title: In situ passive sampling of sediments in the Lower Duwamish Waterway Superfund site: Replicability, comparison with ex situ measurements, and use of data.
abstract: Superfund sites with sediments contaminated by hydrophobic organic compounds (HOCs) can be difficult to characterize because of the complex nature of sorption to sediments. Porewater concentrations, which are often used to model transport of HOCs from the sediment bed into overlying water, benthic organisms, and the larger food web, are traditionally estimated using sediment concentrations and sorption coefficients estimated using equilibrium partitioning (EqP) theory. However, researchers have begun using polymeric samplers to determine porewater concentrations since this method does not require knowledge of the sediment's sorption properties. In this work, polyethylene passive samplers were deployed into sediments in the field (in situ passive sampling) and mixed with sediments in the laboratory (ex situ active sampling) that were contaminated with polychlorinated biphenyls (PCBs). The results show that porewater concentrations based on in situ and ex situ sampling generally agreed within a factor of two, but in situ concentrations were consistently lower than ex situ porewater concentrations. Imprecision arising from in situ passive sampling procedures does not explain this bias suggesting that field processes like bioirrigation may cause the differences observed between in situ and ex situ polymeric samplers.
authors.affiliation: R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Electronic address: japell@mit.edu.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Apell
authors.affiliation: R.M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Gschwend
mesh_terms: D001673:Biodegradation, Environmental; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D020387:Food Chain; D019015:Geologic Sediments / Q000737:chemistry*; D006801:Humans; D008404:Massachusetts; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D016062:Porosity; D012015:Reference Standards; D012037:Refuse Disposal; D015203:Reproducibility of Results; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Bioirrigation; In situ concentrations; Passive sampling; Polychlorinated biphenyls (PCBs); Porewater; Sediment