Microplastics (MPs) in Water Column of the Peripheral Rivers and Lake of Dhaka City

Abstract

Microplastics (MPs) pollution in developing countries deserves more attention consider ing the rapid industrialization in such countries and toxic nature of MPs. The concern has attracted public attention in recent decadesdue to its pervasiveness, including massive ad verse impacts. The lack of studies onmicroplastics in freshwater ecosystems has hindered understanding the source and fate of microplastics. The study of water column throughout the peripheral urban river systems and lake of Dhaka city is provided a first representative example of urban river input of microplastics from a mega-city of Bangladesh.Goals of this study to investigate occurrences of MPs(microplastics) in the urban river and lake en vironment. Thus, thirty-six (twenty locaions from rivers of peripherial rivers of Dhaka city and eight are from Dhanmondi lake) water column samples were collected from dif ferent locations that were exposed to various point sources as well as non-point sources of contaminants into the rivers named Buriganga ,Turag, Balu & Dhanmondi lake in Bangla desh. The samples were then analysed using modified NOAA laboratory analysis methods which involve digestion, density separation, and microscopic inspection. MPs were ex tracted from water samples using the density separation and wet peroxidation methods . . Attenuated total reflectance-Fourier transform infrared spectroscopy was used to identify the MP particles. This investigationresults indicated a medium-level abundance of micro plastics in comparison with many other studies in the freshwater column throughout the world . The predominant characteristics were fibre shape. The abundance of extracted mi croplastics in rivers varied from 6 to 52 particles/L on average value of 29 particles/L. In terms of mass concentration, the value ranged from 10.65 to 57.44 mg/L on average of 34.045 mg/L. Meanwhile in Dhanmondi Lake , the abundance of microplastics varied from 8-40 particles/L and in terms of mass concentration the value ranged from 9.98- 44.41 mg/L. In Dhanmondi Lake beside a huge amount of fibre , we got only two film particles which were not found in the river water column eventually. In our whole study we got highest amount and highest size of microplastics Turag river and those were mostly black in colour. Industrial and commercial regions in the study area tended to pose higher MPs concentration than open and residential area. The pollution load index (PLI) was used to evaluate the pollution level and risk category of MPs respectively. Most of 3 the particles were found to be smaller (< 2 mm) in size with fibers and black being the predominant size and color, respectively. Assessment of microplastic pollution in river. Sediment is essential for its role as a sink. In contrast, accumulation of microplastics in nver Sediment can alter some physical properties of the sediment, such as bulk density, water holding capacity, and also affect the functioning of benthic organisms (Amrutha et al., 2022) .This study can contribute to the source control of MPs pollution and urban plan ning in Dhaka city to achieve United Nations Sustainable Development Goals (SDGs