Microplastic contamination in water, sediment, and fish from the Kahayan River, Indonesia

Microplastic occurrence in the aquatic ecosystem has become of great concern worldwide because of its persistence, durability, and toxicity. Microplastics are found ubiquitous in freshwater environments, including rivers. Thus, our study assesses microplastic pollution in water, sediment, and fish of the Kahayan River, Indonesia. We first evaluated microplastics' occurrence, abundance, and characteristics in Central Kalimantan, Indonesia. The average abundance of microplastic in water was 2.92 ± 2.62 items/L, while in sediment was 6.93 ± 3.15 items/Kg dry weight. We found 53 out of 90 fish (58.89%) had microplastics in their digestive tracts with an average abundance of 2.03 ± 3.416 items/Ind. The predominant characteristics in water were fragment and fibre and size of 150-<300 µm. Microplastics present in the sediment and the digestive tract of fish have similar dominant fibre. In terms of size, sediments and fish were dominated by 150-<300 µm, 1000–5000 µm, and 500-<1000 µm respectively with different order of proportions. The infrared spectroscopic analysis confirmed the most common polymer type to be polyvinyl chloride in water and sediment, while polyethylene was predominant in fish. Our study provides the current status of microplastic contamination for further evaluation and management of the Kahayan River, Indonesia.