Characterizing the Emissions of Polybrominated Diphenyl Ethers

Jan 26, 2010 - 3045. Fax: +886-7-7332204. E-mail: [email protected]., †. Department of Chemical and Materials Engineering, Cheng Shiu University. , ...
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Environ. Sci. Technol. 2010, 44, 1240–1246

Characterizing the Emissions of Polybrominated Diphenyl Ethers (PBDEs) and Polybrominated Dibenzo-p-dioxins and Dibenzofurans (PBDD/Fs) from Metallurgical Processes L I N - C H I W A N G , * ,†,† Y A - F E N W A N G , § HSING-CHENG HSI,| AND G U O - P I N G C H A N G - C H I E N †,† Department of Chemical and Materials Engineering and Super Micro Mass Research and Technology Center, Cheng Shiu University, 840 Chengching Road, Kaohsiung 833, Taiwan, R.O.C., Department of Bioenvironmental Engineering, Chung Yuan Christian University, 200 Chung-Pei Road, Chung-Li 320, Taiwan, R.O.C., and Institute of Environmental Engineering and Management, National Taipei University of Technology, 1, Sec. 3, Chung-hsiao East Road, Taipei, 10608, Taiwan, R.O.C.

Received October 14, 2009. Revised manuscript received December 29, 2009. Accepted January 14, 2010.

This study investigated the characteristics of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in the stack flue gases of the metallurgical processes. An examination of the PBDEs existing in the stack flue gases of sinter plants revealed that PBDEs can form during the combustion processes through the similar formation conditions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The PBDD/F and PBDE emission rates of the metallurgical facilities were 0.446-3.19 µg TEQ/h and 4470-27000 µg/h, correspondingly. Both emission rates could reach several orders higher than those of the reported sources, revealing that the metallurgical facilities are not only important PCDD/F but also significant PBDD/F and PBDE emission sources to the environment. BDE-209 is the most abundant PBDE congener in the emissions of metallurgical facilities and is found to be dominant in the atmosphere and soils. However, few studies have considered metallurgical facilities as potential PBDE contributors to the environment. Because PBDEs could form or not be completely destroyed in the feeding materials in the combustion system, PBDE contributions from combustion emission sources to the atmosphere should not be ignored and need further investigation.

Introduction Polybrominated diphenyl ethers (PBDEs), structurally similar to polychlorinated dibenzo-p-dioxins and dibenzofurans * Corresponding author. Tel.: +886-7-7310606, ext. 3045. Fax: +886-7-7332204. E-mail: [email protected]. † Department of Chemical and Materials Engineering, Cheng Shiu University. † Super Micro Mass Research and Technology Center, Cheng Shiu University. § Chung Yuan Christian University. | National Taipei University of Technology. 1240

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(PCDD/Fs) and polychlorinated biphenyls (PCBs), are extensively used as brominated flame retardants (BFRs) in furniture, electronic goods and other consumer items. However, due to health risks, the commercial penta-BDE and octa-BDE mixtures were banned within the European Union in 2004. Meanwhile, the European Court of Justice ruled against the exemption of deca-BDE from the RoHS directive and decided that its use must be phased out by July 1, 2008 (1). The formation of polybrominated dibenzo-pdioxins and dibenzofurans (PBDD/Fs) could occur during either processing PBDE-containing plastics or when incinerating waste that contains BFRs (2, 3). With similar toxicity to PCDD/Fs (4), and the more and more extensive use of BFRs, concerns about PBDD/Fs have increased recently. PBDEs with high octanol-water partition coefficients (KOW) and high octanol-air partition coefficients (KOA) can biomagnify in water-respiring and air-breathing organisms (5). PBDEs are now not only ubiquitous in the environment (6, 7), but also highly accumulated in humans (8) and top predators, such as polar bears (9) and birds of prey (10). Metallurgical processes, including electric arc furnaces (EAFs) and sinter plants are the dominant emission sources, contributing 99% of the aggregate PCDD/F health risk to residents in the densely populated area of southern Taiwan (11). In addition, research conducted to establish PCDD/F inventories (12, 13) also revealed that metallurgical processes are the major PCDD/F emission sources. Nevertheless, our research (14) found that besides PCDD/Fs, the mean atmospheric PBDD/F concentration (seven congeners, 46 fg/Nm3, 12 fg TEQ/Nm3) in the heavy steel complex area was four- and 2-fold higher than those of the rural (11 fg/Nm3, 2.7 fg TEQ/Nm3) and urban areas (24 fg/Nm3, 6.4 fg TEQ/ Nm3), respectively. Similarly, higher atmospheric PBDE concentrations in industrial sites than those in urban and residential areas have also been recently reported (15, 16). Furthermore, PBDEs were identified in the scrap raw materials for an aluminum recycling plant, in amounts of 245 - 67 450 ng/g (17). The above results suggest that it is necessary to characterize the PBDE and PBDD/F emissions from metallurgical processes. However, few studies identified metallurgical processes as the emission sources of PBDEs (18) and PBDD/Fs, nor have PBDE and PBDD/F emissions from their stack flue gases received much attention. This could be attributed to the fact that PBDE emissions to the atmosphere from combustion sources are believed to be much smaller than those from PBDE-containing products (19, 20), and many studies have reported that environmentally ubiquitous PBDEs are mainly the result of using PBDEcontaining products indoors (7, 19, 20). This study characterized the metallurgical processes, including EAFs, EAF fly ash treatment plants and sinter plants, their PBDE, PBDD/F and PCDD/F emissions from the stack flue gases, providing useful information for further research on the emission inventory, their influence on the environment, risk assessment, and so on. The concentrations, emission rates, emission factors and congener profiles of the PBDEs and PBDD/Fs of these metallurgical facilities are compared with each other to clarify the influential factors of their emissions. Furthermore, the similarities or differences in formation and removal among these three structurally similar compounds emitted from the stack flue gases of the metallurgical facilities are discussed.

Materials and Methods Basic Information Concerning the Metallurgical Facilities. The basic and operational information of these metallurgical 10.1021/es903128e

 2010 American Chemical Society

Published on Web 01/26/2010

facilities is described in Table S1 in the Supporting Information. The EAFs (m ) number of sampled facilities, m ) 6) can be further classified as carbon steel (m ) 4) and stainless steel EAFs (m ) 2) according to the final products. Sinter plants (m ) 5) are also classified into two subcategories according to whether their air pollution control devices (APCDs) operate with (m ) 3) or without (m ) 2) selective catalytic reduction (SCR) (21). The investigated EAF fly ash treatment plants (m ) 2) were established to recover the remaining iron from EAF fly ashes. EAF fly ash, flux, and fine coke were pelleted together to make the size of the raw materials uniform prior to feeding into the furnace. Sampling Procedures. All the stack flue gas samplings, as well as chemical analyses in this study, were carried out in 2008 by our accredited laboratory, which specializes in PCDD/F sampling and analysis in Taiwan. The stack flue gas samples were collected isokinetically following U.S. EPA Modified Method 23 (22) using a U.S. EPA Modified Method 5 sampling train (23). The sampled flue gas volumes were normalized to the dry condition of 760 mm Hg and 273 K, and denoted as Nm3. Three stack flue gas samples were collected for each facility, and the collection time for each sample lasted for about 3 h. Although 8 h sampling time for one stack flue gas sample increases the PBDD/F mass for analyses, too much interference from PBDEs will make the PBDF identification more difficult (24). For EAFs, each stack gas sampling time combined three whole batch operating process, and one batch includes stages of feeding, smelting, oxidation, reduction, and steel discharge. Sample Analyses. After the Soxhlet extraction of each stack flue gas sample, the extracted solution was divided equally into flasks A and B to be able to measure the PCDD/Fs, PBDD/ Fs, and PBDEs in one stack flue gas sample. All the A flasks were measured for PCDD/Fs individually. For PBDD/F and PBDE measurement, all the B flasks from the same facility were combined into one, and one tenth of the combined solution was used to measure PBDEs, while the remainder was used to measure PBDD/Fs owing to the detection limit. That is, one facility had data for three PCDD/F, one PBDD/ F, and one PBDE stack flue gases. Compared to the PCDD/Fs, which had 17 congeners reported, only 12 of the possible 17 2,3,7,8-substituted PBDD/F congeners were reported because of the lack of a standard. As for PBDEs, the samples were analyzed for 30 PBDE congeners. Without a mature separating and identifying method, the PBDD/F congeners cannot be distinguished from the fragment ions of PBDE during GC/MS measurement (24). By using active carbon column chromatography in the final procedure, we found that PBDEs were well separated from PBDD/Fs in an elution test with reference standards (25). The active carbon column was sequentially eluted with 25 mL dichloromethane/hexane (40/60, v/v) for PBDEs, followed by 35 mL of toluene for PBDD/Fs. The detailed analytical procedures for PCDD/Fs and PBDD/Fs are given in our previous works (25, 26), whereas the detailed PBDE analyses are described in the Supporting Information. In brief, the concentrated extract was treated with concentrated sulfuric acid, and this was followed by a series of sample cleanup and fractionation procedures, including a multilayered silica column and alumina column. The eluate was concentrated to approximately 1 mL and transferred to a vial. The concentrate was further concentrated to near dryness, using a stream of nitrogen. Immediately prior to analysis, the standard solution for recovery checking was added to the sample. A high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) was used for PCDD/F, PBDD/F and PBDE analyses. For PBDEs, the HRGC (HewlettPackard 6970 Series gas chromatograph, CA) was equipped with a DB-5HT capillary column (L ) 15 m, i.d. ) 0.25 mm,

film thickness ) 0.1 µm) (J&W Scientific, CA), and with a splitless injection (injector at 250 °C, transfer glass line at 280 °C). The HRMS (Micromass Autospec Ultima, Manchester, U.K.) mass spectrometer was equipped with a positive electron impact (EI+) source, and the selected ion monitoring mode was used with a resolving power of 10 000. The detailed instrumental analysis parameters of PBDEs, PBDD/Fs and PCDD/Fs are given in our previous works (25-27). The quality assurance and quality control (QA/QC) are described in the Supporting Information, which included field and laboratory blanks, as well as the recoveries of the surrogate and internal standards.

Results and Discussion PCDD/F, PBDD/F, and PBDE Concentrations. Figure 1 illustrates the PCDD/F, PBDD/F and PBDE concentrations measured in the stack flue gases of the metallurgical facilities, with individual values detailed in Tables S2-S7 in the Supporting Information. Horizontal lines represent the 10th, 50th, and 90th percentiles, and the boxes represent the 25th to 75th percentiles. The geometric mean (GM) PCDD/F concentrations in the stack flue gases of EAFs, fly ash treatment plants, and sinter plants were 0.172, 0.0772, and 0.456 ng I-TEQ/Nm3, respectively. The PCDD/F I-TEQ concentrations emitted were comparable to or lower than other reported results (21, 28) because of the recent adoption of more stringent emission regulations. Only one EAF and one sinter plant exceeded the Taiwan PCDD/F emission limits (EAFs: 0.5 ng I-TEQ/Nm3; the others: 1 ng I-TEQ/Nm3) (see Tables S2 and S5 in the Supporting Information), indicating that most of the investigated facilities were operated in good condition. The international toxic equivalency factors (I-TEFs) of PCDD/Fs were used as tentative TEFs for PBDD/Fs to evaluate their toxicity. WHO suggested that until TEFs for PBDD/Fs are established, the preliminary use of the same TEF values for the chlorinated analogues appears to be justified (3). The GM PBDD/F mass concentrations in the stack flue gases of the EAFs, fly ash treatment plants and sinter plants were 0.148, 0.0655, and 0.399 ng/Nm3, respectively, whereas the corresponding GM TEQ concentrations were 0.00188, 0.00157, and 0.00416 ng TEQ/Nm3, respectively. Their PBDD/F concentrations were comparable to those (0.0653-0.0881 ng/Nm3, 0.00190-0.00314 ng TEQ/Nm3, n ) 7) (27) of the municipal solid waste incinerators (MSWIs) equipped with dry scrubbers, activated carbon injections, and fabric filters. The GM PBDE concentrations (30 congeners) in the stack flue gases of the EAFs, fly ash treatment plants and sinter plants were 15.7, 15.7, 35.2 ng/Nm3, respectively. Their PBDE concentrations were lower than that (109 ng/Nm3) of MSWIs with industrial wastes comprising 60% of the total feeding wastes, but were comparable to that (26.1 ng/Nm3) of MSWIs with lesser industrial wastes (20% of the total feeding wastes) (27). Surprisingly, PBDEs and PBDD/Fs also exist in the stack flue gases of sinter plants whose the feedstock contained coke, lime and iron ore, but not any BFRs-containing wastes, revealing sinter plants could generate PBDEs and PBDD/Fs through the similar PCDD/F formation conditions. Although bromine content in the feedstock of sinter plants had not been measured, one of the bromine sources for PBDE and PBDD/F formation is believed to originate from coal (29). The PBDE and PBDD/F formation had also been observed in the MSWIs (27). We found that when the flue gases flowed from the superheaters to the economizers, the PCDD/F contents in the ashes of the economizers whose operational temperatures (339-396 °C) were within the region of optimal PCDD/F formation were much higher than those in the ashes of the superheater whose temperature (480-537 °C) were not favorable for PCDD/F formation. The PBDD/F and PBDE contents in the ashes of the economizers also reached six VOL. 44, NO. 4, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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FIGURE 1. PCDD/F, PBDD/F, and PBDE concentrations in the stack flue gases of the metallurgical facilities.

FIGURE 2. PCDD/F, PBDD/F, and PBDE emission rates of the metallurgical facilities.

times higher than those in the ashes of the superheater, suggesting that de novo syntheses could also occur among PBDD/Fs and PBDEs (27). PBDE concentrations in indoor and workplace air are listed in Table S8 in the Supporting Information, and are 1-3 orders lower than those in the stack flue gases of the metallurgical facilities. An exception was the dismantling area (650 ng/Nm3) of an electronics recycling facility that lacked air filtration systems (30). Consequently, although commercial products used indoors can be in part responsible for the presence of PBDEs in our environment, the high PBDE concentrations and huge flow rates of stack flue gases demonstrate that the metallurgical processes can be an important source of PBDEs in the atmosphere. This supports

observations in Turkey that the atmospheric PBDE concentrations (BDE-28, -47, -99, -00, -53, -154, and -209) at industrial sites (149 pg/m3) was about 14 times higher than that (11 pg/m3) in urban area (15). Emission Rates of PCDD/Fs, PBDD/Fs, and PBDEs. Figure 2 illustrates the PCDD/F, PBDD/F, and PBDE emission rates of the metallurgical facilities, with the individual values detailed in the Supporting Information, Tables S9-S14. Sinter plants exhibited the highest GM PCDD/F, PBDD/F and PBDE emission rates (349 µg I-TEQ/h, 3.19 µg TEQ/h, and 27 000 µg/h), whereas the fly ash treatment plants had the lowest ones (22.0 µg I-TEQ/h, 0.446 µg TEQ/h, and 4 470 µg/h). The PBDD/F and PBDE emission rates (0.446-3.19 µg TEQ/h; 4470-27000 µg/h) of the metallurgical facilities could reach

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three and one order of magnitude higher than those (0.0102-0.350 µg TEQ/h; 2530-16500 µg/h) of the MSWIs, respectively (27). BDE-209 is the main congener of the commercial decaBDE mixtures (31) and has a larger production volume than other commercial PBDE mixtures. The Japanese BDE-209 inventory included emissions from textile processing (0.18 kg/year), plastics processing (0.28 kg/year), dismantling and crushing (27 kg/year), deca-BDE production (84 kg/year), and indoor house dust (54 - 120 kg/year) (19). Emissions from the plastics processing and the dismantling and crushing of home appliances were obtained by measuring the exhausts of individual processes, whereas the others were estimated by using emission factors based on expert judgment (19). Compared to the calculated BDE-209 emission rates from flue gases of plastics processing (7.99-704 µg/h) and the dismantling and crushing of home appliances (43.3-25500 µg/h), the BDE-209 emission rates (1580-41400 µg/h) from the stack flue gases of the metallurgical facilities in this study (data not shown) were much higher. On the basis of the above results, metallurgical facilities are not only PCDD/F emission sources, but also important ones for PBDD/Fs and PBDEs. Emission Factors of PCDD/Fs, PBDD/Fs, and PBDEs. The carbon steel EAFs and stainless steel EAFs investigated in this study all have bag filter as their APCDs, and exhibit similar types of furnaces and operation processes. The most obvious difference among them is the feeding scrap. The production of stainless steel requires scrap with fewer impurities and less contamination than the production of carbon steel (see the Supporting Information). Comparing the emission factors of carbon steel EAFs and stainless steel EAFs, which were calculated on the basis of product production (see the Supporting Information, Tables S15 and S16), the PCDD/F, PBDD/F and PBDE emission factors of carbon steel EAFs were about three to eighteen times higher than those of stainless steel EAFs. Similar results (28) for PCDD/F emission (carbon steel EAFs, 1.6-2 µg I-TEQ/tonnefeedstock; stainless steel EAFs, 0.52 µg I-TEQ/tonnefeedstock) have been observed and attributed to the influence of feeding materials. Consequently, the higher PBDD/F and PBDE emission factors of carbon steel EAFs than those of stainless steel EAFs may also result from the higher bromine, PBDD/F and PBDE content in the feeding materials of the former. Furthermore, in the process stages of feeding and smelting of EAFs, the thermal desorption of PBDEs and PBDD/Fs as the impurities of the commercial PBDE mixtures could contribute their emission. This may explain why the differences in the PBDD/Fs and diocta BDE emission factors between these two kinds of EAFs (18 and 5 times) were much higher than the corresponding PCDD/F emission factors (3 times). Similar phenomena had been reported in our recent study (27) concerning MSWIs. MSWI1 with operational units similar to those of MSWI2 but fed with a larger percentage of the industrial waste obviously exhibited higher PCDD/F, PBDD/F, and PBDE emission factors. The PCDD/F emission factor ratios of MSWI1 to MSWI2 were between 1.1 and 2.8. For PBDD/Fs and PBDEs, the divergence between MSWI1 and MSWI2 was more apparent, and the ratios of emission factors could reach between 6 and 22. Figure 3 illustrates the PCDD/F, PBDD/F, and PBDE emission factors of the metallurgical facilities with values detailed in the Supporting Information, Tables S15 and S20. In contrast to the emission rates, the fly ash treatment plant exhibited the highest GM PCDD/F, PBDD/F and PBDE emission factors (4.99 µg I-TEQ/tonne-product, 0.101 µg TEQ/ tonne-product, and 1010 µg/tonne-product), while the sinter plants had the lowest ones (1.02 µg I-TEQ/tonne-product, 0.00934 µg TEQ/tonne-product, and 79.0 µg/tonne-product). The characteristics of feeding materials should be the

FIGURE 3. PCDD/F, PBDD/F, and PBDE emission factors of the metallurgical facilities. important factors affecting the levels of PCDD/F, PBDD/F and PBDE emission factors. The EAF fly ashes contained PBDEs and PBDD/Fs that were not destroyed or formed during the combustion process, and the elevated emission factors of the EAF fly ash treatment plants could be attributed to the higher PCDD/F, PBDD/F, and PBDE content in the EAF fly ashes as compared to those in the feeding materials of EAFs or sinter plants (iron ore, coke, flux). Many studies (21, 32) had indicated that the destruction mechanism of PCDD/Fs with SCR is dechlorination. Although the lighter chlorinated PCDD/F congeners could be formed via dechlorination of highly chlorinated congeners, and the I-TEF values of lighter chlorinated PCDD/Fs are much higher than those of highly chlorinated ones, the destruction VOL. 44, NO. 4, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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FIGURE 4. PBDD/F congener profiles in the stack flue gases of metallurgical facilities. efficiencies of the total PCDD/Fs still ranged from 61.8 to 99.9% (21). The sinter plants investigated in this study belong to the same one integrated steel plant, and therefore use a similar sinter process, operational conditions, and raw materials, except that some sinter plants used SCR as one of APCDs, whereas others did not. Therefore, the estimated destruction efficiency of PCDD/Fs, PBDD/Fs, and PBDEs by SCR is calculated as follows destruction efficiency (%))(A - B)/A × 100% where A is the emission factor of sinter plants without SCR, and B is the emission factor of sinter plants with SCR. The destruction efficiencies of total PCDD/Fs, PBDD/Fs and PBDEs by SCR (see the Supporting Information, Table S21) based on GM are 56.7-73.9% on mass basis, and 60.6-76.1% on toxicity basis. The destruction efficiencies of PCDD/Fs (56.8-60.6%) are comparable to those (69.0-75.5%) found in our previous study (21). The similar chemical structure and the close SCR destruction efficiencies among these three compounds both revealed that the destruction mechanisms of PBDD/Fs and PBDEs with SCR should also be through debromination of the congeners. However, due 1244

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to the weaker binding energy of C-Br compared to C-Cl (2), the destruction efficiencies of PBDD/Fs (73.9-76.1%) are higher than those (56.7-59.7%) of their chlorinated analogues. The destruction efficiencies of the PBDEs increase along with bromination (Σ9-10 BDE, 61.6%; Σ2-8 BDE, 35.1%), because the lighter brominated PBDE congeners may be formed from debromination of highly brominated ones. Congener Profiles of PCDD/Fs, PBDD/Fs, and PBDEs. The PBDD/F and PBDE congener profiles in the stack flue gases of these metallurgical facilities are illustrated in Figures 4 and 5, whereas their PCDD/F congener profiles are illustrated in the Supporting Information, Figure S1. The PCDD/F congener profiles obtained from these metallurgical facilities are comparable to the results of our previous works (12, 21, 28) and other studies (33), revealing that 2,3,7,8TeCDF, 1,2,3,7,8-PeCDF, and 2,3,4,7,8-PeCDF are the more prominent congeners in the stack flue gases of the metallurgical facilities. The PBDD/F congener profiles were very different to the corresponding PCDD/F congener profiles. 1,2,3,4,6,7,8-HpBDF and OBDF, the highly brominated PBDF congeners, were the most abundant congeners, whereas the others were all quite minor. Similarly, the most dominant

FIGURE 5. PBDE congener profiles in the stack flue gases of metallurgical facilities. PBDE congeners in the stack flue gases of the metallurgical further study on polychlorinated diphenyl ethers as comfacilities were also the highly brominated-substituted conbustion products and PCDD/F precursors, as well as their geners, namely BDE-209, -208, -207, -206, and -183. Among influence on the atmosphere through combustion sources. the low to medium brominated congeners, BDE-47 and BDEBDE-209 can undergo long-range transport and meta99 were relatively dominant. The PBDE congener profiles of bolically or photocatalytically degrade to lower brominated the EAFs leaned more to the lighter brominated congeners congeners with enhanced toxicity and greater ability to (e.g., BDE-47 18.8% and BDE-99 12.2%) than those of the fly bioaccumulate relative to the parent (34). BDE-209 has been ash treatment plants and sinter plants; however, BDE-209 found to be relatively abundant in most or some ambient air was still the most abundant. samples in the east-central United States (6), China (35), and No raw materials containing PBDEs and PBDD/Fs were the Arctic (36). Furthermore, BDE-209 is also the major BDE fed into the sinter plants. The bromination pattern of PBDFs congener in reference soil samples from a Swedish study resembling the bromination pattern of PBDEs in the stack (37) and in terrestrial wildlife in northern China (10). However, flue gases of the sinter plants is due to the combustion few studies consider metallurgical facilities or other comformation. In other words, PBDE and PBDD/F formations bustion emissions as potential PBDE sources to the environduring the combustion processes prefer highly brominated ment, because there is little understanding of their PBDE congeners. Consequently, the abundant BDE-47 and -99 of emission characteristics. However, because PBDEs could the EAFs may be attributed to the thermal desorption of the form or not be completely destroyed in the feeding materials commercial penta-BDE mixtures which were the impurities in the combustion system, PBDE contributions from comin the feeding scrap. The PBDF thermal desorption from the bustion emission sources to the atmosphere should not be feeding scraps may also contribute 1,2,3,4,6,7,8-HpBDF and ignored, and thus need further investigation. OBDF in the stack flue gases of the EAFs. As for the EAF fly Acknowledgments ash treatment plants, the prominent BDE-209 could be We thank the National Science Council of Taiwan for formed through combustion processes, which is similar to supporting this research work under Grant NSC-96-2221that of sinter plants, as well as from the undestroyed BDEE-230-004. 209 in the EAF fly ashes. The formation of PBDFs from PBDEs requires only an Supporting Information Available intramolecular elimination of Br2 or HBr from a mechanistic Detailed basic information concerning the metallurgical point of view (2). The much higher fractions of PBDFs found facilities; detailed PCDD/F, PBDD/F, and PBDE concentrain the stack flue gases of the sinter plants may indicate that tions, emission rates, and emission factors of the metallurgical PBDEs were available as precursors, and that phenolic facilities (PDF). This material is available free of charge via compounds associated with PBDDs played only a very minor the Internet at http://pubs.acs.org. role. The mass concentrations of the PCDD/Fs in the Literature Cited metallurgical facilities were about one order higher than those of PBDD/Fs (see the Supporting Information, Table S7). The (1) Judgement of the European Court of Justice on Joint Cases C-14/06 and C-295/06. http://eur-lex.europa.eu/LexUriServ/ relevance of PBDEs and PBDD/Fs suggested the need for VOL. 44, NO. 4, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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