A Model Using Local Weather Data to Determine the Effective Sampling Volume for PCB Congeners Collected on Passive Air Samplers

Influence of oil extraction on concentration distributions, migration, secondary formation and carcinogenic risk of NPAHs and OPAHs in air and soil in an oilfield development area in China

Oil extraction leads to environmental pollution from the oilfields and dweller activities, however, knowledge of the concentration distributions, migration, secondary formation and toxicity of nitrated/oxygenated polycyclic aromatic hydrocarbons (N/OPAHs) in oilfield regions is limited. In this research, atmospheric and soil samples in 7 different location types in an important oil industrial base in China were gathered. The ΣNPAHs and ΣOPAHs in the air ranged from 0.05 to 2.47 ng/m3 and 0.14-22.72 ng/m3, respectively, and in soil ranged from 0.22 to 17.81 ng/g and 9.69-66.86 ng/g, respectively. Both NPAHs and OPAHs in the atmosphere exhibited higher concentrations during winter. The atmospheric NPAH concentrations decreased exponentially with distance from urban area especially in the summer, revealing the impact of vehicles on the air in the Yellow River Delta area. High NPAH and OPAH concentrations were found only in soil near oil extraction facilities, indicating that the impact of oil extraction is limited to the soil near the extraction facilities. The air-soil exchanges of N/OPAHs were assessed through fugacity fraction analysis, and NPAHs were in the equilibrium-deposition state and OPAHs were in the net-deposition state in the winter. Higher incremental lifetime cancer risk (ILCR) occurred at the urban, industrial, and oilfield sites in the atmospheric samples, and the soil samples had the largest ILCR values in the oilfield sites. However, ILCR values for both air and soil did not exceed the threshold of 10-6.

Calibration and Application of PUF Disk Passive Air Samplers To Assess Chlorinated Paraffins in Ambient Air in Australia, China, and Vietnam

Ambient air samples were collected in Brisbane (Australia), Dalian (China), and Hanoi (Vietnam) during Mar 2013-Feb 2018 using polyurethane foam based passive air samplers. A sampling rate calibration experiment was conducted for chlorinated paraffins (CPs, i.e., short-chain, medium-chain, and long-chain CPs), where the sampling rates were 4.5 ± 0.7, 4.8 ± 0.3, and 4.8 ± 2.1 m3 day-1 for SCCPs, MCCPs, and LCCPs, respectively. The atmospheric concentration of CPs was then calculated and the medians of ∑CPs were 0.079, 1.0, and 0.89 ng m-3 in Brisbane, Dalian, and Hanoi, respectively. The concentration of CPs in Brisbane's air remained at low levels, with no significant differences observed between the city background site and the city center site, indicating limited usage and production of CPs in this city. The highest concentration of MCCPs was detected in Dalian, while the highest concentration of SCCPs was detected in Hanoi. A decrease of SCCP concentration and an increase of MCCPs' were found in Brisbane's air from 2016 to 2018, while increasing trends for both SCCPs and MCCPs were observed in Dalian. These results indicated impacts from different sources of CPs in the investigated cities.

Genome-Resolved Metagenomics and Metatranscriptomics Reveal Insights into the Ecology and Metabolism of Anaerobic Microbial Communities in PCB-Contaminated Sediments

Growth of organohalide-respiring bacteria such as Dehalococcoides mccartyi on halogenated organics (e.g., polychlorinated biphenyls (PCBs)) at contaminated sites or in enrichment culture requires interaction and support from other microbial community members. To evaluate naturally occurring interactions between Dehalococcoides and key supporting microorganisms (e.g., production of H2, acetate, and corrinoids) in PCB-contaminated sediments, metagenomic and metatranscriptomic sequencing was conducted on DNA and RNA extracted from sediment microcosms, showing evidence of both Dehalococcoides growth and PCB dechlorination. Using a genome-resolved approach, 160 metagenome-assembled genomes (MAGs), including three Dehalococcoides MAGs, were recovered. A novel reductive dehalogenase gene, distantly related to the chlorophenol dehalogenase gene cprA (pairwise amino acid identity: 23.75%), was significantly expressed. Using MAG gene expression data, 112 MAGs were assigned functional roles (e.g., corrinoid producers, acetate/H2 producers, etc.). A network coexpression analysis of all 160 MAGs revealed correlations between 39 MAGs and the Dehalococcoides MAGs. The network analysis also showed that MAGs assigned with functional roles that support Dehalococcoides growth (e.g., corrinoid assembly, and production of intermediates required for corrinoid synthesis) displayed significant coexpression correlations with Dehalococcoides MAGs. This work demonstrates the power of genome-resolved metagenomic and metatranscriptomic analyses, which unify taxonomy and function, in investigating the ecology of dehalogenating microbial communities.

Distributions of PAHs, NPAHs, OPAHs, BrPAHs, and ClPAHs in air, bulk deposition, soil, and water in the Shandong Peninsula, China: Urban-rural gradient, interface exchange, and long-range transport

A systematic study of the movement of PAHs (Polycyclic aromatic hydrocarbons) and their derivatives through air, soil, and water is key to understanding the exchange and transport mechanisms of these pollutants in the environment and for ultimately improving environmental quality. PAHs and their derivatives, such as nitrated PAHs (NPAHs), oxygenated PAHs (OPAHs), brominated PAHs (BrPAHs) and chlorinated PAHs (ClPAHs), were analyzed in air, bulk deposition, soil, and water samples collected from urban, rural, field, and background sites on the eastern coast of China. The goal was to investigate and discuss their spatiotemporal variations, exchange fluxes, and transport potential. The concentrations of PAHs and their derivatives in the air and bulk deposition displayed distinct seasonal patterns, with higher concentrations observed during the winter and spring and lower concentrations during the summer and autumn. NPAHs exhibited the opposite trend. Significant urban-rural gradients were observed for most of the PAHs and their derivatives. According to the air-soil fugacity calculations, 2-3 ring PAHs, BrPAHs, and ClPAHs were found to volatilize from the soil into the air, while 4-7 ring PAHs, OPAHs, and NPAHs deposited from the air into the soil. The air-water fugacity of the PAHs and their derivatives indicated that surface water was an important source for the ambient atmosphere in Qingdao. The characteristic travel distances (CTDs) and persistence (Pov) for atmospheric transport were much lower than that for the water samples, which may be due to the longer half-lives of PAHs and their derivatives in water. NPAHs and ClPAHs with long transport distances and strong persistence in water could lead to a significant impact on marine pollution.

Trace Metals in Global Air: First Results from the GAPS and GAPS Megacities Networks

Trace metals, as constituents of ambient air, can have impacts on human and environmental health. The Global Atmospheric Passive Sampling (GAPS) and GAPS Megacities (GAPS-MC) networks investigated trace metals in the air at 51 global locations by deploying polyurethane foam disk passive air samplers (PUF-PAS) for periods of 3-12 months. Aluminum and iron exhibited the highest concentrations in air (x̅ = 3400 and 4630 ng/m3, respectively), with notably elevated values at a rural site in Argentina thought to be impacted by resuspended soil. Urban sites had the highest levels of toxic Pb and Cd, with enrichment factors suggesting primarily anthropogenic influences. High levels of As at rural sites were also observed. Elevated trace metal concentrations in cities are associated with local emissions and higher PM2.5 and PM10 concentrations. Brake and tire wear-associated metals Sb, Cu, and Zn are significantly correlated and elevated at urban locations relative to those at background sites. These data demonstrate the versatility of PUF-PAS for measuring trace metals and other particle-associated pollutants in ambient air in a cost-effective and simple manner. The data presented here will serve as a global baseline for assessing future changes in ambient air associated with industrialization, urbanization, and population growth.

Spatial Distribution, Sources, Air-Soil Exchange, and Health Risks of Parent PAHs and Derivative-Alkylated PAHs in Different Functional Areas of an Oilfield Area in the Yellow River Delta, North China

The knowledge of the spatial distribution, sources, and air-soil exchange of polycyclic aromatic compounds (PACs) in an oilfield area is essential to the development of effective control practices of PAC pollution. In this study, 48 passive air samples and 24 soil samples were collected during 2018-2019 in seven functional areas (e.g., urban, oil field, suburban, industrial, agricultural, near pump units, and background) in the Yellow River Delta (YRD) where the Shengli Oilfield is located, and 18 parent polycyclic aromatic hydrocarbons (PAHs) and five alkylated-PAHs (APAHs) were analyzed from all the air and soil samples. The ΣPAHs in the air and soil ranged from 2.26 to 135.83 ng/m³ and 33.96 to 408.94 ng/g, while the ΣAPAHs in the atmosphere and soil ranged from 0.04 to 16.31 ng/m³ and 6.39 to 211.86 ng/g, respectively. There was a downward trend of atmospheric ΣPAH concentrations with increasing the distance from the urban area, while both ΣPAH and ΣAPAH concentrations in the soil decreased with distance from the oilfield area. PMF analyses show that for atmospheric PACs, coal/biomass combustion was the main contributor in urban, suburban, and agricultural areas, while crude production and processing source contributes more in the industrial and oilfield area. For PACs in soil, densely populated areas (industrial, urban, and suburban) are more affected by traffic sources, while oilfield and near-pump unit areas are under the impact of oil spills. The fugacity fraction (ff) results indicated that the soil generally emitted low-molecular-weight PAHs and APAHs and act as a sink for high-molecular-weight PAHs. The incremental lifetime cancer risk (ILCR) of Σ(PAH+APAH) in both the air and soil, were below the threshold (≤10^-6) set by the US EPA.

Concentration levels, spatial variations and exchanges of polychlorinated biphenyls (PCBs) in ambient air, surface water and sediment in Bursa, Türkiye

In this study, ambient air, surface water and sediment samples were simultaneously collected and analyzed for PCBs to investigate their levels, spatial variations and exchanges between these three compartments at different sampling sites for 12 months in Bursa, Türkiye. During the sampling period, a total of 41 PCB concentrations were determined in the ambient air, surface water (dissolved and particle phase) and sediment. Thus, 945.9 ± 491.6 pg/m³ (average ± STD), 53.8 ± 54.7 ng/L, 92.8 ± 59.3 ng/L and 71.4 ± 38.7 ng/g, respectively. The highest concentrations of PCBs in the ambient air and in water particulate phase were measured at the industrial/agricultural sampling site (1308.6 ± 252.1 pg/m³ and 168.7 ± 21.2 ng/L, respectively), ∼ 4-10 times higher than background sites; while the highest concentrations in the sediment and dissolved phase were measured at the urban/agricultural sampling sites (163.8 ± 27.0 ng/L and 145.7 ± 15.3 ng/g, respectively), ∼ 5-20 times higher than background sites. PCB transitions between ambient air-surface water (f_A/f_W) and surface water-sediment (f_W/f_S) were investigated by fugacity ratio calculations. According to the fugacity ratios obtained, volatilization from the surface water to the ambient air was observed at all sampling sites (98.7 % of f_A/f_W ratios are <1.0). Additionally, it has been determined that there is a transport from the surface water to the sediment (100.0 % of f_W/f_S ratios are higher than 1.0). The flux values in ambient air-surface water and surface water-sediment environments ranged from -1.2 to 1770.6 pg/m²-day and from -225.9 to 0.001 pg/m²-day, respectively. The highest flux values were measured for PCBs with low chlorine content (Mono-, Di-Cl PCBs), while the lowest flux values were measured for the high chlorine content PCBs (Octa-, Nona- and Deca-Cl PCBs). As it was determined in this study that surface waters contaminated by PCBs have the potential to pollute both air and sediments, it will be important to take measures to protect surface waters.

Lab-scale biodegradation assay using passive samplers to determine microorganisms' ability to reduce polychlorinated biphenyl (PCB) volatilization from contaminated sediment

Many PCB-degrading aerobes have been identified which may serve as bioaugmentation strains for aerobic, in situ bioremediation or in combination with dredging operations. The present work describes a lab-scale PCB biodegradation assay which can be used to screen potential bioaugmentation strains or consortia for their ability to decrease PCB mass flux from contaminated sediment to air through biodegradation of freely dissolved PCBs that have desorbed from sediment particles. The assay uses two types of passive samplers to simultaneously measure PCB mass that is freely dissolved in aqueous solution and PCB mass that has volatilized to the headspace of the bioreactor. Using this approach, relative comparisons of PCB mass accumulated in passive samplers between bioaugmented treatments and controls allow for practical assessment of a microbial strain's ability to reduce both freely dissolved and vapor phase PCB concentrations. The method is designed to be conducted using aliquots of homogenized, well-characterized, PCB-contaminated sediment gathered from a field site. This work details the experimental design methodology, required materials, bioreactor set-up, passive sampling, PCB-extraction, sample cleanup, and quantification protocols such that the biodegradation assay can be conducted or replicated. A step-by-step protocol is also included and annotated with photos, tips, and tricks from experienced analysts.•Relative comparisons of PCB mass accumulated in passive samplers between experimental treatments and controls allow for practical assessment of bioaugmentation strain's ability to reduce both freely dissolved and vapor phase PCB concentrations•Passive sampler preparation, deployment, PCB-extraction, cleanup procedures, and quantification are detailed step-by-step and annotated by experienced analysts.

Applying the Global Monitoring Plan and analysis of POPs results in atmospheric air in Mexico (2017-2018)

Air is one of the target matrices of the Global Monitoring Plan (GMP) of the Stockholm Convention to determine concentrations and transport of Persistent Organic Pollutants (POPs). Mexico participates in the GMP for POPs in ambient air through the AIR-Global Environment Facility (GEF) program. The objective of this study was to analyze the results of POPs monitoring of air samples collected in Los Mochis, Sinaloa, Mexico, between 2017 and 2018. Passive samplers were used for the determination of chlorinated basic POPs, indicator polychlorinated biphenyls (Ind. PCBs), polybrominated biphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs). A principal component analysis was applied to determine relationships between pollutants and groups present in the ambient air of the rural study area. Of the total POPs analyzed, 85.56% were detected in ambient air samples from Mexico. Organochlorine compounds, as DDT derivatives, were identified mainly, as well as PBDEs, PCDDs, and PCDFs. The prevalence of compounds differed according to the seasonality of sampling, with no change in average concentration between monitoring years.

Comparability of semivolatile organic compound concentrations from co-located active and passive air monitoring networks in Europe

Passive air sampling (PAS) has been used to monitor semivolatile organic compounds (SVOCs) for the past 20 years, but limitations and uncertainties persist in the derivation of effective sampling volumes, sampling rates, and concentrations. As a result, the comparability of atmospheric levels measured by PAS and concentrations measured by active air sampling (AAS) remains unclear. Long-term PAS data, without conversion into concentrations, provide temporal trends that are similar to, and consistent with, trends from AAS data. However, for more comprehensive environmental and human health assessments of SVOCs, it is also essential to harmonize and pool air concentration data from the major AAS and PAS monitoring networks in Europe. To address this need, we calculated and compared concentration data for 28 SVOCs (including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs)) at the six monitoring sites in Europe with 10 years of co-located AAS (EMEP) and PAS (MONET) data: Birkenes, Košetice, Pallas, Råö, Stórhöfði, and Zeppelin. Atmospheric SVOC concentrations were derived from PAS data using the two most common computation models. Long-term agreement between the AAS and PAS data was strong for most SVOCs and sites, with 79% of the median PAS-derived concentrations falling within a factor of 3 of their corresponding AAS concentrations. However, in both models it is necessary to set a sampler-dependent correction factor to prevent underestimation of concentrations for primarily particle-associated SVOCs. In contrast, the models overestimate concentrations at sites with wind speeds that consistently exceed 4 m s^-1. We present two recommendations that, if followed, allow MONET PAS to provide sufficiently accurate estimates of SVOC concentrations in air so that they can be deployed together with AAS in regional and global monitoring networks.

Combined read- and assembly-based metagenomics to reconstruct a Dehalococcoides mccartyi genome from PCB-contaminated sediments and evaluate functional differences among organohalide-respiring consortia in the presence of different halogenated contaminants

Microbial communities that support respiration of halogenated organic contaminants by Dehalococcoides sp. facilitate full-scale bioremediation of chlorinated ethenes and demonstrate the potential to aid in bioremediation of halogenated aromatics like polychlorinated biphenyls (PCBs). However, it remains unclear if Dehalococcoides-containing microbial community dynamics observed in sediment-free systems quantitatively resemble that of sediment environments. To evaluate that possibility we assembled, annotated, and analyzed a Dehalococcoides sp. metagenome-assembled genome (MAG) from PCB-contaminated sediments. Phylogenetic analysis of reductive dehalogenase gene (rdhA) sequences within the MAG revealed that pcbA1 and pcbA4/5-like rdhA were absent, while several candidate PCB dehalogenase genes and potentially novel rdhA sequences were identified. Using a compositional comparative metagenomics approach, we quantified Dehalococcoides-containing microbial community structure shifts in response to halogenated organics and the presence of sediments. Functional level analysis revealed significantly greater abundances of genes associated with cobamide remodeling and horizontal gene transfer in tetrachloroethene-fed cultures as compared to halogenated aromatic-exposed consortia with or without sediments, despite little evidence of statistically significant differences in microbial community taxonomic structure. Our findings support the use of a generalizable comparative metagenomics workflow to evaluate Dehalococcoides-containing consortia in sediments and sediment-free environments to eludicate functions and microbial interactions that facilitate bioremediation of halogenated organic contaminants.

Distinguishing Aroclor and non-Aroclor sources to Chicago Air

Many polychlorinated biphenyl (PCB) congeners are found in both legacy Aroclor mixtures and modern materials, and both contribute to PCBs levels in ambient air. The various sources of PCBs make it difficult to quantify the relative importance of emissions from remaining legacy materials and emissions of PCBs released from production and use of modern products. To address this challenge, we utilized active and passive sampling, analytical methods optimized for PCBs, and Positive Matrix Factorization (PMF) and cos theta to examine the chemical signature of PCBs in Chicago air. Here we report our findings for over 640 samples collected over 7 years and analyzed for all 209 congeners. We conclude that Aroclor sources (1254, 1016/1242, and 1260) are consistent and dominant contributors to Chicago air. However, non-Aroclors sources accounted for 13%-16% of the total PCBs measured. Our analysis indicates non-Aroclor sources explain 99% of PCB11, 90% of PCB 68, and 58-69% of congeners with 8 to 10 chlorines in Chicago air. All of these are known to be emitted from paints or silicone polymers. Additionally, we identified over 20 congeners that have non-Aroclor contributions of more than 50% including PCB 3 (4-monochlorobiphenyl, 83% non-Aroclor) as well as 7 congeners of unknown sources: PCBs 43, 46, 55, 89, 96, 137, and 139 + 140. Non-Aroclor emission sources contribute to the entire range of congeners from mono- to deca-chlorobiphenyls. We found evidence of highly localized non-Aroclor sources including a signature similar to that of green paint. We also found source signals similar to the PCB congeners volatilizing from and absorbing to neighboring Lake Michigan. The measured profiles vary from season to season: lower chlorinated congeners dominate in winter months while higher chlorinated congeners contribute more in summer.

Spatial and temporal variation, source identification, and toxicity evaluation of brominated/chlorinated/nitrated/oxygenated-PAHs at a heavily industrialized area in eastern China

Some derivatives of polycyclic aromatic hydrocarbons (PAHs) such as chlorinated and brominated PAHs (Cl/BrPAHs), nitrated and oxygenated PAHs (N/OPAHs) have attracted significant concern due to their high toxicity. Knowledge of the profiles, formation mechanisms, and potential sources of these toxic chemicals near the industrial complexes is essential for their pollution control and management. In this study, we monitored Cl/BrPAHs, N/OPAHs, and PAHs at 24 sampling sites near a heavily industrialized area (steel, chemical, and rubber plants) using passive air samplers during the heating period (7 December 2019 to 15 April 2020) and the non-heating period (2 June 2020 to 4 October 2020). The total average concentrations of 16 BrPAHs, 8 ClPAHs, 17 NPAHs, 6 OPAHs, and 18 PAHs during both sampling periods were 471 pg/m³, 229 pg/m³, 312 pg/m³, 2120 pg/m³, and 63.1 ng/m³, respectively. Except for NPAHs, BrPAHs, ClPAHs, OPAHs, and PAHs all showed higher levels during the heating period. The spatial distributions of Cl/BrPAHs, N/OPAHs, and PAHs exhibited a similar pattern, with the highest concentrations detected in the vicinity of the steel industry. Congener profiles of PAH derivatives indicated that mono-substituted low molecular weight compounds (2-3 rings) were dominant. The major formation mechanisms of halogenated PAHs were discussed by correlation analysis and relative Gibbs free energies, and direct bromination of parent PAHs could be the major formation mechanism of BrPAHs in this study. Diagnostic ratios showed that NPAHs were mainly derived from primary emissions, but the contribution of secondary formation was increased at heavily contaminated sites. The positive matrix factorization model extracted four Cl/BrPAHs, three N/OPAHs, and four PAHs factors, and the result showed that PAHs and their derivatives mainly derived from industrial and combustion sources, photochemical reactions, vehicle emissions, and crude oil volatilization, etc.

Atmospheric concentration, spatial variations, and source identification of persistent organic pollutants in urban and semi-urban areas using passive air samplers in Bursa, Turkey

In this study, the concentration of ambient persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) were measured for 12 months in urban and semi-urban areas using a passive air sampler. During the sampling period, a total of 14 PAH (∑₁₄PAH) concentrations measured in urban and semi-urban areas were found to be 54.4 ± 22.6 ng/m³ and 51.7 ± 34.3 ng/m³, respectively. Molecular diagnostic ratios (MDRs) were used to determine PAH sources. According to the MDR values, combustion sources were the most important PAH sources in both sampling areas. However, since the urban area is close to the industrial zone, the combustion sources occurred at high temperatures (> 800 °C), while the sources in the semi-urban area generally consisted of petrogenic fuel combustion. ∑₅₀PCB concentrations measured in the urban and semi-urban areas were found to be 522.5 ± 196.9 pg/m³ and 439.5 ± 166.6 pg/m³, respectively. Homologous group distributions were used to determine the source of PCBs. According to the homologous group distributions, tri-, tetra-, and penta-chlorinated PCBs were dominant in both sampling areas. ∑₁₀OCP concentrations measured in urban and semi-urban areas were found as 242.5 ± 104.6 pg/m³ and 275.9 ± 130.9 pg/m³, respectively. Also, α-HCH/γ-HCH and β-/(α + γ)-HCH ratios were used to determine the source of OCPs. Lindane was the predominant OCP in both sampling areas.

Intracity occurrence and distribution of airborne PCB congeners in Chicago

To evaluate the magnitude and extent of airborne PCBs in an urban area, we measured and investigated the temporal and spatial behavior of atmospheric concentrations of individual polychlorinated biphenyl (PCB) congeners as well as the sum of all congeners (ΣPCB) in both gas and particle phases at 27 locations across the City of Chicago in a single year (2009). In total, 141 gas-phase air samples were collected, including 22 pairs (44 samples) deployed at the same time but at two different locations, and 46 particle-phase samples. ΣPCB in the gas-phase ranged from 80 to 3000 pg/m³, with a geometric mean (GM) of 530 pg/m³, whereas particle-phase ranged from 8 to 160 pg/m³, with a GM of 28 pg/m³. We found the temporal variability to be about three times larger than the variability over space for all gas-phase congeners and ΣPCB. Around 50% of the sample PCB profiles resembled a mixture of a 1:1 vapor Aroclor mixture of 1016 + 1254, with most of the rest (30%) showing enrichment of PCB 3 (>0.1), which did not match any Aroclor profiles. PCB 11 contributed to ~5% in all samples. The fractions of PCB congeners bound to particles ranged from 0.001 to 0.97. Our analysis shows that airborne PCBs are widely distributed across Chicago and confirms that most locations have a similar PCB distribution, but differ in the concentration levels. Volatilization continues to be the main release process of PCBs into the atmosphere, including both Aroclor and non-Aroclor congeners.

Air monitoring with passive samplers for dioxin-like persistent organic pollutants in developing countries (2017-2019)

As part of the global monitoring plan on persistent organic pollutants (GMP) under the Stockholm Convention passive air samplers equipped with polyurethane foam disks (PUFs) were applied to monitor dioxin-like POPs. For sampling, toluene-pretreated PUFs were exposed for three months during two years. Chemical analysis was performed in one accredited expert laboratory using internationally accepted methods; for comparison, all results were normalized to one PUF and 3 month exposure. Total TEQs, using WHO₂₀₀₅-TEFs, were lowest in the Pacific Islands countries (PAC) and had similar mean values in Africa (16.8 pg TEQ/PUF), Asia (16.9 pg TEQ/PUF), and Latin American and Caribbean countries (GRULAC, 13.3 pg TEQ/PUF). Using median values, Asia (13.4 pg TEQ/PUF) and GRULAC (13.1 pg TEQ/PUF) had higher amounts than Africa (6.1 pg TEQ/PUF) and PAC (2.1 pg TEQ/PUF). The contribution of PCDD/PCDF to the total TEQ was 2-3-times higher than from the dl-PCB. Mono-ortho PCB did not play a role in any of the samples. The previous 40 samples during 2010/2011 and the present 195 samples from 2017/2018 did not show a statistical difference (p value = 0.3), only for GRULAC, a downward trend was identified. It is recommended combining 4 PUFs to 'annual' samples.

Air monitoring with passive samplers for perfluoroalkane substances in developing countries (2017-2019)

To support the global monitoring plan on persistent organic pollutants (GMP) under the Stockholm Convention, 41 countries have exposed passive air samplers equipped with polyurethane foam disks (PUFs) to monitor perfluoroalkane substances (PFAS). The recommended procedure had PUFs exposed for three months during two years; analysis was performed in one expert laboratory to generate harmonized results. Chemical analysis using Soxhlet extraction with methanol or a 60:40 MTBE:methanol mixture, solid-phase extraction and UPLC/MSMS detection posed challenges as to matrix interference and sensitivity. Single PUFs as quarterly samples and combination of up to 4 PUFs as annual samples were analyzed; all concentrations were normalized to one PUF and 3 months exposure. Exceptionally high values (up to 36 000 pg SPFOS/PUF) were observed in nine samples from Zambia where a local source was identified. For the remaining 308 PUFs, PFOA had a higher median value (188 pg/PUF) than SPFOS (125 pg/PUF) whereas the mean value of SPFOS (254 pg/PUF) was slightly higher than the mean value for PFOA (230 pg/PUF). PFHxS concentrations were much lower in concentration and detection frequency and FOSA, as the only relevant PFOS precursor compound, showed a median value of zero. No clear regional differentiation was found.

Tracking POPs in Global Air from the First 10 Years of the GAPS Network (2005 to 2014)

The Global Atmospheric Passive Sampling (GAPS) network, initiated in 2005 across 55 global sites, supports the global monitoring plan (GMP) of the Stockholm Convention on Persistent Organic Pollutants (POPs) by providing information on POP concentrations in air on a global scale. These data inform assessments of the long-range transport potential of POPs and the effectiveness evaluation of chemical regulation efforts, by observing changes in concentrations over time. Currently, measurements spanning 5-10 sampling years are available for 40 sites from the GAPS Network. This study was the first time that POP concentrations in air were reported on a global scale for an extended time period and the first to evaluate worldwide trends with an internally consistent sample set. For consistency between sampling years, site- and sample specific sampling rates were calculated with a new, public online model, which accounts for the effects of wind speed variability. Concentrations for legacy POPs in air between 2005 and 2014 show different trends for different organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The POPs discussed in this study were chosen due to being the most frequently detected, with detection at the majority of sites. PCB, endosulfan, and hexachlorocyclohexane (HCH) concentrations in air are decreasing at most sites. The global trends reflect global sources and recycling of HCH, ongoing emissions from old stockpiles for PCBs, and recent use restrictions for endosulfan. These chlorinated OCPs continue to present exposure threat to humans and ecosystems worldwide. Concentrations of other OCPs, such as chlordanes, heptachlor and dieldrin, are steady and/or declining slowly at the majority of sites, reflecting a transition from primary to secondary sources (i.e., re-emission from reservoirs where these POPs have accumulated historically) which now control ambient air burdens.

Room-to-Room Variability of Airborne Polychlorinated Biphenyls in Schools and the Application of Air Sampling for Targeted Source Evaluation

Airborne polychlorinated biphenyl (PCB) concentrations are higher indoors than outdoors due to their historical use in building materials and their presence in modern paints and surface treatments. For some populations, including school children, PCB levels indoors result in inhalation exposures that may be greater than or equivalent to exposure through diet. In a school, PCB exposure may come from multiple sources. We hypothesized that there are both Aroclor and non-Aroclor sources within a single school and that PCB concentration and congener profiles differ among rooms within a single building. To evaluate this hypothesis and to identify potential localized sources, we measured airborne PCBs in nine rooms in a school. We found that schoolroom concentrations exceed outdoor air concentrations. Schoolroom concentrations and congener profiles also varied from one room to another. The concentrations were highest in the math room (35.75 ng m-3 ± 8.08) and lowest in the practice gym (1.54 ng m-3 ± 0.35). Rooms in the oldest wing of the building, originally constructed between 1920 and 1970, had the highest concentrations. The congener distribution patterns indicate historic use of Aroclor 1254 as well as modern sources of non-Aroclor congeners associated with paint pigments and surface coatings. Our findings suggest this noninvasive source identification method presents an opportunity for targeted source testing for more cost-effective prioritization of materials remediation in schools.

Passive air sampling for semi-volatile organic chemicals

During passive air sampling, the amount of a chemical taken up in a sorbent from the air without the help of a pump is quantified and converted into an air concentration. In an equilibrium sampler, this conversion requires a thermodynamic parameter, the equilibrium sorption coefficient between gas-phase and sorbent. In a kinetic sampler, a time-averaged air concentration is obtained using a sampling rate, which is a kinetic parameter. Design requirements for kinetic and equilibrium sampling conflict with each other. The volatility of semi-volatile organic compounds (SVOCs) varies over five orders of magnitude, which implies that passive air samplers are inevitably kinetic samplers for less volatile SVOCs and equilibrium samplers for more volatile SVOCs. Therefore, most currently used passive sampler designs for SVOCs are a compromise that requires the consideration of both a thermodynamic and a kinetic parameter. Their quantitative interpretation depends on assumptions that are rarely fulfilled, and on input parameters, that are often only known with high uncertainty. Kinetic passive air sampling for SVOCs is also challenging because their typically very low atmospheric concentrations necessitate relatively high sampling rates that can only be achieved without the use of diffusive barriers. This in turn renders sampling rates dependent on wind conditions and therefore highly variable. Despite the overall high uncertainty arising from these challenges, passive air samplers for SVOCs have valuable roles to play in recording (i) spatial concentration variability at scales ranging from a few centimeters to tens of thousands of kilometers, (ii) long-term trends, (iii) air contamination in remote and inaccessible locations and (iv) indoor inhalation exposure. Going forward, thermal desorption of sorbents may lower the detection limits for some SVOCs to an extent that the use of diffusive barriers in the kinetic sampling of SVOCs becomes feasible, which is a prerequisite to decreasing the uncertainty of sampling rates. If the thermally stable sorbent additionally has a high sorptive capacity, it may be possible to design true kinetic samplers for most SVOCs. In the meantime, the passive air sampling community would benefit from being more transparent by rigorously quantifying and explicitly reporting uncertainty.

Atmospheric concentration, source identification, and health risk assessment of persistent organic pollutants (POPs) in two countries: Peru and Turkey

It is known that some persistent organic pollutants (POPs) are used worldwide, and these pollutants are dangerous for human health. However, there are still countries where measurements of these pollutants have not been adequately measured. Although many studies have been published for determining the concentrations of POPs in Turkey, there are limited studies in Latin American countries like Peru. For this reason, it is essential both to conduct a study in Peru and to compare the study with another country. This study is aimed at determining the atmospheric POPs such as polycyclic aromatic hydrocarbon (PAH), organochlorine pesticide (OCP), and polychlorinated biphenyl (PCB) concentrations using passive air samplers in Yurimaguas (Peru) and Bursa (Turkey). Molecular diagnosis ratios and ring distribution methods were used to determine the sources of PAHs. According to these methods, coal and biomass combustions were among the primary sources of PAHs in Peru, while petrogenic and petroleum were the primary sources of PAHs in Turkey. Then, α-HCH/γ-HCH and β-/(α+γ)-HCH ratios were used to determine the sources of OCPs. According to the α-HCH/γ-HCH ratios, the primary sources of OCPs in both countries were lindane. Similarly, according to β-/(α+γ)-HCH ratios, the HCHs have been historically used in Peru while they were recently utilized in Turkey. Finally, homologous group distributions were used to determine the sources of PCBs. Similar distributions of homologous groups were observed in the sampling sites in both countries. Also, the homologous group distributions obtained have been determined that industrial activities could be effective in the sampling areas in both countries. When the cancer risks that could occur via inhalation were evaluated, no significant cancer risk has been determined in both countries.

Spatially high-resolved monitoring and risk assessment of polycyclic aromatic hydrocarbons in an industrial city

Polycyclic aromatic hydrocarbons (PAHs) were monitored at 20 sites in semi-rural, urban, and industrial areas of Ulsan, the largest industrial city in South Korea, for one year. The target compounds were the 16 priority PAHs designated by the US Environmental Protection Agency except for naphthalene, acenaphthene, and acenaphthylene. Gaseous PAHs collected using polyurethane foam-based passive air samplers (PUF-PASs) and particulate PAHs predicted using gas/particle partitioning models were used to estimate the human health risks. The mean total cancer risk through inhalation intake and dermal absorption for all target age groups (children, adolescents, adults, and lifetime) ranged from 0.10 × 10^-7 to 2.62 × 10^-7, lower than the acceptable risk level (10^-6), thus representing a safe level for residents. The cancer risk through dermal absorption and inhalation intake was predicted to be highest in winter, mostly due to the higher concentrations of PAHs, especially high-molecular-weight species with greater toxicity. Additionally, gaseous and particulate PAHs contributed more to dermal absorption and inhalation intake, respectively. As a consequence of local emissions and advection, the risks were higher in the industrial and semi-rural areas. This study suggests that human health risks can be cost-effectively mapped on a local scale using passive air sampling.

Growth of Dehalococcoides spp. and increased abundance of reductive dehalogenase genes in anaerobic PCB-contaminated sediment microcosms

Polychlorinated biphenyls (PCBs) contaminate 19% of US Superfund sites and represent a serious risk to human and environmental health. One promising strategy to remediate PCB-contaminated sediments utilizes organohalide-respiring bacteria (OHRB) that dechlorinate PCBs.However, functional genes that act as biomarkers for PCB dechlorination processes (i.e., reductive dehalogenase genes) are poorly understood. Here, we developed anaerobic sediment microcosms that harbor an OHRB community dominated by the genus Dehalococcoides. During the 430-day microcosm incubation, Dehalococcoides 16S rRNA sequences increased two orders of magnitude to 10⁷ copies/g of sediment, and at the same time, PCB118 decreased by as much as 70%. In addition, the OHRB community dechlorinated a range of penta- and tetra-chlorinated PCB congeners including PCBs 66, 70 + 74 + 76, 95, 90 + 101, and PCB110 without exogenous electron donor. We quantified candidate reductive dehalogenase (RDase) genes over a 430-day incubation period and found rd14, a reductive dehalogenase that belongs to Dehalococcoides mccartyi strain CG5, was enriched to 10⁷ copies/g of sediment. At the same time, pcbA5 was enriched to only 10⁵ copies/g of sediment. A survey for additional RDase genes revealed sequences similar to strain CG5's rd4 and rd8. In addition to demonstrating the PCB dechlorination potential of native microbial communities in contaminated freshwater sediments, our results suggest candidate functional genes with previously unexplored potential could serve as biomarkers of PCB dechlorination processes.

Polychlorinated biphenyls in the soil-crop-atmosphere system in e-waste dismantling areas in Taizhou: Concentrations, congener profiles, uptake, and translocation

Samples of soil, air, and locally grown crops from around an old e-waste dismantling area (Fengjiang) and a new e-waste dismantling area (Binhai) in Taizhou were analyzed to investigate the behavior of polychlorinated biphenyls (PCBs) released during e-waste dismantling in the soil-crop-atmosphere system. The results indicated that PCB pollution is still widespread in the study area. The PCB concentrations were clearly higher in soil from FJ than in soil from BH, and the concentrations in the functional zones decreased strongly in the order industry park > residential area > farmland. Historical and current emissions during e-waste dismantling processes are probably the main sources of PCBs to soil because PCB production and use are banned. The long half-lives of PCBs have caused the target congener concentrations in soil not to decrease markedly over 10 years. The "halo effect" may have caused PCBs in soil in the heavily polluted FJ area to diffuse into the surrounding area. Soil-air exchange of PCBs in heavily contaminated FJ area may supply PCBs to air because the temperatures in Taizhou are often high. PCBs can accumulate in crops through various pathways. Less-chlorinated PCBs (mainly including Tri-PCBs) can enter crops by root uptake and translocated to the aerial tissues, and more-chlorinated PCBs (including Penta-PCBs and Hexa-PCBs) at high concentrations in soil can enter underground crop tissues through passive transport. More-chlorinated PCBs in underground tissues cannot be transferred to aboveground tissues of tall crops but may be transferred to aboveground tissues of short crops through the root-to-stem pathway and through soil dust being transferred to aboveground external surfaces.

Theory and modelling approaches to passive sampling

Designs and applications of passive samplers for various environmental compartments have been broadened significantly since their introduction. Understanding the theory behind passive sampling is essential for proper development of sampling methods and for accurate interpretation of the results. Theoretical underpinnings of passive sampling have been explored using different approaches. The aim of this review is to describe passive sampling theory and modelling approaches presented in the literature in a manner that allows researchers to obtain comprehensive understanding of them and to recognize the assumptions behind each approach together with their applicability to a given passive sampling technique. A common approach originates from Whitman's two-film theory and produces an exponential model that describes the entire passive sampling process. This approach, however, is based on several assumptions including linear exchange kinetics between the sampled medium and the passive sampler. Two-phase air passive samplers with a well-defined barrier are commonly modeled based on the zero-sink assumption, which assumes efficient trapping of analytes in the receiving phase. This assumption may become invalid under various scenarios; consequently, other approaches to modelling have been introduced including simulation of the sampling process by approximate temporal-steady states in hypothetical segments in the adsorption phase. Another approach uses dynamic models to determine accumulation of analytes in passive samplers. Dynamic models are capable of describing mass accumulation in the passive sampler, its transient response, and its response to fluctuations in environmental concentrations. Finally, empirically calibrated models, attempting to simplify the process of passive sampling rate determination, are also presented. In general, dynamic models are used to establish a profound understanding of the sampling process and analyse the applicability of the simpler models and their assumptions, while the simplified models are desirable and practical for most users. Nonetheless, due to the advancement in the computational tools, application of the dynamic models could be made simple and user-friendly.

Occurrence of persistent organic pollutants in air at different sites in the province of Córdoba, Argentina

The occurrence of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of six sites with different emission sources in the province of Córdoba, Argentina, was analyzed. The sites included urban, industrial, agricultural, and mountain areas. Samples were collected using passive air samplers (PAS) consisting of polyurethane foam disks (PUF). Samples were analyzed for 12 PAHs, 31 polychlorinated biphenyls (PCBs), 12 organochlorine pesticides (OCPs), and 11 polybrominated diphenyl ethers (PBDEs). The concentrations of PAHs in the atmosphere were elevated at urban sites and were even higher at the industrial site. With respect to OCPs, it was observed that the concentrations of endosulfan were greater at the agricultural site (AGR) (416 ± 4 pg m^-3). For hexachlorocyclohexanes (HCHs), only the alpha isomer was detected and there were minimal differences between the different sampling sites (5.9-13.3 pg m^-3). In the case of dieldrin, the highest concentrations (33.6 pg m^-3) were found at the mountain site, which may have been due to its use for insect control. Although heptachlor epoxide was not detected, the concentration of heptachlor was significantly higher at the agricultural and downtown sites (∼ 3.6 pg m^-3). Regarding DDTs, the isomers p,p'-DDT and p,p'-DDE showed the highest concentrations at the mountain site (ΣDDT 120 ± 12 pg m^-3) and downtown site (ΣDDT 157 ± 62 pg m^-3). The relationship between the isomers suggested that at the downtown site, the contribution of this pesticide to the environment was recent, probably for the control of diseases vectors. The congener pattern of PBDEs was dominated by BDE-47, and BDE-99 at all sites, with the downtown site having the highest concentrations of compound esters (ΣPBDEs 118 ± 38 pg m^-3). Finally, high concentrations of PCBs were found at the industrial site (ΣPCBs 1677 ± 134 pg m^-3), and the predominating homologs were 5-Cl and 6-Cl, in contrast to the other sites where PCBs were dominated by 3-Cl and 4-Cl. This is the first study of POPs carried out in the province of Córdoba.

PCB Emissions from Paint Colorants

Polychlorinated biphenyls (PCBs) are known human carcinogens that are byproducts of pigment manufacturing and found in colorants used to tint consumer paints sold in the United States and elsewhere. PCBs have the potential to be emitted from paint containing these pigments. To quantify the gas-phase emissions of ∑PCBs, we used polyurethane foam (PUF) to capture emissions from freshly applied colorants. Some PCB emissions were detected on the PUF after 1 day. After 6 weeks, all PCBs found in the colorant were also found on the PUF. Even the fully chlorinated PCB209 was emitted from green colorant. Mono- and dichlorinated PCBs were released from the colorant at a faster rate than the higher chlorinated congeners. By the end of the experiment, all the lower chlorinated congeners were absent from the colorant while more than 75% of the higher chlorinated congeners remained in the sample. The rate of PCB emissions from paint colorants is a function of the surface/air equilibrium coefficient, and the presence of water accelerates the emissions. Although concentrations of PCBs in colorants are less than 285 ng g^-1, PCB emissions from colorants in paint can cause environmentally relevant concentrations of ≥500 pg m^-3 within hours of painting a room.

Determination of PCB fluxes from Indiana Harbor and Ship Canal using dual-deployed air and water passive samplers

We have developed a method for measuring fluxes of PCBs from natural waters using air and water passive samplers deployed simultaneously in the Indiana Harbor and Ship Canal (IHSC). Net volatilization of ƩPCBs was determined for 2017, and ranged from 1.4 to 2.8 μg m^-2 d^-1, with a median of 2.0 μg m^-2 d^-1. We confirm earlier findings that the IHSC experiences constant release of gas-phase PCBs. Gas-phase and freely-dissolved water ƩPCB samples median were 4.0 ng m^-3 and 14 ng L^-1, both exhibiting increasing concentrations over the year of study, and with a strong positive correlation between them (R² = 0.93 for ƩPCBs). The relative concentrations of individual PCB congeners were very similar between air and water samples, and resemble Aroclor 1248, a mixture previously reported to contaminate the IHSC sediments. Monthly variability of the volatilization fluxes was primarily driven by the freely-dissolved water concentration changes (R² = 0.87). Although different sampling methods were performed to estimate air-water fluxes between the month of August of 2006 and 2017, ƩPCB net fluxes have decreased by more than 60%, suggesting that either dredging at IHSC from 2012 to 2017 or reduction of upstream sources have decreased the freely-dissolved water concentrations of PCBs, thus reducing the air-water net volatilization in IHSC. Finally, we have shown that this passive sampling approach represents a simple and cost-effective method to assess the air-water exchange of PCBs, increase analytical sensitivity, enable measurements over time, and reduce uncertainties related to unexpected episodic events.

Passive air sampling of flame retardants and plasticizers in Canadian homes using PDMS, XAD-coated PDMS and PUF samplers

Passive air samplers (PAS) were evaluated for measuring indoor concentrations of phthalates, novel brominated flame retardants (N-BFRs), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs). Sampling rates were obtained from a 50-day calibration study for two newly introduced PAS, polydimethylsiloxane (PDMS) or silicone rubber PAS (one with and one without a coating of styrene divinyl benzene co-polymer, XAD) and the commonly used polyurethane foam (PUF) PAS. Average sampling rates normalized to PAS surface area were 1.5 ± 1.1 m³ day^-1 dm^-2 for both unsheltered PDMS and XAD-PDMS, and 0.90 m³ ± 0.6 day^-1dm^-2 for partially sheltered PUF. These values were derived based on the compound-specific sampling rates measured here and in the literature for the PAS tested, to reasonably account for site-specific variability of sampling rates. PDMS and PUF were co-deployed for three weeks in 51 homes located in Ottawa and Toronto, Canada. Duplicate PUF and PDMS samplers gave concentrations within 10% of each other. PDMS and PUF-derived air concentrations were not statistically different for gas-phase compounds. PUF had a higher detection of particle-phase compounds such as some OPEs. Phthalate and OPE air concentrations were ∼100 times higher than those of N-BFRs and PBDEs. Concentrations were not systematically related to PM₁₀, temperature or relative humidity. We conclude that both PAS provide replicable estimates of indoor concentrations of these targeted semi-volatile organic compounds (SVOCs) over a three-week deployment period. However, PUF is advantageous for collecting a wider range of compounds including those in the particle phase.

Community reporting of ambient air polychlorinated biphenyl concentrations near a Superfund site

In this manuscript, we describe the process of establishing partnerships for community-based environmental exposure research, the tools and methods implemented for data report-back to community members, and the results of evaluations of these efforts. Data discovery and report-back materials developed by Statistics for Action (SFA) were employed as the framework to communicate the environmental data to community members and workshops. These data communication and research translation efforts are described in detail and evaluated for effectiveness based on feedback provided from community members who attended the workshops. Overall, the methods were mostly effective for the intended data communication.

PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that are distributed worldwide. Although industrial PCB production has stopped, legacy contamination can be traced to several different commercial mixtures (e.g., Aroclors in the USA). Despite their persistence, PCBs are subject to naturally occurring biodegradation processes, although the microbes and enzymes involved are poorly understood. The biodegradation potential of PCB-contaminated sediments in a wastewater lagoon located in Virginia (USA) was studied. Total PCB concentrations in sediments ranged from 6.34 to 12,700 mg/kg. PCB congener profiles in sediment sample were similar to Aroclor 1248; however, PCB congener profiles at several locations showed evidence of dechlorination. The sediment microbial community structure varied among samples but was dominated by Proteobacteria and Firmicutes. The relative abundance of putative dechlorinating Chloroflexi (including Dehalococcoides sp.) was 0.01-0.19% among the sediment samples, with Dehalococcoides sp. representing 0.6-14.8% of this group. Other possible PCB dechlorinators present included the Clostridia and the Geobacteraceae. A PCR survey for potential PCB reductive dehalogenase genes (RDases) yielded 11 sequences related to RDase genes in PCB-respiring Dehalococcoides mccartyi strain CG5 and PCB-dechlorinating D. mccartyi strain CBDB1. This is the first study to retrieve potential PCB RDase genes from unenriched PCB-contaminated sediments.

Effects of room airflow on accurate determination of PUF-PAS sampling rates in the indoor environment

Accurate and precise interpretation of concentrations from polyurethane passive samplers (PUF-PAS) is important as more studies show elevated concentrations of PCBs and other semivolatile air toxics in indoor air of schools and homes. If sufficiently reliable, these samplers may be used to identify local sources and human health risks. Here we report indoor air sampling rates (Rs) for polychlorinated biphenyl congeners (PCBs) predicted for a frequently used double-dome and a half-dome PUF-PAS design. Both our experimentally calibrated (1.10 ± 0.23 m3 d-1) and modeled (1.08 ± 0.04 m3 d-1) Rs for the double-dome samplers compare well with literature reports for similar rooms. We determined that variability of wind speeds throughout the room significantly (P < 0.001) effected uptake rates. We examined this effect using computational fluid dynamics modeling and 3-D sonic anemometer measurements and found the airflow dynamics to have a significant but small impact on the precision of calculated airborne concentrations. The PUF-PAS concentration measurements were within 27% and 10% of the active sampling concentration measurements for the double-dome and half-dome designs, respectively. While the half-dome samplers produced more consistent concentration measurements, we find both designs to perform well indoors.

Emissions of Tetrachlorobiphenyls (PCBs 47, 51, and 68) from Polymer Resin on Kitchen Cabinets as a Non-Aroclor Source to Residential Air

Both Aroclor and non-Aroclor sources of airborne polychlorinated biphenyls (PCBs) were found in residential homes. We deployed passive air samplers at 16 residences and found PCB-47, PCB-51, and PCB-68 to account for up to 50% of measured indoor ΣPCBs (2700 pg m-3). Although PCB-47 and PCB-51 are neurotoxins present in Aroclor mixtures (<2.5 and <0.3 wt %, respectively), we found them at much higher levels than expected for any Aroclor source. PCB-68 is not present in Aroclor mixtures. Another non-Aroclor congener, PCB-11, a byproduct of pigment manufacturing, was found inside and outside of every household and was frequently the predominate congener. We conducted direct measurements of surface emissions and identified finished cabinetry to be a major source of PCB-47, PCB-51, and PCB-68. We hypothesize that these congeners are inadvertent byproducts of polymer sealant manufacturing and produced from the decomposition of 2,4-dichlorobenzoyl peroxide used as an initiator in free-radical polymerization of polyester resins. The presence of these three compounds in polymer products, such as silicone, has been widely noted, but to our knowledge they have never been shown to be a significant environmental source of PCBs.

Calibration and evaluation of PUF-PAS sampling rates across the Global Atmospheric Passive Sampling (GAPS) network

Passive air samplers equipped with polyurethane foam (PUF-PAS) are frequently used to measure persistent organic pollutants (POPs) in ambient air. Here we present and evaluate a method to determine sampling rates (R_S), and the effective sampling volume (V_eff), for gas-phase chemical compounds captured by a PUF-PAS sampler deployed anywhere in the world. The method uses a mathematical model that requires only publicly available hourly meteorological data, physical-chemical properties of the target compound, and the deployment dates. The predicted R_S is calibrated from sampling rates determined from 5 depuration compounds (¹³C PCB-9, ¹³C PCB-15, ¹³C PCB-32, PCB-30, and d₆-γ-HCH) injected in 82 samples from 24 sites deployed by the Global Atmospheric Passive Sampling (GAPS) network around the world. The dimensionless fitting parameter, gamma, was found to be constant at 0.267 when implementing the Integrated Surface Database (ISD) weather observations and 0.315 using the Modern Era Retrospective-Analysis for Research and Applications (MERRA) weather dataset. The model provided acceptable agreement between modelled and depuration determined sampling rates, with ¹³C PCB-9, ¹³C PCB-32, and d₆-γ-HCH having mean percent bias near zero (±6%) for both weather datasets (ISD and MERRA). The model provides inexpensive and reliable PUF-PAS gas-phase R_S and V_eff when depuration compounds produce unusual or suspect results and for sites where the use of depuration compounds is impractical, such as sites experiencing low average wind speeds, very cold temperatures, or remote locations.

Analysis of polycyclic aromatic hydrocarbons (PAHs) in air using passive sampling calibrated with active measurements

There are limited ambient air measurements of extended (beyond EPA Priority 16) lists of polycyclic aromatic hydrocarbons (PAHs). We measured air concentrations of 45 PAHs using passive and active air sampling at 15 sites in a central urban community and one rural site for two years. Passive sampling was conducted with cylindrical XAD-based samplers deployed to capture spatial variability. High volume active samplers with quartz fiber filters for particles and XAD-4 absorbent for gases were deployed at two urban sites and the rural site to calibrate the passive measurements directly. Estimated passive sampling rates (PSRs) were evaluated as functions of meteorological data, seasons, locations, study year, and compared with other studies. Possible particle collection by the passive samplers was evaluated using a variety of particle measurements (TSP, PM₁₀, PM_2.5 and ultrafines <100 nm). Total PAHs were statistically associated with ultrafine particle concentrations and to a lesser extent PM_2.5 and PM₁₀, but not TSP. PSRs were more variable when PAH mass loadings were lower and near method detection limits; this occurred more often at the rural site. The PSRs were not statistically associated with meteorological conditions in this study, but wind speed had the highest potential to impact PSR results. The resulting passive PAH measurements are reported with respect to proximity to major roadways and other known air emissions types. PSRs were quantifiable for some PAHs that were found predominantly in the particulate phase in active sampling. This information, together with particle fraction calculations from active sampling, were used to estimate the particulate PAH capture of the passive sampler. Summed PAH (∑PAH) passive concentrations were measured within the range of 10-265 ng/m3, with the highest concentrations from naphthalene and the lowest detected concentrations from anthracene. These results indicated a stronger seasonal signal within 200 m of a major roadway.

Airborne PCBs and OH-PCBs Inside and Outside Urban and Rural U.S. Schools

PCBs appear in school air because many school buildings were built when PCBs were still intentionally added to building materials and because PCBs are also present through inadvertent production in modern pigment. This is of concern because children are especially vulnerable to the toxic effects of PCBs. Here we report indoor and outdoor air concentrations of PCBs and OH-PCBs from two rural schools and four urban schools, the latter near a PCB-contaminated waterway of Lake Michigan in the United States. Samples (n = 108) were collected as in/out pairs using polyurethane foam passive air samplers (PUF-PAS) from January 2012 to November 2015. Samples were analyzed using GC/MS-MS for all 209 PCBs and 72 OH-PCBs. Concentrations inside schools were 1-2 orders of magnitude higher than outdoors and ranged from 0.5 to 194 ng/m³ (PCBs) and from 4 to 665 pg/m³ (OH-PCBs). Congener profiles were similar within each sampling location across season but different between schools and indicated the sources as Aroclors from building materials and individual PCBs associated with modern pigment. This study is the first cohort-specific analysis to show that some children's PCB inhalation exposure may be equal to or higher than their exposure through diet.

Passive Air Samplers As a Tool for Assessing Long-Term Trends in Atmospheric Concentrations of Semivolatile Organic Compounds

Many attempts have been made to quantify the relationship between the amount of persistent organic pollutants sequestered by passive air sampling devices and their actual concentrations in ambient air. However, this information may not be necessary for some applications. In this study, two sets of 30 ten-year-long time series of simultaneous passive and high-volume active air sampling carried out at the Košetice observatory in the Czech Republic were used for a comparison of temporal trends. Fifteen polyaromatic hydrocarbons, seven polychlorinated biphenyls and eight organochlorine pesticides were investigated. In most cases, a good agreement was observed between the trends derived from passive and active monitoring with the exception of several compounds obviously affected by sampling artifacts. Two sampling artifacts were observed: breakthrough of high-volume sampler filters for penta- and hexachlorobenzene and semiquantitative values for PAHs with a high molecular weight. It has been suggested before that annually aggregated results of passive air monitoring may be used directly for the assessment of the long-term behavior of these compounds. The extensive set of long-term data used in this study allowed us to confirm this finding and to demonstrate that it is also possible to derive temporal trends and the compounds' half-lives in air from the passive-sampling time series.

Effects of sampling interval on the passive air sampling of atmospheric PCBs levels

In this study, we collected Polychlorinated biphenyls (PCBs) using passive air samplers (PASs), between February 4, 2013 and February 2, 2014, with the sampling periods ranging from 10 to 60 days. The samples were collected with PASs that contained polyurethane foam (PUF). With these samples, 87 PCB congeners were analyzed. Sampling coefficient (R) values for the four seasons were calculated using both the high volume air sampler (HVAS) and PAS samples collected with the same time interval. The average of the annual concentrations of 87 PCB congeners, calculated using the R values specific to this study, was 234 ± 175 pg/m³. PCB congeners with 3- and 4- chlorines were dominant. The samples were collected at the same time interval but at different times to represent accumulation in the PASs. The linear regression coefficients (r) of the PCB mass accumulated in PASs against time ranged from 0.89 and 0.97 indicating that accumulation was linear. Moreover, the concentrations of the PCB congeners were statistically correlated with atmospheric conditions.

Release of Airborne Polychlorinated Biphenyls from New Bedford Harbor Results in Elevated Concentrations in the Surrounding Air

Qualitatively and quantitatively, we have demonstrated that airborne polychlorinated biphenyl (PCB) concentrations in the air surrounding New Bedford Harbor (NBH) are caused by its water PCB emissions. We measured airborne PCBs at 18 homes and businesses near NBH in 2015, with values ranging from 0.4 to 38 ng m^-3, with a very strong Aroclor 1242/1016 signal that is most pronounced closest to the harbor and reproducible over three sampling rounds. Using U.S. Environmental Protection Agency (U.S. EPA) water PCB data from 2015 and local meteorology, we predicted gas-phase fluxes of PCBs from 160 to 1200 μg m^-2 day^-1. Fluxes were used as emissions for AERMOD, a widely applied U.S. EPA atmospheric dispersion model, to predict airborne PCB concentrations. The AERMOD predictions were within a factor of 2 of the field measurements. PCB emission from NBH (110 kg year^-1, average 2015) is the largest reported source of airborne PCBs from natural waters in North America, and the source of high ambient air PCB concentrations in locations close to NBH. It is likely that NBH has been an important source of airborne PCBs since it was contaminated with Aroclors more than 60 years ago.