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Spatio-temporal dynamics and flux of microplastics in the lower Ganges-Brahmaputra-Meghna River system and estuary

Journal of Contaminant Hydrology 2025
Md. Jaker Hossain, Md. Jaker Hossain, Sheikh AftabUddin, Lijun He, Huahong Shi, Huahong Shi, Jing Zhang, Jing Zhang

Summary

Researchers examined the spatial and seasonal dynamics of microplastics across the lower Ganges-Brahmaputra-Meghna River system and estuary, one of the world's largest river systems and a major contributor to global ocean plastic inputs. The study quantified microplastic flux and found significant spatio-temporal variation driven by river discharge, monsoon seasonality, and anthropogenic land use across the catchment.

Polymers
Study Type Environmental

Rivers are major pathways of land-based plastic debris to the oceans, but limited data exist for microplastic (MP) flux from large river systems. This study examines the spatial and seasonal dynamics of MPs in the Ganges-Brahmaputra-Meghna (GBM) River system and estuary, a key contributor to global marine plastic pollution. MP abundances ranged from 1.53 to 8.13 items/L in the dry season and 2.67 to 7.67 items/L in the wet season, with no significant overall seasonal difference (p > 0.05). The dominated shape and color werefiber and blue, respectively, with the size class of 0.02-0.5 mm being predominant. The prevalent polymers during both seasonswere rayon and polyethylene. MP transported into the Bay of Bengal (BoB) were calculated as 9.42 × 10 items/day (1.17 tons/day) during dry season and 33.95 × 10 items/day (10.78 tons/day) in wet season indicating that a substantial amount of MPs are being input tomarine environment from GBM River system compared with other rivers globally. Risk assessments indicated high contamination levels (CF, PLI, and HI) and substantial ecological risks (RI) valuesin the entire study area with maximum pollution level gradient at the Ganges, Meghna and GBM confluence. These findings contribute important quantitativeinformation on spatio-temporal patterns and load of MP, necessary for validation of global-level MP flux models and the development of focused mitigation strategies within the GBM basin.

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