title: Novel passive sampling device for measuring sediment-water diffusion fluxes of hydrophobic organic chemicals.
abstract: Molecular diffusion across the sediment-water interface, as one of the key geochemical processes, dictates whether a sediment is a source or sink of chemicals, providing useful data in designing remedial actions. Despite ample previous efforts in quantifying sediment-water diffusion fluxes, the resulting methods are largely unsatisfactory. Herein, we introduce a novel passive sampling device capable of measuring vertical profiles of chemical concentrations near the sediment-water interface, from which diffusion fluxes can be calculated based on a model that we developed. In laboratory testing, diffusion fluxes (0.032-310 ng m(-2) d(-1)) of dichlorodiphenyltrichloroethane and its metabolites obtained from the present sampling device were consistent with those (0.38-610 ng m(-2) d(-1)) determined by using a conventional active sampling method, solid-phase extraction/liquid-liquid extraction. Field deployment of the sampling device yielded individual diffusion fluxes of p,p'-DDD, p,p'-DDE, p,p'-DDMU, o,p'-DDMU, p,p'-DDNU, and p,p'-DBP in the range of 5.9-150 ng m(-2) d(-1), which were comparable to those (5.5-85 ng m(-2) d(-1)) obtained with a benthic chamber. Moreover, diffusion fluxes of p,p'-DDT and o,p'-DDT obtained with the sampling device were negative; i.e., the sediment is acting as a sink for these chemicals, while that could not be found using the benthic chamber. Thus, the passive sampling device can provide better information about the movement of chemicals through the sediment and overlying water for the choice of remedial strategies.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China.
authors.forename: Hui-Hui
authors.initials: HH
authors.lastname: Liu
authors.forename: Lian-Jun
authors.initials: LJ
authors.lastname: Bao
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Xu
authors.forename: Feng-Chang
authors.initials: FC
authors.lastname: Wu
authors.forename: Eddy Y
authors.initials: EY
authors.lastname: Zeng
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D005618:Fresh Water / Q000032:analysis*; D019015:Geologic Sediments / Q000032:analysis*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D057927:Hydrophobic and Hydrophilic Interactions; D059625:Liquid-Liquid Extraction / Q000379:methods*; D008962:Models, Theoretical; D020959:Polyethylene / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006843:Hydrocarbons, Chlorinated; D014874:Water Pollutants, Chemical; D020959:Polyethylene