Effect-directed analysis and nontarget screening for identifying AhR-active substances in sediments of Gamcheon Harbor, South Korea

Gamcheon Harbor in Busan, the largest port city in South Korea, is contaminated with persistent toxic substances, including polycyclic aromatic hydrocarbons (92 to 1700 ng g−1 dry mass (dm)) and styrene oligomers (17 to 520 ng g−1 dm). This study applied effect-directed analysis and nontarget screening (NTS) to identify aryl hydrocarbon receptor (AhR)-active substances in Gamcheon harbor sediments. Relatively great AhR-mediated potencies were found in RP-HPLC fractions, F2.7–F2.8 (mid-polar, log KOW 6–8) and F3.6–F3.7 (polar, log KOW 5–7). Target AhR agonists comprised up to 43% of total AhR-mediated potencies. NTS using GC-QTOFMS and LC-QTOFMS identified daphnoretin and isorhamnetin as significant AhR agonists, with relative potency values of 0.4 × 10−3 and 6.5 × 10−5, respectively, compared to benzo[a]pyrene. The major AhR agonists in the coastal sediments of Korea appeared to be region-specific. This approach is useful for identifying and managing key toxic substances in coastal ecosystems. [Display omitted] •Sedimentary pollution was assessed using instrumental and bioanalytical tools.•Ship repairs were identified as a major source of AhR-active substances in sediments.•Unmonitored AhR agonists were identified using EDA combined with nontarget screening.•Daphnoretin and isorhamnetin were newly identified as AhR agonists in sediments.•The major AhR agonists in coastal sediments were found to be region-specific.