Field Deployment of Polyethylene Devices to Measure PCB Concentrations in Pore Water of Contaminated Sediment

Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Room 313B Stanford, California 94305-4020, USA.
Environmental Science and Technology (Impact Factor: 5.33). 09/2008; 42(16):6086-91. DOI: 10.1021/es800582a
Source: PubMed


Sediment pore water concentrations of polychlorinated biphenyls (PCBs) in a contaminated mudflat in San Francisco Bay, CA were determined by field-deployed polyethylene devices (PEDs). Sequential sampling of PEDs deployed in the field showed large differences in uptake rates and time to equilibrium compared to PEDs mixed with field-collected sediment in the laboratory. We demonstrate a modeling approach that involves the use of impregnated performance reference compounds (PRCs) and interpretation of the data either by PCB molar volume adjustment or environmental adjustment factors to measure pore water concentrations of 118 PCB congeners. Both adjustment methods predicted comparable sampling rates, and PCB pore water concentrations estimated by use of the molar volume adjustment method were similar to values analytically measured in pore waters from the laboratory and field. The utility of PEDs for sampling pore water in the field was evaluated at a tidal mudflat amended with activated carbon to sequester PCBs. Pore water concentrations decreased up to 60% within 18 months after activated carbon amendment, as compared to a mechanical-mixed control plot Results of this study illustrate PEDs provide an inexpensive, in situ method to measure total PCB contamination in sediment pore water using a small set of PRCs.

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    • "One study with POM was recently performed successfully by Oen et al. (2011), but studies on the utility of PRCs for use with PDMS and POM have been limited so far (Reible and Lotufo 2012). Alternatively, equilibrium in the field can be established by performing 2 different thickness samplers (Reible and Lotufo 2012) or by time series deployment (Tomaszewski and Luthy 2008), staggering the removal schedule of individual samplers over a period within which the establishment of equilibrium can be expected. Assessment of equilibrium for in situ exposures can be time‐ consuming and costly and should be considered at the beginning of the planning process for passive sampler deployment. "
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    ABSTRACT: This manuscript provides practical guidance on the use of passive sampling methods (PSMs) that target the freely dissolved concentration (Cfree ) for improved exposure assessment of hydrophobic organic chemicals in sediments. Primary considerations for selecting a PSM for a specific application include clear delineation of measurement goals for Cfree , whether laboratory-based "ex-situ" and/or field-based "in-situ" application is desired, and ultimately which PSM is best suited to fulfill the measurement objectives. Guidelines for proper calibration and validation of PSMs, including use of provisional values for polymer-water partition coefficients, determination of equilibrium status, and confirmation of non-depletive measurement conditions are defined. A hypothetical example is described to illustrate how the measurement of Cfree afforded by PSMs reduces uncertainty in assessing narcotic toxicity for sediments contaminated with polycyclic aromatic hydrocarbons. The paper concludes with a discussion of future research that will improve the quality and robustness of Cfree measurements using PSMs, providing a sound scientific basis to support risk assessment and contaminated sediment management decisions. Integr Environ Assess Manag © 2013 SETAC.
    Integrated Environmental Assessment and Management 04/2014; 10(2). DOI:10.1002/ieam.1507 · 1.38 Impact Factor
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    • "Although stable isotope labeled analogs are preferred, nonlabeled structural analogs that are not present in the sampled matrix may also be used as PRCs (e.g., unusual PCBs congeners when sampling for PCBs). PRC‐based calibration has been successfully used for disequilibrium corrections in field passive sampling of sediments (Booij et al. 2003; Tomaszewski and Luthy 2008; Fernandez, Harvey et al. 2009; Fernandez, MacFarlane et al. 2009; Oen et al. 2011). The application of PRCs for disequilibrium correction requires additional effort, but can ultimately be integrated within gas chromatography–mass spectrometry (GC‐MS) analysis to reduce time and costs because measurement , equilibrium confirmation and disequilibrium correction can be done with only 1 sampler at each location. "
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    ABSTRACT: Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree ) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree . Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance references compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of (1) contaminant exchange and equilibrium status between sediment and overlying water, (2) benthic bioaccumulation and (3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments. Integr Environ Assess Manag © 2013 SETAC.
    Integrated Environmental Assessment and Management 04/2014; 10(2):197-209. DOI:10.1002/ieam.1508 · 1.38 Impact Factor
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    • "For samplers of identical surface areas, the uptake rate under static conditions in sediment has been shown to be lower than for sediments that have been mixed. Tomaszewski and Luthy (2008) found lower contaminant accumulations in PSMs under field conditions than in the laboratory, but they were able to adjust for this difference using performance reference compounds. Because contaminants accumulated by a PSM constitute an extract from the sediment in which the PSM was deployed, some factors cause uncertainties in the rate of transfer of contaminants from the sediment. "
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    ABSTRACT: This paper details how activity-based passive sampling methods (PSMs), which provide information on bioavailability in terms of freely dissolved contaminant concentrations (Cfree ), can be used to better inform risk management decision-making at multiple points in the process of assessing and managing contaminated sediment sites. Because Cfree is a better predictor of bioavailability than total bulk sediment concentration (Ctotal ) for four key endpoints included in conceptual site models (benthic organism toxicity, bioaccumulation, sediment flux, and water column exposures), PSMs can increase certainty in site investigation and management. Because of their small size, the use of PSDs presents particular challenges with respect to representative sampling for estimating average concentrations and other metrics relevant for exposure and risk assessment. These challenges can be addressed by designing studies that account for sources of variation associated with the PSDs and spatial scales. Possible applications of PSMs include: quantifying spatial and temporal trends in bioavailable contaminants; identifying and evaluating contaminant source contributions; calibrating site-specific models; and, improving weight-of-evidence based decision frameworks. PSM data can be used to: assist in delineating sediment management zones based on likelihood of exposure effects; monitor remedy effectiveness; and, evaluate risk reduction after sediment treatment, disposal, or beneficial reuse following management actions. Examples are provided illustrating why PSMs and Cfree should be incorporated into contaminated sediment investigations and study designs to better understand and focus on contaminant bioavailability, more accurately estimate exposure to sediment-associated contaminants, and better inform risk management decisions. Research and communication needs for encouraging broader use are discussed. Integr Environ Assess Manag © 2013 SETAC.
    Integrated Environmental Assessment and Management 04/2014; 10(2). DOI:10.1002/ieam.1511 · 1.38 Impact Factor
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