning Estuary to inform effective mitigation strategies. Water samples were collected from 3 key locations along the Swan-Canning Estuary, including Matilda Bay, Deep Water Point Reserve, and Bardon Park. Sampling was conducted over 14 runs, with a combination of 5.6 mm (3.5 mesh) and 0.10mm (150 mesh) or 0.074 mm (200 mesh) sieves used to capture microplastics effectively. Approximately 1000 to 2000 litres of water were processed per site through sieving and chemical treatments to isolate MPs, which were subsequently analysed using Raman spectroscopy. The results revealed the highest MP concentration at Matilda Bay, followed by Bardon Park and Deep Water Point Reserve, with no MPs detected at the other sites. Seasonal variations were noted, with higher concentrations during winter compared to summer, necessitating further research to confirm this trend. Polypropylene, commonly associated with fisheries and marine activities, emerged as the most prevalent MP species. This study demonstrates the effectiveness of Raman spectroscopy for microplastic detection and identifies key pollution hotspots in the Swan and Canning Rivers. The findings offer valuable insights for targeted remediation efforts and support broader initiatives to mitigate plastic pollution in urban waterways.