title: Bioavailability of hydrophobic organic compounds in thin-layered capped sediments.
abstract: The effect of a thin sand capping layer (7.5 cm) on the bioavailability of hydrophobic organic compounds (HOCs, i.e., PCBs and naphthalene) was studied using oligochaete worms, and the results compared to previously obtained bioavailability tests with a reactive core mat (RCM) cap. The study investigated the difference in HOC concentration in worms exposed to: (a) a grab sample of sediment used as sampled for PCBs and spiked for PAHs; (b) an initially clean mixture of sand and organic matter (biouptake layer) directly overlying the sediment; and (c) the biouptake layer placed on top of the RCM-capped sediment. Benchscale experiments were performed to induce pore fluid flux through the sediment and into the overlying layer(s). Principal component analysis (PCA) was used to assess PCB homolog group concentrations. Results indicate that the thin sand cap alone reduced the average bioavailability of PCBs by a factor of 100 compared to direct exposure, but had no effect on the bioavailability of naphthalene. However, worms exposed to the RCM-protected biouptake layer show virtually the same HOC concentrations as those in the background worm samples, indicating effective isolation by the RCM.
authors.affiliation: Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering Center, 360 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Dogus
authors.initials: D
authors.lastname: Meric
authors.affiliation: Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering Center, 360 Huntington Avenue, Boston, MA 02115, USA.
authors.forename: Akram N
authors.initials: AN
authors.lastname: Alshawabkeh
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, 401 Park Drive Landmark Center 404-H West, Boston, MA 02215, USA.
authors.forename: James P
authors.initials: JP
authors.lastname: Shine
authors.affiliation: Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering Center, 360 Huntington Avenue, Boston, MA 02115, USA. Electronic address: tsheahan@coe.neu.edu.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Sheahan
mesh_terms: D001682:Biological Availability; D019015:Geologic Sediments / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009930:Organic Chemicals / Q000378:metabolism*; D025341:Principal Component Analysis
chemical_list: D009930:Organic Chemicals
keywords: Bioavailability; Biouptake; Naphthalene; PCBs; Remediation; Sediment