Characterization of polymer coated glass as a passive air sampler for persistent organic pollutants

The use of thin-film polymer-coated glass surfaces or POGs as passive air samplers was investigated during an uptake experiment in an indoor environment with high levels of gas-phase polychlorinated biphenyls (PCBs). POGs consisted of a micron thick layer of ethylene vinyl acetate (EVA) coated onto glass cylinders. The uptake was initially linear with time and governed by the air-side mass transfer coefficient and surface area of the sampler. This was followed by a curvilinear region and finally a constant phase when equilibrium was established between air and EVA. The high surface area-to-volume ratio of the POGs allowed rapid equilibrium with gas-phase PCBs; equilibration times were on the order of hours for the low molecular weight congeners. The equilibrium concentration was dependent on the EVA-air partition coefficient, K(EVA-A), which was shown to be very well correlated to the octanol-air partition coefficient, K(OA). When POGs of varying thickness were equilibrated with air, the amount of PCB accumulated increased with increasing thickness of the EVA, indicating that uptake was by absorption into the entire polymer matrix. A wind field of 4 m s(-1) resulted in an increased uptake rate by a factor of approximately six compared to uptake in relatively still air. This wind speed effect was diminished, however, when POGs were housed in deployment chambers consisting of inverted stainless steel bowls. Relationships based on the air-side mass transfer coefficient and K(EVA-A) were developed for PCBs that describe the entire uptake profile and allow air concentrations to be determined from the amount of chemical accumulated in the POG. It is believed that these relationships are also valid when POGs are used to detect other classes of persistent organic pollutants.     

Analysis of polychlorinated biphenyls in concurrently sampled Chinese air and surface soil

Polychlorinated biphenyl (PCB) concentrations were measured in a concurrent air and surface soil sampling program across China. Passive air samples were collected for approximately 3 months from mid-July to mid-October, 2005 using polyurethane foam (PUF) disk type samplers at 97 sites and surface soil samples were collected in a subset of 51 sites in the same year. As expected, the air concentrations (pg m(-3)) were highest at urban sites (mean of 350 +/- 218) followed by rural (230 +/- 180) and background sites (77 +/- 50). The PCB homologue composition was similar across China, with no distinction among site types, and reflected the profile of Chinese transformer oil with a greater proportion of lower molecular weight (LMW) congeners, particularly the tri-PCBs. This differs from the profile in Chinese soil that was shifted toward the higher molecular weight (HMW) congeners and likely attributed to numerous years of deposition and accumulation in this reservoir. The PCB profile in surface soil also reflects an "urban fractionation effect" with preferential deposition of HMW congeners near sources. The profile of PCBs in Chinese air was shown to be different than reported for Europe and for the Great Lakes Area (GLA) in North America. European and GLA air samples show a distinction between urban and rural/V background sites, with urban sites dominated by tetra- and penta-PCBs, whereas rural and background sites are shifted toward LMW congeners. European and GLA samples also exhibit much higher PCB concentrations at urban sites. This may be attributed to the use of PCBs in building materials in European and North American cities. In China, the difference between urban and rural/background sites is less pronounced. Strong soil-air correlations were found for the LMW PCBs at the background and rural sites, and for the HMW PCBs at the urban sites, a strong evidence of the urban fractionation effect. To our knowledge, this is the first national-scale study in China investigating PCBs in both air and surface soil samples.     

Sampling medium side resistance to uptake of semivolatile organic compounds in passive air samplers

Current theory of the uptake of semivolatile organic compounds in passive air samplers (PAS) assumes uniform chemical distribution and no kinetic resistance within the passive sampling media (PSM) such as polystyrene-divinylbenzene resin (XAD) and polyurethane foam (PUF). However, these assumptions have not been tested experimentally and are challenged by some recently reported observations. To test the assumptions, we performed kinetic uptake experiments indoors using cylindrical PSM that had been concentrically segmented into three layers. Both XAD and PUF were positioned in the same type of sampler housing to eliminate the variation caused by the different housing designs, which enabled us to quantify differences in uptake caused by the properties of the PSM. Duplicated XAD (PUF) samples were retrieved after being deployed for 0, 1 (0.5), 2 (1), 4 (2), 8 (4), 12 (8), and 24 (12) weeks. Upon retrieval, the PSM layers were separated and analyzed individually for PCBs. Passive sampling rates (R) were lower for heavier PCB homologues. Within a homologue group, R for XAD was higher than that for PUF, from which we infer that the design of the "cylindrical can" housing typically used for XAD PAS lowers the R compared to the "double bowl" shelter commonly used for PUF-disk PAS. Outer layers of the PSM sequestered much higher levels of PCBs than inner layers, indicative of a kinetic resistance to chemical transfer within the PSM. The effective diffusivities for chemical transfer within PSM were derived and were found negatively correlated with the partition coefficients between the PSM and air. Based on the results, we conclude that the PSM-side kinetic resistance should be considered when investigating factors influencing R and when deriving R based on the loss of depuration compounds.     

Factors influencing the soil-air partitioning and the strength of soils as a secondary source of polychlorinated biphenyls to the atmosphere

Soils are a major reservoir of persistent organic pollutants, and soil-air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil-air partition coefficients (K(SA)) and soil-air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. K(SA) values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil-air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R(2) ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment.     

Assessing the influence of meteorological parameters on the performance of polyurethane foam-based passive air samplers

Polyurethane foam (PUF) disk passive air samplers were evaluated under field conditionsto assessthe effect of temperature and wind speed on the sampling rate for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). Passive samples integrated over 28-day periods were compared to high-volume air samples collected for 24 h, every 7 days. This provided a large data set of 42 passive sampling events and 168 high-volume samples over a 3-year period, starting in October 2003. Average PUF disk sampling rates for gas-phase chemicals was approximately 7 m3 d(-1) and comparable to previous reports. The high molecular weight PAHs, which are mainly particle-bound, experienced much lower sampling rates of approximately 0.7 m3 d(-1). This small rate was attributed to the ability of the sampling chamber to filter out coarse particles with only the fine/ultrafine fraction capable of penetration and collection on the PUF disk. Passive sampler-derived data were converted to equivalent air volumes (V(EQ), m3) using the high-volume air measurement results. Correlations of V(EQ) against meteorological data collected on-site yielded different behavior for gas- and particle-associated compounds. For gas-phase chemicals, sampling rates varied by about a factor of 2 with temperature and wind speed. The higher sampling rates at colder temperatures were explained bythe wind effecton sampling rates. Temperature and wind were strongly correlated with the greatest winds at coldertemperatures. Mainly particle-phase compounds (namely, the high molecular weight PAHs) had more variable sampling rates. Sampling rates increased greatly atwarmertemperatures as the high molecular weight PAH burden was shifted toward the gas phase and subject to higher gas-phase sampling rates. At colder temperatures, sampling rates were reduced as the partitioning of the high molecular weight PAHs was shifted toward the particle phase. The observed wind effect on sampling for the particle-phase compounds is believed to be tied to this strong temperature dependence on phase partitioning and hence sampling rate. For purposes of comparing passive sampler derived data for persistent organic pollutants, the factor of 2 variability observed for mainly gas-phase compounds is deemed to be acceptable in many instances for semiquantitative analysis. Depuration compounds may be used to improve accuracy and provide site-specific sampling rates, although this adds a level of complexity to the analysis. More research is needed to develop and test passive air samplers for particle-associated chemicals.     

On the relative significance of bacteria for the distribution of polychlorinated biphenyls in Arctic Ocean surface waters

This study presents the first field observations of polychlorinated biphenyls (PCB) in bacteria in oceanic waters. To contribute to the limited knowledge of what role bacteria play in the dynamics of hydrophobic organic contaminants (HOCs) in surface seawater, PCB concentrations were measured in bacteria (0.2-2 microm) collected at seven stations in the northern Barents Sea marginal ice zone (MIZ) and the central Arctic Ocean. Concentrations of individual PCB congeners in bacteria were 0.5-5 ng/g oc (organic carbon), which was as high as or higher than PCB concentrations in bulk particulate organic carbon (POC, "phytoplankton"; > 0.7 microm). Considering the relative biomasses of phytoplankton and bacteria, the amount of PCB in bacteria was generally 5-20% of that in phytoplankton, but at two stations the bacterial biomass contained more PCBs than the phytoplankton pool. This study further showed that efficient PCB uptake in bacteria may be described by an apparent equilibrium partitioning model with linear regressions between the organic-carbon-normalized partition coefficient and the octanol-water partition coefficient (log K(bact-oc)-log K(ow)).     

Temporal trends and controlling factors for polychlorinated biphenyls in the UK atmosphere (1991-2008)

Long-term air monitoring data sets are needed for persistent organic pollutants (POPs), to assess the effectiveness of source abatement measures and the factors controlling ambient levels. The Toxic Organic Micro-Pollutants (TOMPS) program in the United Kingdom started in 1991, generating a data set for polychlorinated biphenyls (PCBs). The history and volumes of production, usage, and subsequent restrictions on PCBs in the UK are well-characterized relative to many countries, providing a valuable case study on the effectiveness of controls and the factors influencing ambient levels and trends of these "model POPs". PCB air concentrations (congeners PCB 28, 52, 90/101, 118, 138, 153, and 180) from six rural and urban monitoring sites are presented. Most show a statistically significant decrease in PCBs levels over time, consistent with estimates of emissions, helping to validate emissions inventories. Times for a 50% decline in concentrations (sometimes called clearance rates) averaged 4.7 ± 1.6 years for all congeners at all sites. The trends at different sites and for different congeners were not statistically different from each other. Concentration differences between sites are correlated with local population density (i.e., the degree of urbanization), which supports approaches to modeling of primary emissions on the national and regional scale. The data set indicates that ambient levels and underlying trends of PCBs continue to reflect the controlling influence of diffuse primary sources from the ongoing stock of PCBs in urban environments. Production and use restrictions came into force in the UK over 40 years ago; trends since monitoring began in the early 1990s should be seen as part of a continuing decline in ambient levels since that time.     

Concentrations and chiral signatures of polychlorinated biphenyls in outdoor and indoor air and soil in a major U.K. conurbation

Concentrations and chiral signatures of polychlorinated biphenyls (PCBs) were measured in outdoor air (using polyurethane foam (PUF)--disk passive samplers) and surface soil samples taken at approximately monthly intervals over 1 year at 10 locations on a rural-urban transect across the West Midlands of the U.K. In both air and soil, concentrations clearly decrease with increasing distance from the city center, supporting the existence of an urban "pulse", that indicate the West Midlands conurbation to be a source of PCBs to the wider environment. Concentrations of PCBs in outdoor air samples in this study are well below those reported previously for indoor air in the West Midlands. This, combined with comparison of chiral signatures in outdoor air and soil with those in samples of indoor air taken in the West Midlands, suggest strongly that the principal contemporary source of PCBs in this conurbation is ventilation of indoor air and not volatilization from soil. Future reductions in PCB concentrations in outdoor air and ultimately human exposure appear best achieved by action to remove remaining sources of PCBs from existing structures.     

PCBs and OCPs on a East-to-West Transect: The Importance of Major Currents and Net Volatilization for PCBs in the Atlantic Ocean

Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually.     

Estrogenic activity of polychlorinated biphenyls present in human tissue and the environment

This study evaluated the estrogenicity of polychlorinated biphenyls (PCBs) present in environmental media and human tissue and assessed exposure pathways for PCB-derived estrogenic potency in air, soil, and dust from New Bedford, MA, an area with a PCB-contaminated Superfund site. Thirty-four PCB congeners were assayed for estrogenic potency using E-SCREEN, an assay based on the estrogen-dependent proliferation of MCF-7 cells in vitro. Childhood exposure to estradiol-equivalents via PCBs in environmental media was estimated byweighting previously reported New Bedford congener-specific concentrations by their relative estrogenic potency and published inhalation and soil ingestion rates. Thirteen congeners were weakly estrogenic in E-SCREEN: PCBs 17, 18, 30, 44, 49, 66, 74, 82, 99, 103, 110, 128, and 179. These PCBs were typically 6 orders of magnitude less potent than 17beta-estradiol, with proliferative potencies ranging from 0.0007% to 0.0040%. Of the environmental media assessed, air (inhalation) had the highest PCB-derived estradiol-equivalent exposure. PCB estrogenic potency information from this study provides an important resource both for preliminary estimation of routes of human exposure to xenoestrogens and for application to human health studies focused on estrogen-responsive health outcomes, such as reproductive development and related malignancies.     

Further studies on the latitudinal and temporal trends of persistent organic pollutants in Norwegian and U.K. background air

Data are presented for PBDEs, PCBs, and selected organochlorine compounds, measured at background locations by passive air samplers (semipermeable membrane devices, SPMDs) along a latitudinal transect from the south of the U.K. to the north of Norway during 2000-2002. This work is part of an ongoing air sampling campaign in which PCB data were previously obtained in 1994-1996 and 1998-2000. Comparisons of the masses of chemicals sequestered by the SPMDs during these different time intervals are used to investigate spatial and temporal trends. The study yielded examples of compounds that increase, decrease, or remain uniform with latitude, suggestive of differences in the relative importance of deposition versus atmospheric reaction in controlling their long-range atmospheric transport potential. The main constituents of the penta-BDE product were detected at amounts equivalent to 2.0 (range 1.1-2.5) and 1.1 (0.8-1.6) pg m(-3) for the U.K. and Norway background sites, respectively. Fractionation of PBDEs was observed, because the amounts of lighter BDEs decreased with latitude, while the heavier molecular weight congeners were quite uniformly distributed. In contrast, the sequestered amounts of the lighter PCBs were uniformly distributed with latitude, with heavier PCBs decreasing. Sequestered amounts of hexachlorobenzene increased with latitude. Preliminary PCB atmospheric clearance rates were derived using the 1994-1996, 1998-2000, and 2000-2002 data. They averaged ca. 3.5 years for all congeners/locations. No systematic differences in congeners or locations were noted, supporting the hypothesis that the underlying trends in European background air are still controlled by primary, rather than secondary, sources.     

Congener-specific survey for polychlorinated biphenlys in sediments of industrialized bays in Korea: regional characteristics and pollution sources

Areas of the Korean coastline with heavy industry and major harbors were investigated for polychlorinated biphenyl (PCB) pollution. This investigation paid attention to variations in the PCB congener patterns for a possible source of contamination. Surface sediments from 49 sites were sampled. Although the occurrence of PCBs in coastal marine environment correlates well with shipping and industrial activities, the contribution from shipping activities is considerable because of its enormous economical importance in Korea. The highest concentrations were found in harbors with heavy ship traffic and ship construction. Principal component analysis (PCA) of congener-specific composition of PCBs revealed distinct regional patterns, especially in a harbor and steel manufacturing area. PCB signatures with enhanced higher chlorinated congeners were typical for harbors with shipping activities and correlated well with commercial formulations that were formerly used in ship painting. Lower chlorinated congeners with up to five chlorines were significantly abundant in steel works zones which differed from harbor zones. This distinction was consistent with the congener patterns in the ambient air and the effluent of the steel works as well as in the nearby surface sediments. This study identified steel manufacturing as a recent and ongoing emission source of PCBs in Korea's coastal zone.     

Watershed processing of atmospheric polychlorinated biphenyl inputs

Indirect atmospheric deposition of PCBs was examined in subwatersheds of the Delaware River Estuary. Tributary PCB loads and atmospheric PCB concentrations were used to understand the pass-through efficiencies for nine rivers/ creeks for which PCB inputs appeared to be dominated by atmospheric deposition. The pass-through efficiency, E, was calculated from tributary loads and atmospheric deposition fluxes. Unfortunately, uncertainties in the gaseous and dry particle deposition velocities, vg and vd, respectively, render the calculated atmospheric deposition fluxes highly uncertain. In order to circumvent this problem, export of PCBs from the watershed was related directly to atmospheric PCB concentrations via a new mass transfer coefficient, the watershed delivery rate or vws, which describes the process by which the watershed transfers PCBs from the airto the River's main stem. vws increases with increasing chlorination and is significantly correlated with vapor pressure. This trend suggests that the transfer of PCBs from the atmosphere to the River via the watershed is more efficient for high molecular weight PCBs than for low molecular weight PCBs. This may indicate that the selected watersheds are at or close to equilibrium with respect to gaseous exchange of PCBs, such that lower molecular weight congeners undergo substantial revolatilization after deposition. The magnitude of the pass-through efficiency, E, depends on the deposition velocities used to calculate the atmospheric deposition flux, but when congener-specific deposition velocities are used, E is independent of vapor pressure and is relatively constant at about 3%.     

Bioaccumulation factors for PCBs revisited

Bioaccumulation factors (BAFs) for individual polychlorinated biphenyl (PCB) congeners in Barents Sea and White Sea marine calanoid copepods were 1-3 orders of magnitude higher than BAFs in the same species in Canadian and Alaskan Arctic Ocean areas, and in freshwater plankton (Lake Ontario) reported from the mid- to early 1980s. The present study reviews variability in PCB BAFs from the North American Great Lakes and the Arctic Ocean, and discusses possible explanations for the large variation among different studies. BAFs are higher in recent arctic marine and Great Lakes studies than previously reported, and they are at least 10 times higher than those predicted from the octanol-water partition coefficient (KOW). If the recent high BAFs are realistic, it means that earlier reported BAFs are too low. This is likely due to earlier erroneously high quantification of water PCB concentrations, and it implies that bioaccumulation in zooplankton is more efficient than previously assumed. Evidence is presented supporting that also trophic transfer and biomagnification of PCBs in zooplankton leads to BAFs well above those predicted by simple equilibrium partitioning. Overall, miss-measurement of water PCB concentrations and biomagnification contribute significantly to variability in BAFs for PCBs within and among studies. This large variability of BAFs for PCBs in zooplankton illustrated in the present study is of importance for future assessments of potential new bioaccumulative chemicals that rely on measured BAFs, such as the European Union Registration, Evaluation and Authorization of Chemicals program (REACH).     

Differential accumulation of polychlorinated biphenyl congeners in the aquatic food web at the Kalamazoo River Superfund site, Michigan

A series of field studies were conducted to gain a better understanding of the bioaccumulation and dynamics of polychlorinated biphenyl (PCB) congeners in the aquatic food web of the Kalamazoo River flood plain. Representative species of passerine birds, mammals, fish, aquatic plants, invertebrates, and colocated sediments were collected from areas located within submerged portions of the former Trowbridge impoundment and also from areas located at an upstream reference location. In most matrixes, total concentrations of PCBs were significantly greater in the downstream study area compared to the upstream reference location. Patterns of PCB congeners varied among trophic levels due to selective bioaccumulation of more chlorinated congeners in upper trophic level organisms. There were no statistically significant differences in total PCB concentrations among sampling grids within either site or temporally among three sampling seasons between May and September. The greatest total PCB concentrations were detected in adult tree swallows (mean = 8.7 mg/kg wet weight (ww)) and fish (mean = 4.4 mg/ kg ww) collected from the former Trowbridge impoundment. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were greatest in egg, nestling, and adult tree swallows collected from the former Trowbridge impoundment. There was not a significant correlation between concentrations of total PCBs and TEQs at either site in the mammalian or avian food webs. The relative potency of the mixture of PCBs, expressed as the ratio of TEQs to total PCBs, increased with trophic position in the avian and mammalian aquatic food webs located within the former Trowbridge impoundment.     

Partitioning and bioaccumulation of PBDEs and PCBs in Lake Michigan

Water from Lake Michigan and fish from all five Great Lakes have been sampled and analyzed for a suite of six polybrominated diphenyl ether (PBDE) congeners and 110 polychlorinated biphenyl congeners (PCBs). The Lake Michigan dissolved phase PBDE congener concentrations (0.2 to 10 pg/L) are similar to dissolved phase PCB congener concentrations (nondetected to 13 pg/L). Partitioning of PBDEs between the particulate and dissolved phases exhibits behavior similar to that of PCBs. Organic-carbon-normalized water-particle partition coefficients (log K(OC)s) ranged from 6.2 to 6.5. Lake trout are depleted in BDE-99 relative to dissolved phase concentrations, and in contrast to what is expected from the PCB congener patterns. This reflects suspected debromination of BDE-99 in the food web of Lake Michigan. A regression of the log of the bioaccumulation factor (BAF) and the log of the octanol-water partition coefficent (K(OW)) indicated a positive relationship for both PCB congeners and PBDE congeners. BDE-99 does not appear to followthe same trend, a further indication that it is subject to biotransformation. Using the PBDE BAFs for Lake Michigan and the PBDE fish concentrations from the other Great Lakes it is expected that the dissolved phase concentrations of congeners in the other lakes would range from 0.04 to approximately 3 pg/L.     

Detecting air-water and surface-deep water gradients of PCBs using polyethylene passive samplers

Polyethylene passive samplers (PEs) were deployed in a vertical array (bottom water, surface water, near-surface air) to study the cycling of active polychlorinated biphenyls (PCBs) between reservoirs in an urban estuary (Narragansett Bay, RI), from May to November 2006. Performance reference compounds were used to account for nonequilibrium of PCBs in PEs. Activity gradients were established from direct comparisons of temperature, salt, and nonequilibrium corrected PE concentrations. The uncertainty of determining air-water gradients was < 70%, and < 50% within the water column. Except during the height of summer, PCB activities were up to 30 times higher in the air than in the surface water, but closer to equilibrium in the water column. Surface waters became depleted in PCBs during periods of highest temperature and stratification, leading to the uptake of gaseous PCBs. Our results demonstrate that passive samplers are powerful tools to determine the flux directions of organic contaminants in the environment.     

Field calibration of rapidly equilibrating thin-film passive air samplers and their potential application for low-volume air sampling studies

This paper reports on a field calibration and ambient deployment study with rapidly equilibrating thin-film passive air samplers. POlymer-coated Glass (POG) samplers have a coating of ethylene vinyl acetate (EVA) less than 1 microm thick coated on to glass, which can be dissolved off after exposure and prepared for quantification of persistent organic pollutants (POPs) that have partitioned into the film during field exposure. In this study, POGs were exposed for up to 18 d, in a study to assess compound uptake rates and their time to approach equilibrium. Results confirmed theoretical predictions, with time to equilibrium varying between a few hours to ca. 20 d for PCB-18 and PCB-138, respectively. Performance reference compounds and contaminated POGs were used to investigate depuration kinetics, confirming that lighter congeners behave extremely dynamically with substantial losses from the films over periods of a few hours. Repeated deployments of the samplers for different3-d periods yielded detectable levels of a range of PCB congeners, which had partitioned from as little as approximately 2 to 10 m3 air. This highlights the potential utility of POGs for extremely sensitive and dynamic passive air sampling in the future to help improve understanding of sources, environmental fate, and behavior of POPs. Recommendations are made for future improvements/refinements in POG sampling and handling procedures.     

Rapidly equilibrating micrometer film sampler for priority pollutants in air

Modified polymer-coated glass samplers (POGs), termed EVA samplers, consist of micrometer-thin layers of ethylene vinyl acetate (EVA) coated onto a glass fiber filter or aluminum foil substrate. These samplers were designed to equilibrate rapidly with priority pollutants in air, making them ideal for short-term spatial studies in ambient or indoor air. The EVA sampler was calibrated by measuring the uptake of polychlorinated biphenyls (PCBs) over 8 weeks in an indoor environment, and four different film thicknesses were monitored that ranged from 0.1 to 30 μm. The results were used to calculate the average mass transfer coefficient (50.5 m/day) and generate contour maps that provide guidance in choosing an appropriate EVA sampler for a particular study based on film thickness, deployment time, and the log K(OA) of the anlayte. A range of air pollutant classes was also added to the EVA sampler prior to deployment to assess depuration rates. These included polychlorinated biphenyls (PCBs), current-use pesticides (CUPs), perfluorinated compounds (PFCs), and polybrominated diphenyl ethers (PBDEs). On the basis of the depuration profiles, the EVA sampler was a suitable equilibrium sampler for several CUPs and PCBs; however, for the high molecular weight PCBs and PBDEs, the EVA sampler operates as a linear uptake sampler. Samplers were also evaluated for their use as a rapid screening tool for assessing concentrations of siloxanes in indoor air. The EVA sampler was used to estimate air concentrations for D4 and D5 in laboratory air to be 118 and 89 ng/m(3), respectively. Analyses were performed directly using thermal desorption gas chromatography/mass spectrometry (TDS-GC-MS). EVA samplers show promise due to their relatively low cost and ease of deployment and applicability to a wide range of priority chemicals. The ability to alter the film thickness, and hence the sorption capacity and performance of the EVA sampler, allows for a versatile sampler that can be used under varying sampling conditions and deployment times.     

Semivolatile organic compounds in window films from lower Manhattan after the September 11th World Trade Center attacks

The September 11th World Trade Center (WTC) terrorist attacks resulted in the large-scale release of contaminants that were deposited on the environment of New York City (NYC). Six weeks after the attacks, samples of an organic film on window surfaces were collected and analyzed for polybrominated diphenyl ethers (PBDE), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN), polycyclic aromatic hydrocarbons (PAH), and organochlorine pesticides (OCPs). Concentrations dropped by an order of magnitude within 1 km of the WTC and reached background concentrations by 3.5 km. Concentrations within 1 km of the WTC averaged 3280 ng/m2 for sigmaPBDE, 900 ng/m2 for sigmaPCB, 33 ng/m2 for sigmaPCN, and 77100 ng/m2 for sigmaPAH. Congener profiles of the sites nearest the WTC suggested a combination of combustion and evaporative sources of all compounds, whereas the background sites exhibited profiles consistent with evaporative sources. PBDE profiles showed enrichment in lower molecular weight congeners near the WTC, suggesting that these congeners were formed as a result of the combustion conditions. Homologue fractions of PCN combustion markers were approximately 2-9 times greater at near WTC sites compared to background NYC. Gas-phase air concentrations were back-calculated from measured film concentrations using the film-air partition coefficient (KFA), and calculated air concentrations followed spatial trends observed in films.