Tracing microplastic footprints in beach sediments along the Qatar coast: A risk-based approach to pollution assessment

Surface and subsurface sediments from twenty representative beaches along the Qatar coast were analyzed following standardized NOAA protocols, including sieving, density separation, microscopic observation, and ATR-FTIR spectroscopy, to investigate the horizontal and vertical distribution, physical characteristics, polymer composition, and environmental risks of microplastics (MPs). MPs were detected at concentrations ranging from 0 to 855 MPs kg −1 dry sediment. Fragments and pellets were the dominant morphologies, representing 42.98% and 38.96% of the total count, respectively. Polypropylene (PP) and polyethylene (PE) were the dominant polymers, together comprising 60% of identified MPs, reflecting their extensive use in consumer products and packaging. MP abundance decreased with depth; however, given the shallow core depth (25 cm) and dynamic intertidal conditions, this gradient primarily reflects surface enrichment from recent inputs and physical mixing rather than a definitive historical record. Risk assessment using the pollution load index (PLI), polymer hazard index (PHI), coefficient of microplastic impact (CMPI), environmental status index (ESI), potential ecological risk index (PERI), and microplastic pollution index (MPPI) revealed spatial variation in contamination levels. Al Wakrah and Zekreet showed the highest pollution and hazard levels, while northern sites such as Ras Rakan showed relatively moderate contamination. Overall, the findings highlight the ecological threat of MPs along the Qatar coast and the need for targeted mitigation and integrated coastal management to reduce plastic leakage into the marine environment.