Plastitar and pyroplastics as emerging vectors of coastal pollution: Chemical identification from Panjang Island (Java Sea) and Palm Beach, Florida.

Novel plastic-derived materials such as plastiglomerates, pyroplastics, and plastitar have emerged as persistent pollutants in coastal environments, yet their chemical compositions remain inadequately characterized. This study presents a comparative chemical analysis of plastitar and pyroplastic collected from Panjang Island (Java Sea, Indonesia) and Palm Beach (Florida, USA), regions influenced by nearby and/or downstream oil production, refining, natural seeps, and maritime activity. Polymers were identified by infrared spectroscopy as polyethylene, polystyrene, or polyurethane derived from thermally affected plastic debris or embedded in tar matrices. Gas chromatography with flame ionization detection (GC-FID) analysis of Panjang Island samples, supplemented by comprehensive two-dimensional GC × GC-FID for selected specimens, revealed that the oil residue in the plastitar samples is dominated by n-alkanes (n-C16 to n-C37) and contains isoprenoids (pristane and phytane). Meanwhile, the plastic part of the pyroplastic and plasticrust samples without oil residues exhibited irregular, unresolved chromatographic patterns. The plastitar and pyroplastic samples from Panjang Island exhibited exceptionally high concentrations of total PAHs (2399 ± 190 ng g-1 to 247,951 ± 17,176 ng g-1) and total phthalates (1257 ± 24 ng g-1 to 3169 ± 527 ng g-1), with one sample yielding the highest concentration of ΣPAHs ever reported in marine plastic debris. The dominance of high-molecular-weight PAHs and phthalates highlights the dual role of plastitar and pyroplastic as both physical carriers and sources of chemical pollutants. This study contributes to the growing recognition of plastitar and novel thermally altered plastic debris as distinct and hazardous form of marine plastic pollution.