Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in sediment collected from offshore waters of Central Vietnam

Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5 pg g(-1), respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 039 to 2.9, and 1.6 to 22 pg g(-1), respectively. OCDD was detected at the highest concentration, ranged from 100 to 300 pg g(-1). Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths. (C) 2016 Elsevier Ltd. All rights reserved.