Microplastics in Tanguar Haor: abundance, spatial variations, and environmental risks in a Ramsar wetland of Bangladesh.

Microplastic (MP) pollution in aquatic ecosystems is an emerging global concern. This study presents the first comprehensive assessment of MP contamination in Tanguar Haor, the second-largest Haor and a Ramsar site in Bangladesh. Twenty water samples were collected from 20 locations and analyzed using optical microscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). MP concentrations ranged from 10 to 1,290 ± 80.9 items/m3, with an average of 353 ± 98 items/m3. Fibers dominated the MP types (72.1%), followed by fragments, films, foams, pellets, and lines. Polyethylene and polyethylene terephthalate were the most abundant polymers (each 36%). Most MPs were transparent (48%) or red (21%), with sizes mainly between 0.3 and 1.5 mm (83%). SEM analysis revealed rough and weathered surfaces, indicating long-term environmental exposure. High polymer hazard index (550-1,740) and ecological risk index (>600) identified several high-risk sites (S14 > S1 > S2 > S13 > S7), despite relatively low Nemerow pollution and pollution load indices. Major MP sources include river inflow, agricultural and household waste, fishing activities, and tourism. The findings highlight potential risks of MP ingestion and bioaccumulation, threatening aquatic biodiversity and ecosystem health. This study provides baseline data to support future research and policy development for freshwater protection in Bangladesh.