Poly- and per-fluoroalkyl substances (PFAS) and volatile methyl siloxanes (VMS) were monitored at 21 sites in the Global Atmospheric Passive Sampling (GAPS) Network. Atmospheric concentrations ...previously reported from 2009 were compared to concentrations measured at these sites in 2013 and 2015, to assess trends over 7 years of monitoring. Concentrations of the fluorotelomer alcohols (FTOHs) and fluorinated sulfonamides and sulfonamidoethanols (FOSAs and FOSEs) were stable at these sites from 2009 to 2015 with no significant difference (p > 0.05) in concentrations. Elevated concentrations of all the neutral PFAS were detected at the urban sites as compared to the polar/background sites. The perfluorosulfonic acids (PFSAs), meanwhile, saw a significant increase (p < 0.001) in concentrations from 2009 to 2015. The perfluorocarboxylic acids (PFCAs) had elevated concentrations in 2015, however, the difference was not statistically significant (p > 0.05). Concentrations of the PFSAs and the PFCAs were similar at all location types, showing the global reach of these persistent compounds. Concentrations of the cyclic VMS (cVMS) were at least an order of magnitude higher than the linear VMS (lVMS) and the PFAS. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) saw a weak significant increase in concentrations from 2009 to 2013 (p < 0.05), however, hexamethylcyclotrisiloxane (D3) had a strong significant decrease in concentrations from 2009 to 2015 (p < 0.01).
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•PFSA concentrations are significantly increasing at 21 GAPS sites, from 2009 to 2015.•PFCA concentrations were also generally higher in 2015 but not significant.•Neutral PFAS concentrations were stable at these GAPS sites from 2009 to 2015.•D3 significantly decreased and the other siloxanes were stable or increased.•Concentrations at the polar sites were similar to all the background sites.
Atmospheric concentrations of PFAS and VMS were monitored at 21 GAPS sites from 2009 to 2015 and environmental decreases post implementation of regulatory actions are still not being observed.
Results are reported from an ongoing passive air monitoring study for polycyclic aromatic compounds (PACs) in the Athabasca oil sands region in Alberta, Canada. Polyurethane foam (PUF) disk passive ...air samplers were deployed for consecutive 2-month periods from November 2010 to June 2012 at 17 sites. Samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, dibenzothiophene and its alkylated derivatives (DBTs). Relative to parent PAHs, alkylated PAHs and DBTs are enriched in bitumen and therefore considered to be petrogenic markers. Concentrations in air were in the range 0.03-210 ng/m(3), 0.15-230 ng/m(3) and 0.01-61 ng/m(3) for ∑PAHs, ∑alkylated PAHs and ΣDBTs, respectively. An exponential decline of the PAC concentrations in air with distance from mining areas and related petrogenic sources was observed. The most significant exponential declines were for the alkylated PAHs and DBTs and attributed to their association with mining-related emissions and near-source deposition, due to their lower volatility and greater association with depositing particles. Seasonal trends in concentrations in air for PACs were not observed for any of the compound classes. However, a forest fire episode during April to July 2011 resulted in greatly elevated PAH levels at all passive sampling locations. Alkylated PAHs and DBTs were not elevated during the forest fire period, supporting their association with petrogenic sources. Based on the results of this study, an "Athabasca PAC profile" is proposed as a potential source marker for the oil sands region. The profile is characterized by ∑PAHs/∑Alkylated PAHs = ∼0.2 and ∑PAHs/∑DBTs = ∼5.
The study reports on the atmospheric concentrations of per- and polyfluoroalkyl substances (PFAS) and volatile methyl siloxanes (VMS) measured using sorbent-impregnated polyurethane foam disks (SIPs) ...passive air samplers. New results are reported for samples collected in 2017, which extends temporal trend information to the period 2009–2017, for 21 sites where SIPs have been deployed since 2009. Among neutral PFAS, fluorotelomer alcohols (FTOHs) had higher concentrations than perfluoroalkane sulfonamides (FOSAs) and perfluoroalkane sulfonamido ethanols (FOSEs) with levels of ND‒228, ND‒15.8, ND‒10.4 pg/m3, respectively. Among ionizable PFAS, the sum of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) in air were 0.128–781 and 6.85–124 pg/m3, respectively. Longer-chain i.e. C9–C14 PFAS, which are relevant to the recent proposal by Canada for a listing of long-chain (C9–C21) PFCAs to the Stockholm Convention, were also detected in the environment at all site categories including Arctic sites. Cyclic and linear VMS ranged between 1.34‒452 and 0.01–12.1 ng/m3, respectively, showing dominance in urban areas. Despite the wide range of levels observed across different site categories, geometric means of the PFAS and VMS groups were fairly similar when grouped according to the five United Nations regions. Variable temporal trends in air (2009–2017) were observed for both PFAS and VMS. PFOS, which has been listed in the Stockholm Convention since 2009, is still showing increasing tendencies at several sites, indicating constant input from direct and/or indirect sources. These new data inform international chemicals management for PFAS and VMS.
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•First global scale assessment (41 sites) of PFAS and VMS in air from a single program.•Long-chain PFAS were also detected globally in the environment including the Arctic.•Several ionizable PFAS, including PFOS, PFOA and PFHxS, showed increasing trends.•Neutral PFAS and VMS generally showed stable or declining levels.
Mining-related activities in the Alberta Oil Sands Region (AOSR) are known to emit polycyclic aromatic hydrocarbons (PAHs) and related compounds to ambient air. This is a concern due to the toxicity ...of PAHs, including their transformation products such as nitrated (NPAHs) and oxygenated (OPAHs) PAHs. This is the first study that provided a more extensive outlook into the sources, occurrence in air, and spatial and seasonal patterns of NPAHs and OPAHs in the AOSR by using passive air sampling. A sampling campaign from 2013 to 2016 revealed concentrations of NPAHs that were much lower than those of OPAHs. The highest concentrations of NPAHs were concentrated in the region associated with extensive mining activities, with ∑NPAH concentrations ranging from 20 to 250 pg/m3. Within the oil sands (OS) mineable area, NPAHs associated with primary release appear more commonly, while NPAHs produced via oxidative transformation are predominant outside of this area. The concentrations of ∑OPAH ranged from 400 to 2400 pg/m3, with the highest air concentrations in the region located south of the main OS activity zone, with peak concentrations attributed to a 2016 forest fire event. Uptake of PAHs from ambient air and their subsequent conversion to generate OPAHs is believed to play an important role in wildfire emissions of OPAHs. The seasonal trend investigation was inconclusive, with NPAHs slightly higher during the winter, while OPAHs were slightly elevated during summer. A preliminary comparison of ambient concentrations of OPAHs and NPAHs in the AOSR to measurements in the Greater Toronto Area revealed a similar range of concentrations, but also a unique presence of certain NPAHs such as 4-nitrobiphenyl, 2-nitrodibenzothiophene, 2,8-dinitrodibenzothiophene and 6-nitrobenzo-(a)-pyrene. This indicates that AOSR might have its own NPAH profile – creating the need to better understand associated NPAH toxicity and propensity for long range transport.
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•Highest concentrations of NPAHs and OPAHs are associated with areas of intense mining activities.•Emission of OPAHs is strongly correlated with emission of primary pollutants.•A spike in OPAHs that occurred during spring 2016 was attributed to a forest fire.•NPAHs in the Oil Sands exhibit a distinct composition profile in comparison to Toronto.
Eleven organophosphate esters (OPEs) were detected in surface water and sediment samples from yearly sampling (2013-2018) in the Canadian Arctic. In water samples, ∑chlorinated-OPEs (Cl-OPEs) ...concentrations exceeded ∑non-chlorinated-OPEs (non-Cl-OPEs) with median concentrations of 10 ng L
and 1.3 ng L
, respectively. In sediment samples, ∑Cl-OPEs and ∑nonchlorinated-OPEs had median concentrations of 4.5 and 2.5 ng g
, respectively. High concentrations of OPEs in samples from the Mackenzie River plume suggest riverine discharge as an OPE source to the Canadian Arctic. The prevalence of OPEs at other sites is consistent with long-range transport. The OPE inventory of the Canadian Arctic Ocean representative of years 2013-2018 was estimated at 450-16,000 tonnes with a median ∑
OPE mass of 4100 tonnes with >99% of the OPE inventory estimated to be in the water column. These results highlight the importance of OPEs as water-based Arctic contaminants subject to long-range transport and local sources. The high OPE inventory in the water column of the Canadian Arctic Ocean points to the need for international regulatory mechanisms for persistent and mobile organic contaminants (PMOCs) that are not covered by the risk assessment criteria of the Stockholm Convention.
Based on distinct land-use categories, a sampling campaign was carried out at eight locations across Toronto and the Greater Toronto Area in 2016–2017. Source sectors’ dependent patterns of ...atmospheric concentrations of 9 organophosphate esters (OPEs), 9 polybrominated diphenyl ethers (PBDEs) and 5 novel flame retardants (NFRs) showed dominance of OPEs and PBDEs at highly commercialised urban and traffic sites, while NFRs, were dominant at residential sites. Overall, average concentrations of Σ9OPEs (1790 pg/m3) were two orders of magnitude higher than Σ9PBDEs (9.17 pg/m3) and Σ5NFRs (8.14 pg/m3). The atmospheric concentrations of given chemical classes also showed a general trend of lower levels in winter as compared to summer months. Statistically significant negative correlations between the natural logarithm of concentrations and inverse of temperature for some OPEs and PBDEs highlighted the role of volatilization from local sources at given sites as primarily influencing their atmospheric concentrations. Overall, this study adds to the current knowledge of urban settings as a major emitter of the chemicals of emerging concern and their replacements, as well as the ongoing problem of phased out PBDEs due to their presence in existing inventories of commercial/recycled products. It is recommended that long-term monitoring programs targeting flame retardants (FRs) include urban sites, which provide an early indicator of effectiveness of control measures of targeted FRs, while at the same time providing information on emission sources and trends of replacement FR chemicals.
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•Source sector based measurements of FR classes were made in urban air.•OPEs were two orders of magnitude higher than PBDEs and NFRs in Toronto air.•Highly commercialised urban and traffic sites dominate the concentrations' profile.•Lack of strong gradient within sites suggests multitude of sources of FRs to air.
Source sectors based concentrations of three classes of flame retardants in an urban environment.
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
), and the effective sampling volume (V
), 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
is calibrated from sampling rates determined from 5 depuration compounds (
C PCB-9,
C PCB-15,
C PCB-32, PCB-30, and d
-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
C PCB-9,
C PCB-32, and d
-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
and V
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.
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