Microplastic abundance and distribution in surface water and sediment collected from the coastal area

Rapid development has increased the microplastics discharges into marine environments, including coastal waters at Jakarta Bay, Indonesia. This study is proposed to assess microplastics abundance and distribution in surface water and sediment from coastal water at Jakarta Bay.

The samples were collected from 12 locations representing Ancol, Muara Baru, and Muara Angke - Muara Karang. Samples of water and sediment were extracted to obtain the microplastics. The microplastics were identified based on their morphology (shape) and numbered for their abundance. The polymer of microplastics was determined using Raman Spectrophotometer.

The results showed that microplastics were successfully identified and counted in water and sediment samples at all collection points. The number of microplastics was 1532 particles in the water sample and 1419 particles in the sediment sample. The shape of microplastics observed in the water and sediment samples were fibers, films, fragments, and pellets. Among those, fiber and film were the most dominant microplastic detected both in surface water and sediment in all locations. Three polymers, namely polyethylene, polypropylene, and polystyrene, were detected in the microplastic samples. These findings prove that microplastics with their various types are capable contaminate the aquatic environment.

The most common microplastics shapes in sediment were fiber (55.7%) > film (31.1%) > fragment (9.9%) > pellet (3.2%) and for the surface water were film (53.5%) > fiber (33.9%) > fragment (7.8%) > pellet (4.7%). The abundance of microplastics in the sediment (166.8 particles/kg, 95%CI: 148.0-185.0) was significantly higher (p < 0.05) than in surface water (70.9 particles/L, 95%CI: 55.6-86.2). The abundance of microplastics was significantly different among locations (p < 0.05, F = 2.115), with microplastics in sediments were higher in Ancol, and Muara Angke - Muara Karang have the highest microplastics in surface water. These results can provide valuable information on which parts of the Jakarta Bay areas should be prioritized first regarding microplastics management.