Emerging Aryl-Organophosphate Esters in Coastal Sediments: Comprehensive Screening and Transformation Insights from the Beibu Gulf, China

Information on the co-occurrence of organophosphate triesters (tri-OPEs) and their transformation products (OPEtps) in marine environments remains scarce. This study comprehensively investigated 73 traditional and novel tri-OPEs and 24 OPEtps in surface sediments and sediment cores from the Beibu Gulf using a combined targeted and suspect screening strategy. Eight novel tri-OPEs and three OPEtps species were identified for the first time in this region. Aryl-OPEs dominated both targets and suspects, particularly tris(2,4-ditertbutylphenyl) phosphate and its diester product, attributed to their high hydrophobicity and widespread industrial use. Di-OPEs were the primary OPEtps detected, whereas HO-OPEs, typically found in the biota, were rare in sediments. For traditional OPEs in surface sediments, the mean Σ12tri-OPE concentration (10.6 ng/g dw) significantly exceeded Σ7OPEtps (0.9 ng/g dw), reflecting slower formation, lower sediment affinity of OPEtps, and continuous tri-OPE input. Different vertical distribution trends were found for Σ12tri-OPEs and Σ7OPEtps in two sediment cores, with a significant positive correlation between TPHP and DPHP, supporting degradation-driven temporal variations. This study enhances understanding of OPEs’ occurrence and transformation of OPEs in marine sediments and highlights the urgent need for further research on aryl-OPEs and their environmental behaviors in marine ecosystems.