| Summary: | Microplastics (commonly defined as plastic particles smaller than 5mm in size) are widely recognised as a global concern. However, studies of the occurrence of microplastics in freshwater systems, particularly in Malaysia, are limited.
This study aims to assess the sources and levels of microplastic contamination within the Langat River Basin, Malaysia. This study presents the first comprehensive empirical assessment of the contribution of different sources of microplastic as well as the first systemic data on spatio-temporal variability in microplastic concentrations in a Malaysian river. Such data is crucial for the identification of contamination hotspots and, in turn, the development of management strategies. This study is also the first to evaluate the degree of correspondence between microplastics in river water and bed sediments, which is critical for monitoring and assessment of potential risks posed by microplastics to acquatic organisms and human health.
A total of 656 water and sediment samples were collected from 33 sites spread across the Langat River Basin. The samples were treated with Fenton reagent to remove organic material and filtered onto glass microfiber filter papers before enumeration under a stereoscopic microscope.
Road runoff, residential and industrial areas, atmospheric deposition and wastewater treatment plants were significant sources of microplastics in the Langat River, with road runoff being the main contributor. The Langat River had a mean concentration of 4.39±5.11 particles/L, which varied spatially (associated with differences in land-use) and temporally (associated with flow changes). Microplastic was deposited on the bed of the Langat with a mean of 6027.39±16585.87 particles/m2, which did not correspond to the concentrations in the water either at site-scale or patch-scale, suggesting that sampling designed to assess risks posed by microplastic should assess both concentrations in the water and on the bed. Efforts to reduce microplastic contamination should be focused on upstream intervention, including law enforcement, endorsing proper management systems and creating public awareness. Such efforts are sorely needed in Malaysia, due to the rapid pace of development set against limited awareness and poor waste management.
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