Microplastic contamination and ecological risk assessment in sediments and waters of ship-dismantling yards along the Bay of Bengal

This study investigated the extent of microplastic (MP) contamination in sediment and surface water from one of the largest shipbreaking yards along the Bay of Bengal coast. A total of 48 samples (24 each from sediment and water) were collected and analyzed to assess MP abundance, polymer characteristics, sources, and the associated potential ecological risks. MPs were extracted, identified using microscopy and FTIR spectroscopy, and classified by type, color, and polymer composition. MP concentrations averaged 73.54 ± 8.61 items/kg in sediment and 218.56 ± 19.12 items/m³ in water, with fibers being the dominant morphology (87.8-92.1 % in sediment, 91.5-100 % in water). Stations in close to intensive shipbreaking operations exhibited significantly higher abundances. Polymer characterization revealed PET as the dominant type, comprising 37.5 % in water and 25 % in sediment, followed by PS (25 % in both matrices) and PP (12.5 % in water and 25 % in sediment). Ecological risk assessments revealed moderate to considerable contamination levels. Pollution Load Index (PLI) values ranged from 1.02 to 1.433 in sediment and 1.02-1.68 in water. Polymeric Hazard Index (PHI) values reached maximum at 254.37 (sediment) and 265.68 (water), with corresponding Ecological Risk Index (ERI) values reaching 312.88 and 433.06, respectively. Stations S6 and S3, located near areas of intensive shipbreaking activity, exhibited the highest ecological risks. These findings emphasized the urgent need for regulatory intervention and improved waste management.