Macroplastic waste has been spotted around the shoreline and the waters of Lake Singarak, West Sumatra. Macroplastic waste has been the main source of microplastic pollution in the marine and freshwater environment. This study aimed to determine the types and abundance of macroplastic waste in the riparian area of Lake Singkarak. Macropalstic waste collection was carried out using a 0.25 m2 square transect with a radius of 10 m at six sampling locations around the lake. The collected macroplastic waste was then sorted by its type and calculated to determine the abundance of each type. The six collection points, the most abundant macroplastic waste was at a hotel area (Sumpur) with a waste weight of 3.07 kg/m2, while the shoreline area (Batu Baraguang) with less human activity was the location with the lowest waste abundance of 0.53 kg/m2. The dominating types of macroplastic waste at Sumpur Hotel were plastic film (33%) and hard plastic-fragment (19%). Not only at Sumpur Hotel, the plastic film type also became the most dominant type of macroplastic waste observed in all sampling locations, except at the main river inlet area (Sumani) where the most dominant type found was styrofoam. Overall, there were four types of macroplastic waste that dominated in the riparian of Lake Singkarak, namely plastic film, food bag packaging, hard plastic fragments, also bottle and cup packaging. A high abundance of macropalstic waste in the riparian area could pose a risk of microplastic pollution in Lake Singkarak.

Increasing in production and use of synthetic plastic materials constantly are responsible for the global increase in plastic debris in freshwater environments especially rivers. River is believed to be one of the important way to transport microplastics from inland to the Ocean. The study was conducted to assess early detection of the occurrence, abundance and distribution of microplastics (MPs) in lower Cimandiri River, West java, Indonesia, in which its water flows to the Indian Ocean. The water and sediment samples were collected in September 2020 from seven sampling sites in the upstream river tributaries, in the downstream segments and in the estuary. The analyses were done using a monocular stereo microscope in the laboratory. Preliminary detection showed that the abundance of microplastics was as high as 96 - 325 particles/m3 in the water and 620 - 950 particel/kg in the sediment of Lower Cimandiri River. Fibers accounted for > 70 % of the MPs types, and the size of < 300 mμ was the dominant MPs found (> 60%). Predominated small size MPs could pose a threat to the eels population sustainability. High MPs detected in Lower Cimandiri River could be a potential source of MPs pollution to the Indian Ocean.

Microplastic pollution is already at an “alarming” level in Indonesia’s marine and freshwater ecosystems. However, to the best of our knowledge, no study has reported the microplastic occurrence in the lake ecosystem in Indonesia. Lake Singkarak, a big tectonic lake, has been considered one of the priority lakes to be restored. The lake receives a high influx of plastic waste from rivers and catchment runoff. Controlling the outflow through the hydropower dam and the sluice in the main lake outlet may prevent the microplastic’s outflux. The study’s objective was to determine the microplastic first occurrence and abundance in the lake’s surface water. Water samples were collected from three sites in the lake inlet area, one in the intake area of the hydropower dam and one in the outlet area, by performing four parallel trawls in each site using a modified plankton net. The most abundant microplastics in the lake’s surface water were 9 particles/m3 in the lake inlet area, which received a high plastic waste input from the river. The lowest abundance was 2 particles/m3 in the main lake outlet area. Foams and fragments, white and clear in color, size of 300 μm, were the dominant types of microplastics observed. Our preliminary study suggests that the lake could act as a sink of microplastics. Therefore, ceasing the input sources of plastic waste from the river should be prioritized to prevent further microplastic pollution of Lake Singkarak.

Microplastic pollution in the marine and freshwater environment has been a global concern. The pollution in densely populated urban areas may be more severe than in any other environment, especially in areas lacking plastic waste management. Urban lakes in the Megacity of Jakarta, the capital city of Indonesia, and neighboring areas, which is the most populated city in the world, have been severely polluted by plastic waste. The urban lakes studied were located downstream of watershed areas of major rivers that outflow into Jakarta Bay, the Java Sea, and finally the ocean. To our knowledge, no studies have been reported on microplastic pollution in urban lakes in the Megacity of Jakarta. This study investigated the first occurrence of microplastics in the surface water of six urban lakes in the Megacity of Jakarta. Grab water samples were collected in either inlet or outlet areas of lakes. The water samples were pretreated and sieved to separate the microplastics. The quantification and the identification of microplastics were made using a Stereo Microscope. The most downstream urban lakes in the densely populated area close to Jakarta Bay, which is the final disposal of plastic wastes from the river canal and runoff from the surrounding area, had more microplastics than the urban lakes in the area with less population and further from the Bay. The most abundant microplastics found in the lake’s surface water was about 30,000 particles/m3, whereas 300 - 500 µm and the foam were the dominant size and type of microplastics discovered. The concern is that the smallest size of particles of microplastics found in the lake’s water could potentially contaminate aquatic biota, especially fish, not only in the lakes but also in Jakarta Bay, where fishing activities are substantial.