title: Assessing the effectiveness of thin-layer sand caps for contaminated sediment management through passive sampling.
abstract: The effectiveness of thin-layer sand capping for contaminated sediment management (capping with a layer of thickness comparable to the depth of benthic interactions) is explored through experiments with laboratory-scale microcosms populated with the deposit-feeding oligochaete, Ilyodilus templetoni. Passive sampling of pore water concentrations in the microcosms using polydimethylsiloxane (PDMS)-coated fibers enabled quantification of high-resolution vertical concentration profiles that were used to infer contaminant migration rates and mechanisms. Observed concentration profiles were consistent with models that combine traditional contaminant transport processes (sorption-retarded diffusion) with bioturbation. Predictions of bioaccumulation based on contaminant pore water concentrations within the surface layer of the cap correlated well with observed bioaccumulation (correlation coefficient of 0.92). The results of this study show that thin-layer sand caps of contaminated sediments can be effective at reducing the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) provided the thickness of the cap layer exceeds the depth of organism interaction with the sediments and the pore water concentrations within the biologically active zone remain low (e.g., when molecular diffusion controls transport from the underlying sediment layer).
authors.affiliation: Postdoctoral Fellow, The University of Texas at Austin, 1 University Station C1786, Austin, Texas 78712-0273, United States. djlampert@gmail.com
authors.forename: David J
authors.initials: DJ
authors.lastname: Lampert
authors.forename: William V
authors.initials: WV
authors.lastname: Sarchet
authors.forename: Danny D
authors.initials: DD
authors.lastname: Reible
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D008954:Models, Biological; D009835:Oligochaeta / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D012822:Silicon Dioxide