Fraction Of Polychlorinated Biphenyls Research Articles

Current source and migration of polychlorinated biphenyls (PCBs) since the ban: Bridging field data gap of 209 congeners in China’s 23 large lakes

Polychlorinated biphenyls (PCBs) were continuously receiving attention after their ban for use and production, owing to significant persistence, transport, and toxicity at trace level. Due to the field data gap of all 209 PCB congeners in previous studies, the source and environmental migration of lacustrine PCBs were not comprehensively understood. In this study, 209 PCB congeners in 277 water and 155 sediment samples collected from China’s 23 large lakes across a longitudinal transect (18–45 °N) were analyzed. Results showed that the concentrations of Σ209PCBs were 0.03–41.04 ng/L and 0.26–163.82 ng/g dry weight in lake water and sediment, respectively. In lake water, the dominant PCB congeners, detected in over 50% of all samples, were PCB 11, PCB 28+31, PCB 41+64+68, PCB 47+48+75, and PCB 51, with contributions to Σ209PCBs as 39.8%, 6.6%, 3.5%, 18.4%, and 6.4%, respectively. Source apportionment revealed that major contributions of PCB 11, 41+64+68, 47+48+75, 51, and 209, were mainly from unintentionally produced PCBs (UP-PCBs) while PCB 28+31 and the other congeners from historical PCB commercials. Therefore, the selective congener analysis (excluding UP-PCBs) common in previous lake studies was an omission. Simultaneously, the longitudinal fractionation of PCBs was also found in lake waters, likely caused by the East Asian monsoon. Moreover, fugacity fractions of PCBs between water and sediment indicated their overall equilibrium or net sorption. Overall, PCB 28+31 can be well indicative of PCB migration. This study provides basic information for the migration and transformation of trace toxic persistent organic pollutants.

Development of High Surface Area Organosilicate Nanoparticulate Thin Films for Use in Sensing Hydrophobic Compounds in Sediment and Water.

The scope of this study was to apply advances in materials science, specifically the use of organosilicate nanoparticles as a high surface area platform for passive sampling of chemicals or pre-concentration for active sensing in multiple-phase complex environmental media. We have developed a novel nanoporous organosilicate (NPO) film as an extraction phase and proof of concept for application in adsorbing hydrophobic compounds in water and sediment. We characterized the NPO film properties and provided optimization for synthesis and coatings in order to apply the technology in environmental media. NPO films in this study had a very high surface area, up to 1325 m2/g due to the high level of mesoporosity in the film. The potential application of the NPO film as a sorbent phase for sensors or passive samplers was evaluated using a model hydrophobic chemical, polychlorinated biphenyls (PCB), in water and sediment. Sorption of PCB to this porous high surface area nanoparticle platform was highly correlated with the bioavailable fraction of PCB measured using whole sediment chemistry, porewater chemistry determined by solid-phase microextraction fiber methods, and the Lumbriculus variegatus bioaccumulation bioassay. The surface-modified NPO films in this study were found to highly sorb chemicals with a log octanol-water partition coefficient (Kow) greater than four; however, surface modification of these particles would be required for application to other chemicals.

Identification of Species-Specific Prey Uptake and Biotransformation of Chiral Polychlorinated Biphenyls (PCBs) in Riparian and Aquatic Food Webs.

The atropisomeric enrichment of chiral polychlorinated biphenyls (PCBs) can trace the movement of PCBs through food webs, but it is a challenge to elucidate the prey uptake and stereoselective biotransformation of PCBs in different species. The present study investigated the concentrations and enantiomer fractions (EFs) of chiral PCBs in invertebrates, fishes, amphibians, and birds. Chiral PCB signature was estimated in total prey for different predators based on quantitative prey sources. The nonracemic PCBs in snakehead (Ophiocephalus argus) were mainly from prey. EFs of PCBs in amphibians and birds were mainly influenced by biotransformation, which showed enrichment of (+)-CBs 132 and 135/144 and different enantiomers of CBs 95 and 139/149. Biomagnification factors (BMFs) of chiral PCBs were higher than 1 for amphibians and passerine birds and lower than 1 for kingfisher (Alcedo atthis) and snakehead. BMFs were significantly correlated with EFs of chiral PCBs in predators and indicative of atropisomeric enrichment of PCBs across different species. Trophic magnification factors (TMFs) were higher in the riparian food web than in the aquatic food web because of the high metabolism capacity of chiral PCBs in aquatic predators. The results highlight the influences of species-specific prey sources and biotransformation on the trophic dynamics of chiral PCBs.

Polychlorinated biphenyls (PCBs) in the colostrum samples from the Yangtze River Region: Exposure profile and risk assessment

Polychlorinated biphenyls (PCBs) may transfer into the neonates through the placental transfer and via breastfeeding after the delivery, thus might be harmful to the infant. Sixty colostrum samples in the Yangtze River Region were collected to investigate the concentration, distribution pattern, and enantiomer characteristic of the PCB exposure. Among all samples, over 90% of pollutants were tetra-to hepta-chlorinated PCBs. The sum concentration of the PCB was 512 (IQR: 322–856) ng g−1 lipid weight. Enantiomer fraction (EF) of PCB 95 and PCB 149 was found lower than the racemic value, while EFs of PCB 45 and PCB 136 were found higher and near-racemic state, respectively. The concentration pattern and enantiomeric properties of the PCBs indicated that the mothers from Mianyang had a recent exposure to PCBs. Among all samples, similar exposure and metabolic pathways of the PCB congeners were observed. PCB exposure showed no significant correlation with the birth outcome of the infants, but 43.3% of the infants have potential health risks via breastfeeding.

Distribution characteristics and environmental fate of PCBs in marine sediments at different latitudinal regions: Insights from congener profiles

Sediments were sampled from Hangzhou Bay (HB), the South China Sea (SCS), and Antarctica (AZ) to better understand the distribution characteristics and environmental fate of polychlorinated biphenyls (PCBs) at different latitudes. Numerous PCB congeners (68) were detected among the sampling sites, supporting the ubiquity of PCB congeners. High and low chlorinated congeners dominated the PCB profiles of AZ and SCS, respectively, whereas the PCB homologues were evenly distributed in the HB. As a fraction of low chlorinated PCBs originates from an exogenous input, the low mean ratios of ∑Tetra-CBs to ∑PCBs and ∑Tetra-CBs to the sum of ∑Tri- and ∑Di-CBs suggest that microbial transformation of PCBs is weak in marine surface sediments, if any occurs at all. Furthermore, PCB contamination levels in marine sediments may be primarily influenced by latitude rather than pollution sources. Thus, the findings of this study suggest that Antarctica is becoming a prospective hotspot for PCBs.

Atropselective Disposition of 2,2',3,4',6-Pentachlorobiphenyl (PCB 91) and Identification of Its Metabolites in Mice with Liver-Specific Deletion of Cytochrome P450 Reductase.

Hepatic cytochrome P450 enzymes metabolize chiral polychlorinated biphenyls (PCBs) to hydroxylated metabolites (OH-PCBs). Animal models with impaired metabolism of PCBs are one approach to study how the atropselective oxidation of PCBs to OH-PCBs contributes to toxic outcomes, such as neurodevelopmental disorders, following PCB exposure. We investigated the disposition of PCB 91, a para-substituted PCB congener, in mice with a liver-specific deletion of the cytochrome P450 reductase (cpr) gene (KO mice). KO mice and wild-type (WT) mice were exposed orally to racemic PCB 91 (30 mg/kg b.w.). Levels and enantiomeric fractions of PCB 91 and its hydroxylated metabolites were determined in tissues 3 days after PCB exposure and in excreta on days 1-3 after PCB exposure. PCB 91, but not OH-PCB levels were higher in KO compared to WT mice. The elevated fat and protein content in the liver of KO mice resulted in the hepatic accumulation of PCB 91. OH-PCBs were detected in blood, liver, and excreta samples of KO and WT mice. 2,2',3,4',6-Pentachlorobiphenyl-5-ol (5-91) was the major metabolite. A considerable percent of the total PCB 91 dose (%TD) was excreted with the feces as 5-91 (23%TD and 31%TD in KO and WT mice, respectively). We tentatively identified glucuronide and sulfate metabolites present in urine samples. The PCB 91 atropisomer eluting first on the chiral column (E1-PCB 91) displayed genotype-dependent atropisomeric enrichment, with a more pronounced atropisomeric enrichment observed in WT compared to KO mice. E1-atropisomers of 5-91 and 2,2',3,4',6-pentachlorobiphenyl-4-ol (4-91) were enriched in blood and liver, irrespective of the genotype; however, the extent of the enrichment of E1-5-91 was genotype dependent. These differences in atropselective disposition are consistent with slower metabolism of PCB 91 in KO compared to WT mice and the accumulation of the parent PCB in the fatty liver of KO mice.

Atropselective Oxidation of 2,2',3,3',4,6'-Hexachlorobiphenyl (PCB 132) to Hydroxylated Metabolites by Human Liver Microsomes and Its Implications for PCB 132 Neurotoxicity.

Polychlorinated biphenyls (PCBs) have been associated with neurodevelopmental disorders. Several neurotoxic congeners display axial chirality and atropselectively affect cellular targets implicated in PCB neurotoxicity. Only limited information is available regarding the atropselective metabolism of these congeners in humans and their atropselective effects on neurotoxic outcomes. Here we investigate the hypothesis that the oxidation of 2,2',3,3',4,6'-hexachlorobiphenyl (PCB 132) by human liver microsomes (HLMs) and their effects on dopaminergic cells in culture are atropselective. Racemic PCB 132 was incubated with pooled or single donor HLMs, and levels and enantiomeric fractions of PCB 132 and its metabolites were determined gas chromatographically. The major metabolite was either 2,2',3,4,4',6'-hexachlorobiphenyl-3'-ol (3'-140), a 1,2-shift product, or 2,2',3,3',4,6'-hexachlorobiphenyl-5'-ol (5'-132). The PCB 132 metabolite profiles displayed interindividual differences and depended on the PCB 132 atropisomer. Computational studies suggested that 3'-140 is formed via a 3,4-arene oxide intermediate. The second eluting atropisomer of PCB 132, first eluting atropisomer of 3'-140, and second eluting atropisomer of 5'-132 were enriched in all HLM incubations. Enantiomeric fractions of the PCB 132 metabolites differed only slightly between the single donor HLM preparations investigated. Reactive oxygen species and levels of dopamine and its metabolites were not significantly altered after a 24 h exposure of dopaminergic cells to pure PCB 132 atropisomers. These findings suggest that there are interindividual differences in the atropselective biotransformation of PCB 132 to its metabolites in humans; however, the resulting atropisomeric enrichment of PCB 132 is unlikely to affect neurotoxic outcomes associated with the endpoints investigated in the study.

Modeling primary and secondary fractionation effects and atmospheric transport of polychlorinated biphenyls through single-source emissions.

The Chinese Gridded Industrial Pollutants Emission and Residue Model (ChnGIPERM) was used to investigate potential fractionation effects and atmospheric transport of polychlorinated biphenyls (PCBs) derived from single-source emissions in China. Modeling the indicative PCBs (CB28, CB101, CB153, and CB180) revealed spatiotemporal trends in atmospheric transport, gas/particle partitioning, and primary and secondary fractionation effects. These included the inference that the Westerlies and East Asian monsoons affect atmospheric transport patterns of PCBs by influencing the atmospheric transport time (ATT). In this study, dispersion pathways with long ATTs in winter tended to have short ones in summer and vice versa. The modeled partitioning of PCB congeners between gas and particles was mainly controlled by temperature, which can further influence the ATT. The potential for primary and secondary fractionation was explored by means of numerical simulations with single-source emissions. Within ChnGIPERM, these phenomena were mainly controlled by the temperature and soil organic carbon content. The secondary fractionation of PCBs is a slow process, with model results suggesting a timescale of several decades.

Efficacy of carbon-based materials for remediating polychlorinated biphenyls (PCBs) in sediment

Polychlorinated biphenyls (PCBs) are persistent hydrophobic compounds that are present widely in the environment. Due to poorly maintained hazardous waste sites, electrical equipment leakage, and illegal disposal, PCBs were deposited in sediments present in bays and estuaries. PCBs continuously partition into the overlying water posing a long-term exposure risk to the environment and human health. This study demonstrates the efficacy of carbon-based materials in reducing the partitioning of PCBs from sediment to the water column. Both existing carbon-based materials [activated carbon (AC), black carbon (BC)] and emerging nanomaterials [graphene (GE), graphene oxide (GO), carbon nanotube (CNT)] were tested to determine their efficacy to bind PCBs in sediment. The comparison between the sorbents was accomplished by examining their distribution coefficient (Ks). The magnitude of Ks provides an idea about the bioavailable fraction of PCBs in the system; the higher the Ks, the greater the strength of sorption by the sorbent and therefore, the lower the PCB bioavailability. Results from the sorption experiment indicated that CNT performed the best overall followed by AC, BC, GO and GE. Results indicated that the Ks value for CNT was 1.16, 1.15, 1.13 and 1.04 log units greater than GE, GO, BC, and AC.

Released fraction of polychlorinated biphenyls from soil-biosolid system using a leaching procedure and its comparison with bioavailable fraction determined by wheat plant uptake.

The bioavailability of polychlorinated biphenyls (PCBs) in soils amended with biosolids was estimated using an aqueous leaching process of the compounds combined with rotating disk sorptive extraction (RDSE), and compared with bioavailability determined through of PCB absorption in wheat plants growing in the same soil-biosolid matrix. The matrices consisted of soil amended with biosolids at doses of 30, 90, and 200Mg/ha, which increase concomitantly the organic matter content of the matrix. Considering that PCBs were natively absent in both the biosolids and soil used, the compounds were spiked in the biosolids and aged for 10days. For each biosolid dose, the aqueous leaching profile was studied and equilibrium time was calculated to be 33h. The leaching fractions determined by RDSE, considering total PCBs studied, were 12, 7, and 6% and the bioavailable fractions absorbed by the wheat root were found to be 0.5, 0.3, and 0.2% for 30, 90, and 200Mg/ha doses, respectively. Both fractions leachable and bioavailable decrease with both increasing hydrophobicity of the compound (Kow) and increasing in the biosolid dose. It was found that both fractions (leaching and bioavailable) correlated according to the bivariate least squares regression, represented by a coefficient of correlation of 0.86. Therefore, the application of the chemical method involving a leaching procedure is an alternative to estimate the bioavailable fraction of PCBs in wheat plants in a simpler and in a shorter time.

Spatial variation of PAHs and PCBs in coastal air, seawater, and sediments in a heavily industrialized region

Concurrent coastal seawater (n=22), sediment (n=22), and atmospheric samples (n=10) were collected in the Aliaga industrial region, Turkey, to explore the spatial variation, sources, and air-seawater exchange of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Seawater Σ16PAH concentrations (particle+dissolved) ranged between 5107 and 294,624pgL-1, while Σ41PCB concentrations were in the range of 880-50,829pgL-1. Levels in sediments were highly variable ranging between 35.5-49,682 and 2.7-2450μgkg-1 in dry weight for Σ16PAHs and Σ41PCBs, respectively. Atmospheric concentrations varied between 1791-274,974 and 104-20,083pgm-3 for Σ16PAHs and Σ41PCBs, respectively. Sediment organic matter (OM) content and levels of Σ16PAHs and Σ41PCBs correlated weakly (r 2=0.19-0.23, p<0.05) suggesting that the spatial variations of PAHs and PCBs were mainly affected by local sources rather than their sorption to OM. The geographical distribution of PAH and PCB concentrations in air, seawater, and sediment and factor analysis on the sediment levels pointed out that the major sources in the region are steel plants, petroleum refinery, petrochemical complex, ship breaking, loading/unloading activities at the ports, vehicular emissions, and fossil fuel combustion emissions. The direction of the air-seawater exchange was also explored by estimating seawater fugacity fractions of PAHs and PCBs. For PAHs, the number of cases implying deposition (43.0%) and volatilization (39.5%) was similar, while for PCBs, the number of cases implying volatilization (60.4%) was much higher compared to deposition (21.6%). Fugacity fractions were generally <0.36 (deposition) at the sites close to industrial and ship breaking activities where the highest seawater and sediment levels were measured, implying that atmospheric deposition is an important mechanism affecting seawater and sediment PAH and PCB levels.

Particle size distribution and gas-particle partitioning of polychlorinated biphenyls in the atmosphere in Beijing, China.

Size-fractionated samples of urban particulate matter (PM; ≤1.0, 1.0-2.5, 2.5-10, and >10μm) and gaseous samples were simultaneously obtained to study the distribution of polychlorinated biphenyls (PCBs) in the atmosphere in Beijing, China. Most recent investigations focused on the analysis of gaseous PCBs, and much less attention has been paid to the occurrence of PCBs among different PM fractions. In the present study, the gas-particle partitioning and size-specific distribution of PCBs in atmosphere were investigated. The total concentrations (gas + particle phase fractions) of Σ12 dioxin-like PCBs, Σ7 indicator PCBs, and ΣPCBs were 1.68, 42.1, and 345pg/m3, respectively. PCBs were predominantly in the gas phase (86.8-99.0% of the total concentrations). The gas-particle partition coefficients (K p ) of PCBs were found to be a significant linear correlated with the subcooled liquid vapor pressures (P L0) (R 2=0.83, P<0.01). The slope (m r ) implied that the gas-particle partitioning of PCBs was affected both by the mechanisms of adsorption and absorption. In addition, the concentrations of PCBs increased as the particle size decreased (>10, 2.5-10, 1.0-2.5, and ≤1.0μm), with most of the PCBs contained in the fraction of ≤1.0μm (53.4% of the total particulate concentrations). Tetra-CBs were the main homolog in the air samples in the gas phase and PM fractions, followed by tri-CBs. This work will contribute to the knowledge of PCBs among different PM fractions and fill the gap of the size distribution of particle-bound dioxin-like PCBs in the air.

The Abandoned E-Waste Recycling Site Continued to Act As a Significant Source of Polychlorinated Biphenyls: An in Situ Assessment Using Fugacity Samplers.

The recycling of e-waste has attracted significant attention due to emissions of polychlorinated biphenyls (PCBs) and other contaminants into the environment. We measured PCB concentrations in surface soils, air equilibrated with the soil, and air at 1.5-m height using a fugacity sampler in an abandoned electronic waste (e-waste) recycling site in South China. The total concentrations of PCBs in the soils were 39.8-940 ng/g, whereas the concentrations in air equilibrated with the soil and air at 1.5 m height were 487-8280 pg/m(3) and 287-7380 pg/m(3), respectively. The PCB concentrations displayed seasonal variation; they were higher in winter in the soils and higher in summer in the air, indicating that the emission of PCBs from the soil was enhanced during hot seasons for the relatively high temperature or additional sources, especially for low-chlorinated PCBs. We compared two methods (traditional fugacity model and fugacity sampler) for assessing the soil-air partition coefficients (Ksa) and the fugacity fractions of PCBs. The results suggested that the fugacity sampler provided more instructive and practical estimation on Ksa values and trends in air-soil exchange, especially for low-chlorinated PCBs. The abandoned e-waste burning site still acted as a significant source of PCBs many years after the prohibition on open burning.

Atmospheric gas-particle partitioning versus gaseous/particle-bound deposition of SVOCs: Why they are not equivalent

Semi-volatile organic compounds (SVOCs) can be particle-bound or in the gas phase in the atmosphere, depending on the (temperature dependent) gas-particle partitioning of the chemicals and the fraction of particles in air. Several studies linked gas-particle partitioning of SVOCs in the atmosphere directly to the gaseous/particle-bound deposition of these chemicals, i.e. in cases of compounds occurring mainly in the gas phase, the deposition was also assumed to be mainly in gaseous form. In this study, we apply a multi-media fate model to point out that gas-particle partitioning of SVOCs in air and gaseous/particle-bound deposition of SVOCs are driven by different mechanism and, thus, cannot be deduced from each other. We apply our calculations to polychlorinated biphenyls (PCBs), as model SVOCs. We show that the fraction of particle-bound deposition to deciduous forest is 1.5–190 times higher in winter and between 5 and 1000 times higher in summer than the particle-bound fraction of these chemicals in air. The fraction of particle-bound deposition to coniferous forest is 1.5–172 times higher in winter and between 5 and 1000 times higher in summer than the particle-bound fraction of PCBs in air. In addition to the fractions of particle-bound SVOCs in air and particle-bound deposition, we recalculated particle-bound and gaseous deposition velocities to coniferous and deciduous forest for PCBs. The deposition velocities obtained for dry gaseous deposition (<1 m/h) are much lower than the existing values in the literature (10–200 m/h) because earlier studies assumed that for PCBs occurring predominantly in the gas phase, interception was also completely due to dry gaseous deposition.

Atmospheric pollutants in fog and rain events at the northwestern mountains of the Iberian Peninsula

Atmospheric polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) and exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). While the hydrosphere is the main reservoir for PAHs, the atmosphere serves as the primary route for global transport of PCBs. In this study, fog and rain samples were collected during fourteen events from September 2011 to April 2012 in the Xistral Mountains, a remote range in the NW Iberian Peninsula. PAH compounds [especially of low molecular weight (LMW)] were universally found, but mainly in the fog-water samples. The total PAH concentration in fog-water ranged from non-detected to 216ng·L−1 (mean of 45ng·L−1), and was much higher in fall than in winter. Total PAH levels in the rain and fog events varied from non-detected to 1272 and 33ng·L−1 for, respectively, LMW and high molecular weight (HMW) PAHs. Diagnostic ratio analysis (LMW PAHs/HMW PAHs) suggested that petroleum combustion was the dominant contributor to PAHs in the area. Total PCB levels in the rain and fog events varied from non-detected to 305 and 91ng·L−1 for, respectively, PCBs with 2–3 Cl atoms and 5–10 Cl atoms. PCBs, especially those with 5–10 Cl atoms, were found linked to rain events. The occurrence of the most volatile PCBs, PCBs with 2–3 Cl atoms, is related to wind transport from far away sources, whereas the occurrence of PCBs with 5–10 Cl atoms seems to be related with the increase of its deposition during rainfall at the end of summer and fall. The movement of this fraction of PCBs is facilitated by its binding to air-suspended particles, whose concentrations usually show an increase as the result of a prolonged period of drought in summer.

Species-specific bioaccumulation of halogenated organic pollutants and their metabolites in fish serum from an e-waste site, South China.

Halogenated organic pollutants (HOPs)-including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), polybromobiphenyls (PBBs), dechlorane plus (DP), tetrabromobisphenol A (TBBPA), and hexabromocyclododecanes (HBCDs) as well as PCB metabolites (methylsulfone [MeSO2-]) and hydroxylated (OH-) PCBs and OH-PBDEs-were determined in the serum of mud carp and northern snakehead from an electronic-waste (e-waste) site in South China. The average concentrations (mean±SD) of ΣPCBs, ΣPBDEs, ΣOCPs, ΣPBBs, ΣTBBPA, ΣHBCDs, and ΣDP were 1410±324, 70±20, 3.0±0.4, 2.8±0.8, 1.6±0.4, 1.0±0.2, and 0.3±0.03ng/g wet weight (ww) in mud carp and 6430±781, 468±49, 22.4±1.1, 7.0±0.6, 2.9±2.3, 5.5±1.1, and 4.6±0.6ng/g ww in northern snakehead, respectively. MeSO2-PCBs, OH-PCBs, and OH-PBDEs were detected at a total concentration of 0.44±0.03 and 9.7±0.3ng/g ww in mud carp and northern snakehead, respectively. The congener profiles of PCBs, PBDEs, OH/MeSO2-PCBs, and OH-PBDEs were found to be significantly different between the two fish species, possibly as a result of species-specific bioaccumulation and/or metabolism of the HOPs. Chirality of ten PCB congeners and α-HBCD, as well as the f anti values of DP in the serum samples, supported the species-specific biotransformation of HOPs. Furthermore, the presence of covaried and counter-varied enantiomeric fractions of PCBs between the two fish species indicated species- and congener-specific enantiomer enrichment of PCBs.

Autochthonous ascomycetes in depollution of polychlorinated biphenyls contaminated soil and sediment

We investigated the capacity of a consortium of ascomycetous strains, Doratomyces nanus, Doratomyces purpureofuscus, Doratomyces verrucisporus, Myceliophthora thermophila, Phoma eupyrena and Thermoascus crustaceus in the mycoremediation of historically contaminated soil and sediment by polychlorinated biphenyls (PCBs). Analyses of 15 PCB concentrations in three mesocosms containing soil from which the fungal strains had previously been isolated, revealed significant PCB depletions of 16.9% for the 6 indicator PCBs (i-PCBs) and 18.7% for the total 15 PCBs analyzed after 6months treatment. The degradation rate did not statistically vary whether the soil had been treated with non-inoculated straw or colonized straw or without straw and inoculated with the consortium of the six strains. Concerning the sediment, we evidenced significant depletions of 31.8% for the 6 i-PCBs and 33.3% for the 15 PCB congeners. The PCB depletions affected most of the 15 PCBs analyzed without preference for lower chlorinated congeners. Bioaugmented strains were evidenced in different mesocosms, but their reintroduction, after six months treatment, did not improve the rate of PCB degradation, suggesting that the biodegradation could affect the bioavailable PCB fraction. Our results demonstrate that the ascomycetous strains potentially adapted to PCBs may be propitious to the remediation of PCB contaminated sites.

Elevated Levels of Polychlorinated Biphenyls in Plants, Air, and Soils at an E-Waste Site in Southern China and Enantioselective Biotransformation of Chiral PCBs in Plants

E-waste that contains polychlorinated biphenyls (PCBs) is moved across national boundaries, often from industrialized countries in the northern hemisphere, where the items were formerly used, to subtropical and tropical regions in southeastern Asia and Africa. As a result, there is a high likelihood that PCBs will be released into the environment from a primary source due to the elevated temperatures encountered in these low-latitude regions. In the present study, PCBs and enantiomer fractions (EFs) of chiral PCBs (PCB 84, 95, 132, 136, 149, and 183) were analyzed in air, eucalyptus leaves, pine needles, and soil at an e-waste site and a rural site in southern China. The concentrations of PCBs at the e-waste site ranged from 7825 to 76330 pg/m(3), 27.5 to 1993 ng/g, and 24.2 to 12045 ng/g in the air (gas plus particle), plant leaves, and soils, respectively. The atmospheric PCB composition profiles in the present study indicated relatively high abundances of penta- and hexa-PCBs, which were different from those previously observed in the air across China. The Clausius-Clapeyron regression analysis indicated that evaporation from local contaminated surfaces constitutes a primary emission source of PCBs in the air at the e-waste site. The chiral signatures of PCBs in the air at the e-waste site were essentially racemic (mean EFs = (0.484 ± 0.022)-(0.499 ± 0.004) in the gaseous phase) except for PCB 84 (0.420 ± 0.050), indicating that racemic sources dominate the PCB emission in the air. PCB chiral signatures in the soils ((0.422 ± 0.038)-(0.515 ± 0.016)) were similar to those in the air except for PCB 95. However, the chiral PCBs in the plants (especially the eucalyptus leaves) had significantly nonracemic residues ((0.368 ± 0.075)-(0.561 ± 0.045)) compared to those in the air and soil. This finding suggests that enantioselective biotransformation of these atropisomeric PCBs was very likely to occur in the plant leaves, possibly due to metabolism by cytochrome P-450 enzymes in leaves. To our knowledge, this is the first report on the enantioselective metabolism of chiral PCBs in plants under field conditions.

Polychlorinated biphenyls (PCBs) in industrial and municipal effluents: Concentrations, congener profiles, and partitioning onto particulates and organic carbon

Wastewater effluent samples were collected in the summer of 2009 from 16 different locations which included municipal and industrial wastewater treatment plants and petrochemical industrial outfalls in the Houston area. The effluent samples were analyzed for all 209 polychlorinated biphenyls (PCBs) congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) using the USEPA method 1668A. The total PCBs (∑209) concentration in the dissolved medium ranged from 1.01 to 8.12ng/L and ranged from 2.03 to 31.2ng/L in the suspended medium. Lighter PCB congeners exhibited highest concentrations in the dissolved phase whereas, in the suspended phase, heavier PCBs exhibited the highest concentrations. The PCB homolog concentrations were dominated by monochlorobiphenyls through hexachlorobiphenyls, with dichlorobiphenyls exhibiting the highest concentration amongst them at most of the effluent outfalls, in the suspended phase. Both total suspended solids (TSS) and various organic carbon fractions played an important role in the distribution of the suspended fractions of PCBs in the effluents. The log Koc values determined in the effluents suggest that effluent PCB loads might have more risk and impact than what standard partitioning models predict.

Exposure assessment and distribution of polychlorinated biphenyls (PCBs) contained in indoor and outdoor dusts and the impacts of particle size and bioaccessibility

The size fraction, bioaccessibility and associated human daily intake of PCBs via indoor and outdoor dust collected from two most populated urban centers of Pearl River Delta (PRD), China, were studied. The ΣPCBs levels (ngg−1) in indoor (51.9–264) and outdoor (4.02–228) dust in Guangzhou (GZ) were found higher than those in indoor (17.4–137) and outdoor (7.75–114) dust of Hong Kong (HK). Hexa-PCB was the largest contributor in dust samples (29–64%), followed by tri-PCB. The size fraction of PCBs indicated a high accumulation effect of particles less than 63μm, while the lowest was found in 280–2000μm. Toxic equivalency (TEQ) of dioxin-like PCBs in indoor dust of GZ and HK was 2 to 13 times higher than that in outdoor dust. The bioaccessibility of PCBs was determined as 5–61% depending on individual PCB congeners under study and bioaccessible PCB exposure was significantly lower than the estimate for total PCB. The daily intake of bioaccessible PCBs via dust ranged in 0.02–8.95 and 0.37–17.8ngday−1 in GZ while 0.01–4.95 and 0.16–9.83ngday−1 in HK for adults and children, respectively. Dust ingestion contributed to 0.49–10.6% of overall non-dietary PCB exposure (dust ingestion and inhalation) for adults while 12.9–35% for children, indicating the dominant contribution from inhalation.