Identification and prioritization of organophosphate esters and related compounds in offshore sediments across China

Organophosphate esters (OPEs) are prevalent pollutants that are widely detected in offshore sediments worldwide, posing a threat to the health of humans and aquatic ecosystems. However, few studies have comprehensively characterized and risk-assessed the diverse mixtures of traditional and emerging OPEs in these environments. This provincial-scale survey applied suspect and non-target screening to surface sediments and sediment cores across five major offshore regions of China. A total of 22 OPEs were identified, including ten traditional OPEs, ten emerging OPEs (EOPEs), and two organothiophosphate esters (OTPEs), with total concentrations (Σ₂₂OPEs) in surface sediments ranging from 21.6 to 261 ng/g. Tris(2,4-di-tert-butylphenyl) phosphate (AO168=O) emerged as the dominant EOPE, exceeding 50 % of Σ₂₂OPEs in all regions, while other OPE distributions displayed pronounced regional heterogeneity. Sediment core profiles revealed a significant temporal increase in OPE burdens over recent decades, characterized by rising proportions of EOPEs and OTPEs towards shallower depths. Ecological risk assessment using risk quotients indicated that nearly all OPEs posed potential risks in at least one location. Based on combined acute and chronic toxicity data, AO168=O, O-butyl O-(butylmethylphenyl) O-(di-butylphenyl) phosphorothioate (BBMDBPt) and O,O,O-tris(2,4-di-tert-butylphenyl) phosphorothioate (AO168=S) were prioritized as high-risk contaminants. This nationally representative assessment provides critical data on OPE contamination and risks essential for developing targeted monitoring and mitigation strategies in coastal marine environments.