First observation of microplastics in surface sediment of some aquaculture ponds in Hanoi city, Vietnam

A large amount of plastic waste has been released into the environment during the increase in global plastic production in the 21st century. Microplastics (0.1 µm to 5 mm in size) existing in hydro-systems, especially in aquatic sediments, can enter organisms and then human body through food chain. This paper provided the preliminary observation results on microplastic presence in the surface sediment of the aquaculture ponds (fish) in Hanoi city in 2021. Our results showed that microplastic concentrations ranged from 2,767 ± 240 to 2,833 ± 176 items.kg−1 dry weights for the surface sediment of the two aquaculture ponds. Two main shape groups of fiber and fragment were detected, of which fibers were dominated (62% and 82% for the two ponds observed). For microplastic fibers, green, white, black and red were main colors, whereas for fragments, yellow, blue and white were main ones. Polyethylene (PE) and polypropylene (PP) were two main polymer types found in the sediment samples. The sources may mainly come from the microplastic contaminated water of the Nhue River, and the direct aquaculture activities. The results of this study contributed to build a dataset on microplastic pollution in aquatic environment, especially aquaculture ponds in Vietnam. Our study also revealed the need for microplastic observation in different environments and organisms, especially in aquaculture zone in Vietnam.