Sedimentary records of hydroxylated and methoxylated polybrominated diphenyl ethers in the southern Yellow Sea

•The historical trends of OH-/MeO-BDEs are reconstructed in southern Yellow Sea.•The detections of OH-/MeO-BDEs are earlier than the production of artificial PBDEs.•Interconversion of OH-/MeO-BDE pairs is suggested to occur in sediments.•The accumulation of OH-/MeO-BDEs may be controlled by TOC.