Environ. Sci. Technol. 1986, 20, 291-295
Influence of Carbonaceous Particles on the Interaction of Coal Combustion Stack Ash with Organic Matter Wayne H. Griest and Bruce A. Tomkins Analytical Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
Stack ash samples were fractionated by aerodynamic size, and the largest particle size fraction was separated into constituent particle type subfractions. Comparison of the mineral, magnetic, and carbonaceous particles showed that coked coal is responsible for the sorptivity of the large particle size fraction for carbon-14 labeled benzo[a]pyrene ([14C]BaP)and for low solvent extraction recoveries. Elevated levels of organic matter and surface area also are contributed by the carbonaceous particles. In contrast, solvent extraction recoveries of polar degradation products of [14C]BaPare attributable more to the mineral and magnetic particles and to exposure of the ash to light and oxygen. Analysis of bulk ash samples may not fully reflect the true organic composition of stack ash. H
Introduction The particulate component of stack emissions from coal combustion is known ( I , 2) to consist of several types of particles, each with its own structure and chemistry. Particle-associated properties and effects of the stack emissions thus are a complex composite of those of the constituent particle types. Recent studies suggest that carbonaceous particlescomposed primarily of elemental carbon and associated organic matter-play an important role in the atmospheric transformation of pollutants (3),degradation of atmospheric visibility (4),and the atmospheric greenhouse effect (5). Carbonaceous particles have been identified in electrostatic precipitator hopper ash and stack ash from pulverized coal combustion (1,2,6-8) and in the flue gas stream from fluidized bed combustion (9). Previous work has demonstrated that the sorptivity (6, 7) and organic compound content (7,9,10) of carbonaceous particles is greater than that of the bulk ash or of the mineral particles constituting the bulk of ashes from coal combustion. This paper reports our finding that carbonaceous particles strongly influence the interaction between stack ash from coal combustion and organic matter. The results suggest that carbonaceous particles may act as carriers for the release and environmental transport of semivolatile organic compounds. They also appear to influence the chemistry of the organic species present in stack ash. Experimental Section Materials. Stack ash samples from two coal-fired electric power generation plants, each of ca. 500-mW generating capacity, were supplied by Ralph Mitchell of the Battelle Columbus Laboratories, Columbus, OH. The ash samples were collected (11)by aspiration of the postelectrostatic precipitator aerosol at 75 cfm through an insulated bag, made of Teflon, maintained above the dew point of sulfuric acid by the heat of the aerosol. Samples no. 501 and 504 were obtained from plant A during normal combustion conditions. Sample no. 483 was collected at plant B during a low-NO, emission mode of combustion achieved by staggering lean- and rich-fueled burners. Both plants were fueled with coal from Appalachian mines. Uncoated Corning controlled-porosity glass beads (Catalog No. CPG-40,37-74-p.m particle size, 40-Apore, pore volume > 0.1 cm3/g, nominal surface area NO m2/g) were 0013-936X/86/0920-0291$01.50/0
obtained from Pierce Chemical Company (Rockford, IL). The Thermax (amorphous, polyhedral carbon black derived from petroleum, Vanderbilt, Co., Inc., Norwalk, CT) and the AXF (petroleum-derived graphite, finer than 325 mesh, POCO Graphite, Inc., Decator, TX) were donated by W. P. Eatherly of the Oak Ridge National Laboratory Metals and Ceramics Division. Sorbed organic matter was removed from the carbon samples by heating at 650 “C in a stream of helium for 20 h. The 7,10-carbon-14 labeled benzo[a]pyrene ([I4C]BaP), 18.3 mCi/mmol specific acivity, was purchased from the Amersham Corporation (Arlington Heights, IL) and was diluted to an activity of 6 X lo6 dpm/mL in benzene. All solvents were Burdick and Jackson (Muskegon, MI) “distilled-in-glass”grade. Ash Fractionation. The stack ash samples were first fractionated by aerodynamic size, and then the largest particle size fraction of each ash was subfractionated into its constituent particle types according to magnetic properties and geometric size. Ash samples were dried overnight at 105-110 OC and cooled in a desiccator over Drierite. The 1150 pm geometric diameter particles were removed by screening with a 100-mesh brass sieve (U. S. Standard Testing Sieve, ASTM E-11 Specification, Dual Mfg. Co., Chicago, IL). The 1150 pm geometric diameter fraction was separated into six fractions with the indicated range of mass median aerodynamic diameters using a Bahco Microparticle Classifier (Harry Dietert Co., Detroit, MI) operated in an atmosphere of low relative humidity (130%) to minimize ash agglomeration. The 21-150-pm fraction of ash no. 483 was subfractionated by magnetic attracting and screening. The magnetic particle subfraction was separated from the bulk of the fraction by slowly pouring the ash 3 times through a 20-cm length of l-cm-0.d. glass tubing held at an angle of ca. 30° from the horizontal, with three U-shaped magnets positioned around the circumference at the midpoint of the tube. The composited magnetic particle subfraction was repurified by the same procedure. The fraction with magnetic particles removed was then screened into 1 4 5 pm (mineral particle subfraction), 45-75 pm (carbonaceous particle subfraction l), and 75-150 pm (carbonaceous particle subfraction 2) geometric particle diameter subfractions using sieves with mesh numbers 100, 200, and 325, respectively. The 21-150-pm fraction of ash no. 504 was subfractionated by screening into 21-75 pm (mineral particle subfraction) and 75-150 pm (carbonaceous particle subfraction) geometric particle diameter subfractions with sieves. The magnetic particle subfraction was removed by stirring the carbonaceous and mineral particle subfractions with a sealed glass tube containing a magnet. The adhering magnetic particles were collected by placing the sealed end of the glass tubing bearing the particles and magnet into a separate vial and sliding the magnet further up the tubing. The 21-150-pm fraction of ash no. 501 was subfractionated similarly to no. 504, except that magnetic particles were not isolated. Carbon Measurements. Total carbon was measured
0 1986 American Chemical Society
Environ. Sci. Technol., Vol. 20, No. 3, 1986 291
Table I. Static Sorptivity and Total Carbon Content of Particle Size Fractions of Three Stack Ash Samples
no. 483 particle size mass total KL x fraction,a pm fraction,b % C, % 52.3 2.3-3.3 3.3-6.3 6.3-14 14-21 21-150
2.3 18.4 27.0 17.4 13.5 21.5
4.1 3.6 3.4 9.8 28.5 21.1 12.5
no. 504 concn,d mass total Kd’ x pg/g fraction,b % C, % 104c
68 61 45 190 710 1200 1300
1.36 1.24 0.99 2.62 4.28 4.53 4.52
2.8 24.3 30.0 17.0 9.7 13.0
1.1 0.71 0.90 1.3 3.8 6.5 2.0
4.7 0.8
no. 501 concn,d mass total Kd’ x rg/g fraction,b % C, % 104~ 0.11 0.018
ND
ND
8.5 25 190 27
0.19 0.30 1.25 0.48
9.5 35.2 32.0 13.6 4.1 5.5
0.66 0.57 0.67 1.0 4.3 4.0 0.93
concn,d pg/g
2.3
0.03 0.06
ND ND ND
ND ND ND
19
0.40
1.1
bulk ashe 7.9 0.19 ORange of mass median aerodynamic diameters. bMass % of original bulk ash sample. c K L = (ng of [14C]BaP/mg of ash)/(ng of [14C]BaP/mL of benzene); ND, sorptivity not detected. Concentration of [14C]BaP in ash at sorption equilibrium. e Unfractionated ash sample.
by using ASTM method D-3178-73, which consists of combustion and gravimetric measurement of carbon as carbon dioxide. Total organic carbon was estimated with an Oceanography International Corp. (College Station, TX) Model 524 total carbon analyzer and the US.EPA procedure (12) for total organic carbon determination in water and wastes. In this procedure, organic carbon is wet-oxidized to carbon dioxide, which is measured with a nondispersive infrared detector. Inorganic carbon was measured by treating the ash samples only with acid and measuring carbon dioxide with the same instrument. Elemental carbon content was calculated as the difference between total carbon and the sum of organic plus inorganic carbon. Sorptivity Measurements. The sorptivity of ash samples for organic matter was evaluated by use of a static 1iquid:solid distribution procedure patterned after that reported by Fitch and Smith (13). Ash samples were dried overnight between 105 and 110 OC and cooled in a desiccator before study. A 500-ng aliquot of the [14C]BaPtracer was added in a benzene solution to the following samples (mass) contained in 20-mL glass vials: (a) bulk ash no. 483 or its subfractions (100 mg), (b) bulk ash no. 501 or its subfraction (300 mg), (c) bulk ash no. 504 or its subfractions (300 mg), (d) glass beads (300 mg), and (e) graphite or amorphous carbon black (100 mg). Each sample was prepared in duplicate. Extra benzene was added to bring the total liquid volume to 2.0 mL. The vials were immediately closed tightly with Teflon-lined caps and were sealed with tape. The distribution of tracer between the solution and ash was allowed to reach equilibrium over a period of 4 days, with occasional shaking of the vials. At the end of the equilibrium period, the vials were shaken again, and the solids were allowed to settle. A 1OO-pL aliquot of the supernatant was withdrawn and subjected to standard liquid scintillation measurements (14) to determine the [14C]BaPleft in the benzene. The amount of [14C]BaPsorbed by the ash was calculated by subtracting the amount found in solution from that originally added to the vial. Experiments with blanks demonstrated that the glass vial did not significantly sorb [14C]BaPunder these conditions. The sorptivity was calculated as the reciprocal of the conventional distribution coefficient to allow increasing sorptivity to be expressed by increasingly larger numerical results: Kd’ = (ng of [14C]BaP/mg of ash)/(ng of [14C]BaP/mL of benzene)
A distribution coefficient normalized to available surface area also was calculated: Kd” = (ng of [14C]BaP/m2of ash)/(ng of [14C]BaP/mL of benzene) 292
Environ. Sci. Technol., Vol. 20, No. 3, 1986
Surface Area Measurements. Surface areas were measured by using the volumetric BET method (15) and nitrogen as the adsorbing gas at liquid nitrogen temperatures. A homemade apparatus was used to take 10 adsorption measurements for each surface area determination. Solvent Extraction Recovery Measurements. Aliquots of 0.5 g of ash or 10 g of glass beads were slurryspiked (14) with ca. 6 X lo4 dpm (corresponding to 0.25 pg) of [14C]BaPand allowed to dry. The spiked samples were then ultrasonically extraced (14,16, 17) 4 times for 3 min, each with 20 mL of toluene, using a 350-W Branson sonifier (Branson Instruments, Inc., Stamford, CT) operated at ca. 210-W power level. The extracts were pooled, concentrated with a stream of dry, flowing nitrogen under reduced pressure, and fractionated by use of normal-phase, semipreparative scale high-performance liquid chromatography employing a Zorbax aminosilane column (18). Fractions corresponding to [14C]BaPand two polar fractions of [14C]BaPdegradation products were collected and concentrated to near dryness. The residues were dissolved in liquid scintillation solution, and the 14C activity was measured by use of liquid scintillation spectroscopy (14). Microscopy. Loose particle samples were mounted for microscopy by first dipersing 10-20 mg of ash in a few milliliters of ethanol with a sonicator and withdrawing a sample of the dispersion with a pipet while sonicating. The specimen was applied to a polished carbon planchet, allowed to dry, and coated with carbon using a Vactronic Lab Equipment (East Northport, NY) instrument. Scanning electron microscopy of these particles was performed on an International Scientific Instruments (Santa Clara, CA) Model 3 instrument at magnifications of 1003000X.
Results and Discussion The sorptivity of the coal combustion stack ash fractions for radiolabeled benzo[a]pyrene increases with increasing particle size. As shown by the data in Table I, sorptivity parallels the total carbon content of the fractions and is highest in the two largest particle size fractions. It also is slightly elevated in the finest particle size fraction, suggesting a bimodal distribution. Smith et al. (19) have observed a submicrometer made in the carbon distribution. Because elemental carbon constitutes the bulk of the total carbon in these ash samples (8),sorptivity parallels carbonaceous particle content. The relationship between sorptivity and particle composition is much clearer when the ash sample is resolved into particle classes. Figure 1 shows scanning electron microphotographs of representative mineral, magnetic, and carbonaceous particles separated from the 21-150-pm particle size fraction of ash no. 483. The predominant type
Table 11. Properties of Particle Type Subfractions from the 21-150-pm Size Fraction of Three Stack Ash Samples vs. Glass or Carbon Particles
particle size fraction” ash no. 483, 21-150-pm fraction
particle type subfraction
KL
carbon, % sorptivity* specific surface area, m2/g lo4 Kd/l ng/mgc elemental organic
X
ash no. 504, 21-150-pm fraction mineral subfraction magnetic subfraction carbonaceous subfraction ash no. 501, 21-150-pm fraction mineral subfraction carbonaceous subfraction porous glass beads, bulk amorphous carbon black, bulk graphite, bulk
190 65 2.1 6000 20 25 320 11 9200 2700
20.2 4.9 8.8 33.7 56.7 6.23 6.8 0.3 46.8 4.0e 3.9e 10.4e
4.17 1.73 3.11 4.19 4.49 1.25 1.22 0.05 4.68 0.40 0.49 1.49 0.25 4.81 4.60
. 840.96 0.49
1100 110 mineral subfractiond 340 magnetic subfractiond carbonaceous subfraction Id1200 carbonaceous subfraction 2d 2100
50 71 45 25 0.51 500
0.007 112 20.5
1.43 1.14 0.69 2.40 2.96 0.42 0.26 0.41 1.20
0.88 0.34 0.42 1.4 1.6 0.29 0.42 0.03 1.3
169 8.21 13.2
=Particle size fraction of stack ash or unfractionated samples of glass or carbon. *Kd’ = (ng of [14C]BaP/mg of ash)/(ng of [14C]BaP/mL of benzene; Kd/l = (ng of [14C]BaP/m2ash)/(ng of [14C]BaP/mL of benzene). CConcentration of [14C]BaP on ash at equilibrium. dRecoveries of subfractions were 17.6, 46.5, 16.8, and 16.0%, respectively, for the mineral, magnetic, carbon-1, and carbon-2 subfractions. eResult shown is for total carbon, which is expected to consist mainly (290%) of elemental carbon.
of carbonaceous particle in this ash is identified (8) as a coke. This type of activated carbon would be expected to exhibit high sorptivity. In contrast, the mineral and magnetic subfractions are dominated by solid rounded particles composed largely of aluminosilicates and iron oxides, respectively. Based on morphology and bulk composition alone, they should exhibit a much less active surface structure and sorptive capacity than the carbonaceous particles. The results of sorptivity experiments are compared in Table I1 with carbon measurements for mineral, magnetic, and carbonaceous particle subfractions separated from the large particle size fraction of the three stack ash samples. Although the subfractionation procedure was not optimally efficient, considerable enrichment of the carbonaceous particles was achieved. Sorptivity clearly results from the carbonaceous particles. It is evident from Table I1 that the carbonaceous particles contribute significantly also to the surface area and estimated total organic carbon content of the ash. Both properties are enhanced in the carbonaceous particles, as opposed to the mineral or magnetic particles. The specific surface areas of our carbonaceous particles are much lower than those measured by Soltys ( 6 ) . This disparity is probably caused by the different isolation methods employed. We separated carbonaceous particles only from the large particle size fraction (21-150 pm), while Soltys employed a density-based float/sink technique to obtain carbonaceous particles presumably constituting the full range of particle sizes present in their ash samples. On that basis, the higher specific surface areas of their samples would be expected. However, the sorptivities for [14C]BaP of our ash no. 483 carbonaceous particle subfractions 1and 2, normalized to the surface area (Kd” = 50 and 70, respectively), are very close to those calculated for Soltys’ carbonaceous particles from Corrette (Kd” = 61) and Niagara Mohawk (Kd”= 78) ash. The similarities of sorptivities imply a similarity in composition of the two carbonaceous particle sample sets. The carbonaceous particles isolated from our ash no. 504 stand out as the most sorptive particles, more so than even the amorphous carbon sample. The nature of the sorption has been explored by only a few workers (6,16,20,21)and definitive conclusions have not yet been made. The comparative data for porous glass
Table 111. Carbon and Surface Area Measurements of Particle Size Fractions of Stack Ash no. 504
particle size fraction: pm
carbon, % elemental organic 0.81 0.51 0.72 1.08 3.37 6.23 1.79
12.3 2.3-3.3 3.3-6.3 6.3-14 14-21 21-150
bulk ashb a Range of mass Unfractionated.
median
specific surface area, m2/g
0.31 0.20 0.18 0.26 0.41 0.29 0.16
aerodynamic
1.71 1.19 0.99 0.60 0.57 0.42 0.82
diameters.
beads and commercial polymeric carbon samples shown in Table I1 show that high surface area per se does not create sorptivity. The glass beads, with a specific surface area 50-600 times that of the ash fractions, exhibit the lowest sorptivity, as defined by K[. A specific interaction between the [14C]BaPand the carbon surface is indicated for the carbonaceous particles, which have specific surface areas only 2-5 times those of the other ash particle types. We have observed (14) that aromatic hydrocarbons are more strongly sorbed than aliphatic hydrocarbons and that the strength of the sorption increases with increasing polycyclic aromatic hydrocarbon (PAH) ring system size. Daisey has reported (21) that the surface area of charcoal occupied per molecule of pyrene is 2-3 times that of the geometric area of the pyrene molecule. Groszek obtained (22) the same results for pyrene sorbed on graphites, consistent with a parallel planar orientation between the aromatic hydrocarbon and the extended carbon network. We have hypothesized (20)that a T-T association between the ?r-electron cloud of the [14C]BaPmolecule and the extended aromatic system of the polymeric carbon is responsible for at least the first stages of the sorptive interaction. The data presented in Table I11 show the distribution of specific surface area and total organic carbon among the particle size fractions of a stack ash sample. The specific surface area should decrease by a factor of 10 or more between the finest and largest particle size fractions, based on the differences in particle radii alone, whereas a factor of only 4 is observed. The estimated total organic carbon Environ. Sci. Technol., Vol. 20,No. 3, 1986
293
Table IV. Solvent Extraction Recoveries of [‘C]BIp and Degradation Products from Particle Siu, Fractions and Particle Typc Subfractions of Stack Ash no. 504 radiotrscer recovery? W degraded
rg
~ ~ m C l efrom s the IA) mineral Dartlcie (700XL (6) maanetlc D( le ~IOOOX). and (c) carbonace0;s particle (ZOOXI subfrictions of me 21-150-pm particle SIze fraction of stack ash no. 483.
also appears to be evenly distributed throughout the size fractions. In contrast, organic compounds such as polycyclic aromatic hydrocarbons in air particulate matter are largely localized on the particles smaller than 3 pm (23). The particle-type properties reported in Table I1 suggest that thii “leveling out” of specific surface area and organic matter is contributed by the increasing incidence of carbonaceous particles in the larger particle size fractions. Solvent extraction recoveries of [14C]BaPand degraded products of [I4C]BaP from particle size fractions and particle type subfractions of ash no. 504 are listed in Table lV. Ultrasonic extraction was utilized instead of Soxhlet extraction because of its greater efficiency (24) in recovering PAH from stack ash and the greater thermal stress applied to the sample extract by the latter. Four ultrasonic extractions have been found (17) to be optimal. It is interesting to note that, whereas the particle size fractionsdiffer considerably in their sorptivity for [W]BaP (Table I), their extraction recoveries for [WIBaP and 204
Env*on. Scl. Tecmol.. Vd. 20.
No. 3. 1988
[“CIBaP
polar-1
polar4
52.3 fraction 2.3-3.3 fraction 3.3-6.3 fraction 6.3-14 fraction 14-21 fraction 21-150 fraction mineral subfraction magnetic subfraction carbon subfraction bulk ash g h bead8
46 31 22 30 34 30 63 79 28 22 12
3.1 3.0 3.7 2.4 3.1 2.9 2.9 2.6
18 17 19 14 I8 24 2.7 1.8 0.3 15
1.0
2.3 24c
.Particle siu, fraction (mass median aerodynamic diameter range in pm) or particle type subfraction except for unfractionated ash and glass beads. ’Recovery from four. 3-minute ultrasonieatiom at 210 W using 20 mL of toluene for each extraction and normal-phase HPLC fractionation of eample. ‘Sum of recoveries of degraded radiotracer in polar-1 and polar-2 fractions.
I
npure 1. Scanning electron mlcrophotographs of represen
[”ClBaP
ash sample fraction or subfractionO
degradation products are fairly constant. Our finest particle size fraction exhibits a slightly higher extraction recovery than the larger sized fractions. The results for the particle-type subfractions clearly demonstrate that the carbonaceousparticles are controlling the extraction recoveries of [“CIBaP. The extraction recovery is a critical part of most organic compound analysis procedures. Recoveries of [W]BaP fmm the carbonaceous particles are very similar to those of the particle size fractions and the bulk ash. This similarity of recoveries could be explained by carbonaceous particles resorbing [“CIBaP liberated from mineral or magnetic particles during extraction. Alternatively, the carbonaceous particles may have preferentially sorbed the spike as it was applied to the ash sample. In either case, [“CIBaF’ would be more readily recovered if carbonaceous particles were not present in the sample. The data for the particle type subfractionsalso indicate that the mineral or magnetic particles yield a higher recovery of polar degradation products of [“CIBaP. A p proximately 3-fold greater amounts of degradation products were recovered from both the mineral and the magnetic particle subfractions than from the carbonaceous particle subfraction. This observation does not exclude degradation on the latter; the products simply may not have been extractable from our carbonaceous particles. Indeed, Taskar et al. (25). Daisey and Low (26), and Korfmacher et al. (27)have observed degradation of other PAH applied a t relatively high levels to Carbosieve, graphite, and charcoal. However, it is not clear why much higher percentages of degradation products were recovered from our 21-150-pm fraction than from any of its constituent particle-type subfractions. The relatively high result for recovered degradation products from the poroua glass beads (ca. lo3 more surface area per experiment) shows that a high surface area glass particle type could be responsible, but this class of particle should have been included in our mineral subfraction. A synergistic effect may occur when all three particle subfractions are present together and can act in concert upon organic matter. The nature of the degradation products of [“CIBaP was not explored in this study. However, the identification by Daisey et al. (21,26) and Korfmacher et al. (27) of oxygenated PAH degradation products suggests that our polar
degradation products of [14C]BaPare oxygenated. Both Daisey and Low (26)and Korfmacher et al. (27) hypothesize that adsorbed PAH react with oxygen, possibly through a charge-transer complex (26). The oxidation hypothesis is consistent with our observation (17) that the recovery of undegraded [I4C]BaPfrom ash no. 504 is nearly doubled, and the observed degradation products decreased by ca. 25% when light and oxygen are rigorously excluded from the spiked ash before extraction.
(12)
(13) (14) (15)
Conclusions
Carbonaceous particles are a minor component by mass of stack ash, but they strongly influence the sorptivity, specific surface area, and distribution of organic matter in the large particle size fraction. We suspect that their influence extends throughout the particle size range of the stack ash. They also control the extraction recovery of large ring system PAH. However, recovery of degraded PAH is influenced more by the mineral or magnetic particles and exposure of the ash to light and air. Analysis of bulk ash samples thus may not reflect the true composition and heterogenity of distribution of organic compounds sorbed on the different particle types constituting the ash.
(16)
(17)
(18)
(19) (20)
Acknowledgments
We gratefully acknowledge L. B. Yeatts, Jr., and R. R. Reagan for performing some of the fractionation and sorptivity studies and C. S. MacDougall for conducting the microscopy. Registry No. Benzo[a]pyrene, 50-32-8; carbon, 7440-44-0.
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Contract 68-03-1371 to W. Pepelco, HERL, U.S. EPA, Cincinnati, OH, Feb 1, 1979. “Methods for Chemical Analysis of Water and Wastes”; EPA/600/4-79-020, U.S. Environmental Protection Agency, Environmental Monitoring and Support Laboratory, Cincinnati, OH, March 1979. Fitch, W. L.; Smith, D. H. Environ. Sci. Technol. 1979,13, 341-346. Griest, W. H.; Yeatts, L. B., Jr.; Caton, J. E. Anal. Chem. 1980,52, 199-201. Brunner, S.; Emmett, P. H. Teller, E. J. Am. Chem. SOC. 1938,60, 309-319. Griest, W. H.; Caton, J. E.; Guerin, M. R.; Yeatts, L. B., Jr.; Higgins, C. E, In. “Polynuclear Aromatic Hydrocarbons: Chemistry and Biological Effects”; Bjorseth, A., Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1980; pp 819-828. Tomkins, B. A,; Reagan, R. R.; Maskarinec, M. P.; Harmon, S. H.; Griest, W, H.; Caton, J. E. In “Polynuclear Aromatic Hydrocarbons: Formation, Metabolism, and Measurement”; Cooke, M., Dennis, A. J.; Eds.; Battelle Press: Columbus, OH, 1983; pp 1173-1187. Tomkins, B. A.; Griest, W. H.; Caton, J. E.; Reagan, R. R. In “Polynuclear Aromatic Hydrocarbons: Physical and Biological Chemistry”; Cooke, M., Dennis, A. J.; Eds.; Battelle Press: Columbus, OH, 1982; pp 813-824. Smith, R. D.; Campbell, J. A.; Nielson, K. K. Atmos. Environ. 1979, 13, 607-617. Griest, W. H.; Caton, J. E. In “Polynuclear Aromatic Hydrocarbons: Chemical Analysis and Biological Fate”; Cooke, M., Dennis, A. J., E&.; Battelle Press: Columbus, OH, 1981; pp 719-730. Daisey, J. M.; Low M. J. D.; Tascon, J. M. D. In “Proceedings of the Eighth International Symposium on Polynuclear Aromatic Hydrocarbons”; Cooke, M., Dennis, A. J., Eds.; Battelle Press: Columbus, OH, in press. Groszek, A. J. Disscuss. Faraday SOC.1975, 59, 109-116. Pierce, R. C.; Katz, M. Environ. Sci. Technol. 1975, 9, 347-353. Griest, W. H.; Guerin, M. R. “Identification and Quantification of Polynuclear Organic Matter on Particulates from a Coal-Fired Power Plant”; EPRI EA-1092, Interim Report, The Electric Power Research Institute, Palo Alto, CA, June 1979. Taskar, P. K.; Solomon, J. J.; Daisey, J. M. In “Proceedings of the Eighth International Symposium on Polynuclear Aromatic Hydrocarbons”; Cooke, M., Dennis, A. J., Eds.; Battelle Press: Columbus, OH, in press. Daisey, J. M.; Low, M. J. D. ”Reactions of Adsorbed Polycyclic Aromatic Hydrocarbons”; Annual Report for the Period 10/4/82-10/3/83 for Grant R-810099-01,Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC. Korfmacher, W. A.; Mamantov, G.; Wehry, E. L.; Natusch, D. F. S.; Mauney, T. Environ. Sci. Technol. 1981, 15 1370-1375.
Received for review August 27,1984. Revised manuscript received March 18, 1985. Accepted July 24, 1985. This research was sponsored by the Electric Power Research Institute under Interagency Agreement, EPRI 1057-1, DOE RTS 77-85, under Martin Marietta Energy Systems, Inc., Contract DE-ACO584OR-21400, with the U.S. Department of Energy.
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