Abundance and characteristics of microplastics in major urban wetlands of Dhaka, Bangladesh

Abstract The study was performed to evaluate the abundance and characteristics of MPs in water, sediment, and fish samples of three major urban lakes, namely Dhanmondi Lake, Gulshan Lake, and Hatir Jheel Lake in Dhaka, Bangladesh. The abundance of microplastics varied from 0-9 items/L in surface water, 0-16 items/kg in sediment, and 0-17 items/individual; 0-4.88 items/g in the gastrointestinal tract (GIT) of test fish species, respectively. Highest abundance of microplastic in an individual fish was observed in Oreochromis mossambicus from Dhanmondi Lake. The samples were visually observed under a stereo microscope, which showed the dominant type of microplastics in both water and sediment samples were films followed by micro pellets, fragments, fibers, and in fish samples pellets and foams were dominant. According to the Fourier Transform Infrared analysis (FTIR) the dominant polymers in the analyzed samples were High density polyethylene (HDP), Ethylene Vinyl Acetate (EVA), Polyvinyl chloride (PVC), Polycarbonate (PC), Cellulose Acetate (CA), and Polypropylene (PP). In water and sediment samples of Gulshan Lake, MPs were relatively higher than in other lakes, and in fish samples of Dhanmondi Lake MPs were higher. The results of this study indicate that MPs were abundant in studied lakes and suggested a high level of microplastic contamination occurred not only in the water and sediment but also in the resident fishes. The implication of the finding suggests that the presence of MPs in urban lakes has raised concerns about the potential human health impact.