Spatial Distribution, Air-Water Fugacity Ratios and Source Apportionment of Polychlorinated Biphenyls in the Lower Great Lakes Basin

Sources of polychlorinated biphenyls (PCBs) in sediments of the East China marginal seas: Role of unintentionally-produced PCBs

The production and use of intentionally-produced polychlorinated biphenyls (PCBs) in China have a short history compared with countries of North America and Europe, where technical PCB mixtures were manufactured in large amounts for decades before being banned. Unintentionally-produced PCB emissions increased dramatically in China, leading to unique profiles of PCB burdens. This study first time evaluated 208 individual PCB congeners at 94 sites from surface sediments of the East China Marginal Seas (ECMSs) and explored their sources. Non-technical PCBs transported from atmospheric transport and river discharge played a dominant role in most areas of the ECMSs, while historical residuals of technical PCBs occupied the fine-grained sediments in muddy areas of the central Yellow Sea (YS), regarding to the low sedimentation rate in the central YS. Furthermore, emissions from Taizhou located on the coast of the East China Sea (ECS), which is an important electronic waste dismantling site in East China, contributed additional technical PCBs to the inner shelf of the ECS. Our results indicate that non-technical PCBs have become the dominant PCB species in the ECMSs, and emphasize the synergistic effects of large riverine input, long-range atmospheric transport, and muddy shelf deposition on PCB source and sink of in marginal seas.

Chlorinated Paraffin Pollution in the Marine Environment

Chlorinated paraffins (CPs) are ubiquitous in the environment due to their large-scale usage, persistence, and long-range atmospheric transport. The oceans are a critical environment where CPs transformation occurs. However, the broad impacts of CPs on the marine environment remain unclear. This review describes the sources, occurrence and transport pathways, environmental processes, and ecological effects of CPs in the marine environment. CPs are distributed in the global marine environment by riverine input, ocean currents, and long-range atmospheric transport from industrial areas. Environmental processes, such as the deposition of particle-bound compounds, leaching of plastics, and microbial degradation of CPs, are the critical drivers for regulating CPs' fate in water columns or sediment. Bioaccumulation and trophic transfer of CPs in marine food webs may threaten marine ecosystem functions. To elucidate the biogeochemical processes and environmental impacts of CPs in marine environments, future work should clarify the burden and transformation process of CPs and reveal their ecological effects. The results would help readers clarify the current research status and future research directions of CPs in the marine environment and provide the scientific basis and theoretical foundations for the government to assess marine ecological risks of CPs and to make policies for pollution prevention and control.

Gaseous polycyclic aromatic hydrocarbons over the South China Sea: Implications for atmospheric transport under monsoon influences

The seasonal monsoon variations have significant impact on the atmospheric transport of semi-volatile organic pollutants over the South China Sea (SCS). We analyzed polycyclic aromatic hydrocarbons (PAHs) over the basin and island areas (Yongxing Island and Yongshu Island) in 2017. Gaseous PAHs (0.17-1.4 ng m^-3) showed spatio-temporal distinctions in their composition and sources among the basin and island areas. Mixed combustion sources of PAHs were identified over the SCS, including a petroleum source near the island areas. The transport routes of PAHs were inferred by the air mass back trajectories and potential source contribution factor analysis, identifying strong biomass burning signals from the Indochina Peninsula and other Southeast Asian countries. Emissions from approximately 90 % of the combustion sources were transported to basin areas by monsoons, whereas the island areas were dominated by local emissions. This study emphasizes the main potential terrestrial source of PAHs over the SCS under monsoon influences.

Comparison of pollution status and source apportionment for PCBs and OCPs of indoor dust from an industrial city

In this study, the pollution status of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) was investigated in indoor and outdoor dust from three different functional areas of Hefei, China. The relationship between the concentrations of PCBs and OCPs and different influencing factors in dwellings was studied. The results showed that the concentrations of PCBs and OCPs were higher in samples from dwellings with higher smoking frequency, lower cleaning frequency, higher floors and smaller household size. The results of Spearman's correlation coefficient analysis indicated that PCBs and OCPs were not consistently associated with each other, while sources of low-chlorinated PCBs and high-chlorinated PCBs were different. Scanning electron microscopy (SEM) shows the shape of indoor dust was a mixture of blocky, flocculated, spherical structures, and irregular shapes. The results of principal component analysis (PCA) and positive matrix factorization model (PMF) showed that the PCBs and OCPs of indoor dust came from both indoor and outdoor sources between local and regional transport. Carbon (δ¹³C) and Nitrogen (δ¹⁵N) stable isotope results indicate or show that the indoor dust (δ¹³C: - 24.37‰, δ¹⁵N: 6.88‰) and outdoor dust (δ¹³C: - 12.65‰, δ¹⁵N: 2.558‰) is derived from fossil fuel, coal combustion, road dust, fly ash, C4 biomass and soil. Potential source contribution factor (PSCF) and concentration weighted-trajectory analysis suggest that sources of pollutants were local and regional transport from surrounding provinces and marine emissions. The average daily dose (adult: 8.20E-04, children: 2.37E-03) of pollutants and the carcinogenic risks (adult: 1.23E-02, children: 2.65E-02) were relatively greater for children than adults. This study demonstrates the utility of SEM to characterize indoor dust morphology while combining PMF, PSCF, and stable isotope methods in identifying indoor PCBs and OCPs sources and regions.

Spatial characteristics, sources and exposure risk of polychlorinated biphenyls in dusts and soils from an urban environment in the Niger Delta of Nigeria

Chlorinated organic compounds, such as polychlorinated biphenyls (PCBs), are a threat to both humans and the environment because of their toxicity, persistence, and capacity for long-range atmospheric transport. The concentrations of 28 PCB congeners, including 12 dioxin-like and seven indicator PCBs, were investigated in soils, and indoor and outdoor dusts from Port Harcourt city, Nigeria, in order to evaluate the characteristic distribution patterns in these media, their sources, and possible risk. The PCB concentrations varied from 4.59 to 116 ng g^-1 for soils, and from 1.80 to 23.0 ng g^-1 and 2.73 to 57.4 ng g^-1 for indoor and outdoor dusts respectively. The sequence of PCB concentrations in these matrices was soil > outdoor dust > indoor dust. The composition of PCBs in these matrices indicated the prevalence of lower chlorinated PCBs in indoor and outdoor dusts, while the higher chlorinated congeners were dominant in soils. Di-PCBs were the predominant homologues in indoor dusts, while deca-PCBs were the most prevalent homologues in outdoor dusts and soils. The TEQ values of dioxin-like PCBs in 60 % of the soils, 100 % of the indoor dust, and 30 % of the outdoor dust were above the indicative value of 4 pg TEQ g^-1 established by the Canadian authority. The hazard index (HI) values for exposure of adults and children to PCBs in these media were mostly greater than one, while the total cancer risk (TCR) values exceeded the acceptable risk value of 10^-6, which indicate probable non-carcinogenic and carcinogenic risks resulting from exposure to PCBs in these media. Source analysis for PCBs in these matrices shows that they originated from diverse sources.

Gaseous and soil OCPs and PCBs along the Indus River, Pakistan: spatial patterns and air-soil gradients

This study presents first-hand information on the occurrence of persistent organic pollutants (POPs) in the ambient air and surface soil along the Indus flood-plain, Pakistan. The sampling campaign was conducted at 15 site locations during 2014-15, along the Indus River (approximately 1300 km). Composite surface soil samples (N = 15) and passive air samples (N = 15) were collected for the estimation of gaseous POPs as well as air-soil exchange to evaluate the POP emission and distribution or dispersion patterns, source tracking, and contribution of the local and regional sources towards POP accumulation in the Indus River system. Among the studied POPs, levels of DDTs and PCBs were noticeably higher in ambient air (50-560 and 10-1100 pg m^-3) and in soil (0.20-350 and 1.40-20 ng g^-1), respectively. Regarding the spatial patterns, higher DDT concentrations (ng g^-1) were detected in the air and soil samples collected from the wet mountain zone (WMZ) (p < 0.05), followed by the alluvial riverine zone (ARZ), low-lying mountain zone (LLZ), and frozen mountain zone (FMZ). The PCB data did not exhibit significant differences (p > 0.05) for the air samples, while PCB concentrations were significantly higher (p < 0.05) in soil from the LLZ, which may be associated with rapid urbanization and industrial activities in this area. The air-soil exchange of DDTs and PCBs showed net volatilization at most of the studied sites except for a few samples from the FMZ and WMZ. Results of this study about air-soil exchange gradients indicate the long range regional atmospheric transport (LRAT) of POPs to the colder areas (FMZ) of Pakistan, where these act as a secondary source of POPs in these areas.

Chemometers: an integrative tool for chemical assessment in multimedia environments

We propose novel chemometers - passive equilibrium samplers of, e.g., silicone - as an integrative tool for the assessment of hydrophobic organic compounds in multimedia environments. The traditional way of assessing levels of organic pollutants across different environmental compartments is to compare the chemical concentration normalized to the major sorptive phase in two or more media. These sorptive phases for hydrophobic organic compounds differ between compartments, e.g., lipids in biota and organic carbon in sediments. Hence, comparability across media can suffer due to differences in sorptive capacities, but also extraction protocols and bioavailability. Chemometers overcome these drawbacks; they are a common, universal and well-defined polymer reference phase for sampling of a large range of nonpolar organic pollutants in different matrices like biota, sediment and water. When bringing the chemometer into direct contact with the sample, the chemicals partition between the sample and the polymer until thermodynamic equilibrium partitioning is established. At equilibrium, the chemical concentrations in the chemometers can be determined and directly compared between media, e.g., between organisms of different trophic levels or inhabiting different areas, between organs within an organism or between biotic and abiotic compartments, amongst others. Chemometers hence allow expressing the data on a common basis, as the equilibrium partitioning concentrations in the polymer, circumventing normalizations. The approach is based on chemical activity rather than total concentrations, and as such, gives a measure of the "effective concentration" of a compound or a mixture. Furthermore, chemical activity is the main driver for partitioning, biouptake and toxicity. As an additional benefit, the extracts of the chemometers only require limited cleanup efforts, avoiding introduction of a bias between chemicals of different persistence, and can be submitted to both chemical analysis and/or bioanalytical profiling.

Passive water sampling and air-water diffusive exchange of long-range transported semi-volatile organic pollutants in high-mountain lakes

The concentrations of legacy and currently emitted organic pollutants were determined in the freely dissolved phase of water from six high-mountain lakes in the Pyrenees (1619-2453 m) by passive water sampling. Low-density polyethylene (LDPE) and silicone rubber (SR) sheets were exposed for three consecutive periods lasting each one year between 2017 and 2020 for the study of polychlorinated biphenyls (PCBs), organophosphate esters (OPEs), polycyclic aromatic hydrocarbons (PAHs), and other organochlorine compounds (e.g., hexachlorobenzene, HCB). HCB concentrations (1.0-14 pg L^-1) remained essentially the same as those measured with pumping systems over two decades ago in the same area. ƩPAHs (35-920 pg L^-1) were around half of those observed in the past, which agrees with reductions in European atmospheric emissions. ƩPCB concentrations (1.2-2.2 pg L^-1) were substantially lower, although unexpectedly large differences could be due to comparing yearly averages from the present study to seasonally variable (i.e., affected by snowmelt, stratification, and colloidal organic matter) episodic pumping measurements from previous studies. ƩOPEs (139-2849 pg L^-1) were measured for the first time in this area and were found at high concentrations in some sites. Concentrations of most compounds obtained with LDPE and SR samplers agreed with each other by ratios generally lower than three or four times, except for a few PAHs and OPEs. Diffusive exchange flux calculations between the atmospheric gas phase and the freely dissolved water phase revealed net deposition of pollutants from air to water, except for some OPEs and PCBs presenting equilibrium conditions, and HCB with volatilization fluxes. Atmospheric degradation fluxes of PAHs and OPEs pointed at competing removal mechanisms that support the air-to-water direction of their diffusive exchange, while PCBs and organochlorines were not affected by photodegradation. In their current state, these remote lakes accumulate many emerging and legacy pollutants subject to long-range atmospheric transport.

Legacy halogenated organic contaminants in urban-influenced waters using passive polyethylene samplers: Emerging evidence of anthropogenic land-use-based sources and ecological risks

Legacy halogenated organic pollutants, including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), remain ubiquitous in the environment and continue to pose potential (eco-)toxicological threats because of their ongoing releases from land-based sources. This study investigated the spatial trends of freely dissolved PCBs and OCPs by polyethylene passive samplers, and provided evidence of their land-use-based sources and ecological risk in an urbanized estuary area of Narragansett Bay. Dissolved Σ₂₉PCB concentrations ranged from 0.01 to 1.37 ng L^-1, and exhibited higher concentrations in the upper, more urban/built-up watershed, and in north coastal areas. Major inputs of PCBs were urban stormwater or treated wastewater that might carry past releases of Aroclors, pigment manufacturing byproducts, and volatilization-associated PCBs from ageing buildings from the Narragansett watershed to the bay. The dioxin toxicity equivalent values of Σ₅PCBs were 8.6E-03 pg L^-1 in water. Dissolved OCP concentrations had similar spatial trends to PCBs and were dominated by DDTs (average 230 pg L^-1), followed by chlordanes (average 230 pg L^-1), and HCB (average 22 pg L^-1). Secondary sources of past usage and historic contamination were expected to re-enter the surface water via atmospheric transport and deposition. The risk quotients of DDE, DDD, DDT and α-Endosulfane showed medium to high ecological risks in the northern area, while chlordane, HCB, oxychlordane, and heptachlor epoxide showed low to negligible risks in all zones. This study presented new insights into the presence, sources and transport of legacy halogenated organic contaminants in an urban estuary's watershed by combining passive samplers and geographic information system (GIS) technology. The approach is promising and could be extended to get better understand of terrestrial pollutant mobilization into estuaries affected by anthropogenic activities.

Occurrence and air-water diffusive exchange legacy persistent organic pollutants in an oligotrophic north Patagonian lake

In this study, the occurrence and diffusive air-water exchange of POPs in Panguipulli Lake (39°42'S-72°13'W), an oligotrophic lake located in northern Patagonia (Chile), were determined. Air and water samples were collected between March and August 2017 (autumn-winter) and analyzed for concentrations of OCPs (α-HCH, β-HCH, γ-HCH and HCB) and PCBs (PCB-28,-52,-101,-118,-153,-158,-180) using gas chromatography coupled with an electron capture detector. The direction of air-water exchange direction was evaluated using a fugacity approach (ƒ_w ƒ_a^-1), and net diffusive exchange fluxes (F_AW, ng m^-2 d^-1) were also estimated. Total ∑₄OCP levels in air ranged from 0.31 to 37 pg m^-3, with a maximum for β-HCH, while Σ₇PCB levels ranged from 3.05 to 43 pg m^-3. The most abundant congener was PCB-153, accounting for 60% of the total PCBs in air. Surface water ∑₄OCPs measured in this study ranged from 1.01 to 3.9 pg L^-1, with γ-HCH predominating, while surface water Σ₇PCB levels ranged from 0.32 to 24 pg L^-1, with PCB-101, PCB-118, and PCB-153 presenting the highest levels. Diffusive air-water exchanges of HCB, α-HCH, γ-HCH and PCBs in the form of volatilization from the lake to air predominated; in contrast, for β-HCH net deposition dominated during the sampling period. Estimates suggested faster microbial degradation in the dissolved phase compared to atmospheric degradation for all analyzed POPs. Overall, these results could indicate that the oligotrophic lakes of northern Patagonia act as a secondary source of atmospheric POPs, mainly PCBs and some OCPs. This study is a first attempt to understand the occurrence of POPs in air and water, as well as their dynamics in oligotrophic lakes in the southern hemisphere.

The occurrence and sources of polychlorinated biphenyls (PCBs) in agricultural soils across China with an emphasis on unintentionally produced PCBs

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ₂₀₉PCBs in soils across China was in the range of 64.3-4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China.

Unintentionally produced polychlorinated biphenyls in pigments: An updated review on their formation, emission sources, contamination status, and toxic effects

The formation, emission, environmental occurrence, and potential adverse effects of unintentionally produced polychlorinated biphenyls (PCBs) in pigments are reviewed, providing a comprehensive and up-to-date picture on these pollutants. PCBs are typically formed during manufacturing of organic pigments that involve chlorinated intermediates and reaction solvents, rather than those of inorganic pigments. Concentrations and profiles of PCBs vary greatly among pigment types and producers, with total PCB levels ranging from lower than detection limits to several hundred ppm; major components can be low-chlorinated (e.g., CB-11) or high-chlorinated congeners (e.g., CB-209). Pigment-derived PCBs can be released into the environment through different steps including pigment production, application, and disposal. They can contaminate atmospheric, terrestrial, and aquatic ecosystems, and then affect organisms living there. This situation garners scientific and public attention to nonlegacy emissions of PCBs and suggests the need for appropriate monitoring, management, and abatement strategies regarding these pollutants.

Tissue contaminants and wild fish health in the St. Clair River Area of Concern - Part 2: Spatial trends and temporal declines in organics

We explored tissue concentrations of polychlorinated biphenyls (PCBs), chlorinated pesticides, and relevant organochlorines and fish health in the following adult wild fish in the St. Clair River Area of Concern (Ontario, Canada): shorthead redhorse (Moxostoma macrolepidotum), yellow perch (Perca flavescens), and emerald shiner (Notropis atherinoides). We collected adult fish from sites within the river's industrial zone (Stag Island), a downstream site adjacent to Walpole Island (Chenal Écarte), and an upstream reference site in Lake Huron in 2002/2003 and 2014. We tested for trends in tissue concentrations of organic contaminants across sites and over time; we assessed the potential effects of contaminants on morphological indicators of fish health across sites by year. Over the 12-year period, the tissue concentrations of most PCBs declined at the river sites, except for some non-legacy PCBs (PCB11 and 185), which increased in yellow perch at Stag Island, a new observation for fish in the St. Clair River AOC. There was little difference between the concentrations of calculated toxic equivalents (TEQs) of the Lake Huron and the St. Clair River fish in 2014, except for emerald shiners from Stag Island which had elevated ΣPCB and TEQs. Each fish species at all sites exceeded the Canadian tissue residue guideline for PCBs for the protection of mammalian wildlife consumers of aquatic biota, but fish-derived TEQs indicated little potential health risk to fish. Over time, hexachlorobutadiene and hexachlorobenzene concentrations increased in some fish at Stag Island by about 8- and 4-fold, respectively, whereas they decreased at other sampling locations. Principal Component Analysis followed by Linear Discriminant Analysis of the 2014 SHRH data suggested that although the fish separated by site, tissue concentrations of PCB and organochlorine contaminants did not have consistent relationships to the morphological health indicators, including egg production in females, which implied the absence of causative relationships.

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.

Halogenated organic contaminants of concern in urban-influenced waters of Lake Ontario, Canada: Passive sampling with targeted and non-targeted screening

Passive samplers are useful tools for monitoring hydrophobic, persistent, and potentially bioaccumulative contaminants in the environment. In this study, low density polyethylene passive samplers were deployed in urban-influenced and background nearshore freshwaters of northwestern Lake Ontario and analyzed for a broad range of both legacy halogenated organic contaminants (HOCs) and halogenated flame retardants (HFRs). Non-targeted analysis was conducted for screening additional halogenated substances. For most compounds, concentrations were greatest in the industrialized Hamilton Harbour and more generally at sites that have stronger influences of wastewater effluent discharges and stormwater run-off through rivers and creeks. Polychlorinated biphenyls (PCBs) remain the dominant class of HOCs in water, with dissolved-phase concentrations ranging from 10 to 4100 pg/L (ΣPCBs), followed by polybrominated diphenylethers (ΣPBDEs; 14-960 pg/L) and the organochlorine pesticides (OCPs; 22-290 pg/L). Several non-PBDE brominated flame retardants (nBFRs) and chlorinated Dechlorane-related compounds were detected, with hexabromocyclododecanes (ΣHBCDD; sum of 3 diastereoisomers) the most abundant (1.0-21 pg/L). Non-targeted screening of samples by high resolution mass spectrometry using Kendrick mass defect plots for data analysis indicated that several other halogenated compounds were present in waters at relatively high abundances compared to the flame retardants, based on semi-quantitative estimates. These included methyl-triclosan, four halogenated anisoles (2,4,6-tribromoanisole, dimethyl-trichloroanisole, pentachloroanisole, and pentachlorothioanisole), and pentachloro-aniline. Dissolved-phase methyl-triclosan was estimated to contribute up to approximately 40% of the summed target HOC concentrations. Polyethylene passive samplers provided an excellent medium for both non-targeted screening of HOCs not currently included in monitoring programs and tracking brominated and chlorinated chemicals slated for reductions in uses and emissions through international (Stockholm Convention) and binational (Great Lakes) agreements.

In Situ Investigation of Performance Reference Compound-Based Estimates of PCB Equilibrated Passive Sampler Concentrations and Cfree in the Marine Water Column

Low-density polyethylene sheets are used as passive samplers for aquatic environmental monitoring to measure the freely dissolved concentration (Cfree ) of hydrophobic organic contaminants (HOCs). Freely dissolved HOCs in water will partition into the polyethylene until a thermodynamic equilibrium is achieved; that is, the HOC's activity in the passive sampler is the same as its activity in the surrounding environment. One way to evaluate the equilibrium status or estimate the uptake kinetics is by using performance reference compounds (PRCs). A fractional equilibrium (feq ) can be determined for target HOCs, under the assumption that PRC desorption from the passive sampler occurs at the same rate as for the unlabeled target HOCs. However, few investigations have evaluated how effectively and accurately PRCs estimate target contaminant Cfree under in situ conditions. In the present study, polyethylene passive samplers were preloaded with 6 13 C-labeled polychlorinated biphenyls (PCBs) as PRCs; deployed in New Bedford Harbor, Massachusetts, USA; and collected after 30-, 56-, 99-, and 129-d deployments. Using this unique temporal sampling design, PRC results from each deployment were fit to a diffusion model to estimate the Cfree of 27 PCB congeners and compare the results between the different deployment times. Smaller PCBs had variable concentrations over the 4 deployments, whereas mid-molecular weight PCBs had consistent Cfree measurements for all deployments (relative standard deviation <20%). High-molecular weight PCBs had the largest Cfree estimates after 30 d; these estimates and their standard deviations decreased with longer deployment times. These findings suggest that when targeting PCBs with more than 6 chlorines or contaminants with a log octanol-water partition coefficient ≥6.5, a deployment time longer than 30 d may be prudent. Environ Toxicol Chem 2020;39:1165-1173. © 2020 SETAC.

Evidence for Major Contributions of Unintentionally Produced PCBs in the Air of China: Implications for the National Source Inventory

Polychlorinated biphenyls (PCBs) were not widely manufactured or used in China before they became the subject of international bans on production. Recent work has shown that they have reached China associated with imported wastes and that there are considerable unintentional sources of PCBs that have only recently been identified. As such, it was hypothesized that the source inventory and profile of PCBs may be different or unique in China, compared to countries where they were widely used and which have been widely studied. For the first time in this study, we undertook a complete analysis of 209 PCB congeners and assessed the contribution of unintentionally produced PCBs (UP-PCBs) in the atmosphere of China, using polyurethane foam passive air samplers (PUF-PAS) deployed across a wide range of Chinese locations. ∑₂₀₉ PCBs ranged from 9 to 6856 pg/m³ (median: 95 pg/m³) during three deployments in 2016-2017. PCB 11 was one of the most detected congeners, contributing 33 ± 19% to ∑₂₀₉ PCBs. The main sources to airborne PCBs in China were estimated and ranked as pigment/painting (34%), metallurgical industry/combustion (31%), e-waste (23%), and petrochemical/plastic industry (6%). For typical Aroclor-PCBs, e-waste sources were dominated (>50%). Results from our study indicate that UP-PCBs have become the controlling source in the atmosphere of China, and an effective control strategy is urgently needed to mitigate emissions from multiple industrial sources.

Assessment of polychlorinated biphenyls (PCBs) in the Himalayan Riverine Network of Azad Jammu and Kashmir

The emission of polychlorinated biphenyls (PCBs) in South Asian countries is one of the great environmental concerns and has resulted in the contamination of surrounding high altitude regions such as Azad Jammu and Kashmir (AJK), Pakistan. This first investigation of Polychlorinated Biphenyl (PCBs) concentrations in the ambient air, water and surface soil was conducted along the extensive stream network in the AJK valley of the Himalayan Region. In 2014, surface soil samples were taken and passive air and water samplers were deployed along the four main rivers, namely Jhelum, Neelum, Poonch and Kunhar, and analysed for PCBs (33 congeners) using GC-MS/MS. The ∑₃₃PCBs concentrations ranged from 31.17 to 175.2 (mean ± SD: 81 ± 46.4 pg/L), ND to 1908 (1054 ± 588.5 pg/g), and 29.8 to 94.4 (52.9 ± 22.7 pg/m³) in surface water, soil and air matrices, respectively. The levels of dioxin-like PCBs (∑₈DL-PCBs) contributed considerably towards the total PCBs concentrations: 60.63% (water), 43.87% (air) and 13.76% (soil). The log transformed air-water fugacity (log fa/fw) ratios ranged from -9.37 to 2.58; with 86.3% of the sampling sites showing net volatilization of selected PCB congeners. Similarly, the fugacity fractions for air-soil exchange exhibited narrow variation (0.8 to < 1) indicating net volatilization of PCBs. The ecological risk assessment showed low potential ecological risks (E_rⁱ  = 1.58-7.63) associated with PCB contamination. The present findings provide baseline data that suggest cold trapping of POPs in the remote mountainous areas of Pakistan and can support environmental management of POPs at the regional level. This pioneer investigation campaign to assess the PCBs concentrations in Himalayan Riverine Network of Azad Jammu and Kashmir, Pakistan helps to develop baseline data of PCBs from the strategically important riverine environment that would help in future regional as well as global ecological studies. However, the effects of temperature variations on the sampling rates of chemicals across a wide spectrum of volatility along the elevation gradient were not taken under consideration for PCBs atmospheric concentrations.

Evaluation of the effectiveness of different indicator PCBs to estimating total PCB concentrations in environmental investigations

Polychlorinated biphenyls (PCBs) are one of the most widely studied group of persistent organic pollutants (POPs). There are 209 different PCBs, however not all 209 can currently be individually quantified in one analytical run. This means that a subset of PCBs congeners are often determined and reported. Some of the most commonly reported subsets are the 7 indicator PCBs (28, 52, 101, 118, 138, 153 and 180) and the WHO 12 PCBs (77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169 and 189). The WHO 12 congeners are co-planar 'dioxin like' PCBs that are effective for establishing health risks. The 7 indicator PCBs were selected as some of the most common PCBs across the compositional range of the most common technical mixtures (such as Aroclors), and are used to give an indication of the total PCB concentrations. These groups of indicator PCBs were established several decades ago. However, in the environment commercial mixtures are subject to weathering and fractionation processes, and additional sources of non-Aroclor PCBs are also becoming more important. In this manuscript we use existing large scale comprehensive congener specific datasets to evaluate the effectiveness of indicator PCBs to predict total concentrations and establish if they are still fit for purpose. The results indicate that while these traditional indicators are a useful tool to estimate total concentrations in humans with background exposure there are many instances where they are not fit for purpose and can lead to significant under predictions in total PCB concentrations in environmental matrices.

Sedimentary records of polychlorinated biphenyls in the East China Marginal Seas and Great Lakes: Significance of recent rise of emissions in China and environmental implications

Polychlorinated biphenyls (PCBs) in dated sediment cores from the East China Marginal Seas (ECMSs) and the chronology of the net fluxes to sediments were analyzed. The accumulation of 27 PCBs (ΣPCBs) in the ECMS sediments is about 5-26 ng cm^-2, with the net depositional fluxes of ΣPCBs 10 times lower than those observed in the Great Lakes during the 1960s-1970s. Exponential increases in PCB deposition to the ECMS sediments since the 1990s were observed, which closely follows the fast growth of PCB emissions from industrial thermal processes and e-waste related sources in China. Recent PCB fluxes to the study sites in the ECMSs and the Great Lakes are comparable; the former surged forward with a rising tendency, while the latter showed continued decline after the late 1970s. Due to the different PCB application histories and sources between the two regions, the ECMS sediments may remain as a net sink for land-derived PCBs, while sediments in the Great Lake may have been acting as a secondary source releasing PCBs to water. A higher proportion of trichlorobiphenyls in the ECMS sediments than the Great Lakes was indicated, which may imply the net transport of atmospheric PCBs from China.

The risk of endometriosis after exposure to endocrine-disrupting chemicals: a meta-analysis of 30 epidemiology studies

Endocrine-disrupting chemicals (EDCs) are suspected to be associated with endometriosis (EMs). This study aimed to synthesize published data and evaluate the relationship between four classic EDCs exposure and the risk of EMs. A systematic literature search for original peer reviewed papers was performed in the databases PubMed, EMBASE, and Web of Science based on inclusion criteria up to January 2018. Subsequently, a total of 20 papers conducting 30 studies fulfilled the eligibility criteria and were included in this meta-analysis (four studies for bisphenol A (BPA), 12 studies for polychlorinated biphenyls (PCBs), eight studies for organochlorine pesticides (OCPs), and six studies for phthalate esters (PAEs)). The overall odds ratio (OR) across all exposures and EMs was 1.41 (95% confidence interval (CI): 1.23-1.60). When assessing four specific chemicals, respectively, consistent increases in the risk of EMs were found in PCBs group (OR = 1.58; 95% CI: 1.18-2.12), OCPs group (OR = 1.40; 95% CI: 1.02-1.92) and PAEs group (OR = 1.27; 95% CI: 1.00-1.60), while BPA showed no significant association with EMs. Besides, in the di-(2-ethylhexyl)-phthalate (DEHP) group - the most commonly used PAEs, significant risk was also found (OR = 1.42; 95% CI: 1.19-1.70). The current meta-analysis strengthens the evidence that specific EDCs or their metabolites may promote the occurrence of EMs.

Proximity to chemical equilibria among air, water, soil, and sediment as varied with partition coefficients: A case study of polychlorinated dibenzodioxins/furans, polybrominated diphenyl ethers, phthalates, and polycyclic aromatic hydrocarbons

To capture the pollutant distribution status among environmental media and to understand how the distribution varies with the pollutants' properties, we assessed a total of 225 fugacity ratios (FRs) of 45 semi-volatile organic compounds (SVOCs) (polychlorinated dibenzo-p-dioxins/furans (PCDDs/Fs), polybrominated diphenyl ethers (PBDEs), phthalates, and polycyclic aromatic hydrocarbons (PAHs)) for five medium pairs (air-water, air-soil, water-sediment, soil-water, and soil-sediment) using the nationwide multimedia monitoring data. For many of the pollutants, fugacity was greatest in air (PCDFs and 6 heavy PAHs) and in sediment (PBDEs and 9 light PAHs) while lowest in soil for most of the pollutants. PAHs and phthalates appeared to be farther away from equilibrium than PCDDs/Fs and PBDEs. The ratios of "equilibrium improbable" FRs to all the FRs in each chemical group were 2%, 0%, 33.3%, and 28.9% for PCDDs/Fs, PBDEs, phthalates, and PAHs, respectively. FR_water/air of PAHs, FR_soil/air, and FR_{sediment/water} of the pollutant groups (except for PBDEs) decreased significantly (p < 0.01) with the partition coefficients, 1/K_air/water (1/K_aw), K_octanol/air (K_oa), and K_{octanol/water} (K_ow), respectively, even in the field conditions. The findings on FRs values provide valuable clues to identifying the media that would act as sink or source for certain chemicals and to using a more appropriate choice in the coherence test of environmental quality objectives, which should be important considerations in the management of chemical contamination in the environment.

Concentrations, Trends, and Air-Water Exchange of PCBs and Organochlorine Pesticides Derived from Passive Samplers in Lake Superior in 2011

The largest fresh water body in North America, Lake Superior, has the potential to both accumulate and serve as a secondary source of persistent bioaccumulative toxins, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Polyethylene passive samplers (PEs) were thus simultaneously deployed at 19 sites in surface water and near surface atmosphere across Lake Superior to determine air and water concentrations and air-water gradients of 18 PCBs and 24 OCPs. PCBs in the air and water were characterized by penta- and hexachlorobiphenyls with distribution along the coast correlated with proximity to developed areas. Surface water and atmospheric concentrations were dominated by α-HCH (average 250 pg L^-1 and 4.2 pg m^-3, respectively), followed by HCB (average 17 pg L^-1 and 89 pg m^-3, respectively). Decreases in open lake concentrations of PCBs in water and air from spring to summer were consistent with ongoing volatilization from the surface layer as the main cause. Conversely, α-endosulfan was consistently deposited into the surface water of Lake Superior. Results indicated that PCBs were depleted in the surface mixed layer, implying a physical limit on evasive fluxes. This was corroborated with measurements from a vertical profile, displaying greater PCB concentrations at depth.

Air-Seawater Gas Exchange and Dry Deposition of Chlorinated Paraffins in a Typical Inner Sea (Liaodong Bay), North China

As a group of new persistent organic pollutants, short-chain chlorinated paraffins (SCCPs) and medium-chain CP (MCCPs) have attracted extensive worldwide interest in recent years. However, the data regarding to the environmental behavior, especially in atmospheric transfer and air-seawater exchange, are still sparse. In this study, seasonal marine boundary layer air and seawater samples were collected from Chinese Bohai sea and a fugacity model was built to evaluate the air-seawater diffusion and deposition flux of CPs. Generally, the total CP levels in atmosphere and seawater samples in summer were higher than those in spring, and CPs existed mostly in the gaseous phase in air and the dissolved phase in seawater. For SCCPs, C₁₀ and C₁₁ components were the most abundant homologue groups. For MCCPs, the C₁₄ homologue dominated in the particle phase of atmosphere and particulate phase of seawater. The logarithmic fugacity ratios (log f_a/ f_w) of higher chlorinated congeners (Cl₈ to Cl₁₀: 0.71 to 1.32 in May and 1.38 to 2.29 in August) indicated that net deposition was the predominant process, whereas lower chlorinated congeners, especially Cl₅ homologue groups in August, showed a trend of net volitization (log  f_a/ f_w < -0.5). The results of diffusion and dry deposition fluxes indicated that air-seawater gas exchange of CPs was significantly higher than dry deposition in the sampling areas.

Biomonitoring of polychlorinated biphenyls in Bavaria/Germany-long-term observations and standardization

In the 1980s, it was demonstrated that semi-volatile organic compounds (SVOCs) like polychlorinated biphenyls (PCBs) accumulate in plant leaves. Plants are at the base of the food chain, and therefore a starting point for transfer of PCBs to animals and related human exposure. For two decades, the Environment Agency of the German federal state of Bavaria (LfU) has been operating long-term monitoring stations to measure the impact of organic air pollutants. Standardized ryegrass, curly kale, and spruce needles are used as bioindicators for the atmospheric entries of PCBs into vegetation. From the end of 1990s to 2009, there was a marked decline in the concentrations of indicator PCBs (i-PCBs) and a minor decline in PCB-TEQ levels. After 2009, the concentrations leveled off. In rural areas, the median concentrations of Σ6 i-PCB in ryegrass and curly kale were about 3 and 4 μg/kg dm in 2000, and have been about 0.5 and 1 μg/kg dm since 2009, respectively. Concentrations in spruce needles fell from 0.9 to 0.4 μg/kg dm. Median PCB-TEQ concentrations in the bioindicator plants ranged from 0.05 to 0.23 ng/kg dm between 2002 and 2009 and from 0.15 to 0.05 ng/kg dm after 2009. Indicator PCB and PCB-TEQ concentrations were several times higher at the urban station in Munich than at the rural areas, reflecting the emissions from in-use PCB stocks in the building sector. The likely reason of the slower decrease of PCB-TEQ compared to i-PCBs is the formation of PCB-126 by dechlorination of industrial PCBs in open applications.

Persistent organic pollutant emission via dust deposition throughout Pakistan: Spatial patterns, regional cycling and their implication for human health risks

In the current study, Persistent Organic Pollutants (POPs) in outdoor dustfall was monitored for the first time along the Indus river system of Pakistan. Among the studied OCPs (ng/g, dry weight), DDTs (0.16-62) were the predominant contaminants identified in deposited dust followed by HCHs (0.1-10.2), HCB (0.09-7.4) and chlordanes (0.1-2.8). The indicative diagnostic ratio for DDTs and HCHs suggested recent emission of DDTs as well as historical emission of both chemicals in regions where they were used for crop protection and malarial control. The levels of ∑₃₁PCBs (ng/g, dry weight) in dust ranged from 0.95-125, and compositional profiles suggested arochlor-1248, -1254 commercial mixtures as source. A few exceptions were samples from urban areas that reflected the use of aroclor-1260, and-1262 and/or unintentional leakage from several industrial processes. The WHO₀₅-TEQ values for dioxin-like PCBs (with major contributions of PCB-126) were found to be 0.07-34.5 (median; 1.87) pg TEQg^-1dw for all the studied samples. Correlation analysis identified that DDTs, HCHs, HCB and PCBs were significantly associated (r=90; p<0.01) with dusts collected in proximity to urban centers with widespread anthropogenic activities in these areas. A few cases where high levels of POPs from remote mountain highlands were detected, point to the potential for long range transport of these chemicals. Human risk assessment analysis of contaminated dust showed that DDTs and PCBs are major constituent chemicals of concern with regard to the development of cancer in children, with ingestion being the main route of exposure of dust-borne DDTs (0.12-1.03×10^-6) and PCBs (0.86-12.43×10^-6).

Updated Polychlorinated Biphenyl Mass Budget for Lake Michigan

This study revisits and updates the Lake Michigan Mass Balance Project (LMMBP) for polychlorinated biphenyls (PCBs) that was conducted in 1994-1995. This work uses recent concentrations of PCBs in tributary and open lake water, air, and sediment to calculate an updated mass budget. Five of the 11 LMMBP tributaries were revisited in 2015. In these five tributaries, the geometric mean concentrations of ∑PCBs (sum of 85 congeners) ranged from 1.52 to 22.4 ng L^-1. The highest concentrations of PCBs were generally found in the Lower Fox River and in the Indiana Harbor and Ship Canal. The input flows of ∑PCBs from wet deposition, dry deposition, tributary loading, and air to water exchange, and the output flows due to sediment burial, volatilization from water to air, and transport to Lake Huron and through the Chicago Diversion were calculated, as well as flows related to the internal processes of settling, resuspension, and sediment-water diffusion. The net transfer of ∑PCBs is 1240 ± 531 kg yr^-1 out of the lake. This net transfer is 46% lower than that estimated in 1994-1995. PCB concentrations in most matrices in the lake are decreasing, which drove the decline of all the individual input and output flows. Atmospheric deposition has become negligible, while volatilization from the water surface is still a major route of loss, releasing PCBs from the lake into the air. Large masses of PCBs remain in the water column and surface sediments and are likely to contribute to the future efflux of PCBs from the lake to the air.

Using Polyethylene Passive Samplers To Study the Partitioning and Fluxes of Polybrominated Diphenyl Ethers in an Urban River

In the aquatic environment, the behavior of hydrophobic organic contaminants (HOCs), such as polybrominated diphenyl ethers (PBDEs), depends on the congeners' physicochemical properties, environmental conditions and the presence of competing natural sorbents, including particulate and dissolved organic carbon (DOC) and black carbon (BC). Although BC is known as an important sedimentary sorbent for HOCs, its affinity for PBDEs has been poorly constrained. To better understand the biogeochemical controls on PBDEs, 12 PBDE congeners were measured in air, water, sediment and porewater of the lower Passaic River. BDE-47 and BDE-99 dominated in all media. In sediments and water, the dual OC + BC approach better predicted PBDE partitioning compared to the simple OC isotherm. Field-derived K_BC values for PBDEs were inversely correlated with aqueous solubility [log K_{BC sediments(water)} = -log C_w^sat * 0.95 (1.2) + 0.36 (-0.69)]; they reflected near background to highly contaminated regions across the Passaic River. In the water column, PBDEs appeared at equilibrium partitioning between particles and colloids: OC + BC were responsible for the sorption of 65% of PBDEs, followed by colloids (30%); only 5% of PDBEs were truly dissolved. Calculated sediment-water diffusive fluxes greatly overwhelmed the atmospheric depositional flux to the river.

Polycyclic aromatic hydrocarbons (PAHs) in Chinese forest soils: profile composition, spatial variations and source apportionment

Previous studies reported that forest ecosystems can play a vital role in scavenging anthropogenic polycyclic aromatic hydrocarbons (PAHs) and act as primary reservoirs of these environmental pollutants. The present study aimed to investigate the occurrence, spatial pattern and source apportionment of PAHs across Chinese background forest soils (O- & A-horizons). The 143 soils collected from 30 mountains showed significantly (p < 0.05) higher levels of ∑₁₅PAHs (ng g⁻¹ dw) in O-horizon (222 ± 182) than A-horizon (168 ± 161). A progressive increase in the levels of lighter PAHs was observed along altitudinal gradient, however heavier PAHs did not show any variations. Carbon contents (TOC & BC) of forest soils were found weakly correlated (p < 0.01) with low molecular weight (LMW)-PAHs but showed no relation with high molecular weight (HMW)-PAHs. Source apportionment results using PMF and PCA revealed that PAHs in forest soils mainly come from local biomass burning and/or coal combustion and attributed that forest soils may become a potential sink for PAHs in the region.

Organochlorine pesticides and polychlorinated biphenyls in surface water around Beijing

Contaminant concentrations, sources, seasonal variation, and eco-toxicological risk of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface water around Beijing from summer to winter in 2015 and 2016 were investigated. The concentrations of ∑OCPs and ∑PCBs ranged from 9.81 to 32.1 ng L^-1 (average 15.1 ± 7.78 ng L^-1) and from 7.41 to 54.5 ng L^-1 (average 21.3 ± 1.87 ng L^-1), respectively. Hexachlorocyclohexane (HCHs) were the dominated contamination both in aqueous and particulate phase. For PCBs, lower chlorinated PCBs were the major contaminants. Compositions of HCHs, dichlorodiphenyltrichloroethane (DDTs), and PCBs indicated that the sources of OCPs and PCBs in water were due to historical usage in the study areas. For OCPs, there was an obvious variation among three seasons, while insignificant change was shown for PCBs. Water quality standards for China's surface water were not exceeded in this study. Concentrations at Miyun Reservoir, the primary source of drinking water to Beijing, when compared to the USEPA's criterion for cancer risk was below the level of risk.

Estimation of Uncertainty in Air-Water Exchange Flux and Gross Volatilization Loss of PCBs: A Case Study Based on Passive Sampling in the Lower Great Lakes

Compared with dry and wet deposition fluxes, air-water exchange flux cannot be directly measured experimentally. Its model-based calculation contains considerable uncertainty because of the uncertainties in input parameters. To capture the inherent variability of air-water exchange flux of PCBs across the lower Great Lakes and to calculate their annual gross volatilization loss, 57 pairs of air and water samples from 19 sites across Lakes Erie and Ontario were collected using passive sampling technology during 2011-2012. Error propagation analysis and Monte Carlo simulation were applied to estimate uncertainty in the air-water exchange fluxes. Results from both methods were similar, but error propagation analysis estimated a smaller uncertainty than Monte Carlo simulation in cases of net deposition. Maximum likelihood estimations (MLE) of wind speed and air temperature were recommended to quantify the site-specific air-water exchange flux. An assumed 30-40% of relative uncertainty in overall air-water mass transfer velocity was confirmed. MLEs of volatilization fluxes of total PCBs across Lakes Erie and Ontario were 0.78 and 0.53 ng m^-2 day^-1, respectively, and gross volatilization losses of total PCBs over the whole lakes were 74 kg year^-1 for Lake Erie and 63 kg year^-1 for Lake Ontario. Mass balance analysis across Lake Ontario indicated that volatilization was the uppermost loss process of aqueous PCBs.

Source attribution of poly- and perfluoroalkyl substances (PFASs) in surface waters from Rhode Island and the New York Metropolitan Area

Exposure to poly and perfluoroalkyl substances (PFASs) has been associated with adverse health effects in humans and wildlife. Understanding pollution sources is essential for environmental regulation but source attribution for PFASs has been confounded by limited information on industrial releases and rapid changes in chemical production. Here we use principal component analysis (PCA), hierarchical clustering, and geospatial analysis to understand source contributions to 14 PFASs measured across 37 sites in the Northeastern United States in 2014. PFASs are significantly elevated in urban areas compared to rural sites except for perfluorobutane sulfonate (PFBS), N-methyl perfluorooctanesulfonamidoacetic acid (N-MeFOSAA), perfluoroundecanate (PFUnDA) and perfluorododecanate (PFDoDA). The highest PFAS concentrations across sites were for perfluorooctanate (PFOA, 56 ng L^-1) and perfluorohexane sulfonate (PFOS, 43 ng L^-1) and PFOS levels are lower than earlier measurements of U.S. surface waters. PCA and cluster analysis indicates three main statistical groupings of PFASs. Geospatial analysis of watersheds reveals the first component/cluster originates from a mixture of contemporary point sources such as airports and textile mills. Atmospheric sources from the waste sector are consistent with the second component, and the metal smelting industry plausibly explains the third component. We find this source-attribution technique is effective for better understanding PFAS sources in urban areas.

Levels, sources and chemical fate of persistent organic pollutants in the atmosphere and snow along the western Antarctic Peninsula

The Antarctic continent is among the most pristine regions; yet various organic contaminants have been measured there routinely. Air and snow samples were collected during the austral spring (October-November, 2010) along the western Antarctic Peninsula and analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) to assess the relative importance of long-range transport versus local primary or secondary emissions. Highest concentrations of PCBs, PBDEs and DDTs were observed in the glacier's snow sample, highlighting the importance of melting glaciers as a possible secondary source of legacy pollutants to the Antarctic. In the atmosphere, contaminants were mainly found in the vapor phase (>65%). Hexachlorobenzene (33.6 pg/m(3)), PCBs (11.6 pg/m(3)), heptachlor (5.64 pg/m(3)), PBDEs (4.22 pg/m(3)) and cis-chlordane (2.43 pg/m(3)) were the most abundant contaminants. In contrast to other compounds, PBDEs seem to have originated from local sources, possibly the research station itself. Gas-particle partitioning for analytes were better predicted using the adsorption partitioning model than an octanol-based absorption approach. Diffusive flux calculations indicated that net deposition is the dominant pathway for PBDEs and chlordanes, whereas re-volatilization from snow (during melting or metamorphosis) was observed for PCBs and some OCPs.

Gaseous and Freely-Dissolved PCBs in the Lower Great Lakes Based on Passive Sampling: Spatial Trends and Air-Water Exchange

Polyethylene passive sampling was performed to quantify gaseous and freely dissolved polychlorinated biphenyls (PCBs) in the air and water of Lakes Erie and Ontario during 2011-2012. In view of differing physical characteristics and the impacts of historical contamination by PCBs within these lakes, spatial variation of PCB concentrations and air-water exchange across these lakes may be expected. Both lakes displayed statistically similar aqueous and atmospheric PCB concentrations. Total aqueous concentrations of 29 PCBs ranged from 1.5 pg L(-1) in the open lake of Lake Erie (site E02) in 2011 spring to 105 pg L(-1) in Niagara (site On05) in 2012 summer, while total atmospheric concentrations were 7.7-634 pg m(-3) across both lakes. A west-to-east gradient was observed for aqueous PCBs in Lake Erie. River discharge and localized influences (e.g., sediment resuspension and regional alongshore transport) likely dominated spatial trends of aqueous PCBs in both lakes. Air-water exchange fluxes of Σ7PCBs ranged from -2.4 (±1.9) ng m(-2) day(-1) (deposition) in Sheffield (site E03) to 9.0 (±3.1) ng m(-2) day(-1) (volatilization) in Niagara (site On05). Net volatilization of PCBs was the primary trend across most sites and periods. Almost half of variation in air-water exchange fluxes was attributed to the difference in aqueous concentrations of PCBs. Uncertainty analysis in fugacity ratios and mass fluxes in air-water exchange of PCBs indicated that PCBs have reached or approached equilibrium only at the eastern Lake Erie and along the Canadian shore of Lake Ontario sites, where air-water exchange fluxes dominated atmospheric concentrations.

An overlooked environmental issue? A review of the inadvertent formation of PCB-11 and other PCB congeners and their occurrence in consumer products and in the environment

Polychlorinated biphenyls (PCBs) are banned from production and use in most countries as they are persistent organic pollutants (POPs) of concern for environment and health. Recent research has pointed at a new environment issue resulting from the inadvertent formation of PCBs in certain processes, in particular the pigment production. PCB-11 is a major by-product in these processes, but PCB-28, PCB-52, PCB-77 as well as the nonachlorinated PCBs and PCB-209 have been found in pigments and consumer products as well. In addition to environmental emissions via point sources, in particular related to industrial and municipal wastewater, atmospheric transport seems to be important for the global distribution of PCB-11. Thus, PCB-11 has also been detected in the polar regions. Worldwide air concentrations appear relatively uniform, but maxima have been found in urban and industrialised areas. Data on the uptake and accumulation of PCB-11 in the food chain are still inconclusive: Although food web studies do not show biomagnification, PCB-11 has been detected in humans. The human exposure might originate from the direct contact to consumer products as well as from the omnipresence of PCB-11 in the environment.

Inventory of PCBs in Chicago and Opportunities for Reduction in Airborne Emissions and Human Exposure

Urban areas are important regional sources of airborne polychlorinated biphenyls (PCBs) and population-scale airborne exposure, yet a comprehensive bottom-up source inventory of PCB emissions has never been quantified at urban scales in the United States. Here we report a comprehensive parcel level inventory of PCB stocks and emissions for Chicago, Illinois, developed with a transferable method from publicly available data. Chicago's legacy stocks hold 276 ± 147 tonnes ∑PCBs, with 0.2 tonnes added annually. Transformers and building sealants represent the largest legacy categories at 250 and 20 tonnes, respectively. From these stocks, annual emissions rates of 203 kg for ∑PCBs and 3 kg for PCB 11 explain observed concentrations in Chicago air. Sewage sludge drying contributes 25% to emissions, soils 31%, and transformers 21%. Known contaminated sites account for <1% of stocks and 17% of emissions to air. Paint is responsible for 0.00001% of stocks but up to 7% of ∑PCBs emissions. Stocks and emissions are highly concentrated and not correlated with population density or demographics at the neighborhood scale. Results suggest that strategies to further reduce exposure and ecosystem deposition must focus on the largest emissions sources rather than the most contaminated sites or the largest closed source legacy stocks.