Spatial Distribution and Index-Based Assessment of Microplastic Pollution in the Southern Black Sea

Microplastic contamination in coastal environments has become an increasing environmental concern due to its persistence, widespread distribution, and potential ecological impacts. However, comprehensive assessments that integrate microplastic abundance, polymer composition, and pollution indices for both coastal waters and sediments remain limited in the southern Black Sea. Therefore, this study presents an integrated assessment of microplastic contamination in surface waters and coastal sediments from eleven locations along the southern Black Sea coast by combining particle characterization, polymer identification, and pollution assessment. The mean microplastic abundance was determined as 138.6 ± 65.1 MP/L in surface waters and 195.8 ± 91.9 MP/kg dry weight in sediments. Fragments were the dominant particle type in both environmental compartments, where black and transparent particles constituted the most abundant colour categories, while smaller size fractions (<1000 µm) predominated in surface waters. ATR-FTIR analysis identified polyethylene and ethylene-vinyl acetate as the dominant polymers, followed by polyethylene terephthalate, acrylic polymers, polyvinyl stearate, and poly(α-methyl styrene). Spatial differences were evident among the sampling stations, with the highest microplastic abundance in surface water observed at Station S11 and the highest sediment abundance at Station S1, reflecting the influence of local anthropogenic activities and environmental conditions. Pollution index results revealed spatial variability among sampling locations, indicating differences in microplastic accumulation patterns and potential contamination levels associated with local anthropogenic pressures and coastal activities. Overall, the predominance of secondary microplastics and the spatial variation in pollution indices provide baseline information for future monitoring and support management strategies aimed at reducing plastic pollution along the southern Black Sea coast.