Dataset Information

Assessing soil-air partitioning of PAHs and PCBs with a new fugacity passive sampler.

ABSTRACT: Soil-air fluxes of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined using a novel application of passive samplers to measure air and soil air, which is air in close proximity and in equilibrium with soil. Existing methods to measure flux of semi-volatile compounds between soil and air require collecting samples from the top soil layer. Yet, the top soil layer is hard to define and oversampling may misrepresent the exchangeable fraction. Alternatively, modified active samplers can measure soil air in situ, but require electricity while deployed. We present a new method to measure time-weighted averages of soil air concentrations in situ using passive sampling and requiring no electricity: a box is placed over low-density polyethylene passive samplers deployed 1cm above the soil. Passive air samplers were also co-deployed 1.5m above the soil to measure ambient air concentrations in three U.S. LOCATIONS:near a former PCB manufacturing facility in Anniston, Alabama; on a former creosoting and the current Wyckoff/Eagle Superfund site near Seattle, Washington; and near the site of a recent oil-train derailment and fire in Mosier, Oregon. Following n-hexane extraction, sampler extracts were analyzed for PAHs with gas chromatography-tandem mass spectrometry and PCBs with dual gas chromatography-electron capture detectors. PAHs were generally depositing at Anniston and Mosier sites, but volatilizing from soil in Wyckoff, the site with historically-contaminated soil. PCBs were detected most frequently at the Anniston site, although levels were lower than previous reports. Variability in concentration measurements was greater among soil air samplers than air samplers, likely due to soil heterogeneity. Environmental conditions under the novel soil air box did not substantially change soil-air partitioning behavior. This method of measuring soil air in situ will allow for understanding of source-sink dynamics at sites with recent and historical contamination, and where conventional sampling is challenging.

SUBMITTER: Donald CE

PROVIDER: S-EPMC5549629 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Assessing soil-air partitioning of PAHs and PCBs with a new fugacity passive sampler.

Donald Carey E CE Anderson Kim A KA

The Science of the total environment 20170421

Soil-air fluxes of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined using a novel application of passive samplers to measure air and soil air, which is air in close proximity and in equilibrium with soil. Existing methods to measure flux of semi-volatile compounds between soil and air require collecting samples from the top soil layer. Yet, the top soil layer is hard to define and oversampling may misrepresent the exchangeable fraction. Alternatively, ...[more]

PMID: 28437648

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Project description:Mobile monitoring has provided a means for broad spatial measurements of air pollutants that are otherwise impractical to measure with multiple fixed site sampling strategies. However, the larger the mobile monitoring route the less temporally dense measurements become, which may limit the usefulness of short-term mobile monitoring for applications that require long-term averages. To investigate the stationarity of short-term mobile monitoring measurements, we calculated long term medians derived from a mobile monitoring campaign that also employed 2-week integrated passive sampler detectors (PSD) for NOx, Ozone, and nine volatile organic compounds at 43 intersections distributed across the entire city of Baltimore, MD. This is one of the largest mobile monitoring campaigns in terms of spatial extent undertaken at this time. The mobile platform made repeat measurements every third day at each intersection for 6-10 minutes at a resolution of 10 s. In two-week periods in both summer and winter seasons, each site was visited 3-4 times, and a temporal adjustment was applied to each dataset. We present the correlations between eight species measured using mobile monitoring and the 2-week PSD data and observe correlations between mobile NOx measurements and PSD NOx measurements in both summer and winter (Pearson's r = 0.84 and 0.48, respectively). The summer season exhibited the strongest correlations between multiple pollutants, whereas the winter had comparatively few statistically significant correlations. In the summer CO was correlated with PSD pentanes (r = 0.81), and PSD NOx was correlated with mobile measurements of black carbon (r = 0.83), two ultrafine particle count measures (r =0.8), and intermodal (1-3 μm) particle counts (r = 0.73). Principal Component Analysis of the combined PSD and mobile monitoring data revealed multipollutant features consistent with light duty vehicle traffic, diesel exhaust and crankcase blow by. These features were more consistent with published source profiles traffic-related air pollutants than features based on the PSD data alone. Short-term mobile monitoring shows promise for capturing long-term spatial patterns of traffic-related air pollution, and is complementary to PSD sampling strategies.

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Dataset Information

Assessing soil-air partitioning of PAHs and PCBs with a new fugacity passive sampler.

Publications

Assessing soil-air partitioning of PAHs and PCBs with a new fugacity passive sampler.

Similar Datasets

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