Microplastics contamination in sediments and pensi clams (Corbicula sumatrana Clessin) in the waters of Lake Singkarak

Microplastics are plastic particles <5 mm in size that pose a threat to aquatic biota, especially filter-feeder biota such as pensi (Corbicula sumatrana) living in Lake Singkarak. This study aimed to determine the characteristics and abundance of microplastics in sediments and pensi and analyze differences in microplastics abundance based on the size of pensi. This research was conducted from October 2024 to January 2025, using a survey method with purposive sampling. Sampling was carried out at five locations: the Sumani River Outlet, Paninggahan River Outlet, Hydropower Intake Area, Sumpur River Outlet, and Ombilin River Inlet. Samples were treated with 30% H2O2 and 5 M NaCl, then filtered using Whatman No.42 filter paper. Observations were made under a stereo microscope. The results showed that the microplastic shapes consisted of fragments, films, lines, foams, and pellets, with black being the dominant color and most sizes ≤100 µm. The average abundance of microplastics in sediments in Lake Singkarak ranged from 1600 to 2440 particles/kg dry weight, while in Pensi it ranged from 1633 to 2650 particles/kg dry weight. In pensi with shell lengths ≤10 mm, 10-20 mm, and >20 mm, the average abundance of microplastics found was 1490, 2080, and 2700 particles/kg dw. These findings indicate that sediments and pensi in Lake Singkarak have been contaminated with various shapes, colors, and sizes of microplastics, which may be harmful not only to pensi but also to humans who consume them. Furthermore, an increase in Pensi size corresponded to a higher abundance of microplastics.