Abstract: The vertical distribution of highly brominated polybrominated diphenyl ethers (HB-PBDEs,including nona-and deca-BDEs) in drilling sediments from five inland lakes (Lake Chaohu,Lake Dianchi,Lake Hongfeng,Lake Qinghai and a maar Lake Sihailongwan) were examined using GC/MS method.The composition and potential environmental degradation of these compounds were also identified.The results indicated that TOC normalized total HB-PBDEs contents in the five surface sediments ranged from 17.5 to 977.9 ng/g,with relatively high levels obtained from Dianchi,Hongfeng and Chaohu,which were still far less than reported data from other areas in China and developed countries.The composition of HB-PBDEs in these sediment cores suggested that considerable degradation of BDE-209 occurred not only during long-range atmospheric transport,but also in the lake sediments.Because BDE-209 can degrade to more toxic low brominated congeners in the environment,it is of great importance to further investigate the environmental degradation of BDE-209.