Profiles and inventories of organic pollutants in sediments from the central Beibu Gulf and its coastal mangroves

Sediment cores from the central Beibu Gulf and its northern coastal mangroves were analyzed for polycyclic aromatic hydrocarbons (PAH), the organo-chlorine pesticides dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene (HCB), and polychlorinated biphenyls (PCB), to reconstruct the organic pollution history of developing south-west China. Reflecting regional development, in the gulf Sigma PAH (38-74 ng g(-1)) decreased towards the surface after peak concentrations near 10 cm, while Sigma DDT (ND - 0.5 ng g(-1)) increased due to fresh inputs, and HCB (ND - 0.04 ng g(-1)) occurred only in surface sediments. Profiles in mangrove sediments showed a continuing local scale increase in Sigma PAH (29-438 ng g(-1)) as well as Sigma DDT (0.2-41.0 ng g(-1)) and HCB (0.01-1.01 ng g(-1)) pollution, despite some variability. No trend was evident for Sigma PCB (ND - 0.22 ng g(-1)), which was not detected in the central gulf. Calculated loads estimate that 2816 ng cm(-2) PAHs and 7 ng cm(-2) DDTs are stored in depositional areas of the Beibu Gulf. Mangrove sediments, threatened by land-use-change, contain 1400-4600 ng cm(-2) PAHs and 34-39 ng cm(-2) DDTs. (C) 2016 Elsevier Ltd. All rights reserved.