Abstract The purpose of this study was to determine the type and abudance of microplastics in the water and sediment of the Siak Watershed. this study was conducted from March to May 2023. Sampling was done once a month for three months. There were 4 research stations, namely Air Hitam River, Sago River, Umban Sari River and Pengambang River. Surface water samples were taken as much as 10 lit…