Microplastic profile in the sediment of Jakarta Bay estuary, Indonesia: Characterization based on size fraction and the potential risk to the ecosystem

Jakarta Metropolitan is known as the most populated and busiest city in Indonesia and among the top urban areas in the world with a common problem of solid and liquid waste. The present study aimed to assess the occurrence of microplastic (MP) pollution in sediment from the downstream rivers and coastal water of Jakarta Bay and estimate the potential risk to the ecosystem. Two composite sediment samples (river and coastal) were collected from the Jakarta Bay estuary. Distribution of sediment size showed that the medium size (100–500 µm) was the most dominant in river and coastal samples. Our finding demonstrated the highest MP concentration reported from the estuary ecosystem, i.e., 1184–1337 particles/100 g of river sediment and 804–1055 particles/100 g of coastal sediment. Classification based on size category revealed that the medium size (100–500 µm) was the most dominant MP in river sediment, while the smaller one (50–100 µm) was the most dominant MP in the coastal sediment. The present study indicates that terrestrial origin contributes to the MP pollution of Jakarta Bay. Polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) were the most dominant polymers in the river and coastal sediments. The risk assessment of MP pollution in Jakarta Bay estuary potentially exhibits a very high risk to the ecosystem, primarily related to polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polyurethane (PU) polymers and the MP sizes.