Targeted and suspect screening reveal traditional and novel organophosphate esters in philippine sea sediment cores.

Information on the co-occurrence of traditional and novel organophosphorus flame retardants (OPFRs) in the marine environment remains limited, hindering a comprehensive understanding of their pollution dynamics. This study comprehensively investigated 10 traditional OPFRs and 55 suspect compounds in four deep-sea sediment cores from the Philippine Sea. The total concentrations of targeted OPFRs (Σ10OPFRs) ranged from not detected to 24.7 ng/g dw, indicating moderate contamination in the studied area. Aryl-OPFRs dominated, with triphenyl phosphate (TPHP) as the major compound. Among the suspects, tris(2,4-di-tert-butylphenyl) phosphate (AO168=O), bis(2-ethylhexyl) phenyl phosphate (BEHPP), and dibutyl phenyl phosphate (DBPP) were confirmed and quantified, with total concentration of Σ3OPFRsuspects ranged not detected-1207.3 ng/g dw, which was much higher than the traditional ones. AO168=O was the most abundant compound, likely due to its extensive industrial use and strong hydrophobicity. Sediment properties and ocean currents were important factors influencing the vertical distribution of OPFRs in deep-sea sediments. Risk assessment revealed that tris (2-ethylhexyl) phosphate (TEHP), TPHP, and AO168=O posed moderate to high risks to deep-sea benthic organisms. These results will advance knowledge of the fate and ecological risks of OPFRs in deep-sea environments, offering essential scientific guidance for their ecological management and conservation.