Environ. Sci. Technol. i987, 21, 869-875
Hodgsen, J. F. Soil Sei. SOC.Am. Proc. 1960,24,165-168. Farrah, H.; Pickering, W. F. Water, Air, Soil Pollut. 1978, 9,491-498. Gadde, R. R.; Laitenen, H. A. Anal. Chem. 1974, 46, 2022-2026. Kinniburgh, D. G.; Syers, J. K.; Jackson, M. L. Soil Sci. SOC.Am. Proc. 1975,39,464-470. Corey, R. B. In Adsorption of Inorganics at Solid-Liquid Interfaces;Anderson, M. A., Rubin, A. J., Eds.; Ann Arbor Science: Ann Arbor, MI, 1981; pp 161-182. Farley, K. J.; Dzombak, D. A,; Morel, F. M. M. J. Colloid Interface Sci. 1985, 106, 226-242. Davis, J. A.; Fuller, C. C.; Cook, A. D. Geochim. Cosmochim. Acta, in press. Leckie, J. 0.;Appleton, A. R.; Ball, N. B.; Hayes, K. F.; Honeyman, B. D. Electric Power Research Institute: Palo Alto, CA, in press.
Leckie, J. 0.; Benjamin, M. M.; Hayes, K. F.; Kaufman, G.; Altmann, S. Final Report EPRI-RP-910-1;Electric Power Research Institute: Palo Alto, CA, 1980. Dugger, D. L.; Stanton, J. H.; Irby, B. N.; McConnelI, B. L.; Cummings, W. W.; Maatman, R. W. J. Phys. Chem. 1964, 68, 757. Kinniburgh, D. G.; Jackson, M. L. In Adsorption of Inorganics at Solid-Liquid Interfaces;Anderson, M. A., Rubin, A. J., Eds.; Ann Arbor Science: Ann Arbor, MI, 1981; pp 91-160. Schindler, P. W. In Adsorption of Inorganics at SolidLiquid Interfaces;Anderson,M. A,, Rubin, A. J., Eds.; Ann Arbor Science: Ann Arbor, MI, 1981; pp 1-49. James, R. 0.;Healy, T. W. J . Colloid Interface Sei. 1972, 40, 53. Benjamin,M. M.; Leckie, J. 0. Environ. Sci. Technol. 1981, 15, 1050-1057. Davis, J. A.; Leckie, J. 0. J. Colloid Interface Sci. 1978, 67,90-107.
Schultz, M. F. MSE Thesis, University of Washington, Seattle, WA, 1985.
Received for review July 24, 1986. Revised manuscript received February 2, 1987. Accepted April 1, 1987.
Experimental System for Investigating Vapor-Particle Partitioning of Trace Organic Pollutantst Wllllam T. Foremantis and Terry F. Bidleman*itglI Department of Chemistry and Marine Science Program and Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, South Carolina 29208
rn An experimental system was designed to equilibrate urban air particulate matter on a filter with controlled vapor concentrations of semivolatile organic compounds (SOC) at 20 "C under simulated high-volume air sampling conditions. Vapor-particle distributions (V/P) for organochlorine pesticides and three- to four-ring polycyclic aromatic hydrocarbons were estimated from laboratory measurements of the apparent partition coefficient A[TSP]/F, where A and F a r e the adsorbent- and filterretained SOC concentrations (ng/m3) and [TSP] is the total suspended particle concentration (pg/m3). Laboratory measured A[TSP]/F correlated well with the subcooled liquid-phase vapor pressures ( p o L )of the SOC tested but not with their solid-phase vapor pressures. Comparisons of field and laboratory A[TSP]/F are made, and implications of pol-dependent partitioning to the atmospheric chemistry of SOC are discussed.
Introduction Semivolatile organic compounds (SOC), including three to four ring polycyclic aromatic hydrocarbons (PAH), pesticides, polychlorinated biphenyls (PCB), dibenzo-pdioxins (PCDD), and dibenzofurans (PCDF), are present in air in gaseous and particulate forms. Knowledge of SOC vapor/particle distribution (V/P) is important to understanding the atmospheric transport of these pollutants, because V/P influences the process by which the contaminant returns to the earth and the atmospheric residence time. V/P is also an important consideration in developing This is Contribution No. 684 of the Belle W. Baruch Institute.
*Departmentof Chemistry.
f Present address: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309. "Marine Science Program and Belle W. Baruch Institute for Marine Biology and Coastal Research.
0013-936X/87/0921-0869$01.50/0
sampling methods and designing pollution control systems. Factors influencing V/P in ambient air can be investigated with conventional high-volume (hi-vol) sampling. Air is pulled through a glass-fiber filter (F) to collect particles and then through an adsorbent trap (A) to collect the vapors. The apparent V / P is operationally estimated by the adsorbent-to-filter retained ratio (A/F). Values of A/F for organochlorines (OC) (1) and PAH (2,3)were determined from hi-vol field experiments in several cities. Results of these studies showed that A/F was related to the average sampling temperature (T,kelvin) and the total suspended particle concentration (TSP, pg/m3) by log (A[TSP]/F) = m / T b (1) where A is the adsorbent-retained SOC and F is the filter-retained SOC, both in nanograms per cubic meter. A[TSP]/F has units of nanograms of SOC per cubic meter of air inanograms of SOC per microgram of particles = vapor concentration in air + concentration on particles =
+
CA/CP.
The strong dependence of A/F on temperature suggested a general relationship based on SOC volatility. Plots of field A[TSP]/F at 20 "C vs. OC and PAH vapor pressures revealed that A/F partitioning is controlled largely by the subcooled liquid-phase vapor pressure boL) rather than the solid-phase vapor pressure @Os) ( I , 4 ) . How closely A/F represents the true V/P in the atmosphere remains uncertain. Sampling times of 12 h or more are usually necessary to collect enough SOC for analysis. During the collection period, SOC concentrations and especially ambient temperatures are likely to change, resulting in blow-off losses from or adsorption gains to the particle load on the filter (4-10). Other factors that may affect A/F are variations in particulate matter, including size distribution, surface area, and content of carbonaceous material. The influence of relative humidity on A/F is also unknown. Additional considerations include the possibility
0 1987 American Chemical Society
Environ. Sci. Technol., Vol. 21, No. 9, 1987 869
Vapor Generation
Filler Holders
Columns
I
Particle Loaded
I
- Serum C a p - Syringe Barrel
Syringe Needle
Analyte Coated Glass -Beads or Sand
Glass Wool
0.2 u m Acrodisc
Charcoal
Figure 1. Laboratory system for equilibrating particle-loaded filters with SOC vapors.
of degradative losses, for example, in reactions of PAH with O3 and NO, (11-16). In a previous paper (I) we estimated vapor-particle partitioning from ambient air sampling in several cities. In this companion paper, we describe a laboratory equilibration system for investigating the adsorption of OC and PAH vapors to particle-loaded filters. The apparatus was designed and constructed to closely simulate a hi-vol sampler but was operated under controlled temperature and vapor concentration conditions not attainable in field work.
Experimental Section Field Collection and Analysis of Particles. Particle-loaded filters used in laboratory equilibration experiments were obtained by pulling air at approximately 1.0 m3 min-' for 45-76 h through a 20 X 25 cm type A/E glass-fiber filter (Gelman Sciences, Ann Arbor, MI) with conventional hi-vol TSP collectors (General Metal Works Inc., Cleves, OH) (17). Filters were precleaned by wrapping them in solvent-rinsed aluminum foil and baking at 425 "C for 6 h. Three sets of particle-loaded filters were collected on the roof of a two-story building in Columbia, SC, used by the South Carolina Department of Health and Environmental Control as a TSP monitoring site. Four or five particle-loaded filters were obtained on each sampling date, one of which was used for total carbon (TC) and total nitrogen (TN) analyses. An additional sampler containing a filter backed with three 7.8 cm diameter X 7.6 cm thick polyurethane foam (PUF) plugs (density = 0.022 g ~ m - provided ~) both particle and vapor-phase SOC collection. Details for preparing and precleaning PUF plugs and collecting field samples have been published elsewhere (2, 18-21). Before and after sampling, filters were desiccated overnight over anhydrous calcium sulfate (Drierite) and weighed to obtain TSP. TC and TN were determined on 2 cm diameter disks cut from four to six sections of a particle-loaded filter with a cork borer. Each disk was finely ground with an agate mortar and pestle. The ground material (19-24 mg) was weighed into an aluminum boat with a Sartorius Model 4530 microanalytical balance. Oxidizing catalyst (type 185, Hewlett-Packard, Avondale, PA) was added to each boat, and the samples were combusted in a Hewlett-Packard Model 185B CHN analyzer under standard operating conditions (22). NBS standard cystine 143B (29.99% C, 11.66% N) was used to prepare a calibration curve. Combustion of 0.12-0.24 mg of activated carbon gave 84 f 1%recovery. Blanks were analyzed to correct for TC and TN in the filter matrix. Analytical procedures for extraction, cleanup, fraction, and quantification of PAH and OC on filters and PUF plugs are detailed below. Vapor-Particle Equilibration System. The apparatus used to equilibrate particle-loaded filters with SOC vapors (V-P experiments)is shown in Figure 1. A prefilter assembly to provide particle- and SOC-free laboratory air 870
Envlron. Sci. Technol., Vol. 21, No. 9, 1987
...
I
Mixing Chamber Flgure 2. Apparatus used to generate vapor-phase SOC.
was composed of a glass-fiber filter in a 20 X 25 cm hi-vol filter holder followed by an 8.3 cm diameter X 3 cm thick bed of activated carbon (Fisher Scientific, 6-14 mesh, resieved, precleaned by extraction in a Soxhlet apparatus with acetone and dichloromethane, and vacuum-dried at 40 "C) sandwiched between two 1.5 cm thick PUF plugs. The prefilter was followed by a 12.5 X 15.0 X 100 cm stainless steel mixing chamber where SOC vapors were introduced from generator columns and then by two 20 X 25 cm filter holders attached face-to-face and containing the particle-loaded (front) and clean (back) filters. SOC vapor concentrations behind the filters were monitored by two 7.8 cm diameter X 7.6 cm thick PUF plugs in an aluminum canister, which was attached by 5 m of flexible hose to a Rotron DR-313 brushless pump (Rotron Corp., Woodstock, NY). The apparatus was located in a room thermostated at 20 f 1 "C, and the pump exhaust was vented to the outside. All seals were made with solventrinsed silicone rubber gaskets (Niantic Rubber, Cranston, RI). Flow rates were related to the pressure drop behind the sampling train by using an orifice calibrator. Measurements of pressure drop in the system in front of and immediately following the loaded filter holder indicated reductions of 0.040 and 0.063 atm, respectively. Generator columns to produce SOC vapors are shown in Figure 2. The columns were prepared by packing precleaned glass beads (2-mm diameter) or sand (6-14 mesh, washed with 12 M HC1 and deionized water and baked at 1000 "C for 6 h) into a solvent-rinsed 5- or 10-mL plastic syringe barrel. Approximately 50-75 mg of test compound in dichloromethane was added, and the column was allowed to stand uncapped overnight in a hood to ensure complete evaporation of the solvent. Silanized glass wool was placed on top of the support, and the column was capped with either a rubber serum cap (most volatile compounds), a one-holed No. 0 rubber stopper (column flows of 7-20 mL/min), or a plug of PUF (least volatile compounds,column flows >20 mL/min) depending on the flow rate (vapor concentration) requirements. Syringe needles (16-27 gauge, 1.2-0.22-mm i.d.) pushed through the serum cap provided a method of varying flow rates (2-7 mL/min) through generator columns containing the more volatile SOC. The Luer-lock end of the generator column was fitted with an Acrodisc CR 0.2-pm filter (Gelman Sciences), and the tapered end of the Acrodisc was connected to the mixing chamber of the equilibration apparatus with a rubber stopper. Before beginning the V-P experiments, the generator columns were preconditioned by running the apparatus for 3-4 h without the test filters in place. Test compounds were phenanthrene (PH), anthracene (AN),fluoranthene (FLA),and pyrene (PY), obtained from the Foxboro Co., New Haven, CT, and hexachlorobenzene (HCB), a- and y-hexachlorocyclohexane (a-HCH and
y H C H ) , cis- and trans-chlordane, 2,2-bis(2-chlorophenyl)-1,l-dichloroethene (p,p'-DDE), and 2,2-bis(2chloropheny1)-l,l,l-trichloroethane (p,p'-DDT) obtained from the EPA Pesticide and Industrial Chemicals Repository, Research Triangle Park, NC. Procedure. V-P experiments were conducted by exposing two 20 X 25 cm filters to vapors of test compounds at 20 f 1"C for varying times and air volumes. The front filter was loaded with approximately 100-250 mg of urban air particulate matter collected in Columbia, SC, as described above. The back filter was a blank to correct for adsorption to the filter matrix. The first plug in the PUF trap behind the filters was changed every 2-3 h and analyzed to determine changes in vapor concentration with time. The backup plug acted as a procedural blank, except for HCB and a-HCH, which were volatile enough to exhibit slight breakthrough from the first plug (G?% of the total vapor-phase material collected during a run). Analytical Methods. Filters were cut into strips and refluxed for 24 h in dichloromethane. PUF plugs were extracted in a Soxhlet apparatus for 24 h in petroleum ether. Extracts were reduced to 5 mL on a rotary evaporator, and filter extracts were transferred to hexane during this step. For V-P experiments involving only OC, column chromatography cleanup and fractionation was not necessary, and filter and plug extracts were analyzed at this point by electron capture gas chromatography (GC-ECD) as described below. Field samples and V-P experiment filter samples involving PAH were cleaned and fractionated with an alumina-silicic acid column chromatography procedure previously described (2),except that the column was eluted with 25 mL of petroleum ether (fraction 1)and then 20 mL of 30% dichloromethane petroleum ether (fraction 2). Fraction 1contained PCB, HCB, and p,p'-DDE; fraction 2 contained PAH, HCH, p,p'-DDT, cis- and trans-chlordane, trans-nonachlor, and toxaphene components. Fractions were reduced to 2 mL with a gentle stream of Nz and transferred to 10-mL centrifuge tubes. Fraction 2 eluates were transferred to hexane during this step. Sample volumes were then adjusted for quantitative analysis with a stream of N2. PAH in fraction 2 were analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection. The HPLC system was the same as that previously described (2),except that the compounds were separated on a 25 cm X 4.6 mm i.d. Vydac 201TP104 10-pm reversed-phase C-18 column (The Separations Group, Hesperia, CA), preceded by a MPLC NewGuard guard column containing an RP-18 cartridge (Brownlee Laboratories, Santa Clara, CA). Field samples analyzed for three to five ring PAH were run with the following solvent program: initial 55% CH3CN-HzO; increasing at 2.4% CH3CN min-l to a final 95% CH3CN-H20 mixture. V-P experiment samples were analyzed only for PH, AN, FLA, and P Y by using a 65% CH3CN-HzO isocratic mobile phase. OC were determined by GC-ECD after the extracts were shaken with concentrated H2S04to remove interfering compounds. Analyses were carried out on a Varian 3700 instrument using splitless injection (1-2 pL, 30 s), with the column held at 90 "C for 1 min and then increased at 5 deg/min to 275 "C. Either a 12 m or a 25 m X 0.22 mm i.d. BP-5 column (SGE Inc., Austin, TX) with a 0.25-pm film thickness was used. Other analysis conditions were as follows: H, carrier gas 2 mL/min; split flow 80 mL/min; injector and detector temperatures 220 and 320 "C, respectively. Chromatographic data were collected with a
Table I. Filter Collection Data and Aerial Concentrations of SOC in Columbia, SC sampling date Oct 30Nov 1,
April
1984
m3 of air temperature, "C median range TSP, wg/m3 total carbon, % of TSP total nitrogen, % of TSP organochlorines (A + F), ng/m3c y-HCH trans-chlordane cis-chlordane trans-nonachlor p,p'-DDE p , p '-DDTd Aroclor 1016 Aroclor 1254 toxaphene PAH (A + F)c fluoranthene pyrene benzo [h]fluoranthene benzo [a]pyrene benzo[ghi]perylene + dibenz[a,h]anthracene indeno[ 1,2,3-cd]pyrene coronene
Aug
2-5, 1985
26-28, 1985
126gaa2800b 2006," 4850b 1535," 3300b 20.6 18.9-29.4 46.6 16
18.3 5.0-28.3 49.8 19
25.5 22.2-31.7 59.4 12
2.6
2.0
1.6
0.31 0.81 0.40 0.31 0.11 0.12 0.55 0.47 1.5
0.14 0.29 0.14 0.11 0.033 0.026 0.74 0.32 0.43
0.43 1.3 0.78 0.50 0.17 0.068 1.7e 0.59 1.4
4.9 6.3
7.2 12 0.10 0.11 1.0
12 16 0.078 0.12 0.55
0.54
0.33
0.84
0.51
Filter-PUF sampler used for field SOC collection. Filter-only samplers used to obtain particle-loaded filters for laboratory equilibration experiments. HCB, a-HCH, phenanthrene, and anthracene were not quantitatively collected because of breakthrough losses on PUF. dEstimated concentration due to coelution with toxaphene components. e PUF only.
Hewlett-Packard 3390A or a Shimadzu Chromatopac CR3A integrator. PAH and OC were quantified from peak area and height, respectively. Results and Discussion Collection and filter analytical data and SOC aerial concentrations for the three field collection periods are summarized in Table I. Concentrations of TSP, TC, OC, and PAH were comparable to those previously reported for Columbia (2, 20, 21, 23). Although present, HCB, a-HCH, PH, and AN are not reported, since these compounds were not quantitatively collected on PUF at the high air volumes sampled over 48 h. Ten V-P experiments were conducted over the range of vapor concentrations and equilibration times (air volumes) in Table 11. Up to eight compounds could be tested during a single run. No y H C H generator column was used for four of the seven runs, even though this compound was detected in the vapor phase and on the particle-loaded filter for these experiments. Subsequent analysis of material in the a-HCH generator column revelaed that the y isomer was present at 0.3% of the a-HCH, so the low levels of y H C H in these experiments probably arose from this source. When ambient air was sampled, filter-retained quantities of the three-ring PAH and the more volatile organochlorines (HCB, HCH, and chlordanes) were often near the detection limit at 20 "C. Vapor concentrations of these SOC in the V-P experiments were maintained consideraEnviron. Sci. Technol., Vol. 21, No. 9, 1987
871
Table 11. Range of Experimental Conditions and Residues on Back Filter in Laboratory Vapor-Particle Equilibration Experiments
compound
expts
vapor concn, ng/m3
phenanthrene anthracene fluoranthene pyrene hexachlorobenzene CY-HCH Y-HCH trans-chlordane cis-chlordane p,p'-DDE p,p'-DDT
6 5 7 5 7 7 7 7 8 8 6
445-574 22-30 4.8-45 9.7-22 30-87 53-160 1.0-252 17-56 8.7-40 0.11-27 0.013-1.5
air vol, m3
av % on back filtera
153-1357 153-1357 153-1357 153-1357 153-828 229-794 153-794 229-794 153-794 153-1357 229-1357
NDb NDb 1.2 f 1.1 0.2 f 0.5 5.3 f 5.1 6.5 f 5.3 7.4 7.1 10.6 f 10.3 6.3 f 6.7 2.3 f 2.3 6.9 f 5.0
*
"(ng on back filter f ng on front particle-coated filter) X 100. bNot detected. (Limits of detection were 7 ng of P H and 1.5 ng of AN.)
-2.5
-
-3.0
-
e
rn
-3.5rn C Y
0" -4.00
2
-4.5
-
-5.0 - 2 - 1
0
1
LOG C A
.
ra-HCH HCB
compound
. I
0.101
//+ p,p'-DDT
t
0 . 0 1 1 , 0
1
150
,
[
300
,
I
Table 111. Comparison of A [TSP]/F from Laboratory Experiments and Field Studies
C-CHLOR
-
-
,
450
1
800
,
3
Figure 4. Concentration of particle-adsorbed OC (C,)vs. concentration in the vapor phase (C,) for three OC from six to eight V-P experiments.
PH
12-
2
(nglm3)
1
750
,
I 900
phenanthrene anthracene fluoranthene pyrene hexachlorobenzene a-HCH Y-HCH trans-chlordane cis-chlordane p,p'-DDE p,p'-DDT
A[TSP]/F, 20 "C" laboratoryb field" (9.4 f 1.1) x (6.5 f 1.1) x (5.0 f 1.5) x (2.8 f 0.7) x (6.8 f 2.9) X (2.3 0.4) x (8.1 f 1.6) X (1.1 f 0.2) X (1.0f 0.1) x (4.5 1.2) x (5.6 f 1.8) X
104 104 103 1.3 x 103, 2.8 x 103 103 1.2 x 103, 1.9 x 103 lo5 5.7 X lo4, 9.7 X 105 7.6 x 104, 1.8 x 1 0 5 d lo4 lo4 9.1 X 104 103 4.0 x 103 lo2 6.1 X lo2
nunits of A[TSP]/F are ng of SOC/m3 of air + ng of SOC/pg of particles. *Average f one standard deviation. Obtained from plots of eq 1. First PAH value taken from ref 2; second PAH value taken from ref 3. All OC field values taken from ref 1. dSecond field value for HCB and a-HCH extrapolated from eq 1 plots of field data using slope m' = -AHv,L/2.3R as described in ref 1. e Includes trans- and cis-chlordane and trans-nonachlor.
m3 A I R
Figure 3. Changes in vapor concentration (C,) with air volume in laboratory equillbration system.
bly above those in Columbia ambient air (Tables I and 11) to obtain easily measureable levels on the V-P experiment filters. Filter-retained fractions of the four-ring PAH, p,p'-DDE, and p,p'-DDT were greater, and for these SOC we were able to work at vapor concentrations down to those in ambient air (Tables I and 11). Figure 3 depicts changes in vapor concentration (CA) behind the exposed filters with air volume (time). The PAH curves represent one run totaling 587 m3 of air (about 22 h) and the OC a different experiment totaling 770 m3 (30 h), with each point representing 3-h intervals. Concentrations of the more volatile compounds stabilized quickly and remained reasonably constant over the entire run. A lag time of about 3-9 was observed before the less volatile compounds reached stable levels. In these cases, CAwas obtained by using the final points in the plateau region, e.g., the mean of the last four p,p'-DDT points in Figure 3. The rapid attainment of steady state by the more 872
Environ. Sci. Technol., Vol. 21, No. 9, 1987
volatile compounds suggests that the lag time observed for the heavier SOC was due to their adsorption by the particles on the filter. SOC residues on backup filters averaged 10% or less of those on the particle-loaded filters (Table 11),and an exposure experiment conducted with two clean filters in the V-P apparatus reveded that some SOC were being adsorbed by the filter matrix itself. Migration of very small particles from the particle-loaded filter might also account for SOC on the back filter, but since back filters appeared white, this possibility was not considered likely. Back filter quantities were subtracted from those on the front filter to provide the mass of SOC on particles. Figure 4 is a log-log (Freundlich) plot of Cp vs. CA for three OC. Slopes of these plots were 0.96,0.93, and 0.87 for y-HCH, p,p'-DDT, and p,p'-DDE, respectively, and r2 values were 0.995, 0.964, and 0.984 for the same compounds. The fact that the slopes were close to unity indicates that the partition coefficient A[TSP] / F = C A / C ~ was nearly constant over 2 orders of magnitude change in CA.
Table IV. Saturation Vapor Pressures of Test Compounds
t
5.5
n
d
t-CHLOR C-CHLOR PnP'-DDE
-
0
200
400
600 3 M
800
6r
1000 1200 1 4 0 0
10-5
10-5 10-5
10" 10-7
' 8 2.
i4L
t
t
156 230 159 112 106 106 89 109
AIR
t
5.5
N
111
P0S
9.3 x loF4 4.3 X 5.1 X 3.2 X 10-3 1.2 x 2.5 X 10-4 2.8 x 3.9 X 3.0 X 2.5 X 10-6 1.6 x 10-4
nAverage p 0 s of values reported in the literature and summarized in ref 31, except for the chlordanes. poLwere estimated from p o s with eq 2 , except for the chlordanes, whose p o L were determined by a GC method (31). bEstimated from poL using eq 2.
Flgure 5. log A [TSPIlFat 20 "C for OC vs. air volume. Equilibration times ranged from about 9 h at 150 m3 to 54 h at 1360 m3. Compound abbreviations given under Experimental Section.
0
poL
6.1 x 4.1 X 4.2 X 7.5 X 1.6 x 6.3 X 2.4 x 2.9 X 2.2 X 1.2 X 1.2 x
101 216
phenanthrene anthracene fluoranthene pyrene hexachlorobenzene wHCH Y-HCH trans-chlordane cis-chlordane p,p'-DDE p,p'-DDT
+
2.0 0
," 5.0
vapor pressure, Torr, 20 "C"
melting point, "C
54
,
3
4
PH
.
3.
6m
AN ~
-7
-6
-5
-4
-3
LOG P i , TORR FLA
PY
0
200
400
600 800 3 M AIR
Figure 7. Relationship between the average laboratory A [TSPIIF and p o s at 20 "C for OC (1 = HCB, 2 = a-HCH, 3 = y-HCH, 4 = trans-chlordane, 5 = cis-chlordane, 6 = p,p'-DDE, and 7 = p,p'DDT).
//
1000 1 2 0 0 1 4 0 0
Flgure 6. log A [TSP] I F at 20 "C for PAH vs. air volume. Abbreviations given under Experimental Section.
A[TSP]/F from V-P experiments are summarized in Table I11 and Figures 5 and 6. Slopes of A[TSP]/F vs. m3 of air were not significantly different from zero a t the 95% confidence level for any of the OC or PAH. The linearity of the Freundlich plots (Figure 4) and the constancy of A[TSP]/F with air volume (Figures 5 and 6) are rather remarkable, considering that three different lots of urban air particulate matter were used for the experiments. Field studies of OC and PAH partitioning at various urban sites have likewise indicated that the particulate matter source is less important than other factors (1-3). Saturation vapor pressures of the crystalline solid (Pos) and subcooled liquid (PoL)PAH and OC are given in Table IV. The vapor pressures can be interconverted through 1n (P"L/P"~)= 6*8(3"m - T ) / T (2) where T, and T a r e the melting point and ambient temperatures (kelvin) and 6.8 is a coefficient related to the entropy of fusion (24). Differences between p o s and poL increase rapidly with melting point. At 20 "C, p,p'-DDE (mp 89 "C) has a poL5 times higher than p o s ,whereas the difference is a factor of 130 for HCB (mp 230 "C) (Table IV). Figure 7 shows a log-log plot of the average laboratory A[TSP]/F for OC a t 20 "C (Table 111)vs. p o s . This plot
"0 N
u
4
0
0
2
*-AN
3I
4
2
-7
-6
LOG
-5
-4
-3
PF, T O R R
Figure 8. Relationship between the average laboratory A [TSPIlFand p o L at 20 "C for OC (B) and PAH ( 0 ) . OC numbering same as in Figure 7.
shows some scatter (r2= 0.800), especially for the higher melting compounds a-HCH and HCB (Table IV). A similar plot vs. poL (Figure 8) gave an excellent correlation (r2= 0.998). A[TSP]/F from hi-vol collections in several cities were also well correlated with poL(1,251. The vapor pressure over a solid is reduced relative to its subcooled liquid because of the crystal lattice energy. When individual solute molecules condense on an indifferent surface (i.e., physical adsorption), no solute crystal lattice is present, and the adsorption might be expected to be controlled by poLrather than pas. Several lines of evidence Environ. Sci. Technol., Vol. 21, No. 9, 1987
873
1
60 "0
AN
A
-
FLA
N
.
4 -
n fn + v
3-
0 A!
ELD
u
.ePH
P Y
LA
J
4
A A -7
-6
-5
-4
0 -3
-7
+
+
indicate that some environmentally important phase distributions are controlled by liquid-phase physical properties: Yamasaki et al. (25) found that the heats of adof PAH onto urban air particulate matter sorption (A",) were close to the subcooled liquid PAH heats of condensation ( A H c , ~ )We . observed similar behavior for OC ( I ) . Breakthrough of PAH and OC vapors on solid adsorbent collection traps is better correlated with poLthan with p o s (26, 27). Bioconcentration factors and octanol-water partition coefficients are inversely related to the water solubility of the subcooled liquid phase (28). Figure 8, along with field data ( I ) , supports poLas the relevant property for describing A/F partitioning of nonpolar OC. A[TSP]/F for the four PAH in relation to the OC are also shown in Figure 8. The PAH correlation to poL(r2 = 0.904) is not as close as in the case of the OC (r2= 0.998), though it is much better than the correlation with p o s (r2 = 0.445). The PAH also exhibit a somewhat greater affinity for the particle-loaded filter than do the OC. One explanation is that PAH are planar molecules and may be adsorbed more strongly than most of the OC, only one of which is flat (HCB). As pointed out in our earlier paper ( I ) , differences between H A and H c , L should be larger for PAH than for OC to support this hypothesis. However, field results indicate that fitted HA - AH,,, for OC ( I ) were about the same as those for PAH (25). An alternate explanation is that urban air particulate matter contains some nonexchangeable PAH. These PAH molecules may be bound to highly active sites on the particle surface or they may have become trapped within the particle matrix. This bound material would be unavailable for V-P partitioning but would be extracted with solvent during analysis and counted along with the exchangeable fraction. Eiceman and Vandiver (29) presented evidence for nonexchangeable PAH adsorption to fly ash at low vapor concentrations. A[TSP]/F from field (1) and laboratory experiments with OC are c.ompared in Table I11 and Figure 9. Also included in this plot is a field value for higher molecular weight PCB (Aroclor 1254),with a mixture vapor pressure of 1.4 X Torr a t 20 "C (1). The field and laboratory agreement is good for the chlordanes, p,p'-DDE, and p,p'DDT, and the field Aroclor 1254 point is also close to the laboratory line. However, the agreement is less satisfactory for a-HCH and HCB. As mentioned previously ( I ) , filter-retained quantities of these two volatile OC in field samples were difficult to determine except at cold tem874
Environ. Sci. Technol., Vol. 21, No. 9, 1987
"
-6
" " " -5 -4 -3
L O G POL, T O R R
LOG P i , T O R R
Figure 9. Comparison of laboratory (H) and field (circles) A [TSPIIF at 20 "C for OC. Compound identifications 1-7 given in Figure 7; 8 = trans- cis-chlprdanes transdnonachlor,and 9 = Aroclor 1254. Ranges of field A [TSPIIF are shown for HCB and a-HCH assuming eq 1 fitted slope m = AHA/2.3R (0)and slope m' = AHc,,/2.3R (broken circles) as described in ref 1.
B(a1P B ( ~ ) P
"
Figure 10. Comparison of laboratory (0)and field (triangles) A [TSPIIF at 20 "C for PAH: A = PAH in Tokyo, ref 3; A = PAH in Columbia, ref 2; BkF = benzo[k]fluoranthene; BaP and BeP = benzo[a]- and benzo[e]pyrene.
peratures, and the uncertainties in extrapolating eq 1plots to 20 "C were large. This may in part account for the field and laboratory differences seen in Figure 9. The agreement for a-HCH can be improved by assuming a slope for its eq 1 plot equal to m' = H c C / 2 . 3 R (dashed circle in Figure 9) (1). However the situation of HCB is not greatly improved. A comparison of field (triangles) (2,3) and laboratory (circles) A[TSP]/F for the PAH is given in Table I11 and shown in Figure 10. The open triangles are field data from Columbia (2), and the solid triangles are the Tokyo field data of Yamasaki et al. (3). Yamasaki et al. were unable to separate P H and AN by GC, but since urban air contains 1 order of magnitude more P H than AN (2), the A[TSP]/F was plotted against the poL of PH. As with HCB, the PAH field A[TSP]/F fell slightly below their laboratory values. An explanation for PAH and also HCB may lie in the different ways that SOC become bound to particles in urban air vs, in V-P experiments. Vapors introduced in the V-P experiments probably condensed on the surface of the particles on the filter. SOC on filters from the field collections also included material trapped within the particle matrix or strongly adsorbed to active sites, Le., nonexchangeable SOC. Differences between laboratory and field A[TSP]/F might be expected to be greatest for SOC that become incorporated into the particles at the time of formation and less for SOC that condense onto the particles later in their lifetimes. SOC in the former category include combustion-derived compounds such as PAH and HCB (XI),and it is for HCB that we found the greatest difference between laboratory and field A[TSP]/ F . OC pesticides probably enter urban air as vapors via transport from agricultural land or by evaporation from treated areas within the city (e.g., chlordane, used in structural termite control) and then condense onto urban aerosols. For these compounds, laboratory and field A[TSP]/F agree well. Acknowledgments Thanks to John Cooper and Gene Slice of the South Carolina Department of Health and Environmental Control for their help in sample collection and to Eric Tappa for help with TOC measurements. Special thanks to Mark Zaranski, Michael Walla, and Jim Saad for technical assistance. Registry No. a-HCH, 319-84-6; 7-HCH, 319-86-8;p,p'-DDE, 72-55-9; p,p'-DDT, 50-29-3; phenanthrene, 85-01-8; anthracene, 120-12-7; fluoranthene, 206-44-0; pyrene, 129-00-0; hexachlorobenzene, 118-74-1; trans-chlordane, 5103-74-2; &-chlordane,
Environ. Sci. Technol. 1987, 21, 875-883
(16) Pitts, J. N.,Jr.; Sweetman, J. A.; Zielinska, B.; Winer, A. M.; Atkinson, R. Atmos. Environ. 1985, 19, 1601-1608. (17) Code of Federal Regulations, Title 40, Protection of the Environment; Part 50, Subchapter C, Appendix B; p 533. (18) Bidleman, T. F.; Olney, C. E. Bull. Enuiron. Contam. Toxicol. 1974, 11, 442-447. (19) Simon, C. G.;Bidleman, T. F. Anal. Chem. 1979, 51, 1110-1113. (20) Billings, W. N.; Bidleman, T. F. Atmos. Enuiron. 1983, 17, 383-391. (21) Billings,W.N.; Bidleman, T. F. Environ. Sci. Technol. 1980, 14, 679-683. (22) CHN Analyzer Model 185B Operating and Service Manual No. 00185-93001; Hewlett-Packard: Avondale, PA, 1971. (23) Shah, J. J.; Johnson, R. L.; Heyerdahl, E. K.; Huntzicker, J. J. J. Air Pollut. Control Assoc. 1$36, 36, 254-257. (24) Mackay, D.;Bobra, A.; Chan, D. W.;Shiu, W. Y. Environ. Sci. Technol. 1982, 16, 645-649. (25) Yamasaki, H.; Kuwata, K.; Yoshio, K. Nippon Kagaku Kaishi 1984,1324-1329; Chem. Abstr. 1984,101,156747p. (26) Bidleman, T.F.; Simon, C. G.; Burdick, N. F.; Feng, Y. J . Chromatogr. 1984, 301, 448-453. (27) Feng, Y.; Bidleman, T. F. Environ. Sci. Technol. 1984, 18, 330-333. (28) Mackay, D.Environ. Sci. Technol. 1982, 16, 274-278. (29) Eiceman, G. A.; Vandiver, V. J. Atmos. Environ. 1983, 17, 461-465. (30) Oberg, T.;Aittola, J.-P.; Bergstrom, J. G. T. Chemosphere 1985,14, 215-221. (31) Bidleman, T. F. Anal. Chem. 1984, 56, 2490-2496.
5103-71-9; trans-nonachlor, 39765-80-5;Aroclor 1016, 12674-11-2; Aroclor 1254, 11097-69-1; toxaphene, 8001-35-2; benzo[k]fluoranthene, 207-08-9; benzo[a]pyrene, 50-32-8; benzo[ghi]perylene, 191-24-2; dibenz[a,h]anthracene, 53-70-3; indeno[1,2,3-cd]pyrene, 193-39-5; coronene, 191-07-1. L i t e r a t u r e Cited (1) Bidleman, T.F.; Billings, W. N.; Foreman, W. T. Environ. Sci. Technol. 1986,20, 1038-1042. (2) Keller, C. D.; Bidleman, T. F. Atmos. Environ. 1984, 18, 837-845. (3) Yamasaki, H.; Kuwata, K.; Miyamoto, H. Environ. Sci. Technol. 1982, 16, 189-194. (4) Bidleman, T. F.; Foreman, W. T. In Sources and Fates of Aquatic Pollutants; Hites, R. A., Eisenreich, S. J., Eds.; Advances in Chemistry 216; American Chemical Society: Washington, DC, 1987; p p 27-56. (5) Schwartz, G. P.; Daisey, J. M.; Lioy, P. J. Am. Znd. Hyg. ASSOC.J. 1981, 42, 258-263. (6) Konig, J.; Funke, W.; Balfanz, E.; Grosch, G.; Potts, F. Atmos. Environ. 1980, 14, 609-613. ( 7 ) Spitzer, T.;Dannacker, W. Anal. Chem. 1983,55,2226-2228. (8) Grosjean, D. Atmos. Environ. 1983, 17, 2565-2573. (9) Broddin, G.; Cautreels, W.; Van Cauwenberghe, K. Atmos. Enuiron. 1980, 14, 895-901. (10) Van Vaeck, L.; Van Cauwenberghe, K.; Janssens, J. Atmos. Environ. 1984, 18, 417-430. (11) Van Vaeck, L.;Van Cauwenberghe, K. Atmos. Environ. 1984, 18, 323-328. (12) Brorstrom, E.; Grennfelt, P.; Lindskog, A. Atmos. Enuiron. 1983, 17, 601-605. (13) Brorstrom-Lunden, E.; Lindskog, A. Enuiron. Sci. Technol. 1985,19, 313-316. (14) Yokley, R. A.; Garrison, A. A.; Mamantov, G.; Wehry, E. L. Chemosphere 1985, 14, 1771-1778. (15) Pitts, J. N., Jr.; Zielinska, B.; Sweetman, J. A.; Atkinson, R.; Winer, A. M. Atmos. Environ. 1985, 19, 911-915.
Received for review July 3, 1986. Revised manuscript received February 9, 1987. Accepted April 3, 1987. This project was supported by a grant from the Agricultural Research Service, U S . Department of Agriculture, Specific Cooperative Agreement 58-32U4-4-750.
Linear Alkylbenzenes in Urban Riverine Environments in Tokyo: Distribution, Source, and Behavior Hideshige Takada" and Ryoshi Ishiwatari
Department of Chemistry, Faculty of Science, Tokyo Metropolitan University, Fukasawa, Setagaya-ku, Tokyo 158, Japan
and The distribution Of linear linear alkylbenzenesulfonates (LASS) in river sediments, suspended river particles, domestic wastes, and waste effluents around the Tokyo city area was investigated. LABs as well as LASS with alkyl carbon chain lengths in the range from to 14 were found in all environmental ples and LAS-type synthetic detergents examined. These results indicate that LABS are carried into aquatic environments as a result of the use of synthetic detergents around the Tokyo metropolitan area. Further results are (1)LABSin urban river sediments originate predominantly from untreated domestic wastes, final effluents contributing only a minor portion of the LABs in sediments, (2) the isomeric composition of the LABs changes systematically during biodegradation, and (3) the ratio of LAS to LAB decreases as fo~~ows: mnmercial synthetic detergents > suspended Particles in domestic wastes > river sediments > Tokyo Bay sediments. Introduction
Linear alkylbenzenes (LABS)whose alkyl carbon num*Address correspondence to this author at his present address: Department of Environmental Science and Conservation, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183, Japan. 0013-936X/87/0921-0875$01.50/0
bers are 10-14 are used as a raw materaial for synthesizing linear alkylbenzenesulfonates (LASs). The latter are major constituents of commonly used synthetic detergents. Recently the po~~ution of aquatic environments by LABs has been recognized In a previous paper ( I ) , we reported the presence of LABs in surficial sediments of Tokyo Bay and the Tamagawa River, which flows through the area adjacent to Tokyo and into the bay. We concluded that the LABS in these sediments have Probably ~ ~ l t from e d incomplete sulfonation of LABS during the synthesis of LAS-type surfactants and subsequent discharge to aquatic environments by the use of synthetic detergents (LASS). Eganhouse et al. (3) have also drawn a similar conclusion on the basis of detailed studies of the distribution and homologous composition of LAB in coastal sediments, suspended matter, and waste effluents in LOSAngeles and in commercial laundry detergents. Since LABs are thought to be more resistant to microbial degradation in aquatic environments than LASs ( I ) , LABs are useful as molecular tracers of domestic wastes and, more specifically, synthetic detergent pollution. In urban areas, a significant portion of domestic wastes is usually discharged into adjacent rivers, causing heavy river pollution. Ammonium (413 ABS (5),LAS (6, 71, and COprOStanOl (8-12) are well-known pollutants originating from domestic wastes. In order to control the pollution
0 1987 American Chemical Society
Environ. SCI.Technol., Vol. 21, No. 9, 1987 875
