Microplastic Pollution in the Surface Water of Karnaphuli Estuary: Understanding Spatial Variation and Ecological Impacts

Abstract

Microplastics (MPs) emerged as global contaminants of concern for their widespread occurrence in aquatic systems, which are mainly produced from the degradation of larger plastics and various industrial activities, posing notable threats to marine ecosystems. Since research on pollution for the abundance of MPs in coastal and estuarine areas of Bangladesh remains limited, this study examined MP contamination in surface water collected from ten stations of the Karnaphuli estuary (KE) during February 2023. The presence of MPs was assessed in terms of distributions, abundances, and potential risks through National Oceanic and Atmospheric Administration procedures. Results showed a considerable presence of MPs, dominated by fibers (86 %), followed by fragments (8 %) and foam (6 %). In terms of color, black and transparent MPs were most common, while green MPs were least observed, as well as particle size of MPs with a size smaller than 1 mm was more frequent. Attenuated Total Reflectance Fourier Transform Infrared spectroscopy characterization confirmed the presence of polymers, including ethylene vinyl acetate, nylon, polystyrene, acrylonitrile butadiene styrene, acrylic, and polyethylene as MPs. Risk evaluation through contamination factor (CF), Pollution Load Index (PLI), Polymer Hazard Index (PHI), and Potential Risk Index (PRI) revealed moderate to very high risks across the stations. All PLI values exceeded 1.0, confirming significant pollution; however, PHI values indicated a moderate hazard but were skewed by high-risk stations. Additionally, PRI values also varied widely, with most stations showing considerable risk, which corresponds to the sources including industrial effluents, agricultural runoff, and urban wastes, confirmed by Land Use Land Cover analysis. Thus, the results of this study highlight the urgent need for effective pollution control based on long-term monitoring of MPs in the KE.

Dhaka Univ. J. Sci. 74(1): 36-45, 2026 (January)