Coastal environments are increasingly threatened by emerging contaminants; however, integrated assessments of multiple pollutant classes remain scarce. This study provides a simultaneous investigation of microplastics (MPs) and total petroleum hydrocarbons (TPHs) in seawater and sediments along the southwestern coast of the Caspian Sea. Samples were collected from fourteen coastal stations during the dry season. MPs were characterized by type, size, shape, color, and polymer composition using microscopy and Raman spectroscopy, while TPHs were quantified using GC-MS. The results revealed MP abundances ranging from 0.05 to 2.35 articles L⁻¹ in water and from 2.01 to 24.13 particles kg⁻¹ in sediment. Fibers and fragments in the 100–500 μm size class were dominant, with polyethylene (PE) and polyethylene terephthalate (PET) identified as the most prevalent polymers. TPH concentrations varied from not detected to 20.152 μg L⁻¹ in water and from 8.37 to 1835.29 μg kg⁻¹ in sediment. Spatial analysis showed no overlap between the contamination hotspots of MPs and TPHs, indicating distinct sources and transport pathways. This concurrent assessment underscores a complex contamination profile in the region and highlights potential ecological risks from both physical and chemical stressors. The distinct spatial patterns provide critical information for designing targeted pollution control measures.
Shahbazi et al. (Fri,) studied this question.