Spatio-temporal distribution patterns and risk assessment of microplastics along a coastal beach in southern Bangladesh.

This study provides a detailed, bi-seasonal analysis of microplastic (MP) distribution in Kuakata's coastal region, which is influenced by both terrestrial and marine pollution sources. The research documented spatio-temporal variation of MP pollution, with the use of stereomicroscopy for morphological characterization and ATR-FTIR for polymer identification. The analysis revealed that MP concentration peaked during the monsoon season, with river flow identified as the primary distributing factor. Higher degree of contamination was observed along the eastern coastline, attributed to land-based sources and degradation of larger plastics like polyethylene (PE) and polypropylene (PP). White, grey, and transparent MPs (70.06%) were dominant, while fragments were the most prevalent morphological shape (59.67%). Based on these findings, it is speculated that long-distance river transport is the major contributor to MP accumulation, overshadowing local sources and tourist activities. The combination of morphological study with grain size analysis depicts the factors influencing MP degradation, transport, and accumulation. Additionally, SEM analysis revealed surface irregularities like cracks and pits, indicating environmental breakdown. Detailed risk assessments, including pollution load index (PLI), potential risk index (PRI), potential ecological risk index (PERI), and polymer hazard index (PHI), highlighted varying ecological risks. Although hazardous polymers like polyvinyl chloride (PVC) were found in small level, their high hazard score contributed to elevated risks. Principal component analysis (PCA) revealed distinct distribution patterns and common origins for different plastic types. Pellet, film, and fiber particles showed potential commonalities in origin and transport pathways. The findings provide dynamic insights into the MP pollution scenario, offering a foundation for future advanced research.