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[en] Quantifying polychlorinated biphenyl (PCB) residues in nestlings of avian species is a common method for assessing trophic transfer and risk at PCB-contaminated sites. The proportion of nestling PCB mass due to maternal transfer is often accounted for by subtracting total PCB mass in eggs from nestlings. However, variation in physicochemical properties and metabolism among congeners may lead to differences between egg contribution based on total PCBs and dioxin-like congeners. We examined congener-specific variation in contribution of PCBs from eggs to nestlings in tree swallows and European starlings. Egg contribution of total PCB mass was 14.3 and 16.2%, respectively, whereas contribution based on dioxin-like congeners was 14.8 and 13.6%, respectively. These data suggest that using total PCB mass in eggs to adjust estimates of PCB accumulation in nestlings may not reflect patterns for dioxin-like congeners, potentially over or under-estimating the risk of toxicity of PCBs. - Congener-specific contribution of PCBs from egg to nestlings was examined.
[en] The story of the successful cleanup undertaken at the former CN Rail Kempt Road site in Halifax, Nova Scotia, was told. The ten-acre site was found to be potentially contaminated with trace metals and PCBs by various occupants of the facilities over a ten year period. Approximately 3,000 tonnes of soil were identified as PCB and metal-contaminated. In 1996 the Canada Lands Company, a provincial Crown corporation, assumed responsibility for the property. Various clean-up options have been examined for environmental impact, human health and sustainable development. The separation and incineration of the PCBs, with disposal of the remaining soil in a secure landfill option was eventually approved. Cintec Environnement Inc., of Quebec was contracted: (1) to use their patented process of soil washing to separate the PCBs from the soil, (2) to send the PCBs for incineration to the Swan Hill, Alberta, incinerator for destruction, and (3) to dispose of the decontaminated soil in their LaSalle, Quebec, landfill which is approved for receiving hazardous materials. The soil was transported to Cintec by Laidlaw in trucks during a thirty day period. The soil washing and PCB separation process was successfully and safely concluded within three months. The role of the environmental consultant - OCL Services - and the extensive public communications program were said to have been crucial to the success of this project
[en] Studies have been conducted to identify fast-acting bacteria that are capable of breaking down polychlorinated biphenyls (PCBs). Four naturally-occurring enzymes have been identified that equip common soil bacteria with the means to at least partially degrade 30 or 40 of the more than 200 PCB compounds in existence. This study also examined how certain enzymes enable bacteria to break down some PCB components but not others. An enzyme modification phase of the research is underway. The goal of the project is develop a comprehensive set of PCB-degrading bacteria. It was suggested that bioremediation could be applied in new ways to deal also with other persistent toxic compounds such as poly aromatic hydrocarbons (PAHs), dioxins and furans
[en] Attention was drawn to the many active PCB storage sites in Canada which exist despite the fact that no PCB has been sold in Canada since 1976. The hazards posed by these storage sites, the technologies that have been developed and are now available to power generators, and a list of significant elements that power generators should take into consideration before deciding how best to deal with their PCB waste in order to minimize the potential liability and risk, are described. Among the elements discussed are a closure plan for the generation facility, including specific coverage for the PCB waste, detailed plans for trucking waste from generators to the disposal site, plans for the disposal of contaminated components, and specific sampling procedures for decontaminated material. The conclusion is that with the disposal and treatment options available for PCB material in Canada today, there is no excuse to hold this waste in inventory with the associated mounting risks of aging storage sites
[en] Cintec Environnement Inc., of Quebec has developed a soil-washing technology that has helped to reduce the problem of eliminating PCBs from the Canada Lands Company Kempt Road site in Halifax, NS. The physical/chemical process is typically used for soils contaminated with heavy metals. In the process, incoming truck-loads of soil are sampled and segregated by type of contamination. Material registering under 50 ppm PCB go directly to Cintec's landfill which is approved for receiving hazardous material. The remainder is screened to remove particles larger than two inches in diameter, and tested again. Material with more than 50 ppm PCBs is mixed with water and treated by hydrocycloning, attrition and flotation to further separate the material, and isolating particles smaller than 80 microns. This material is treated with a specially-developed proprietary chemical reagent that dissolves the PCBs. As a measure of the success of this process, of 2,171 tonnes of material received, only two tonnes of highly concentrated PCB-contaminated material remained after treatment. This was incinerated at the Chem Security incinerator at Swan Hills, Alberta
[en] Organohalogen pollutants are of concern in many river and estuarine environments, such as the New York-New Jersey Harbor estuary and its tributaries. The Hackensack River is contaminated with various metals, hydrocarbons and halogenated organics, including polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins. In order to examine the potential for microbial reductive dechlorination by indigenous microorganisms, sediment samples were collected from five different estuarine locations along the Hackensack River. Hexachlorobenzene (HCB), hexabromobenzene (HBB), and pentachloroaniline (PCA) were selected as model organohalogen pollutants to assess anaerobic dehalogenating potential. Dechlorinating activity of HCB and PCA was observed in sediment microcosms for all sampling sites. HCB was dechlorinated via pentachlorobenzene (PeCB) and trichlorobenzene (TriCB) to dichlorobenzene (DCB). PCA was dechlorinated via tetrachloroaniline (TeCA), trichloroanilines (TriCA), and dichloroanilines (DCA) to monochloroaniline (MCA). No HBB debromination was observed over 12 months of incubation. However, with HCB as a co-substrate slow HBB debromination was observed with production of tetrabromobenzene (TeBB) and tribromobenzene (TriBB). Chloroflexi specific 16S rRNA gene PCR-DGGE followed by sequence analysis detected Dehalococcoides species in sediments of the freshwater location, but not in the estuarine site. Analysis targeting 12 putative reductive dehalogenase (rdh) genes showed that these were enriched concomitant with HCB or PCA dechlorination in freshwater sediment microcosms. - Highlights: • Indigenous bacteria from Hackensack River sediments were capable of dehalogenating hexachlorobenzene and pentachloroaniline. • Dehalococcoides species were enriched in freshwater sediment spiked with hexachlorobenzene and pentachloroaniline. • Putative reductive dehalogenase genes were enriched in hexachlorobenzene and pentachloroaniline dechlorinating microcosms. - Halogenated aromatic pollutants are reductively dehalogenated by indigenous microorganisms in an estuarine river system.
[en] Purpose. To report initial experience with the Peripheral Cutting Balloon (PCB) in treatment of failing hemodialysis shunts. Methods. A total of 190 patients (95 men, 95 women; average age 64.4 ± 11.9 years, range 32-87 years) who were treated with the PCB for pressure-resistant stenosis, restenosis or failed percutaneous transluminal angioplasty (PTA) in the venous limb of an arteriovenous shunt were followed in seven European centers using a simple registry. The group consisted of 109 de novo lesions (57%) and 79 restenotic lesions (43%). Results. Technical success was achieved in 88.9% of cases. Primary patency was as follows (the results for whole group and simultaneous results for de novo lesions and restenoses are presented): 1 month (140 patients followed): 94%, 98%, and 93%; 3 months (116 patients followed): 93%, 98%, and 92%; 6 months (40 patients followed): 85%, 92%, and 79%; 12 months (27 patients followed): 74%, 87%, and 48%. No complication occurred. Patients experienced an equal or lower level of pain during the procedure compared with conventional PTA. Conclusion. The PCB proved to be successful in dilating pressure-resistant stenoses. We cannot conclude whether PCB angioplasty can lower the restenosis rate in hemodialysis access lesions, but the long-term patency for de novo lesions is high. A further randomized study is advisable
[en] A kinetic model for the electrochemical dechlorination of polychlorinated biphenyls (PCBs) will be an important contribution to the design and optimization of a continuous reactor. Initially, the electrocatalytic hydrodechlorination of 2-chlorobiphenyl (2-ClBP) to biphenyl at a palladium-modified nickel foam (Pd/Ni) cathode in a batch reactor was used as a model reaction for a quantitative study of the influences of the operating parameters, including temperature, the initial concentrations of PCBs, current density and the amount of Pd loading, on the apparent reaction rate. The dechlorination was found to follow pseudo first-order kinetics with respect to the 2-ClBP concentration. It was also found that a simple global power law rate equation, with Arrhenius dependency, can be used to describe the correlation between the pseudo first-order reaction rate constants and the reaction conditions. Subsequently, a mathematical model for predicting the performance of reductive dechlorination of 2-ClBP on Pd/Ni electrodes in a continuous stirred tank reactor was constructed, based on the batch-reaction kinetics. The suitability of the model was validated by performing experiments in and out of the range of reaction conditions applied in the batch reactor. The results show that the calculated values are a good fit to the experimental data
[en] Polychlorinated biphenyl (PCB) congeners (PCB 52, 77, and 153) singly and in mixture were spiked and aged in soil microcosms and subsequently planted with switchgrass (Panicum virgatum) or poplar (Populus deltoids x nigra DN34). The planted reactors showed significantly greater reductions in PCB parent compounds when compared to unplanted systems after 32 weeks. There was evidence of reductive dechlorination in both planted and unplanted systems, but the planted microcosms with fully developed roots and rhizospheres showed greater biotransformation than the unplanted reactors. These dechlorination products accounted for approximately all of the molar mass of parent compound lost. Based on the transformation products, reductive dechlorination pathways are proposed for rhizospheric biotransformation of PCB 52, 77, and 153. This is the first report of rhizosphere biotransformation pathways for reductive dechlorination in marginally aerobic, intermittently flooded soil as evidenced by a mass balance on transformation products. -- Highlights: •Soil was spiked and aged and then planted with poplar and switchgrass. •Planted microcosms showed significant reductive dechlorination and greater biotransformation than unplanted reactor. •Rhizospheric reductive dechlorination pathways are proposed. -- This study provides insight into rhizospheric transformation of PCBs
[en] A comprehensive process which combines chemical with thermal treatment by controlled counterflow oxidation has been developed for disposal of PCBs in transformer oil. PCBs which not completely removed by chemical treatment, after being filtered with appropriate adsorbent during the oil circulations, was thermally treated. Destruction efficiencies of better than 99.99% was obtained, with no measurable formation of PCDDs (polychlorinated dibenzo-p-dioxins) of PCDFs (polychlorinated dibenzofurans). The combination also permits high recovery of oil and inorganic supports from scrap power transformers. The process is environmentally benign, easy to use and less capital intensive than other available technologies