Macroplastic pollution in the Kalni River basin: Implications for sustainable water management

Macroplastic pollution in freshwater systems poses severe ecological and public health risks, yet its extent in Bangladesh’s rivers remains poorly understood. This study presents the first comprehensive assessment of macroplastic contamination in the Kalni River, a critical waterway in northeastern Bangladesh. Eight sampling stations along a 40 km stretch were surveyed to determine macroplastic abundance, polymer types, and associated water quality parameters. The dominant items were PET (Polyethylene Terephthalate) and LDPE (Low-Density Polyethylene), followed by PP (Polypropylene) fragments. Spatial analysis identified pollution hotspots at Stations S1, S2, and S5, strongly linked to high human activity and inadequate waste management. Macroplastic density peaked at S2 (0.08 items/m²). Physicochemical parameters such as temperature, TDS (Total Dissolved Solids), with S1 recording 39.60 ± 3.56 mg/L, and pH varied significantly (p < 0.05) among sites. PCA (Principal Component Analysis) revealed clustering of stations based on pollution intensity and water quality. The Water Pollution Index (WPI) ranged from 2.61 to 2.95, indicating moderate pollution. A socio-economic survey of 126 riverside residents revealed high exposure risks, with 71% reporting skin ailments associated with contaminated water. These findings underscore the urgent need for targeted waste management, public awareness, and policy interventions to mitigate macroplastic pollution and protect aquatic ecosystems and community health. • To the best of current knowledge, this is the first comprehensive assessment of macroplastics in the Kalni River. • PET and LDPE dominate macroplastic types across sampled stations. • Macroplastic density peaks at S2 with 0.08 items/m², marking a pollution hotspot. • WPI of 2.61–2.95 indicates moderate pollution with clear health risks.