Environ. Sci. Technol. 1989, 23, 462-470
Polychlorinated Dibenzofurans and Other Thermal Combustion Products from Dielectric Fluids Containing Polychlorinated Biphenyls Mitchell D. Erlckson,* Stephen E. Swanson,+ Jalrus D. Flora, Jr., and Gary D. Hlnshaw Midwest Research Institute, Kansas City, Missouri 641 10
The combustion of transformer dielectric fluids containing polychlorinated biphenyls (PCBs) was investigated for formation of toxic products such as polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-pdioxins (PCDDs). Using a bench-scale flowing reactor system, conditions for PCDF formation from PCBs were optimized and the potential for formation of PCDFs and PCDDs from combustion of selected PCB-containing dielectric fluids was studied. The results indicated that optimum conditions for PCDF formation from PCBs are near 675 OC with 8% excess oxygen. Variation of retention time from 0.3 to 1.5 s did not affect the PCDF formation as significantly. Under these conditions, percentage levels of PCDFs are formed from mineral oil or silicone oil contaminated with PCBs at 5 ppm or greater. PCDF formation from PCBs is independent of matrix (mineral versus silicone oil) and is directly dependent (i.e., linear) on PCB concentration. About 1%of the PCBs fed into the system were converted to PCDFs. PCDDs were found but only a t much lower concentrations and may be products of the combustion of the chlorinated benzenes in some reaction materials. Chlorophenylacetylenes,chlorophenols, chloronaphthalenes, and chlorodihydronaphthalenes were also identified as reaction products.
temperatures to 550 or 850 O C in -55 s, held at these temperatures for 5 s, and then cooled at an unspecified rate. In these experiments, more than half of each of the chlorinated biphenyl congeners (2,6,2',6'-tetrachloro, 2,4,5,2',4',5'-hexachloro, and 2,4,6,2',4',6'-hexachloro) had decomposed at 550 "C. Above 650 "C, decomposition was essentially complete. The hexachlorobiphenyls formed tetrachloro- and pentachlorodibenzofuransat 550-650 OC at yields of 0.1-1.6%. At temperatures above 700 "C, apparently complete destruction of the PCDFs was observed. In a much more thorough study (23), 18 individual PCB ccngeners were pyrolyzed in the presence of air at 600 "C in sealed ampules. From this study, four thermochemical reaction mechanisms were proposed for the formation of PCDFs from PCBs. The four reaction mechanisms are illustrated below. mechanism 1 loss of ortho Clp. example: CI c
12%) is oxygen rich. Both extremes were limited by system constraints on balancing the air and nitrogen flow rates. A range of 0.3-1.5 s in residence time was selected, also based on system flow rate constraints. The assumption was made that, in a real fire situation, the PCBs would not likely be in the temperature range of 450-750 "C for much longer than 1 s. The nominal and actual conditions are summarized in Table IV. The experiments were conducted sequentially, using intermediate results to guide selection of conditions in subsequent tasks. Results and Discussion Optimum Conditions. The conversion efficiencies of the specific PCB congeners to the anticipated percentage yield of PCDF are shown in Table V. The runs are ar-
ranged and grouped in order of the low- to high-level conditions that are given in Table IV. The primary PCDFs formed from the three individual PCB congeners were the 1,2,4-tri-CDFand 173,7,9-tetra-CDF.In contrast, relatively low levels of the penta-CDF and hexa-CDF were found. The maximum conversion efficiency observed for producing 1,2,4-tri-CDF was 2.2%, for 1,3,7,9-tetra-CDF, 0.43%, for 1,3,4,7,9-penta-CDF7 0.03%, and for 2,3,4,6,7,8-hexa-CDF,0.03%. Apparently, the reactions to produce the higher PCDFs are not as efficient as those yielding the tri- and tetra-CDF. The maximum total conversion efficiency of PCBs to PCDFs during these experiments was 0.78% for run no. 7-19-26-M+M+M. In most samples only 1,2,4-tri-CDF and 173,7,9-tetraCDF were observed, as predicted by the previously documented reaction mechanisms. In those samples that had the highest concentration of these isomers (e.g., 7-19-26M+M+M), up to 10 additional isomers for each homologue was observed a t concentrations less than one-tenth the predicted isomer. These isomers were not included in the results listed in Table V, but their presence suggests that reaction pathways, in addition to those described in the mechanisms above, or interconversion of the PCDF products (28,32),occur during the combustion process. These reactions may involve dechlorination of the 1,3,4,7,9-penta- or the 2,3,4,6,7,8-hexa-CDFs,or they may involve rearrangements of the 1,2,4-tri- or the 1,3,7,9-tetra-CDFs. To identify optimum conversion conditions, total measured efficiencies of conversion from PCBs to PCDFs relative to temperature, oxygen, and residence time, Table V (excludingblank runs), were analyzed statistically. The total conversion efficiency was used as the dependent variable for analysis. Conversion efficiencies of the PCB to the 1,3,7,9-tetra-CDFwere also evaluated individually in view of the reported higher toxicity and general environmental concern of some tetra-CDF congeners. The results from the analysis of variance for the reduced model that includes main effects and the significant interactions are shown in Table VI. As can be seen from the low values in the P column, the main effects of temperature and oxygen are statistically significant (P < 0.05). These results show that the mean conversion efficiency differed among the levels of the temperature and oxygen but not by residence time. The model had an R-squared of 94% , indicating that the effects in the model explained 94% of the variance of the conversion efficiencies. The top part of Table VI includes the estimate of the overall mean, the partition of the sums of squares into components due to the model and about the model, and an overall F test for the model. The second part of the table contains Environ. Sci. Technol., Vol. 23, No. 4, 1989
465
Table V. Conversion Efficiencies (PCBs to PCDFs)O for Optimization Experiments run no.* 6-14-06-LLL 7-10-18-LLM 7-10-19-LLM(B)f 7-05-17-LML 6-14-07-LMM 6-22-14-LMM 7-03-16-MLL 6-13-05-MLM 6-15-08-MML 7-03-15-MMM 7-12-20-MMM 7-20-27-MMM 7-26-32-MMM+ 6-20-12-MMHg 6-20-13-MMH 7-26-31-MMH 7-31-37-MMH 7-31-38-MMH(B)f 7-19-25-MM+M 6-19-11-MHM 7-16-23-MHH 7-30-35-MHH 7-30-36-MHH 7-17-24-M+MM 7-25-30-M+MM+ 7-27-33-M+MH 7-27-34-M+MH(B)f 7-19-26-M+M+M ll-14-90-M+M+M ll-14-19-M+M+M ll-16-92-M+M+M 6-19-10-HMM 7-13-21-HMH 7-16-22-HHM 6-18-09-HHH
tri-CDF, %
tetra-CDF: %
penta-CDF: %
hexa-CDF,C %
P C D F S , ~%
NDe ND ND ND ND ND ND ND 0.17 ND ND 0.44 0.15 0.22 0.32 0.15 0.13 ND 0.54 0.22 0.28 0.44 0.52 0.28 0.51 0.50 ND
0.036 ND ND 0.11 0.020 0.032 0.042 0.019 0.03 0.12 0.02 0.090 0.055 0.059 0.12 0.033 0.061 ND 0.094 0.077 0.029 0.14 0.15 0.040 0.12 0.15 ND
0.0006 ND ND ND 0.0042 ND ND 0.0017 0.0038 ND ND 0.0007 0.015 0.0056 0.012 0.0067 0.021 ND 0.0022 0.0023 0.0054 0.026 0.026 0.0045 0.024 0.030 ND
ND ND ND ND ND ND ND ND 0.0005 ND ND ND 0.052 0.0009 ND 0.0017 0.0089 ND ND ND ND 0.0309 0.0284 ND 0.0230 0.0200 ND
0.020 ND ND 0.059 0.013 0.016 0.022 0.012 0.060 0.061 0.011 0.16 0.074 0.089 0.15 0.057 0.075 ND 0.19 0.096 0.088 0.20 0.23 0.094 0.20 0.22 ND
2.2 0.61 1.14 0.88 0.052 0.021 0.0084 0.047
0.43 0.20 0.37 0.29 0.033 0.0067 0.0014 0.0028
0.012 0.035 0.046 0.12 0.0028 0.0006 ND ND
ND 0.021 ND 0.077 ND ND ND ND
0.78 0.37 0.85 0.39 0.031 0.0091 0.0028 0.013
*
Conversion efficiency (%), (ng of PCDF formed/ng of PCB fed) X 100. Month-day-sequential run number-conditions (temperature, oxygen, residence time). See Table IV for explanation of conditions. For example, the first entry is a sample created on June 14, the sixth in the run sequence, the nominal conditions were 450 OC (L), 1% oxygen (L), and 0.3-9 residence time (L). ‘The nanograms of PCDF homologue observed are divided by the nanograms of corresponding PCB fed according to the reaction mechanisms presented in the text. dThe total nanograms of the four PCDF homologues observed are divided by the total of the three PCB congeners fed in the feed oil. This is not an average of the four individual conversion efficiencies. ‘ND, not detected; 0.1). Therefore, the conclusion is that PCDF formation efficiency under these
optimum conditions (675 "C and 8% excess oxygen) is reproducible. Effects of PCB Concentration and Matrix on PCDF Production. A series of experiments was conducted using Aroclor 1254 in either mineral oil or silicone oil as the feed to study the effects of PCB concentration and the matrix on the conversion efficiency. The PCB mixture was combusted at the optimum conditions established in the optimization experiments. Tests a t each matrix/concentration value were conducted in duplicate. Despite all efforts to control the combustion system, conditions varied among the tests. As indicated in Table 11, the combustion efficiency ranged from 12 to 99%, and there was no apparent correlation with matrix or PCB concentration. Likewise, the PCB destruction efficiency, which varied between 70 and >99%, showed no apparent correlation with matrix or PCB concentration. The silicone oil presented two operational difficulties. Some of the fine particulate silica (SiOJ formed in the combustion system passed through the XAD-2 sampling train, plugged the filters in the continuous monitors, and generally contaminated the system. In addition, the 400 "C temperature in the vaporization furnace was insufficient to volatilize the silicone oil, which resulted in the accumulation of an oily residue. Slow decomposition of this residue probably accounted for the high CO levels observed during the blank runs (see Table 11). The conversion efficiencies to PCDF and the homologue distributions are shown in Table VIII. These conversion efficiencies were calculated by dividing the total amount of each PCDF homologue by the total amount of PCB fed during the test. Penta-CDDs were found at low levels (2 X and 4 X lo4 conversion efficiency) in the effluent from the two tests of 500 ppm Aroclor 1254 in silicone oil (8-22-51-S500 and 8-22-52-S500). This low observed conversion, and the fact that only penta-CDD was detected in only this pair of tests, indicate that this may be an artifact. In the two askarel runs (8-30-61-ASKL and 830-62-ASKL), hepta-CDD (1 and 0.7 X 10" conversion, respectively) and octa-CDD (0.1 and 0.2 X 10" conversion, respectively) were observed. These may be products from the tri- and tetrachlorobenzenes in the feed, since PCDDs are not known to form from PCBs and since PCDD formation was observed in our experiments only where chlorobenzenes were present in the feed. Although a single value is reported for each homologue, characteristic clusters of isomers generally were observed for both the PCDFs and the PCDDs. The responses for all identified peaks were summed to give the reported values. Figure 2 summarizes the data presented in Table VI11 with respect to concentration and matrix. Clearly, for both the mineral oil and silicone oil, the PCDF production increases with PCB feed concentration. Except for runs 11-28-97-M50 and 11-28-98-M50, which are discussed below, the data for total PCDF and the four individual homologues that were sufficient (tri- through hexa-CDF) were statistically analyzed by multiple regression. The statistical analysis indicates that PCDF formation is approximately linear with the amount of PCBs in the feed, with a zero intercept. Specifically, all five of the variables analyzed were consistent with a zero intercept. That is, the intercept did not differ significantly from zero ( P > 0.05) in any case. The quadratic term was also not significant a t the 5% level, so the linear component in the means is sufficient. The mean PCDF values from the PCBs in silicone oil were about twice those from the PCBs in mineral oil. However, the differences were not statistically significant Environ. Sci. Technol., Vol. 23, No. 4, 1989 467
Table VIII. Conversion Efficiencies (PCBs to PCDFs) run n0.O 8-15-43-M5 8-15-44-M5 8-17-47-S5 8-20-48-S5 8-16-45-M50 8-16-46-M50 11-28-97-M50 11-28-98-M50 8-21-49450 8-21-50-S50 8-13-40-M500 8-14-41-M500 8-22-51-S500 8-22-52-S500 8-30-61-ASKL 8-30-62-ASKL
rnonoCDF, % -b
-
-
-
-
-
0.49 0.013 0.0002 0.006
diCDF, 70 0 0.35 0.0015 0.0021
triCDF,%
tetraCDF, %
pentaCDF, 70
3.4 1.0 0.71 0.74 0.55 0.40 0.78 1.6 0.64 0.38 0.56 1.3 0.13 0.067
1.3 0.55 0 0.21 0.31 0.22 0.69 0.55 0.20 1.9 0.19 0.18 0.21 0.54 0.43 0.34
NQe 0 2.5 3.6 0.11 0.058 0.082 0.058 0.17 0.25 0.012 0.048 0.096 0.044 1.9 1.4
hexaCDF, %
heptaCDF,% -
Od
0 0 0 0.024 0.0060 0 0.091 0 0 0.0020 0.0037 0.013 0.0031 0.28 0.20
octaCDF,% -
-
0 0.047 0 0 0 0 0 0.0087 0.0056
total PCDF,% 4.7 1.6 3.2 4.5 1.0 0.67 0.77 0.70
0 0 0 0 0 0 0
1.1
3.8 1.3 0.61 0.88 2.3 2.8 2.0
0.0010 0.0004
“ M , mineral oil; S, silicon oil; S, 5, 50, and 500 indicate Aroclor 1254 concentration (in K g / g ) ; ASKL is Aroclor 1260 (70%)/trichlorobenzene (30%). b - , not analyzed. cNQ,not quantitated. not detected.
r
1,000,000
PC3 Feed
1t
100,000
10.000
/
/
/
\
\.4
‘*
t I
I
50
500
/
c
for the total or for any homologue except penta-CDF. This is interpreted to mean that, under these conditions, production of PCDFs may be higher for silicone oil. The differences, although substantial, were not statistically significant, probably because of large variability of the data and relatively small sample size. No significant interaction between concentration and oil type was found. Two additional tests of the 50 ppm Aroclor 1254 in mineral oil (11-28-97-M50 and 11-28-98-M50)were conducted several months after the other test reported in Table VIII. These tests were made to assess the reproducibility of the system and to verify that the earlier PCB-to-PCDF conversion efficiencies were still observable. The PCDF results for these two runs are similar to the earlier runs (8-16-45-M50 and 8-16-46-M50);in fact, the total PCDF for each of the latter runs is between the two previous total values. Statistical analysis continued to indicate that the PCDF formation is approximately linear with the amount of PCBS in the feed. In summary, the amount of PCDF formed is directly dependent on the amount of PCBs fed into the combustion zone. Regardless of PCB concentration, about 1% of the PCBs fed into the system were converted to PCDFs. The mean PCDF values from the PCBs in silicone oil were about twice those from the PCBs in mineral oil. However, 468
Environ. Sci. Technol., Vol. 23, No. 4, 1989
\
\
\
0 -
PCB Concentration (pprn)
Flgure 2. Average total PCDF formation versus PCB concentration for PCBs in silicone or mineral oil. A 1 % theoretical conversion is shown for reference.
\
0%
Detected Mono
1
I
Di
Tri
I Tetro
I Peoto
I Hexa
I Hepta
I Octo
PCDF
Figure 3. Comparison of PCDFs formed with PCB feed composition (500 ppm Aroclor 1254 in silicone oil). Open diamonds are single points; solid diamonds are averages of duplicate measurements. Solid circles are from the literature ( 19). PCB Feed 130 03’0,300 \
1%.
1,303,003
2
1,000
Detected
Mono
I
I
I
I
I
1
1
Di
Til
letro
Penfa
Hexo
Hepta
Ocla
I Nono
PCDF
Figure 4. Comparison of PCDFs formed with PCB feed composition (askarel; 70% Aroclor 1260). Diamonds are averages of duplicate measurements. Solid circles are from the literature (19).
a statistical difference could not be demonstrated from the data. Comparison of Feed and Product Compositions. As can be seen from the results (Table VI11 and Figures 3 and
Table IX. Other Chlorinated Organics Identified in Thermal Combustion Effluent Samples
formula
possible structure (parent name)
no. of isomers 4 1 3 4
c hlorophenylacetylene 3 3 3 1
1
C10H6C12
C10H6C13 C10H4C14 C10H3C16
chloronapht halene
C10H2C16 C10HC17
10 11
C10H7C13
C10H6C14 C10H6C16
5 3 3 4 1
10 chlorod ihydronaphthalene
Tentative identification; see text. 4), the PCDFs formed from the feed oils containing PCBs have a homologue distribution that maximizes at tri-CDF for the Aroclor 1254 feeds and at penta-CDF for the askarel (Aroclor 1260) feeds. Figures 3 and 4 present the data shown in Table VI11 with an overlay of the Aroclor feed (19). The PCDF curve is -2 orders of magnitude lower, reflecting 1% conversion efficiency, as noted in Table VIII. In addition, the PCDF profile peaks at a lower chlorination number than for the corresponding PCB feed, indicating a loss of chlorine in the thermochemical reactions. The PCDFs formed from the M500 and S500 oils contained, on the average, 2.7 and 3.0 chlorines/molecule, respectively. Aroclor 1254 has an average of 5 chlorines (19),indicating that the average reaction has a loss of about 2 chlorines. This would be consistent with mechanism 1 in the reaction schemes described earlier. Aroclor 1260, with an average of 6.25 chlorines per molecule (19),was also fed. The PCDF composition of the products had an average of 4.8 chlorines/molecule. Thus, for these runs, the average reaction involved a loss of 1.5 chlorines, indicating that other mechanisms, besides those of mechanism 1,may be involved. Other Combustion Products. The results of full-scan analysis indicate that other compounds besides PCDFs and PCDDs were formed during the thermal combustions tests. Table IX lists the compounds that were identified in the effluent samples from the askarel runs (Aroclor 1260 and trichlorobenzene). PCBs and chlorobenzenes were detected in the samples but were also present in the feed. Other degrees of chlorination of the compounds listed in Table IX, as well as chlorinated cyclopentadienes, biphenylenes, hydroxybiphenyls, xanthenes, anthracenes, and pryrenes, were specifically sought in the data interpretation but were not found in the full-scan analysis. None of these other combustion products, including chlorobenzenes, was detectable in the lower concentration (Mi500 and S500) runs because of matrix interferences. The first two compounds in Table IX (C4H4-,C1,) could have either of the structures listed, although these compounds do not appear to be sufficiently stable to survive the sampling and analysis process (e.g., refluxing hexane in a Soxhlet extractor). However, the spectra for these
-
species were distinct and there were no higher mass ions to indicate that these structures were fragments of larger molecules. In addition, the retention times of these compounds (eluting prior to the chlorinated benzenes) are indicative of small, volatile molecules. These identifications should be confirmed by a t least one independent technique. Acknowledgments
We thank Daniel T. Heggem of the Office of Toxic Substances, U.S. Environmental Protection Agency, for his guidance and advice. John Stanley of Midwest Research Institute provided helpful technical advice. Fred C. Hopkins of Midwest Research Institute assisted with operation of the combustion system. Kelly R. Thornburg of Midwest Research Institute assisted with mass spectral analysis. Registry No. TriCDF, 43048-00-6; tetraCDF, 30402-14-3; pentaCDF, 30402-15-4; hexaCDF, 55684-94-1; monoCDF, 42934-53-2; heptaCDF, 38998-75-3; octaCDF, 39001-02-0; diCDF, 43047-99-0; heptaCDD, 37871-00-4; pentaCDD, 36088-22-9; octaCDD, 3268-87-9; Aroclor 1254, 11097-69-1; Aroclor 1260, 11096-82-5; trichlorobenzene, 12002-48-1; tetrachlorobenzene, 12408-10-5; 2,3,5,6-tetrachlorobiphenyl, 33284-54-7; 3,3',4,4',5,5'-hexachlorobiphenyl, 32774-16-6; 2,2/,4,4',6,6'-hexachlorobiphenyl, 33979-03-2.
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Electric Power Research Institute: Palo Alto, CA, 1984; CS/EL-4104, pp 3-1-3-8. (26) Cooke, M.; De Roos, F. L.; Rising, B.;Martin, W. H.; Rappe, C.; Slayback,J. In Workshop Proceedings: PCB By-Product Formation; Komai, R. Y., Addis, G., Eds.; Electric Power Research Institute: Palo Alto, CA, 1984; CS/EL-4104, pp 3-9-3-12. (27) Rubey, W. A.; Dellinger, B.; Hall, D. L.; Mazer, S. L. Chemosphere 1985, 14, 1483-1494. (28) Swanson, S. E.; Erickson, M.; Moody, L.; Heggem, D. In Chlorinated Dioxins and Dibenzofurans in Perspective; Rappe, C., Choudhary,G., Keith, L. H., Eds.; Lewis: Ann Arbor, MI, 1986; pp 109-119. (29) Swanson, S. E.; Erickson, M. D.; Moody, L. Products of Thermal Degradation of Dielectric Fluids; Environmental Protection Agency, Office of Toxic Substances: Washington, DC, 1985; EPA 560/5-85-022,p 30. (30) Hinshaw, G.; Jungclaus, G. Laboratory-Scale Hazardous Waste Incineration as a Research Tool. National Conference Hazardous Waste and Environmental Engineering; Cincinnati, OH; 1985; pp 14-16. (31) U S . EPA Determination of 2,3,7,8-TCDDin Soil and Sediment. Environmental Protection Agency, Region VI1 Laboratory: Kansas City, KS, 1983. (32) Ballschmiter, K.; Zoller, W.; Buchert, H.; Class, Th. Fresenius 2.Anal. Chem. 1985, 322, 587-594. Received for review April 12,1988. Revised manuscript recieved November 4,1988. Accepted December 19,1988. This research was performed pursuant to Contract No. 68-02-3938 with the U.S. Environmental Protection Agency. Portions of this work were presented at the 189th National Meeting of the American Chemical Society, April 28-May 3, 1985, in Miami, FL.
Collection and Quantitation of Methoxylated Phenol Tracers for Atmospheric Pollution from Residential Wood Stoves Steven B. Hawthorne," Mark S. Krieger, David J. Miller, and Mary B. Mathiason University of North Dakota, Energy and Mineral Research Center, Grand Forks, North Dakota 58202
Samples of particulate- and vapor-phase organics from the smoke plumes of 28 different wood stove and fireplace installations were collected onto quartz fiber filters backed by polyurethane foam (PUF) sorbent plugs. Twenty-seven different organic compounds, primarily syringol (2,6-dimethoxyphenol) and guaiacol (Zmethoxyphenol) derivatives, were quantitated in each sample by GC/MS analysis of the acetone extracts. The concentrations (per weight of particulate carbon) of guaiacol derivatives were consistent whether hardwoods or softwoods were being burned. Total average concentrations of the guaiacol derivatives in hardwood smoke (106 pglmg) and in softwood smoke (111pg/mg) were nearly identical. In contrast, the concentrations of syringol derivatives were consistent in hardwood smoke, but were 2 orders of magnitude lower in softwood smoke. This study demonstrates that guaiacol derivatives should be useful tracers of atmospheric wood smoke pollution regardless of the type of wood burned, while the measurement of syringol derivatives can be used to differentiate the type of wood burned.
Introduction Emissions from residential wood-burning appliances account for as much as 80% of the air fine-particulate loading in several communities and may contribute more mutagenic polycyclic organic compounds to the atmosphere than any other single source (1-5). Wood smoke 470
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particulates are predominantly carbonaceous and are almost entirely in the inhalable size range (3,6-8). Studies of the relative impact of wood smoke, vehicle exhaust, and other sources of atmospheric organic pollutants are presently limited by a lack of tracer species unique to wood smoke particulates. The use of methyl chloride and potassium (and the K/Fe ratio) has been limited by their variable concentrations in smoke, and by high and variable background levels (8-13). Organic compounds including retene (l-methyl-7-isopropylphenanthrene)and levoglucosan (the anhydride of P-glucose) as well as measurements of 14C have also been suggested as tracers for wood smoke pollution, but their use has been limited (14-1 6).
An earlier report has described the identification of approximately 30 guaiacol (2-methoxyphenol) and syringol (2,6-dimethoxyphenol) derivatives in unfractionated extracts from wood smoke particulates (17). As pyrolysis products of wood lignin, these species should be unique to wood smoke in urban atmospheres, and since they are present in high concentrations, their use as tracers for atmospheric wood smoke pollution was suggested (17). The present report describes the development of techniques to collect, extract, and quantitate the particulateand vapor-phase organics from smoke plumes of individual wood-burning appliances. Hardwood and softwood smoke was collected from 28 wood stoves and fireplaces and 27
0013-936X/89/0923-0470$01.50/0
0 1989 American Chemical Society
