Characterization, identification of ambient air and road dust polycyclic aromatic hydrocarbons in central Taiwan, Taichung

Science of the Total Environment 327 (2004) 135–146

Characterization, identification of ambient air and road dust polycyclic aromatic hydrocarbons in central Taiwan, Taichung Guor-Cheng Fanga,*, Cheng-Nan Changb, Yuh-Shen Wua, Peter Pi-Cheng Fuc, I-Lin Yangb, Ming-Hsiang Chenb a

Air Toxic and Environmental Analysis Laboratory Hungkuang University, Sha-Lu, Taichung 433, Taiwan, ROC b Department of Environmental Science, Tunghai University, Taichung 407, Taiwan, ROC c Division of Biochemical Toxicology National Center for Toxicological Research, Jefferson, AR 72079, USA Accepted 14 October 2003

Abstract The concentrations of ambient air polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously in an industrial area (Taichung Industrial Park, TIP) and suburban area (Tunghai University, THU) in central Taiwan, Taichung. A total of samples were collected simultaneously at the two sites between August 2002 and March 2003. Particle-bound PAHs (p-PAHs) were collected on quartz filters and gas-phase PAHs (g-PAHs) on glass cartridges using polyurethane foam sampler, respectively. Both types of samples were extracted with dichloromethaneyn-hexane mixture (50y50, vyv) for 24 h, then the extracts were subjected to gas chromatographyymass spectrometric analysis. Moreover, the roadside dust particle PAHs composition were also collected and analyzed at TIP, THU and traffic road sampling sites. The five main road lines in Taichung City were selected as traffic road sampling sites. Correlation studies between PAHs concentrations and meteorological parameters were revealed that temperature has greater effects (P)0.6) than other meteorological parameters such as wind speed, relative humidity and atmospheric pressure on g-PAHs and p-PAHs. PAHs sources were resolved by using principal component analysis and diagnostic ratios. The major sources of PAHs were combustion, traffic vehicle exhaust (diesel and gasoline engine), incinerator and industrial stationary sources at both sampling sites in central Taiwan. 䊚 2003 Elsevier B.V. All rights reserved. Keywords: Ambient air; Road dust; Gas-phase; Particle-phase; Source attribute; Polycyclic aromatic hydrocarbons; Industrial; Suburban

1. Introduction Due to the rapid growth of industrial activities, population and traffic density, people in Taiwan are facing serious air pollution problems (Yang et al., 2002). It is a well-known fact that polycyclic aromatic hydrocarbons (PAHs) are partitioned *Corresponding author. Tel.: q886-4-2631-8652x1110; fax: q886-4-2350-2101. E-mail address: [email protected] (G.-C. Fang).

between particulate matter and gas phase in ambient air. Because of their biological properties, PAHs existence in the surrounding air has a direct impact on the human population. For example, the lung cancer mortality is increasing in major countries of the world (Liu et al., 2001). In addition, PAHs which possess a range of chemical, physical and toxicological characteristics in urban and industrial atmospheres are almost entirely anthro-

0048-9697/04/$ - see front matter 䊚 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2003.10.016

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pogenic in origin and are major byproducts of the incomplete combustion of all types of organic matter (Park et al., 2002; Wingfors et al., 2001). Besides, PAHs are ubiquitous environmental pollutants that are formed in the combustion of carbonaceous materials such as gasoline, diesel and other fuels at high temperature (Liu et al., 2001; Kavouras et al., 2001). Atmosphere is a major pathway for the transport and deposition of PAHs. Atmospheric deposition is an important mechanism controlling the fate of air borne toxics and their transfer from the atmosphere to natural surfaces. Source of PAHs in the rural areas is open burning of agricultural and other wastes. PAHs in large particles might be transported from urban areas. Small particles contain more PAHs per unit mass concentration than large particles. It has been known that when PAHs compounds emitted in the gaseous phases were condensed into particle phase, PAHs compounds were mostly distributed to small particles (Bae et al., 2002). Although washout, dry deposition and mixing decrease the concentration of PAHs in the atmosphere during transport from urban areas, decomposition of these compounds via photooxidation is also expected to reduce levels reaching non-urban areas (Odabasi et al., 1999). Because some PAH are more volatile than others, it is important to evaluate the contributions of both particle-bound PAHs (p-PAHs) and gas-phase PAHs (g-PAHs) to the health-risks associated with the exposure of the total PAH content. It was found that gaseous-phase PAHs contained higher fractions of low molecular weight PAH (including 2- to 3-ringed; (178 g moly1) homologues, whereas p-PAHs contained higher fractions of high molecular weight PAH homologues (including 5to 7-ringed; 0228 g moly1). In general, PAH homologues with high molecular weights are often more carcinogenic than those with low molecular weight (Tsai et al., 2002; Park et al., 2002). The implication of human exposure to mixtures of PAHs, rather than to individual substances, is important. People are seldom exposed to a single PAH compound, but rather to a mixture of PAHs. In spite of this, BaP concentration is still a great concern because BaP has been shown to be a potent carcinogen in studies on laboratory animals,

has been very extensively documented and is readily measured. In addition, BaP is often used as a marker for total PAH exposure in industry and in the environment (Lin et al., 2002). PAH profiles, or the relative abundance of the different species in particulate emissions from different combustion sources, have been suggested as reliable source signatures where inorganic marker elements are not available. In urban areas vehicular emissions are likely to be a significant contributor to PAH concentrations with additional local contributors like cooking fuel or industrial emissions (Kulkarni and Venkataraman, 2000; Fraser et al., 1999). G-PAH and p-PAH were analyzed in samples of ambient air collected at industrial Taichung, Taiwan (Taichung Industrial Park, TIP) and rural Taichung, Taiwan (Tunghai University, THU). Traffic vehicles, stationary industrial and outdoor combustion are the major sources of pollutants for these two sampling sites. The purpose of this study was to characterize and compare profiles of PAHs in TIP and THU. The results from this study will provide a baseline reference for global database as well as for regulatory action to improve air quality in the central Taiwan. 2. Experimental 2.1. Sampling program Location of sampling sites in Taichung city is given in Fig. 1. TIP represents a typical largescale multiple-industry in Taiwan. TIP was developed on 580 ha of land, and there are more than 800 factories at TIP, which included chemical industry, petroleum industry, plastic industry and electronics industry, etc. The sampling site was located on roof of a pharmaceutical factory (15 m in height), which is located in center of TIP. Another sampling site was selected in THU as a background site to compare with the neighbor industrial park. THU is located between Taichung City and Taichung County, which is surrounded by trees, and has approximately 15 000 students and faculty members. Taichung Veterans General Hospital Incinerator (combustion source) and Taijunggang Road (the main line in Taichung City)

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Fig. 1. Schematic of Taichung city of two sampling sites (TIP and THU), which include Taichung Wen Shen Incinerator, Taichung Veterans General Hospital Incinerator and Taijunggang Road.

are in opposite of THU. The sampling site was located in Tunghai University Campus, the sampling heights were in the range of 1–1.5 m above ground level to simulate the breathing zone. THU sampling site was described previously (Fang et al., 2000). In addition, Taichung Thermal Power Plant (TTPP) which developed on 281 ha and located along the coast of the west side of central Taiwan was established in order to promote longterm economical development of Taiwan at 1986. Therefore, TTPP can afford approximately 4400 MW electric powers per day to supply the requirement of electric force. Fourty-eight hour consecutive sampling for 1– 3 times per month for PAHs in ambient air were performed between August 2002 and March 2003 at TIP and THU sampling sites simultaneously. A summary of sampling information (sampling date and meteorological conditions) was also provided in Tables 1a and 1b. The range of temperature, relative humidity, average wind speed and atmospheric pressure during sampling period were 16– 40 8C, 40–90%, 0.4–12.5 m sy1 and 1002.8– 1024.9 hPa, respectively. The prevailing wind was blowing directly from north in this study. 2.2. Sample collection The sampling system and sampling procedure for ambient air samples were based on previous

studies (Fang et al., 2002, 2003). Airborne samples were collected using PS-1 samplers (GPS1 PUF sampler, General Metal Work) with a pump drawing air through a tissue quartz filter (2500 QATUP, Dimension 102 mm) to collect airborne p-PAHs and total suspended particle. The filter was followed by a glass cartridge containing a 5cm long polyurethane foam (PUF) plug, which in turn was followed by 3 cm thick packing of XAD16 resin (Amberlite), and finally by a 2 cm long PUF plug to collect the g-PAHs. During sample transportation and storage, the PUF plug and resin were stored in a clean jar wrapped with aluminum foil, and quartz filters were placed in sealed CD box. Quartz filters were weighed before and after sampling to determine the weight of particulate matter collected. Before sampling, quartz filters were baked in an oven at 450 8C for 8 h to remove organic impurity. Glass cartridges were cleaned by sequential Soxhlet extractions with distilled-deionized water, methanol, dichloromethane (DCM) and a mixture of DCMyn-hexane (50y50, vyv) for 24 h in turn and finally dried in a clear oven at 45 8C to remove residual solvent. Previous studies have revealed that gasyparticle distributions of atmospheric semi-volatile organic compounds (SOCs) are often measured using filterysorbent samplers. Unfortunately, the adsorption of gaseous SOCs onto a filter can cause positive

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Table 1a Sampling information and meteorological condition during August 2002 to March 2003 (ns19) Month

August, 2002

September, 2002

October, 2002

November, 2002

Sampling date na Temperature (8C) RH (%) Wind speed (m sy1) Pressure (hPa)

1–3, 13–15, 19–21 3 32–40 58–67 0.4–5.8 1002.8–1009.2

25–27 1 27.5–36.5 56–74 0.9–5.4 1010.7–1013.4

7–9, 9–11, 28–30 3 24–33 52–59 0.9–12.5 1011.3–1014.8

1–3, 4–6 2 23.3–25.5 40–80 0.4–8.9 1012.8–1020.9

a

Sampling number.

Table 1b Sampling information and meteorological condition during August 2002 to March 2003 (ns19) Month

December, 2002

January, 2003

February, 2003

Mar., 2003

Sampling date na Temperature (8C) RH (%) Wind speed (m sy1) Pressure (hPa)

4–6, 9–11, 11–13 3 13.2–25.3 44–82 0.4–9.4 1017.8–1026.2

7–9, 13–15, 15–17 3 16–24 58–90 0.4–10.3 1017.9–1024.9

11–13, 17–19, 19–21 3 14.8–21.6 63–82 0.4–8.9 1017.5–1020.1

25–27 1 21.9–23.2 66–69 0.4–4.9 1019.6–1019.8

a

Sampling number.

biases in the measured particle-phase concentrations, and negative biases in the measured gasphase concentrations, thus leading to overestimate of g-PAH. The sampling media, device used here is the same as above study. This study is inevitably has above phenomena. Thus, the concentrations of g-PAHs in this study will be overestimate by no more than "10% (Mader and Pankow, 2001). Roadside dust particle samples were collected using a vacuum cleaner, air dried for 3 days and sieved to get particles (300 mm. The particles were stored in a 500 ml glass jar, homogenized, and approximately 2 g of roadside dust particles was extracted by Soxhlet. The extracts were then cleaned, concentrated and made up to 1 ml with DCM. 2.3. Chemical analysis For PAH analysis of the samples, after final weighing, all quartz filters and glass cartridges were placed separately in appropriate Soxhlet extractors and extracted with a DCMyn-hexane mixture (50y50, vyv) for 24 h. The extract was then concentrated under a rotary evaporator,

cleaned by clean columns which consist of sodium sulfate, silica gel and glass wool, then let the solution into the clean columns. Elute with approximately 250 ml of n-hexane. Discard the first 10 ml of the eluent and then collect the remaining solution. And then re-concentrated with ultra-pure nitrogen to exactly 1 ml using a procedure that was described previously by previous studies (Lee et al., 1995; US EPA, 1999). All extracts were analyzed using a gas chromatographymass selective detector (Varian GC3800 with Saturn MS2000) with an GC capillary column (30 m=0.25 mm=0.25 mm, DB-5). A computer-controlled automatic sampler (Varian Model 8200) was used in conjunction with the gas chromatographyymass spectrometric system. All injections were splitless and volume was 1 ml. Injector and transfer line temperatures were 310 and 300 8C, respectively. The temperature program used was as follows: 35 8C hold for 3 min, ramp to 180 8C at 25 8C miny1 and hold for 2 min, ramp to 200 8C at 20 8C miny1 and hold 2 min, ramp to 300 8C at 2 8C miny1 and hold 6.4 min, total time 70 min. The analytical method was based on the USEPA Method TO-13 (US EPA, 1999).

G.-C. Fang et al. / Science of the Total Environment 327 (2004) 135–146

2.4. Quality control After each 48 h sampling period, the filter and glass cartridges were stored at 4 8C and analyzed within 15 days from collection. Quantification of PAHs were according to the retention times and peak areas of the calibration standards (16 PAHs were produced by Mixture 610-M, Supelco; the others were produced by Merck). The instruments were calibrated using at least five standard concentrations covering the concentration of interest for ambient air work. Correlation coefficient of the calibration curve was )0.995 for linear leastsquares fit of the data. Recovery efficiency of PAHs ranged from 77 to 98% (average 86%). Method detection limits were between 0.039 ng (BghiP) and 0.531 ng (CHR). The concentrations of the following 21 PAHs were quantified in this study. Those PAHs were according to their elution orders as followed: naphthalene (Nap, myz 128), acenaphthylene (AcPy, myz 152), acenaphthene (Acp, myz 154), fluorene (Flu, myz 166), phenanthrene (PA, myz 178), anthracene (Ant, myz 178), fluoranthene (FL, myz 202), pyrene (Pyr, myz 202), cyclopenta(c,d)pyrene (CYC, myz 226), benzo(a)anthracene (BaA, myz 228), chrysene (CHR, myz 228), benzo(b)fluoranthene (BbF, myz 252), benzo(k)fluoranthene (BkF, myz 252), benzo(e)pyrene (BeP, myz 252), benzo(a)pyrene (BaP, myz 252), perylene (PER, myz 252), indeno(1,2,3,-cd)pyrene (IND, myz 276), dibenzo(a,h)anthracene (DBA, myz 278), benzo(b)chrycene (BbC, myz 278), benzo(ghi)perylene (BghiP, myz 276) and coronene (COR, myz 300). 3. Results and discussion 3.1. PAHs in ambient air PAHs can be classified by their number of aromatic ring as follows: 2-ring including Nap; 3ring including AcPy, Acp, Flu, PA and Ant; 4-ring including FL, Pyr, BaA and CHR; 5-ring including CYC, BbF, BkF, BeP, BaP and PER; 6-ring including IND, DBA, BbC and BghiP; 7-ring including COR. Average concentrations of g-PAH and pPAH at TIP and THU sampling sites are shown in

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Table 2, respectively. At TIP sampling site, most of the total individual PAHs concentrations were higher than those of the THU sampling site. This way be attributed to washout, dry deposition and mixing during transport from urban areas; decomposition of these compounds via photo-oxidation may also reduce PAH levels during atmospheric transport (Odabasi et al., 1999). BaA and DBA were two exceptions for these sampling sites. Nap was the most abundant with average concentrations of 330 ng my3 and 25.7% of total individual PAHs (1300 ng my3) at TIP sampling site, while 2- and 3-ring had total average PAHs concentrations 912 ng my3, 4-ring total average PAHs concentrations was 184 ng my3, 5-ring total average PAHs concentrations was 146 ng my3, 6- and 7-ring total average PAHs concentrations was 55 ng my3, respectively. As for THU sampling site, Nap was also found the abundant and principal, with average concentrations of 163 ng my3 and 25.2% of total PAHs (646 ng my3). Moreover, 2- and 3-ring had total average PAHs concentrations 427 ng my3, 4-ring total average PAHs concentrations was 97 ng my3, 5-ring total average PAHs concentrations was 86 ng my3, 6- and 7-ring total average PAHs concentrations was 38 ng my3, respectively. 3.2. Effects of meteorological parameters Seasonal variations in PAH concentration are generally attributed to increased emissions during the cold season. Higher fuel consumption coupled with meteorological conditions such as lower mixing layer height and lower air temperature are the likely cause of the high PAH concentrations in winter. Higher temperatures are associated with lower PAH concentrations (Park et al., 2002). Pearson correlation matrix between PAHs and other meteorological parameters at TIP and THU sampling sites were shown in Table 3. No significant correlations were observed between PAHs concentration and meteorological parameters such as wind speed, relative humidity and atmospheric pressure. Among the meteorological parameters the correlation between temperature and PAHs concentration were the highest. Temperature between g-PAHs and total-PAHs (t-PAHs) concentration showed a moderate level of negative cor-

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Table 2 Total PAHs concentrations which including g-PAHs and p-PAHs in ambient air at the two sampling sites between August 2002 and March 2003 (ns19) Date

TIP

2002y08y01–03 2002y08y13–15 2002y08y19–21 2002y09y25–27 2002y10y07–09 2002y10y09–11 2002y10y28–30 2002y11y01–03 2002y11y04–06 2002y12y04–06 2002y12y09–11 2002y12y11–13 2003y01y07–09 2003y01y13–15 2003y01y15–17 2003y02y11–13 2003y02y17–19 2003y02y19–21 2003y03y25–27 Average

THU

g-PAH

p-PAH

t-PAH

g-PAH

p-PAH

t-PAH

715.2 873.1 964.7 534.7 1524.9 1327.9 592.5 1056.2 3112.8 3476.6 2704.0 552.9 285.7 413.8 377.6 1074.7 427.0 398.6 2233.4 1191.9

201.8 90.0 234.7 49.9 76.3 50.0 59.3 31.2 64.1 246.4 63.2 72.2 159.5 222.0 136.2 36.9 22.0 15.0 159.2 104.7

917.0 963.1 1199.4 584.6 1601.2 1377.8 651.8 1087.4 3176.9 3723.0 2767.2 625.1 445.2 635.8 513.8 1111.6 449.0 413.6 2392.7 1296.7

460.4 427.3 367.0 433.5 919.5 199.0 324.8 1156.5 1297.0 1335.3 847.3 1145.1 86.1 252.5 195.2 170.8 207.6 263.7 1136.3 590.8

52.4 131.5 152.1 61.3 52.2 73.6 19.1 31.3 95.3 26.4 63.0 7.6 83.1 141.3 11.0 1.9 5.9 15.7 28.1 55.4

512.7 558.8 519.1 494.8 971.7 272.6 343.9 1187.8 1392.3 1361.7 910.3 1152.7 169.2 393.9 206.2 172.7 213.5 279.4 1164.4 646.2

Concentrations in ng my3.

those reports which demonstrated that higher temperature is associated with lower g-PAHs concentration (Park et al., 2002). However, temperature and p-PAHs had low negative correlation coefficients (RTHUsy0.022 and RTIPsy0.216) at TIP and THU sampling site, respectively. TSP and

relation at two sampling sites. The correlation coefficients between temperature and g-PAHs were RTHUsy0.459 and RTIPsy0.604, respectively, and the correlation coefficients between temperature and t-PAHs were RTHUsy0.481 and RTIPs y0.607, respectively. This observation agreed with

Table 3 Pearson correlation matrix between PAHs and other meteorological parameters 1 (1) (2) (3) (4) (5) (6) (7) (8)

Temperature RH WS P TSP conc. g-PAHs p-PAHs t-PAHs

2 0.080

0.080 y0.205 y0.754 0.014 y0.604 y0.216 y0.607

0.055 0.152 y0.258 y0.540 0.350 y0.502

3

4

5

6

7

8

y0.205 0.055

y0.754 0.152 0.257

y0.106 y0.491 y0.368 y0.441

y0.459 y0.352 y0.029 0.211 0.548

y0.022 y0.044 y0.328 y0.034 y0.078 y0.347

y0.481 y0.372 y0.075 0.215 0.559 0.992 y0.223

0.257 y0.637 y0.202 y0.388 y0.227

y0.239 0.17 y0.07 0.161

0.564 0.421 0.583

0.26 0.997

0.33

Note: Value in row i and column j of the upper triangle were the correlation between compound i and compound j for the meteorological parameters and pollutant concentrations at THU sampling site; value in row i and column j of the lower triangle give the correlation between compound i and j for the meteorological parameters and pollutant concentrations at TIP sampling site. RH, Relative humidity; WS, Wind speed; P, Atmospheric pressure; g-PAHs, gas-phase PAHs; p-PAHs, particle-phase PAHs; t-PAHs, total PAHs (gasqparticle phase).

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PAHs also have moderate correlation at THU and TIP sampling sites, suggesting that TSP and PAHs came from the same source at both sampling sites. The highest position correlation of g-PAHs and tPAHs are found in this study, which indicated that g-PAHs were the major portions of t-PAHs. The influence of temperature on atmospheric PAH concentrations was explicitly assessed by examining the logwPAHxvapor (ng my3)saqmyT (K) relationship, where a and m are the intercept and slope obtained by a least-squares linear regression (Park et al., 2002). As g-PAH concentrations increasing, many low molecular weight PAHs might combine with other pollutant matter to form derivatives, which might contain more toxic composition to endanger human health. Besides, these gas phase pollutants might transport to long-distance regions by atmospheric circulation. 3.3. PAHs composition in ambient airborne particle and roadside dust Fig. 2a summarizes the results for the composition of ambient air p-PAHs at TIP and THU sampling sites during sampling period. Fig. 2b summaries the roadside soil particle PAHs composition at TIP, THU and traffic road (Fig. 2b). Traffic road sampling site is the average PAHs composition of roadside dust particles for five main road lines in Taichung City. The total p-PAHs ambient air composition at TIP sampling site was found to be 831 mg gy1, which individual PAHs composition was ranged from 8 (BaA) to 208 (COR) mg gy1. THU ambient air sampling site had total PAHs composition of 727 mg gy1, individual PAHs composition was ranged from 4 to 87 mg gy1 (Fig. 2a). The results show that most PAH occurred at higher concentrations at the TIP sampling site than THU sampling site, and the only exceptions were Nap, Acp, Flu, PA, Ant, Pyr, CYC and BghiP. These PAHs species are indicative of combustion sources and traffic vehicle emission (Ho et al., 2002; Park et al., 2002; Yang et al., 1998). A likely reason the concentrations were higher at THU than TIP is local traffic source (Taijunggang Road—the main line in Taichung city) and nearby outdoor combustion.

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The main PAHs measured and quantified at roadside dust were the same as those collected in ambient air particles. The total composition at roadside dust was found to be 65.8, 16.1 and 26.7 mg gy1 at traffic road, THU and TIP sampling sites, respectively (Fig. 2b). In general, the p-PAH levels in the roadside dust particles collected at the TIP sampling site were on average approximately 1.7 times higher than those measured at THU sampling site, but were 2.5 times lower than the samples measured at traffic road samples. The value obtained at road dust site in this study is similar those measured in urban Pasadena, CA, USA which is recorded as 58.68 mg gy1 (Rogge et al., 1993) and urban Birmingham, UK which is measured as 12.56–93.70 mg gy1 (Smith et al., 1995), but higher than the urban Kuala Lumpur Malaysia which is recorded as 6.28 mg gy1. As for industrial (TIP) sampling site, the value obtained in this study is higher than an industrial site in Lahore, Pakistan which is recorded as 0.2 mg gy1. As for suburban sampling site (THU), the value obtained in this study was lower than those of USA and UK urban sampling sites, but higher than Malaysia urban and rural Lahore, Pakistan which is recorded as 0.12 mg gy1 (Smith et al., 1995). The PAHs species distribution indicated that PA, FL, Pyr, BghiP and COR were the most abundant PAHs in the roadside dust samples. In particular, the result of previous studies (Omar et al., 2002) indicated that lower molecular weight PAHs, namely PA, FL and Pyr, were also the predominant PAHs in street dust samples collected from Kuala Lumpur. Lower molecular weight PAHs were more enriched in roadside dust particles, whereas high molecular weight PAHs were more abundant in atmospheric particles. This may be because lower molecular weight PAHs predominate in larger particles, which deposit faster whereas high molecular weight ones predominate in the smaller particles that deposit more slowly from the atmosphere (Venkataraman and Friedlander, 1994). 3.4. Principal components analysis of PAHs concentration Principal component analysis (PCA) is the oldest and most widely used multivariate statistical

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Fig. 2. Composition of PAHs in (a) ambient air particles and (b) roadside dust particle.

technique in the atmospheric sciences. The principle of PCA is to transform the original set of variables into a smaller set of linear combinations that account for most of the variance of the original set. The primary function of this analysis is the reduction of the number of variables while retaining the original information as much as possible, and thus variables with similar characteristics can be grouped into factors (Ho and Lee, 2002).

Source groupings were determined using PCA with varimax rotation and retention of principal components having eigenvalues )1 of the complete the data set of PAHs concentrations. Factor analysis in this study was carried out using the statistical analysis SPSS 8.0 software. PCA results show which factors are able to explain the main part of the data variance, therefore individual PAHs representative of each factor

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Fig. 3. PCA of ambient air PAHs concentration at TIP and THU sampling sites. PC1, PC2 and PC3 presents 31.7, 19.8 and 15.2% of the variance at TIP sampling site, respectively, 26.2, 22.0 and 17.7% of the variance at THU sampling site, respectively. PC1, PC2 and PC3 were indicated as combustion, stationary and incineration sources, respectively.

were chosen as source tracers (Fang et al., 2003). Fig. 3 shows the factor loading of three retained factors that account for ambient air PAHs data at TIP and THU sampling sites. At TIP sampling site, Factor 1 (PC1) explained 31.7% of the variance of data and has high loading for Nap, AcPy, Acp, Flu, PA, Ant and FL, which was identified as ‘Combustion’. Previous studies (Park et al., 2002; Yang et al., 1998) point out that

indicatory PAHs of combustion were Nap AcPy, Acp, Flu, PA and Ant. Factor 2 (PC2) presents 19.8% of the variance and a close association between Pyr, PER, Bap, IND, CHR, DBA and CYC. PC2 is likely related to exhaust emissions from ‘Stationary’ sources. Previous studies (Yang et al., 1998; Kulkarni and Venkataraman, 2000) indicate that BaP, BaA, PER, BeP, COR and CYC derive in large amount for the products of steel.

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Table 4 Concentrations diagnostic ratios of ambient air PAHs for major emission sources at TIP and THU sampling sites Diagnostic ratios

INDy(INDqBghiP)a

Fluy(FluqPyr)a

Bepy(BepqBap)b

INDyBghiPc

BaAyCHRd

BbFyBkFd

This study THU TIP

0.50 0.38

0.62 0.65

0.74 0.78

1 0.6

0.88 1.15

0.80 0.68

Other investigations Gasoline Diesel Wood combustion Smelters Coalycoke

0.18 0.35–0.7 – – –

0.4 0.6–0.7 0.74 – –

0.6–0.8 0.29–0.4 0.48 – –

0.27–0.4 1 0.23–0.33 0.88–1.18 1.06–1.12

0.47–0.59 – 0.66–0.92 0.54–0.66 1.05–1.17

1.07–1.45 – 0.76–1.08 2.49–2.89 3.53–3.87

a

Kavouras et al. (2001) and Mandalakis et al. (2002). Kavouras et al. (2001). c Dickhut et al. (2000) and Park et al. (2002). d Dickhut et al. (2000). b

Pyr, PA, Flu, IND and CHR have been identified as markers for incineration source. CYC and DBA are related to thermal power plant which used coal as fuel. Factor 3 (PC3) had 15.2% of variance and high loading for BeP, BghiP and COR, which identifying ‘Diesel and gasoline engine emission’ source. Other experimental studies have shown that AcPy, FL, Flu, PA, Pyr, CHR and BeP derived almost exclusively from diesel vehicle emission; Flu, CHR, IND, BghiP, CYC and COR are considered good markers for gasoline vehicle emission (e.g. Yang et al., 1998; Kulkarni and Venkataraman, 2000; Ho et al., 2002; Caricchia et al., 1999; Omar et al., 2002). As for THU sampling site, three factors were also obtained and analyzed. PC1, PC2 and PC3 at THU sampling site were associated with ‘Combustion’, ‘Gasoline vehicle emission’ and ‘Diesel vehicle sources’, respectively. The data were recorded as PC1 had high loading for Nap, Acp, Flu, PA, Ant and FL. PC2 had high loading for CYC, COR, BghiP, while PC3 showed high loading for BeP, CHR and Pyr, respectively.

0.50 and 0.38 at THU and TIP sampling sites, respectively. This ratio is similar to the value of 0.35–0.7 measured for diesel engine emission. The mean Fluy(FluqPyr) and INDyBghiP at these two sampling sites displayed the similar results which revealed that they were source of diesel vehicle. The mean Bepy(BepqBap) ratio was 0.74 and 0.78 at THU and TIP sampling sites, respectively. This implies that the source of PAHs at these two sampling sites is gasoline engine emission (ratio ranged 0.6–0.8). The mean BaAy CHR ratio was 1.15 at TIP sampling site, which is similar to that for coal and coke emission (ratio ranged 1.05–1.17) (Mandalakis et al., 2002). The mean BbFyBkF ratio was 0.8 at THU sampling site, which is similar to the study for wood combustion (ratio ranged 0.76–1.08) (Dickhut et al., 2000). The result of diagnostic ratio was consistent with result obtained by method of PCA, and it provided a useful method for identification of PAHs sources (Table 4).

3.5. Concentrations diagnostic ratios of PAHs for major emission sources

The average total ambient air PAHs concentration at TIP and THU sampling sites of central Taiwan were found to be 1300 and 646 ng my3, respectively. At TIP (industrial site) sampling site, most of the total individual PAHs concentrations were higher than those of the THU (suburban site) sampling site. Temperature is the most important

Ambient air PAHs concentrations diagnostic ratios which characterize the anthropogenic emissions at TIP and THU sampling sites are shown in Table 3. The mean INDy(INDqBghiP) was

4. Conclusions

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