From the experiments performed here, the overall oxygen consumption mechanism in humic-colored waters can be summarized as follows. Free Fe(I1) and a Fe(I1)-humic complex are oxidized by oxygen to Fe(II1) and a Fe(II1)-humic complex, respectively, and any free Fe(II1) formed is complexed strongly by humic material in the system. The Fe(II1)-humic complex is slowly reduced to the Fe(I1) complex by humic matter in the dark; the reduction occurs more rapidly in light through a ligand-to-metal charge transfer, producing CO2 and other oxidation products. The Fe(I1)-humic complex may dissociate and replace the free Fe(I1) originally oxidized. The overall result is a catalytic redox cycle whereby iron and light cause the production of one-half molecule of COa for every turn of the reaction cycle. Literature Cited (1) Wetzel, R. G “Limnology”; W. B. Saunders: Philadelphia, PA,
1975; pp 123-41. (2) Yoshimura, S. Sci. Rep. Tokyo Bunrika Daigaku, Sect. C 1938, 8,63-227. (3) Lonnerblad, G. Acta Uniu. Lund. 1931, NF Adv. 2.27, No. 14. (4) Hutchinson, G . E. “A Treatise on Limnology”; Wiley: New York, 1957; pp 557-652. (5) Gjessing, E. T.; Gjerdahl, T Vatten 1970,26,144-5. (6) Schnitzer, M.; Khan, S. U. “Humic Substances in the Environment”; Marcel Dekker: New York, 1972. (7) Shapiro, J. J. J. Am. Water Works Assoc. 1964,56,1062-82. (8) Stumm, W.; Lee, G. F. Ind. Eng. Chem. 1961,53,143-6.
(9) Stumm, W.; Morgan, J. J. “Aquatic Chemistry”; Wiley-Interscience: New York, 1970. (10) Trott. T.: Henwood. R. W : Laneford. C. H Enuiron. Sci. Technol. 1972,6; 367-8. ‘ (11) ShaDiro. J. Science 1961,133.2053-64. (12) American Public Health Association. “Standard Methods for the Examination of Water and Wastewater”, 14th ed.; New York, 1976. (13) Fresenius, W.; Schneider, W. Z. Analyt. 1965,209, 340-1. (14) Sung, W.; Morgan, J. J. Enuiron. Sci. Technol. 1980, 24,5611
1
1
’
8.
(15) Just, G. Z. Phys. Chern. 1908,63,385. (16) Singer, P. C.; Stumm, W. Science 1970,167,1121-3. (17) Cotton, F. A.; Wilkinson, G. “Advanced Inorganic Chemistry”, 3rd ed.; Wiley-Interscience: New York, 1972. (18) Theis, T. L.; Singer, P. C. In “Trace Metals and Metal-Organic Interactions in Natural Waters”; Singer, P. C., Ed.; Ann Arbor Science Publishers: Ann Arbor, MI, 1973; pp 303-20. (19) Ghosh, M. M.; O’Connor, J. T.; Englebrecht, R. S. J. Am. Water Works Assoc. 1967,59,897-905. (20) Langford, C. H.; Wingham, M.; Sastri, V. S. Enuiron. Sci. Technol. 1973,7,820-2. (21) Hutchard, C. G ;Parker, C. A. Roc. R. SOC. London, Ser. A 1956, 235,518-36. (22) Langford, C. H.; Carey, J. H. Can. J. Chem. 1975,53,2430-5. (23) Baker, A. D.; Casadavell, A.; Gafney, H. D.; Gellender, M. J . Chem. Educ. 1980,57,314-5. (24) Theis, T. L.; Singer, P. C. Enuiron. Sci. Technol. 1974, 8, 569-73. (25) Fair, G. M.; Geyer, J. C.; Okun, D. A. “Water and Wastewater Engineering”; Wiley: New York, 1968; Vol. 2. Receiued for review December 12,1980.Accepted May 14,1981.
Polychlorinated Biphenyls in Effluents from Combustion of CoaVRefuse John J. Richard and Gregor A. Junk* Ames Laboratory,? Iowa State University, Ames, Iowa 5001 1 Polychlorinated biphenyls (PCBs) were observed in all of the effluents from an electrical power plant equipped to burn coal and mixtures of coal and refuse-derived fuel (RDF). Test combustions with and without refuse were made, and no correlation could be established between the PCB content of any of the effluents and the fuel being combusted. The effluents studied were grate ash, fly ash, stack ash, stack gas, sluice water, and sluice sediment. The PCB content of the coal and RDF fuels and the air used to support the combustion were also measured. The fate of the average low PCB level of 0.1 pg/m3 in this air could only be approximated. However, the appreciable amounts of PCBs which averaged 8500 pglkg in the RDF were almost completely destroyed, leaving less than 1%to be distributed in the environment via stack emissions and disposal of grate and fly ash. The PCBs present in these ash effluents averaged less than 5 pg/kg. H
Introduction
Municipal refuse as a supplemental source of energy has become more attractive recently because the costs of waste disposal and conventional fuels have increased dramatically. Many municipal incinerators in the U.S.A. are used mainly for volume reduction of refuse. A few have provisions for energy recovery. Some of these systems which combine waste to energy and volume reduction are or will be located in urban areas ( 1 ) . It is important to determine whether the use of t Operated for the U.S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82.
0013-936X/81/0915-1095$01.25/0 @ 1981 American Chemical Society
municipal waste in this manner as either a supplemental or primary fuel adds significant amounts of pollutants to the immediate surroundings. Part of this determination is the subject matter of this report. One group of organic pollutants of concern is the polychlorinated biphenyls (PCBs). Although the use of PCBs has been restricted since 1971,high levels still occur in many paper products, especially paperboard ( 2 , 3 ) .This is caused by the repeated recycle of waste paper which contains PCBs. For example, levels as high as 7% were in carbonless copy paper in 1971 ( 4 ) . These PCBs, as Aroclor 1242, were purposely added as microcapsules. The carbonless copy paper then became a component of wastepaper which was recycled. Inevitably the PCBs were introduced into various other products by the recycle process. Thus many paper products contaminated with PCBs and some of the original carbonless copy paper eventually end up as components of municipal refuse. In addition to paper products, other common materials in refuse such as plasticized paint, adhesives, plastic fireproofing agents, and discarded electronic equipment contain PCBs. Only limited reports are available for PCB emissions from the combustion of refuse. Measurements of stack gas and ambient air upwind and downwind from a Chicago incinerator have been reported ( 5 ) .The average PCB associated with the particulate matter was 33 pg/m3 of stack gas effluent. Averages of 0.17 and 0.14 pg/m3 were measured upwind and downwind from the site, respectively. The emissions of PCBs to the atmosphere as vapor and as particulate matter were also measured for incineration of municipal and industrial waste and sewage sludge (6). At five municipal incinerators the PCB levels were 34, 10,8,6, and 5 pg/m3. At two industrial incinVolume 15, Number 9, September 1981 1095
erators the levels were 200 and 0.0007 pg/m3, At two sewage sludge incinerators the amounts were 249 and 4 pg/m3. The stack gas from another municipal incinerator at Braintree, T N , had 4 pg/m3 (7). No PCBs were detected on the particulate taken from the electrostatic precipitator a t that facility. In a separate study 1pg/kg of PCBs was found in two of five particulate samples taken from the electrostatic precipitators of incinerators burning domestic refuse (8). Only one report is available for PCB emissions from coal combustion. Particulate matter and vapor samples were collected from the Widow’s Creek coal-fired generating station near Bridgeport, AL (9). The average PCB values for the particulate matter collected a t three locations in the plant were as follows: bottom ash at 20 pg/kg, superheater ash at 90 pg/kg, and dust collector ash a t 70 pglkg. The PCBs were detected at low unspecified levels in the stack vapor a t sampling points before and after the mechanical dust collector. No reports of PCB emissions from the combustion of mixtures of coal and processed municipal refuse, frequently called refuse-derived fuel (RDF), have appeared in the literature. The results of a search for PCB in all of the emission effluents and in the fuel and air influents at a facility geared to generate electricity and a perspective interpretation of these data are the subject matter of this report.
Experimental Section Facilities. The City of Ames, IA, has been operating a system for energy and material recovery from municipal solid waste since November 1975. The Ames solid-waste recovery system consists of a 136 Mg/day refuse processing plant, a 454-Mg storage bin €or the processed refuse, and the original Ames municipal power plant. The shredded refuse is air classified at the processing plant, stored, and eventually used as a fuel supplement to coal. The descriptive characteristics of the boiler systems at the power plant are given in Table I. Most of the samples for PCB analyses were taken from the suspension fired unit 7 . Only the grate and precipator ash samples taken from the spreader stoker units 5 and 6 were analyzed for PCBs. Experimental Design. Samples were collected under different coal-to-RDF fuel ratios and loads for the steam
Table 1. Characteristics of the Boilers at Ames Municipal Power Plant * unit no. nom
manufacturer coal firing equipment dust collection
equipment
5
Riley
Union Iron Combustion Works Engineering spreader spreader pulverized stoker stoker suspension Western American American Multiple Multiple Electrostatic Cyclone Cyclone Precipitator
stack height, m 60 heat input at nominal 37 capaclty, kcal X 10e/h coal burning capacity, 6.9 metric tons/h refuse burning capacity (metric tonslh) for different coal/refuse ratios: 9 4 1
7
6
1.4 2.7 6.6
60
60
48
109
9.1
20.8
generator. The following effluents were sampled and analyzed for PCBs: fly ash; grate ash; stack ash; and stack gas. The levels in the air used to support combustion, sluice water, sediment from a settling pond, processed refuse, and the coal were also measured. Pertinent details of the collection and extraction procedures for these various samples are described below. Refuse. The refuse and other paper products were shredded in a blender, and 1-g samples were Soxhlet extracted with benzene or methylene chloride. Coal. Coal samples were ground to 40-60 mesh and Soxhlet extracted with benzene. Particulate Matter. Recoveries of PCBs from portions of the same fly ash sample were measured by using Soxhlet and ultrasonic extraction with a variety of solvents. On the basis of interpretation of these data shown in Table 11, the Soxhlet procedure and methylene chloride solvent were used. Particulate samples of 10-g size were extracted for 24 h by using a 35 X 90 mm glass thimble. A glass-wool mat helped prevent clogging of the sintered glass. After the extraction, -5 mL of hexane was added, and the solvents were evaporated to -0.5 mL. This procedure removed the methylene chloride. The PCBs were separated from interfering components in the hexane extract by column chromatography employing either Florisil ( 1 1 ) or basic alumina (12). Stack Gas. Stack samples were taken initially under strict isokinetic conditions by using a modified EPA Method 5 sampling train with an XAD-2 trap substituted for the first impinger. Insufficient vapor samples were collected for accurate PCB analyses. Later samples were taken under approximate isokinetic conditions by using a source assessment sampling system (SASS) (13) where much larger volumes of stack gas were sampled at fast flow rates. Stack samples were also taken with a simple glass system of our own design which included a probe, a filter, an ice-cooled impinger, and a XAD-2 trap. This Ames vapor sampling system (AVSS) was used primarily for sampling before the electrostatic precipitator. When a glass-wool plug was used in the end of the probe as a filter, the amount of stack gas that could be sampled was limited because of clogging of this filter with particles. T o alleviate this problem, we designed the filter shown in Figure 1. It is a lOO-mL, pear-shaped flask containing -15 holes of -1-cm diameter and a 14/20 3 joint for connection to the end of the probe. The tufts of glass wool in the holes and the glass wool inside the flask provided effective filtration at high particle loads and allowed uninterrupted sampling of 5000-7000 L of stack gas during 7-8 h. In situ tests of recovery of PCBs were accomplished by into the glass spiking 1pg of 2,2’,4,4’,5,5’-hexachlorobiphenyl wool at the end of the probe of the AVSS. The probe was then inserted into a sampling port a t the power plant and -1000 L of stack gas was drawn through the system. The apparatus was taken back to the laboratory, where diethyl ether was used to cleanse the probe, elute the XAD-2 resin, and solvent extract the water condensate. The ether was dried by adding
Table II. Comparative Analyses of PCBs in Fly Ash Using Soxhlet and Ultrasonic Extraction with Various Solvents solvent
1.7 3.4 8.6
4.0 7.9 NA
Summarized from extensive data reported by Hall et ai. ( 70). Not available.
1096 Environmental Science 8 Technology
benzene isopropyl alcohol benzenelmethyl alcohol hexandacetone methylene chloride
concn, p g l k g Soxhlei ultrasonic
1.6
2.0
1.2
1.2
1.9 1.o
1.5 0.9
2.2
0.6
b z3
1
*
t
Figure 1. Filter for the Ames vapor sample system (AVSS) showing glass-wool tufts projecting through holes in lOO-mL, pear-shaped flask equipped with a 14/20 5 joint.
v, 2
W
t
z
10-15 mL of hexane and 2-3 g of Na2S04 to the separatory funnel used to extract the condensate and shaking for 30 s. The ethedhexane was transferred to a 150-mL beaker and evaporated to -1 mL. Basic alumina was used for sample cleanup. The recovery of hexachlorobiphenyl was greater than 90%. Similar recovery efficiencies were obtained for in situ tests of spikes as low as 0.1 pg and 5000-L volumes of stack gas. All analyses of the PCBs in the vapor phase were based on stack gas volumes equal to 4 m3. Air. Air volumes of 5 m3 were taken from within and outside the power plant at a flow rate of 15 L/min by using a XAD-2 trap to collect the PCB vapors. A 0.45-pm silver membrane filter was used before the XAD-2 to remove the particulate matter. The recovery of Aroclor 1254 was measured by adding 1pg to a glass-wool plug in the end of the sample probe and drawing 1000 L of heated laboratory air through the probe and XAD-2 trap. The probe was rinsed with diethyl ether, and the rinsate was used to elute the XAD-2 trap. The eluate was concentrated and analyzed by electron capture gas chromatography. The recovery was 89%. Separate tests with 2,2'dichlorobiphenyl yielded 81% recovery by using the same spiking and analytical procedure.
W
concn, CBlkg
Sluice Water. The XAD-2 resin extraction procedure of Junk et al. (14) was used for 4-L sample volumes. Sluice Sediment. Ten-gram sediment samples from the settling pond were extracted with hexane/acetone according to the procedure of Woolson (15). Quantification. The PCBs were separated and measured by using a 4 mm X 2 m 4% SE-30/6% SP-2401 glass column at 200 "C and a Tracor Model 550 gas chromatograph equipped with a 63Nielectron capture detector at 325 O C . Quantification was based on peak heights of the seven major GC peaks shown in Figure 2 for an Aroclor 1254 standard. Detection limits were 0.01 pg/kg and 0.01 pg/m3. Blank levels were at the detection limits. Gas-chromatographic reproducibility was f 5 % , but precisions for all reported values which include the uncertainties of the entire analytical scheme are estimated to be &loo%. Haile and Baladi (6) and Armour (16) have proposed perchlorination using antimony pentachloride to simplify the
concn
Des Moines Register (DMR)
16
computer printouts
10
18
cardboard
39
colored comics (DMR)
31
computer cards
24 140
magazine covers
paper towels RDF
I 12
I
a
TIME, MJN
product
colored sport section (DMR)
I 4
Figure 2. Comparative electron capture chromatograms of Aroclor 1242 (a), Aroclor 1254 (b), refuse extract (c), and an extract of ambient air (d) used to support combustion.
Table 111. Concentration of PCBs in Local Ppaer Products and Processed Refuse (RDF) product
L
0
139
8500
Table IV. Average Concentration of PCB in Particulate Samples concn,
grate ash % refuse
units 5 and 6
0
2.5 (1-6)
10 20 50
unit 7
4.3 (1-7) 8.1 (2-13)
unlts 5 and 6
1.6 (1-4)
8.2 (6-1 1) 1.7 (1-2)
figlkg fly ash
stack ash unlt 7
1.9 (1-3) 1.7 (1-2) 1.4 (1-2)
unlt 7 a
2.4 (1-5) 2.5 (1-4)
unit 7 b
11.6 (10-16) 8.8 (8-10)
1.2 (1-3)
a Stack ash which settled into troughs placed inside the stack. 3-10-prn fraction collected in the cyclones of the SASS. Range in parenthesis. Average values based on three to six measurements at each firing condition.
Volume 15, Number 9, September 1981
1097
Table V. PCB Levels in Stack Gas from Unit 7 and Air from the Power Plant Yo
concn, pg/m3
refuse
before ESP
UNK UNK UNK UNK UNK UNK 0 0 0
0.04 0.01 0.01 0.01 0.01 0.01 0.01
20
0.01 0.01 0.01
0.02
0.02
20 20
stack
c c c c
C
C
C C
c 0.01 0.02 0.04
C
c c c C
0.02
0.01
C
0.02 0.01
0.02 0.02
alr
0.14 0.03 0.05 0.03 0.07 0.11 0.14 0.14
0.12 0.27 c
fresh sluice water aged sluice water sluice sediment
measurement procedure and to increase the detection limit sensitivity for PCBs. This procedure converts all of the individual PCB components to a single compound, decachlorobiphenyl. However biphenyl is also perchlorinated. Since small amounts of biphenyl are expected in stack gases and were found in all samples analyzed by GC/MS, perchlorination was not used in our studies of PCB emissions. Verification. The PCBs were confirmed by capillary column GC/MS techniques using coincidence of the capillary retention times for specific isomers and proper distributions of the chlorine isotopes.
Results Refuse. The PCBs in the refuse were measured periodically. The values varied between 500 and 45 000 pg of PCB/kg of refuse. When the PCB levels were below -1000 pg/kg, the GC profile closely resembled that observed for Aroclor 1254. At higher PCB levels the profile was closer to Aroclor 1242 and 1248. Over 50% of the analytical results for the refuse were between 5000 and 10 000 pg/kg. Local paper products known to be part of the processed refuse were analyzed separately. The results of these analyses and the average values for 10 analyses of the processed refuse are given in Table 111. Coal. No PCBs were detected in any of the coal samples analyzed. Particulate Matter. The amounts of PCBs in different grate and fly ash samples are given in Table IV. Samples collected at from 80% to 100%burning capacity showed no difference in the level of PCB. Stack Gas. The PCBs were measured for stack gas samples collected ahead of and after the electrostatic precipitator of unit 7 and are listed as part of Table V. Comparative analytical results by two different sampling methods are also given for samples taken after the precipitator. Indoor Air. The PCB results are also given in Table V for samples of air taken from the room used to provide the support gas for combustion. Sluice Water and Sediment. The average amounts of PCB in fresh sluice water, settling pond water which corresponds to aged sluice water, and sediment from the settling pond are given in Table VI.
Discussion The finding of PCBs in all effluents from a power plant burning coal/refuse mixtures was not unexpected considering the amount of PCBs in the refuse and the thermal stability of these compounds. The surprising observation was compa-
0.016 (0.016-0.030)
0.002 (0.001-0.003) 5.9 (1.9-13.4)
a Range in parenthesis. Average values based on three to eight measurements.
Table VII. PCB Data from Different Fuels and Stationary Combustion Chambers fuel
cornbustlon chamber
coal llrefuse coal 2lrefuse coal 1 coal 2 coal 2 coal 3 wood/paper softwoods woodlpaper hardwoods softwoods
plant A plant A plant A plant A plant B plant B fireplace A fireplace A fireplace B fireplace B fireplace B
0.11
.
Environmental Science & Technology
concn, a pglkg
sample stack a
Ames vapor sampling system (AVSS). Source assessment sampling system (SASS). Not measured
1098
Table VI. Average PCB Amounts in Sluice Water and Sediment
a
PCB confirmed in fly ash grate ash
a Yes Yes a a
Yes Yes yes Yes Yes
Not measured
rable levels of PCBs in the effluents when no refuse was being burned. This observation of PCBs in the effluents when the fuel contains no PCB was confirmed at a second power plant which has never burned refuse. Here the PCBs were again observed in the emissions when two different coals were being used as fuel. Several fireplaces used as combustion chambers in households were also investigated. The fuels were paper, hardwoods, and softwoods. In all cases, PCBs were observed in the effluents. A summary of the analytical data from these investigations is given in Table VII. In all cases where emission of PCBs were confirmed, the chlorine content of the fuel ranged from 0.02% to 0.5%.From these data one can speculate about the formation of PCBs and probably other chlorinated compounds whenever an organic fuel which contains chlorine is combusted. We have been unable either to verify or to negate this speculation by small-scale combustion studies or from interpretation of the data obtained a t the power plant when coalhefuse was being combusted. Another source of PCBs in effluents from these combustion processes is the air being used to support the combustion. The sources of the generally higher PCB levels found in indoor atmosphere have been reported (17,18) to be defective light ballasts, capacitors in small electrical equipment, and caulking compound used in duct work. Indoor air was used to support the combustion in all of the chambers that we have studied. The air intakes for the boilers in the power plant which burned coal/refuse were located inside the plant near the ceiling. As shown by the data in Tables V and VIII, the amount of PCBs in the air inside the plant was at least 10 times higher than in the stack gas and in the air outside the power plant. The PCB profile from these indoor air samples resembled that of Aroclor 1254, as shown by the similarity of chromatograms b and d in Figure 2. The PCB profile for extracts of refuse samples resembled that of Aroclor 1242, as shown by the comparison of chromatograms a and c. The PCB profiles for extracts from all combustion samples were very similar to
Table VIII. PCB Vapor Concentration (pg/m3) in Continental U.S.A. Ambient Air locatlon
Vineyard Sound, MA Chesapeake Bay Chicago, IL Mammouth Cave, KY Columbia, SC Jacksonville, FL Ames, IA
ref
range
0.004-0.005 0.001-0.002 0.0076 0.0067 0.0001-0.0064
0.003-0.036 0.002-0.010
b
20 21 22 22 23 24
present work
the Aroclor 1254 chromatogram. Two representative chromatograms, one for stack vapor and the other for stack ash, which show this similarity, are reproduced in Figure 3. The seven major GC peaks numbered on the Aroclor 1254 chromatogram in Figure 2 are present here and were present in all other extracts from combustion samples. The most obvious and consistent divergence of the Aroclor 1254 profile from that observed for the combustion samples was an intensity shift for peaks 4 and 4a. More subtle differences such as the appearance of peaks with long retention times in the combustion extracts were also observed. Nevertheless, the basic profile is that of Aroclor 1254. All of the possible sources of PCBs in the emission from the power plant when coal fuels having no PCB content are burned cannot be identified or quantified. However, when refuse containing a relatively high PCB level is used as a supplementary fuel, a very rough mass balance for PCB may be calculated. The mass balance can be used as a clue to the formation and destruction of PCB in the combustion process. These mass balance calculations for unit 7 at the Ames power plant were made by using mass burn rates and PCB levels reported in Tables I and 111-V of this paper and ash and stack air flow rates reported previously (10)to be 821 kg/h for grate ash, 1310 kg/h for gly ash, 100 kg/h for stack ash and an air flow rate of 43 m3/s when 20% RDF is mixed with coal and combusted at 100% load. These data were used to calculate a destruction of 99.98% of the PCBs if the refuse contained the average amount of 8500 pg/kg during the times that the PCBs were measured in the various effluents. The extremely heterogeneous nature of the refuse makes concentration measurements very tenuous. However, the lowest and highest concentrations can be used to estimate the probable confidence in the value reported for the percent destruction. When the lowest value of 500 pg/kg and the highest value of 42 000 yglkg in the refuse are used, the calculated destructions are 99.70% and 99.997%, respectively. The actual value is dependent on the exact composition of the refuse which can be determined effectively only in bench-scale studies. Therefore, a conservative estimate of the destruction percent is >99%. This estimation agrees with expectations based on the results of a study ( 1 9 ) of the decomposition of PCB at temperatures as low as 1200 O F . The temperature of the primary combustion zone in unit 7 at the Ames facility is >2000 O F . This boiler actually has two combustion zones when refuse is being burned. The refuse is blown into the furnace along with coal into the primary fire zone where part of the refuse is burned. The unburned refuse then falls onto the dump grates where the rema'nder burns. Even though PCBs have been identified and quantified in all of the emissions from the Ames power plant, these emissions have a minimal impact on the surrounding environment. Ambient PCB levels for the Ames area were determined several miles upwind from the power plant. The results tabulated in Table VI11 show a range of values from 0.002 to 0.10 pg/m3
4
8
12
16
230
4
8
12
16
TIME, MIN
Figure 3. Electron capture chromatogram of extract of stack vapor (a) and stack ash (b).
which agree with those reported for other locations in the U.S.A. The average value calculated from data in Table V for PCBs in the vapor phase inside the stack is 0.02 pg/m3. The total PCB being emitted includes the vapor-phase amount plus that present on the suspended particulates. An average concentration of 10 pg of PCB/kg of particulates and a particle load of 0.52 g of particulate/m3 was used to calculate an emission of 0.005 pg/m3. The total emission then becomes 0.02 pg/m3 for the vapor phase plus 0.005 pg/m3 on particulates or 0.025 pg/m3. Because of the rapid dispersion, this small amount would be indistinquishable from that present in the surrounding atmosphere.
Conclusions (1) The -99% destruction of PCBs in the combustion of coal/refuse mixtures to produce electricity is an apparent environmental asset relative to the direct land disposal of the refuse. (2) The burning of RDF which contains significant amounts of PCBs as a fuel supplement to coal for the generation of electricity has a negligible impact on the environment with respect to these chlorinated compounds. (3) A prohibitively expensive sampling and analysis regime would be necessary to determine the exact differences in PCB emissions when refuse is added to coal at an operating power plant. (4) As many influent and effluent streams as possible should be analyzed, and these results should be interpreted in toto to arrive at the best estimate of environmental impact and of abatement procedures for deleterious effluents. (5) In the absence of a critical mass balance study which would be very costly and might not even produce the desired results, the exact origin of any PCBs in the effluents from many stationary combustion sources cannot be determined. The probable origins are (a) degassing of the fuel, (b) air used to support the combustion, (c) contamination from components of the ducts leading to and from the combustion chamber, (d) chlorination of biphenyl in or after the combustion chamber, and (e) formation in the combustion zone by a series of complex reactions similar to those proposed for formation of polycyclic aromatic hydrocarbons from fuels as simple as methane. Present data do not allow the distinction of these possibilities, but indirect evidence suggests that all are operable. Acknowledgment Special thanks go to Mike Avery, Howard Shanks, Jerry Hall, A1 Joensen, Glenn Norton, Ray Vick, and the staff at the Volume 15, Number 9, September 1981 1099
Ames Power Plant for Technical assistance and to V. A. Fassel and H. J. Svec for administrative aid.
Literature Cited (1) National Center for Resource Recovery Bulletin, 1979, No. 3, pp 70-6. (2) Trout, P. E. Enuzron Health Perspect 1972, I , 63-5. (3) Haney, J. S. Conf.Proc --Natl Conf.Polychlorinated Biphenyls, 1975, 1976,362-5. (4) Kuratsune, M.; Masuda, Y. Enuiron Health Perspect 1972,1, 61-2. (5) Timm, C. M. “Sampling Survey Related to Possible Emission of Polychlorinated Biphenyls from the Incineration of Domestic Refuse”, NTIS Pub. No. PB-251-285,1975. (6) Haile, C. L.; Baladi, E. “Methods for Determining the Polychlorinated Biphenyl Emission from Incineration and Capacitors and Transformer Filling Plants, NTIS Pub. No. PB-276-745, 1977. (7) Golembiewski,M.; Ananth, K.; Tricham. G.; Baladi, E. “Environmental Assessment of a Waste-To-Energy Process, Braintree Municipal Incinerator”, Midwest Research Institute Report Nos. 38216 and 4033-C, 1976. (8) Eiceman, G. A.; Clement, R. E.; Karasek, F. W. Anal Chem 1979, 51,2343-50. (9) Cowherd, C.; Marcus, M.; Guenthes, C. M.; Spigarelli, J. L. “Hazardous Emission Characteristics of Utility Boilers”, NTIS, Pub. NO. PB-245-017-19BA,1975. (10) Hall, J. L.; Severns, G. A.; Shanks, H. R.; Joensen, A. W.; Van Meter, D. B.; Olexsey, R. A. “Environmental Emissions from a Suspension Fired Boiler While Burning Refuse Derived Fuel and Coal Mixtures”, Proceedings of the IXth Biannual Conference, ASME, Washington, DC, 1980, pp 497-512. (11) Reynold, L. M. Bull Enuzron Contam Toxzcol 1969,4,12843.
(12) Buser, H. R.; Bosshardt, H. P. Chemosphere 1978,7,165. (13) Blake, D. E. “Source Assessment Sampling System: Design and Development“, EPA-600/7-78-018,1978. (14) Junk, G. A,; Richard, J. J.; Grieser, M. D.; Witiak, D.; Witiak, J. L.; Arguello, M. D.; Vick, R.; Svec, H. J.; Fritz, J. S.; Calder, G. V. J . Chromatogr. 1974,99,745-62. (15) Woolson, E. A. J . Assoc. O f f .Anal. Chem. 1974,57,604-9. (16) Armour, J. A. J. Assoc. Off. Anal. Chem. 1973,56,987-93. (17) William, D. T.; LeBel, G. L.; Furmaczyk, T. Chemosphere 1980, 9, 45-50. (18) Macheod, K. A. “Sources of Emission of Polychlorinated Biphenyls into the Ambient Atmosphere and Indoor Air”, NTIS Pub. No. PB 297122,1979. (19) Sebastian, F. P.; Kroneberger, G. F.; Lombana, L. A.; Napoleon, J. M. Proc. Am. Ind Chem. Eng. Workshop 1974,5,67-72. (20) Harvey, G. R.; Sheinhauer, W. G. Atmos Enuiron. 1974, 8, 777-82. (21) Bidleman, T. F.; Rice, C. P.; Olney, C. E. In “Marine Pollutant Transfer”; Windom, H. L., Duce, R. A., Eds; Health and Co.: Lexington, MA, 1978;pp 323-51. (22) Murphy, T. J.; Rzeszutko, C. P. “Polychlorinated Biphenyl in Precipitation in Lake Michigan Basin”, NTIS Pub. No. PB-286363,1978. (23) Bidleman, T. J.; Christensen, E. J. J . Geophys. Res. 1979,84, 7857-62. (24) Fuller, B.; Gordon, J.; Kornreich, M. “Environment Assessment of PCBs in the Atmosphere”, EPA Report No. EPA-450/3-77-045, The Mitre Corp., McLean, VA 1977.
Received for reuiew December 29,1980. Accepted April 23,1981. This research was supported by the Assistant Secretary for Enuironment, Office of Health and Enuironmental Research, WPAS-HA-02-04-01 and HA-02-03-02,
NOTES
Characterization of Copper Binding Capacity in Lake Water Harry Blutstein”7 and Roman F. Shaw Department of Inorganic and Analytical Chemistry, Latrobe University, Victoria 3083, Australia
Introduction T o assess the impact of heavy metal pollutants on aquatic biota, toxicity testing correlating total metal concentration has been shown to be misleading because it ignores metal speciation (1-4). For example, Chakoumakos e t al. ( 5 ) have shown that free copper ions and hydroxyl species are toxic forms of copper t o cutthroat trout, while carbonatocopper species are nontoxic. Particulate and organic material have also been shown t o modify the toxicity of trace metals (6). Elaborate analytical schemes have been developed t o measure different species (7, 8) by using anodic stripping voltammetry (ASV). In an untreated sample this technique detects only “labile” metal species, which are operationally defined and include ionic, and some dissociable, complexed metal species. Other fractions can be determined quantitatively by subjecting the sample to various physicochemical treatments, so as to convert other forms to labile metal. The released metal is determined by difference, and, depending on the sample pretreatment, it is possible to obtain estimates + Present address: Laboratory Services Branch, Environment Protection Authority, 240 Victoria Parade, East Melbourne, Victoria 3002. Australia.
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of metal associated with organic material, colloids, and particulate matter. An alternative approach is indirect, in that the concentration of complexing agents is estimated. A filtered sample is titrated with ionic copper and the labile copper is measured by differential pulse anodic stripping voltammetry (DPASV). The intercept of the resultant bilinear amperometric curve yields the apparent complexing capacity (9). Although this is the most frequent method used, doubts have been expressed of the accuracy of this approach ( 1 0 , l l ) . Other techniques have been used to estimate the apparent complexing capacity such as the ion-selective electrode for titration with copper(I1) ions (12, 13), solubility determinations (14),and the ion exchange equilibrium method (15).It would be useful t o be able to identify the components that make up the total binding capacity. Adsorption onto particulate matter and colloids, and chelation with organic compounds, may contribute. Smith (16) combined ultrafiltration with complexing capacity measurements so that he could determine the apparent complexing capacity of specific molecular weight fractions. However, these measurements were restricted to the filtered portion of the sample. In this work the respective binding capacities of filtered and unfiltered aliquots of a lake water sample have been measured. 0013-936X/81/0915-1100$01.25/0 @ 1981 American Chemical Society
