O

<D(D<D(D<D(D(D®(D(D(D®® ccccccccccccc <D<D<D<D<D<D<D(Da)<l><l>(D<D

<D(D<D(D<D(D(D®(D(D(D®® ccccccccccccc <D<D<D<D<D<D<D(Da)<l><l>(D<D

Polycyclic aromatic hydrocarbon

FIGURE 10.3 Average mass percent contributions (gas + particle phase) of 13 PAHs collected in urban Chicago air during 15 sampling events in February/March 1995. Open bars, approximate percentage in gas phase; solid bars, approximate percentage in particle phase. 2-Ring PAHs not determined. Average percent of total mass in the particle phase was 4.4 and 42.9 for 3- and 4-ring PAHs, respectively. Averages: EPAHs = 58 ng m~3; TSP = 66 ¿ig m~3; temperature f°C (range 0 to - 4°C). Sampling apparatus, double glass fiber filters and two PUF plugs (adapted from Harner and Bidleman, 1998).

Polycyclic aromatic hydrocarbon

FIGURE 10.3 Average mass percent contributions (gas + particle phase) of 13 PAHs collected in urban Chicago air during 15 sampling events in February/March 1995. Open bars, approximate percentage in gas phase; solid bars, approximate percentage in particle phase. 2-Ring PAHs not determined. Average percent of total mass in the particle phase was 4.4 and 42.9 for 3- and 4-ring PAHs, respectively. Averages: EPAHs = 58 ng m~3; TSP = 66 ¿ig m~3; temperature f°C (range 0 to - 4°C). Sampling apparatus, double glass fiber filters and two PUF plugs (adapted from Harner and Bidleman, 1998).

consistently higher than for the daytime periods, ranging from 3000 to 6100 ng m-3 (overall average 4300) at night compared to 2000-4300 (overall average 3100 during the day). This was also true for the methylnaph-thalenes and the six other volatile PAHs. Concentrations of the 2-methyl isomer were always significantly higher than those of the 1-methyl isomer, averaging 240 vs 130 ng m 3 daytime and 710 vs 370 ng m~3 nighttime.

Concentrations of the gaseous nitroarenes, f- and 2-nitronaphthalene, and 3-nitrobiphenyl in these 18 samples were determined concurrently with the PAHs, in this case sampling with a Teflon-impregnated glass fiber filter (TIGF)/polyurethane foam (PUF) apparatus (Fig. 10.4). The PUF plugs quantitatively trapped the gas-phase nitroaromatics, but not naphthalene and biphenyl and several 3-ring PAHs.

Cass and Fraser (private communication) and Fraser et al. (1998) have used another technique, collection in an internally electropolished stainless steel canister, to collect naphthalene and the 1- and 2-methylnaph-thalenes and several monoaromatics, e.g., benzene and toluene. Semivolatile 3- and 4-ring PAHs were sampled with a glass fiber filter (GFF)/PUF system (see later).

Naphthalene concentrations averaged 6000 ng m 3 and ranged from 0.0 to 22,600 ng m~3, consistent with the measurements of Arey et al. (1989a) discussed earlier (see Table 10.10).

However, Fraser et al. (1998) noted that this canister sampling technique may underestimate the methyl-naphthalenes. Thus, their methylnaphthalenes/naph-thalene ratios were lower than those obtained by Arey et al. (1989a) using Tenax-GC solid adsorbent. This may be due to significant adsorption of the methyl isomers to the canister (Arey, personal communication). Zielinska and co-workers (1996) evaluated measurement methods for VOCs up to C20 emitted from motor vehicles and reported that C8-Cl2 hydrocarbons were more stable on the Tenax cartridge than in canisters. Similar problems with canister sampling for organics are discussed in Chapter ff.A.4e.

A variety of filters have been used to collect 5- and 6-ring particulate PAHs. These include glass and quartz fiber, GFF and QFF (e.g., Ligocki et al., f 989; Fraser et al., 1998), Teflon membrane, TM (e.g., Ligocki et al., 1989; Smith and Harrison, 1996), and Teflon-impregnated glass fiber filters, TIGF (e.g., Arey et al., 1987; Feilberg et al., 1999a).

A common type of apparatus for determining total PAH and PAC concentrations and their gas-particle partitioning that has found widespread use is shown in Fig. 10.4 and is illustrated by studies such as those by Cautreels and Van Cauwenberghe (1978), Thrane and Mikalsen (1981), Yamasaki et al. (1982), Atkinson et al. (1988a), Arey et al. (1989a, 1992), Harger et al. (1992), Sasaki et al. (1995), Gupta et al. (1996), and Fraser et al. (1998). A Teflon-impregnated glass fiber filter that collects particle-associated PAHs is followed by three glass cylinders packed with polyurethane foam ("PUF plugs") that trap the gas-phase PAHs that pass through the particle filter. The filter and the PUF plugs are extracted by organic solvents (e.g., CH2C12) and the particle-phase and gas-phase PAHs (and PACs) identified and quantified by various techniques. Generally, a conventional Hi-Vol sampler draws the polluted ambient air through the apparatus; however, given the availability of highly sensitive analytical techniques and microbiological assays (e.g., the "microsuspension modification" to the Ames Salmonella typhimurium bacterial assay; see Section C.2.c), medium- and low-volume samplers are often used as alternatives.

Two to four PUF plugs are typically used in the sampling train, depending on sampling conditions (e.g., ambient temperature) and the volatility of the PAHs

TABLE 10.8 Sum of the Particle-Associated (Filter) and Gas-Phase (Solid Adsorbent, PUF Plugs' or Tenax Cartridges8) Concentrations of EPA Priority PAH Pollutants and the Percentage of Each PAH in the Particle Phase

Polycyclic aromatic hydrocarbon, formula, and molecular weight

Total concentration (filter + solid adsorbent, ng m 3) and percentage (in parentheses) of specific PAHs in particle phase

Birmingham University, U.K."

Los Angeles Air Basin'

Torrance, CAd

Portland, ORc

Naphthalene, CrH,,,, 128 Acenaphthylene, C12HS, 152 Acenaphthene, C12H10, 154 Fluorene, C|3H10, 166 Phenanthrene, C14H]0, 178 Anthracene, C14H]0, 178

CifiH, Pyrene, C|()H10, 202 Cyclopenta[o/]pyrene,' C]SH]0, 226 Benz[a]anthracene, C]SH]2, 228 Chrysene, C18 H,„ 228 Benzo[6]fluoranthene, C2I1H12, 252 Benzo[/c]fluoranthene, C20H12, 252 Benzo[e]pyrene,' C2(IH12, 252 Benzo[a]pyrene, C20H12, 252 Benzo[g/îi']perylene, C22H]2, 276 Indeno[l,2,3-crf]pyrene, C22H12, 276 Dibenz[fl,/î]anthracene, C22H!4, 278

13.7 (7.7) 24.1 (4.5) 4.49 (8.7) 12.4 (9.4) 38.0 (6.2)

5.12 (2.1) 2.84 (6.3) 3.46 (23) 3.79 (21) 4.08 (64) 1.41 (56) 1.62 (75) 1.78

29.8 (0) 50.3 (0) 3.04 (0) 9.85 (0.7) 7.30 (1.0) 0.40 (35) 0.25 (60) 0.78' (44)

0.22 (100) 0.22 (100) 0.14 (100) 0.77 (100) 0.29 (100)

11.1 (0.6) 26.3 (1.0) 3.44 (0.9) 8.42 (4.9) 7.33 (7.1)

" From Smith and Harrison (1996). Sampler elevation 15 m, situated ~300 m from a high traffic "spine roadway." Particle phase collected on Teflon membrane filter (TMF); gas-phase species trapped downstream on PUF plugs. Daily 24-h samples collected during February 1992; mean TSP during that period 60 ¡j.g m~3.

h From Baek et al. (1992). Annual average concentrations derived from 48 week-long curbside samples collected throughout 1987 at an urban, tralfic-dominated site in south Kensington, London. Sampler elevation 5 m; particle-associated PAHs collected on a PTFE filter (Millipore Ltd.) and gaseous PAHs on a cartridge containing Tenax-TA adsorbent.

' From Fraser et al. (1998). Average concentrations of eight 4-h samples collected day and night at four sites in southern California (see Fig. 10.2) during an intense two-day photochemical smog episode, September 8-9, 1993 (1-h average 03 peaked at 0.29 ppm at Claremont, California). Volatile PAHs collected in stainless steel canisters, with the remainder collected with a quartz fiber filter/PUF solid adsorbent system. Average daytime and nighttime temperatures (°C): Long Beach, 22.2 (19.6); downtown Los Angeles, 25.8 (20.6); Azusa, 28.5 (22.9); Claremont, 30.4 (23.1) (Cass and Fraser, personal communication, 1999).

'' From Arey et al. (1987). Site, a roof (9-m elevation) at El Camino Community College in Torrance, California (20 km south of central Los Angeles). Daytime 12-h sampling period, 0600 to 1800 hours, February 25, 1986; maximum temperature 35°C at 1100 hours. Sampling systems: Tenax-GC cartridge for naphthalene and phenanthrene; Teflon-impregnated glass fiber filter (TIGF) and PUF plugs for phenanthrene and heavier PAHs (see diagram, Fig. 10.4).

'' From Ligocki and Pankow (1989). One sampling system had a glass fiber filter (GFF) and backup PUF plugs. Others employed either two GFFs or a single Teflon membrane filter (TMF); both had downstream PUF plugs. See original article lor experimental details. Samples collected during February and April 1984 and February and April 1985; overall mean sampling temperatures were 8 and 5°C, respectively. Sampling periods 5-30 h. For gas- and particle-phase concentrations of those PACs that were copollutants with these PAHs, see Table 10.11.

' Gas-phase PAHs collected on PUF plugs unless otherwise noted (e.g., on Tenax-GC or Tenax-TA adsorbents).

s Collected on a Tenax-filled cartridge.

h Collected in a canister sampler.

' Chrysene/triphenylene.

k Same value for collection on Tenax-GC cartridge and the sum of the concentrations of phenanthrene trapped on three PUF plugs in series.

' Not EPA priority pollutants.

TABLE 10.9 Calculated Effect of Vapor Pressure and Aerosol Concentration on the Percentage in the Aerosol Phase of Phenanthrene, Pyrene, and Benzol alpyrene"

Aerosol concentration' (fig m ')

Aerosol size ((Jim)

Percentage of PAH in particle phase

Phenanthrene Pyrene (5.3 X 10 4(3.3 X KT5)"

Benzo[a]pyrene (9 X Krs)fi

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