Airborne PM2.5/PM10-Associated Chlorinated Polycyclic Aromatic ...

Article pubs.acs.org/est

Airborne PM2.5/PM10-Associated Chlorinated Polycyclic Aromatic Hydrocarbons and their Parent Compounds in a Suburban Area in Shanghai, China Jing Ma,† Zuyi Chen,† Minghong Wu,*,† Jialiang Feng,† Yuichi Horii,§ Takeshi Ohura,∥ and Kurunthachalam Kannan*,‡,⊥ †

School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, New York 12201-0509, United States § Center for Environmental Science in Saitama, 914 Kamitanadare, Kisai-machi, Kitasakitama, Saitama, 347-0115, Japan ∥ Faculty of Agriculture, Meijo University, 1-501 Tempaku, Nagoya, 468-8502, Japan ⊥ International Joint Research Center for Persistent Toxic Substances, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China ‡

S Supporting Information *

ABSTRACT: Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have been reported to be formed during incineration processes. Despite dioxin-like toxicities of ClPAHs, little is known on the occurrence of these chemicals in the environment. In this study, concentrations of 24-h airborne PM10 and PM2.5-associated ClPAHs and their corresponding parent PAHs were monitored from October 2011 to March 2012 in a suburban area in Shanghai, China. In addition, daytime and nighttime particle samples were collected for 7 days in April from the same sampling site. Twelve of twenty ClPAH congeners were found in PM10 and PM2.5 at concentrations ranging from 2.45 to 47.7 pg/m3 with an average value of 12.3 pg/m3 for PM10, and from 1.34 to 22.3 pg/m3 with an average value of 9.06 pg/m3 for PM2.5. Our results indicate that ClPAHs are ubiquitous in inhalable fine particles. The concentrations of ∑ClPAHs and specific congeners such as 9-ClPhe, 3-ClFlu, 1-ClPyr, 7-ClBaA, and 6-ClBaP in particles collected during nighttime were higher than those collected during daytime, which suggests not only diffusion of ClPAHs in air by atmospheric mixing but also photochemical degradation during daylight hours. Among the individual ClPAHs determined, 6-ClBaP, 1-ClPyr, and 9-ClPhe were the dominant compounds in PM10 and PM2.5. The percent composition of 6-ClBaP, 1-ClPyr, 7-ClBaA, and 3-ClFlu between PM10 and PM2.5 was similar. Significant positive correlations were found between concentrations of ClPAHs and their corresponding parent PAHs, particle mass, and total organic carbon (organic carbon plus elemental carbon), indicating that ClPAHs are sorbed onto carbonaceous matter of PM. Concentrations of parent PAHs predicted by multiple linear regression models with PM mass, total organic carbon, temperature, and relative humidity as variables reflected the measured concentrations with a strong coefficient of determination of 0.917 and 0.946 for PM10 and PM2.5, respectively. However, the models generated to predict ClPAH concentrations in PM did not yield satisfactory results, which suggested the differences in physical−chemical properties and formation processes between ClPAHs and their corresponding parent PAHs. 7-ClBaA and 6-ClBaP collectively accounted for the preponderance of the total dioxin-like TEQ concentrations of ClPAHs (TEQClPAH) in PM samples. Exposure to toxic compounds such as ClPAHs and PAHs present in PM2.5 can be related to adverse health outcomes in people.

■

by numerous epidemiological studies.5−8 The effects of PM on human health are thought to depend not only on their morphological/physical characteristics, such as particle size, but also on the reactive/toxic chemical compounds absorbed onto

INTRODUCTION

Airborne particulate matter (PM) has been used as an indicator for evaluating the quality of air in many developed and some developing countries. Atmospheric levels of PM10 (particles below 10 μm size) and PM2.5 (particles below 2.5 μm) have become a major research issue worldwide because of their significance and relevance to human health, visibility impairment, and effects on climate processes.1−4 Adverse effects of PM exposure on human health have been consistently demonstrated © 2013 American Chemical Society

Received: Revised: Accepted: Published: 7615

January 22, 2013 May 15, 2013 June 14, 2013 June 14, 2013 dx.doi.org/10.1021/es400338h | Environ. Sci. Technol. 2013, 47, 7615−7623

Environmental Science & Technology

Article

the particles.1,4,5 Some organic compounds that are sorbed onto inhalable PM, such as polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and quinones, have attracted most attention so far, and these compounds were considered to play a key role in eliciting adverse health effects.9−14 However, to our knowledge, the focus on chlorinated PAHs (ClPAHs), which are dioxin-like toxic organics, formed through atmospheric reactions is limited. ClPAHs are a class of anthropogenic compounds with one or more chlorines substituted on the aromatic rings of a PAH molecule.15 ClPAHs have been reported to be carcinogenic and mutagenic and possess toxic potentials similar to those of PCDD/Fs.16,17 Evidences of toxicological significance of ClPAHs have evoked interest in analysis, occurrence, fate, and behavior of these micropollutants in the environment, with studies documenting the occurrence in tap water, sediments, waste incineration processes, automotive exhaust, and dust and soil from electronic waste (e-waste) recycling operations.18−23 Pioneering studies on atmospheric levels of ClPAHs have been carried out by various investigators over the last 20 years,24−29 but the earlier studies were focused on total suspended particles (TSP). Respirable PM, especially PM2.5, can act as a vector for organic contaminants to humans through inhalation, thus affecting the health. Therefore, monitoring of occurrence of ClPAHs in respirable fine particles and determination of the effects of PM mass, organic carbon (OC), and elemental carbon (EC) on the concentrations of ClPAHs are important for better understanding the fate of these compounds in air. The objectives of this study were to determine the concentrations and profiles of ClPAHs and their corresponding parent PAHs in PM10 and PM2.5 in suburban air from Shanghai during winter, and to evaluate the role of PM mass, and total organic carbon (TC) content of PM in influencing the concentrations. An attempt to predict the concentrations of PM10/PM2.5-associated ClPAHs and PAHs was presented by utilizing multiple linear regression models that incorporate the concentrations of PM, OC, EC, temperature, and relative humidity as variables. Dioxinlike toxic equivalents (TEQs) of ClPAHs in PM10 and PM2.5 were calculated to enable an understanding of potential toxic effects of these emerging environmental contaminants.

samples were collected during the study period. In addition, a total of 28 12-h daytime−nighttime airborne particle samples were taken from April 2 to 8, 2012 at the same sampling site. Samples were collected from 07:00 to 19:00 (daytime samples) and from 19:00 to 07:00 (nighttime samples), and there was no wet precipitation during the sampling week. All the quartz filters were preheated at 450 °C for 6 h before being used, for the removal contaminants that might have been present. After the collection of samples, the filters were wrapped in precleaned aluminum foil, sealed in plastic bags, and stored at −29 °C until extraction. Twenty individual ClPAHs, representing mono- through trichloroPAHs, were determined: 9-monochlorofluorene (9-ClFle), 9-monochlorophenanthrene (9-ClPhe), 3,9-dichlorophenanthrene (3,9-Cl2Phe), 1,9-dichlorophenanthrene (1,9-Cl2Phe), 9,10-dichlorophenanthrene (9,10-Cl2Phe), 3,9,10-trichlorophenanthrene (3,9,10-Cl3Phe), 2-monochloroanthracene (2-ClAnt), 9-monochloroanthracene (9-ClAnt), 9,10-dichloroanthracene (9,10-Cl2Ant), 3-monochlorofluoranthene (3-ClFlu), 8-monochlorofluoranthene (8-ClFlu), 5,7-dichlorofluoranthene (5,7-Cl2Flu), 3,8-dichlorofluoranthene (3,8-Cl2Flu), 3,4-dichlorofluoranthene (3,4-Cl2Flu), 1-monochloropyrene (1-ClPyr), 6-monochlorochrysene (6-ClChr), 6,12-dichlorochrysene (6,12-Cl2Chr), 7-monochlorobenz[a]anthracene (7-ClBaA), 7,12-dichlorobenz[a]anthracene (7,12Cl2BaA), and 6-monochlorobenzo[a]pyrene (6-ClBaP). 2-ClAnt and 9-ClAnt were purchased from Aldrich (St. Louis, MO, USA). 9-ClPhe was obtained from Acros Organics (Geel, Belguim). The remaining ClPAHs standards were synthesized at the University of Shizuoka (Shizuoka, Japan). The purity of the synthesized ClPAH standards was greater than 95% (confirmed by gas chromatograph interfaced with mass spectrometer, GC/MS).19,27 In addition, 16 U.S. Environmental Protection Agency (EPA) priority PAHs were determined. Sixteen PAHs and deuterated PAH standard mixtures, including naphthalene-d8, acenaphthene-d10, phenanthrene-d10, chrysene-d12, and pyrene-d12 were purchased from AccuStandard (New Haven, CT, USA). Silica gel (grade 635, 60−100 mesh) was obtained from Aldrich and was activated at 130 °C for 6 h prior to use. Chemical Analysis. The field blanks comprising actual quartz filters that had been maintained at 40% relative humidity and 20 °C for over 48 h were weighed before and after sampling. OC and EC in PM10 and PM2.5 were determined from a 1.5-cm2 punch taken from each half quartz filter sample used for ClPAHs analysis with a Desert Research Institute (DRI) carbon analyzer using IMPROVE thermal/optical reflectance (TOR).30 The quartz filter punch was heated stepwise at temperatures. The carbon that evolved at each temperature was oxidized to carbon dioxide (CO2), and then reduced to methane (CH4) for quantification with a flame ionization detector.30 Total organic carbon (TC) is defined as the sum of OC and EC. Instrument blanks were tested every day and one duplicate sample was analyzed for every ten samples. The method detection limits for OC and EC were below 0.2 μg C/cm2. The methods for the analysis of ClPAH and parent PAH congeners were similar to that described previously.18 Briefly, half of each quartz filter sample, from which the 1.5 cm2 punch used for OC and EC analysis was subtracted when calculating concentrations, was cut into small pieces and then spiked with deuterated PAHs standards, followed by accelerated solvent extraction (ASE-150, Dionex, Sunnyvale, CA, USA) with dichloromethane (DCM) and n-hexane solution (3:1, v/v) at 100 °C at 10 MPa. The concentrated extracts were fractionated using activated silica gel column (2 g) chromatography by 20 mL of 20% DCM in n-hexane (denoted as F1) after a prewash step,

■

MATERIALS AND METHODS Sample Collection and Target Compounds. Atmospheric samples of PM10 and PM2.5 were collected at the rooftop (approximately 20 m above ground level) of a building on the campus of Shanghai University in Baoshan District, Shanghai (latitude 31°19′ N, longitude 121°23′ E). The sampling site is 1.5 km from the nearest highway with heavy traffic and is surrounded by small cement and chemical industrial plants and residential areas. The sampling location is a typical suburban residential area in China. Samples were collected for 24 h on quartz fiber filters (GM-A, 20.3 cm × 25.4 cm, PALL Pallflex Inc., Ann Arbor, MI, USA) with two high-volume air samplers (GUV-15HBL1, Thermo Andersen, Smyrna, GA, USA) equipped with a cutting head for 2.5 and 10 μm particle sizes. The samplers were operated at a constant flow rate of 1.13 m3/min. Each sample of 24-h duration was collected for every six days, and this was done for 6 months (from October 26, 2011 to March 28, 2012, the winter season). During the days of wet precipitation, the air sampling was delayed until the weather became clear. Thus, a total of 44 24-h 7616

dx.doi.org/10.1021/es400338h | Environ. Sci. Technol. 2013, 47, 7615−7623


Article

Figure 1. Concentrations of (A) total PM10-bound ClPAHs (pg/m3) and PM10 mass (μg/m3), (B) total PM2.5-bound ClPAHs (pg/m3) and PM2.5 mass (μg/m3), (C) PM10-bound 16PAHs (pg/m3) and total organic carbon (TC, μg/m3), and (D) PM2.5-bound 16PAHs (pg/m3) and TC (μg/m3) in suburban air in Shanghai, China, during the sampling period of October 2011−March 2012.

(deuterated PAHs) were analyzed after every five samples to monitor for instrument stability and for recovery calculation. Recoveries of deuterated PAHs spiked into individual samples were 43 ± 16% for naphthalene-d8, 78 ± 13% for acenaphthened10, 95 ± 20% for phenanthrene-d10, 93 ± 19% for chrysene-d12, and 97 ± 21% for pyrene-d12. Low concentrations of 9-ClFle (0.12 pg/m3 on average), 9-ClPhe (0.26 pg/m3), 2-ClAnt (0.05 pg/m3), 9-ClAnt (0.01 pg/m3), and Phe (0.01 ng/m3) were detected in some field blanks. Reported concentrations were not corrected for the recoveries of surrogate standards. The limit of quantification (LOQ) was set at 3 times the standard deviation of the peak area at the lowest concentration of calibration standard, which was from 0.11 to 0.26 pg/m3 for ClPAHs, and from 0.49 to 1.13 pg/m3 for parent PAHs in air samples. Data Analysis. For statistical analysis, values below the LOQ, but above method detection limit (MDL, which was set to be 3 times S/N), and nondetects (ND) were set to be zero, whereas concentrations below the LOQ (but above MDL) are presented in the Supporting Information. Statistical analyses were performed using SPSS version 15.0. Nonparametric Spearman’s rho test was used to investigate the correlations between ClPAHs and parent PAHs and the mass of particulate matter.

by elution of n-hexane. Then the fraction, F1, was concentrated to 1 mL, and injected into a gas chromatograph−mass spectrometer (GC/MS; Shimadzu QPlus 2010, Shimadzu, Kyoto, Japan) for 16 PAHs analysis. Then the F1 was purified with a disposable polypropylene filtration column for SPE (3 mL, 6.5 cm length × 0.9 cm i.d., ANPEL, Shanghai, China) packed with a 0.2-g mixture of activated carbon and silica gel (1:40, w/w; for activated carbon, G-60, 60−100 mesh). The column was precleaned by elution of toluene and n-hexane. After loading the fraction F1, the self-packed column was eluted with 50 mL of 20% DCM in n-hexane (F1−1), and then the column was reversed and eluted with 100 mL of toluene (denoted as fraction F1−2). The fraction F1−2 that contained ClPAHs was concentrated to 200 μL, and analyzed by GC/MS. GC separation was accomplished by a 30-m Rxi-5MS fused silica capillary column (0.25 mm i.d., 0.25 μm film thickness; Restek, Bellefonte, PA, USA). Aliquots of 2 μL of extract were injected in splitless mode, at 280 °C for ClPAHs and at 260 °C for PAHs. The column oven temperature was programmed from 80 °C (1 min) to 140 °C at a rate of 15 °C/min, and then raised to 300 °C at 5 °C/min and held at 300 °C for 5 min for ClPAH analysis. For PAH analysis, the oven temperature was ramped from 60 (2 min) to 130 °C at a rate of 10 °C/min, and then to 270 °C at 5 °C/min, and then finally to 300 °C (5 min hold) at 10 °C/min. The MS was operated in an electron impact (70 eV) selected ion monitoring (SIM) mode. Quality Assurance/Quality Control. Field blanks (n = 8) were analyzed with every batch of samples to monitor for contamination or interferences. Sample concentrations were determined from external calibration curves prepared at concentrations ranging from 0.5 to 1000 ng/mL for ClPAHs and from 1 to 2000 ng/mL for PAHs. Quality control standards

■

RESULTS AND DISCUSSION Mass Concentrations of PM10, PM2.5, OC, and EC. The concentrations of 24-h PM10 and PM2.5 at the monitoring site on Shanghai University Campus are shown in the Supporting Information (Table S1). The average concentrations of 24-h PM10 and PM2.5 were 150 and 90.5 μg/m3 during the sampling period, respectively. The PM2.5 concentrations in the suburban air were 2.59 times higher than the new annual standard of 7617



Article

35 μg/m3 set by China’s National Ambient Air Quality Standards (NAAQS);31 the U.S. annual health standard for PM2.5 is 12 μg/m3.32 The concentrations of PM10 and PM2.5 in this suburban area were as high as the concentrations reported for other metropolises such as Guangzhou (China) and Zonguldak (Turkey).8,30 The average ratio of 24-h PM2.5/PM10 concentrations was 0.63, which was generally ascribed to high contributions from secondary particles and combustion-related sources.33,34 OC and EC have important roles and effects on human health due to their physical and chemical characteristics.35 The average OC concentrations of PM10 and PM2.5 were 19.3 and 12.8 μg/m3, respectively, and the average EC concentrations of PM10 and PM2.5 were 11.7 and 8.52 μg/m3, respectively. The total organic carbon (TC; OC plus EC) concentrations in PM10 and PM2.5 were 30.9 and 21.3 μg/m3, respectively. EC and primary OC may result from fossil fuel and biomass burning locally; secondary OC is formed from gas-particle conversion processes in the atmosphere. The ratio of (OC/EC)min has been used as a tracer for the evaluation of origin of carbonaceous matter in the atmosphere.36 If there was a constant regional contribution of aged aerosol with high secondary OC, the (OC/EC)min ratios would increase.35 The (OC/EC)min ratios were low, 1.19 for PM10 and 1.08 for PM2.5, with relatively high average EC concentrations in our sampling site, which suggests pollution from fresh local emissions rather than regional and long-range transported secondary organic aerosols (SOA). In addition, the low ratios suggest that the origin of organic contaminants in particulate matter was mainly from the local emissions. PM10/PM2.5-Associated ClPAHs and Parent PAHs. The total concentrations of ClPAHs associated with airborne PM10 and PM2.5 are illustrated in Figure 1A and B, and the concentrations for individual compounds are presented in the Supporting Information (Tables S2 and S3). During the study period, 12 of the 20 target ClPAH congeners were found at detection rates ranging from 86% to 100% in PM10, and from 82% to 100% in PM2.5, indicating that ClPAHs are ubiquitous in atmospheric particulate matter. ∑ClPAHs is referred to as the sum of concentrations of the 12 individual ClPAH congeners that were detected in PM samples. The mean and median concentrations of ∑ClPAHs in PM10 were 12.3 and 10.1 pg/m3, respectively, with a range of 2.45−47.7 pg/m3. For PM2.5, the mean and median concentrations of ∑ClPAHs were 9.06 and 7.31 pg/m3, respectively, with a range of 1.34−22.3 pg/m3. Our results indicate that the concentrations of PM2.5-associated ClPAHs were slightly lower than the PM10-associated concentrations. Overall, concentrations of ∑ClPAHs and individual ClPAH congeners associated with PM10 and PM2.5 were lognormally distributed, as determined by one sample Kolmogorov−Smirnov test (p > 0.05). TSP-associated ClPAH concentrations have been reported for urban air in Japan during 1992− 2002 (sum of 7 ClPAH concentrations ranged from BaA > Pyr > Phe > Ant > Fle, both in PM10 and PM2.5, which is slightly different from the order found for the corresponding ClPAHs (Figure 3), but similar to that reported for TSP-bound PAHs in urban air from Japan.25 The mean concentrations of PAHs were 3−4 orders of magnitude higher than those of the corresponding ClPAHs. The formation of ClPAHs by chlorination of PAHs in the presence of various chlorine sources, UV irradiation, pH, and metallic catalysts has been studied.40−43 Horii et al.20 suggested that ClPAHs were formed directly from the chlorination of parent PAHs in waste incinerators. In our previous study, we found PAHs in particulate emissions from a diesel engine fueled with biodiesel, ultra low sulfur diesel, and low sulfur diesel;44 nevertheless, no ClPAH was detected in the particulate samples. These results suggested that some ClPAHs were not released from the automobile exhaust directly, but were potentially formed by secondary reactions in the atmosphere. More research on the mechanism of formation of ClPAHs and their primary and secondary sources in air is needed to gain better insight on the behavior of these compounds in the environment. Relationships of Parent PAHs, Particulate Mass, and Total Organic Carbon with ClPAHs. The relationship between the concentrations of ClPAHs and their parent PAHs has been investigated in sediment, TSP, fly ash from waste incineration, and dust/soil from an e-waste recycling facility.18−21,25 In addition, correlations between temperature, TSP mass, incinerator capacity, and urbanization process, with the concentrations of ClPAHs, were also reported.20,21,25 In our study, we investigated the relationship between ClPAH and parent PAH concentrations, particulate mass, and total organic carbon (Table 2). Significant positive correlations were found between ∑ClPAHs, 9,10-Cl2Phe, 3-ClFlu, 8-ClFlu, 3,4-Cl2Flu, 1-ClPyr, 7-ClBaA, and 6-ClBaP, with their corresponding parent PAHs in PM10. Similar correlations were also found for PM2.5 except for 6-ClBaP and 9,10-Cl2Phe. Concentrations of 3-ClFlu, 8-ClFlu, 3,4-Cl2Flu, 1-ClPyr, 7-ClBaA, 6-ClBaP, and ∑ClPAHs in PM10 and PM2.5 were significantly correlated with TC levels in PM. Airborne carbonaceous materials, EC and OC, are the largest contributors to the particle burden in air.30,45 PAHs and other components with possible mutagenic and carcinogenic

Table 1. Concentration Ratios of Selected ClPAHs Normalized to 1-ClPyr and 3-ClFlu suburban air (campus)a

6-ClBaP/1-ClPyr 3-ClFlu/1-ClPyr 7-ClBaA/1-ClPyr 6-ClBaP/3-ClFlu 1-ClPyr/3-ClFlu 7-ClBaA/3-ClFlu

urban air (campus)b

urban streetc

road tunnelc

PM10bound

PM2.5bound

TSP-bound

TSPbound

TSPbound

2.35 0.89 0.81 2.64 1.13 0.91

2.24 0.87 0.55 2.58 1.15 0.63

2.83 0.60 0.60 4.84 1.68 1.00

0.39 0.53 0.08 0.73 1.88 0.15

0.41 0.68 0.16 0.61 1.47 0.23

a

Mean concentrations were used in this study. bData calculated from TSP-bound ClPAH compounds (mean concentrations) by Kitazawa, et al.25 cData calculated from particulate phase by Nisson and Ö stman.24

2.35 and 2.24, respectively. The ratios were similar to those reported for fly ash from waste incinerators,20 and in dust/soil from an e-waste recycling facility,18 but were higher than the ratios reported for automobile exhaust samples.24 In addition, the ratios of 3-ClFlu and 1-ClPyr were similar to those found in automobile exhaust, and 7-ClBaA/3-ClFlu ratios were similar to those found in chlorine-chemical related industrial activities.18 Our results indicate that automobile exhaust, incineration, emissions from chemical industry, and other unknown sources have collectively contributed to the measured concentrations of ClPAHs found in the suburban air. The fate and sources of ClPAHs in air are not well-known, and further investigations are needed in this regard. Sixteen parent PAHs were found in all PM10 and PM2.5 samples (Figure 1C and D; Tables S6 and S7). The detection frequencies of individual PAHs in PM ranged from 18% to 100%. The mean and median concentrations of ∑16PAHs in PM10 were 37 000 and 22 900 pg/m3, respectively, with a range of 5400−136 000 pg/m3. For PM2.5, the mean and median concentrations were 28 600 and 20 400 pg/m3, respectively, with a range of 3810−15 000 pg/m3. These results suggested that most PAHs were predominantly sorbed onto fine particulates, which is similar to what was found for ClPAHs. Particle size is a major determining factor in the atmospheric behavior of aerosol particles and can influence the residence time and removal 7619



Article

Table 2. Correlation between ClPAH and Corresponding Parent PAH Concentrations, Particle Mass, and Total Organic Carbon PM10-bound compound 9-ClFle 9-ClPhe 3,9-Cl2Phe 9,10-Cl2Phe 2-ClAnt 9-ClAnt 3-ClFlu 8-ClFlu 3,4-Cl2Flu 1-ClPyr 7-ClBaA 6-ClBaP ∑ClPAHs Fle Phe Ant Flu Pyr BaA BaP ∑7PAHs a

parent PAH a

0.523* 0.189 0.344 0.694** −0.052 0.213 0.781** 0.738** 0.808** 0.736** 0.843** 0.619** 0.712**

PM2.5-bound

PM

TC

parent PAH

PM

TC

0.274 0.155 0.358 0.529* 0.182 0.432* 0.660** 0.427* 0.486* 0.503* 0.628* 0.532* 0.592* 0.439* 0.784** 0.744** 0.787** 0.773** 0.633** 0.663** 0.782**

0.116 0.149 0.485* 0.723** 0.111 0.363 0.743** 0.663** 0.714** 0.670** 0.807** 0.579** 0.700** 0.326 0.827** 0.829** 0.899** 0.848** 0.792** 0.796** 0.927**

0.175 0.477* 0.102 −0.049 0.254 0.193 0.770** 0.784** 0.818** 0.889** 0.862* 0.340 0.713**

−0.250 −0.034 0.056 −0.084 −0.189 −0.064 0.693** 0.549** 0.458* 0.543** 0.589** 0.429* 0.432% 0.418 0.625** 0.632** 0.670** 0.623** 0.638** 0.589** 0.668**

−0.294 −0.049 0.071 −0.048 −0.176 0.022 0.692** 0.635** 0.590** 0.631** 0.694** 0.448* 0.482* 0.331 0.628** 0.686** 0.729** 0.684** 0.765** 0.700** 0.773**

Correlation coefficient: **p < 0.01 (2-tailed). *p < 0.05 (2-tailed).

effects have been detected in OC.46,47 The correlation of OC with ClPAHs suggests that ClPAHs are sorbed onto organic carbon of PM. Nevertheless, we found no correlation between ClPAHs and temperature, or relative humidity. Contrarily, significant correlations were found between particulate mass, total organic carbon, temperature, and humidity, with the concentrations of parent PAHs except for Fle. Prediction of Concentrations of PM-Associated Total ClPAHs and Parent PAHs. Multiple linear regression analysis (MLRA) has been used by many researchers to predict the ambient concentrations of PAHs.8,48,49 In this study, MLRA was performed to further investigate the effect of PM, TC, and meteorological conditions, such as temperature and relative humidity, on airborne concentrations of ClPAHs and parent PAHs. On the basis of statistical significance and ability to predict concentrations, PM, TC, temperature, and humidity were selected for MLRA of parent PAHs (p < 0.01). Although no correlation between ClPAHs and temperature was found in our study, a significant negative correlation was reported between ClPAHs and temperature in an earlier study.25 Thus, the same independent variables that were selected for the prediction of atmospheric PAH concentrations were included in the regression analysis to predict ClPAH concentrations (p < 0.01). The predicted total concentrations of PM10- and PM2.5-associated ClPAHs and parent PAHs were compared with the measured data (from this study). The comparison of predicted and measured total concentrations of PM10-PAHs, PM2.5-PAHs, PM10-ClPAHs, and PM2.5-ClPAHs are shown in Figure 4A−D. The predicted concentrations of parent PAHs agreed well with the measured ones with strong coefficients of determination of 0.918 and 0.950 for PM10- and PM2.5-associated parent PAH concentrations, respectively. However, the models did not yield satisfactory results for predicting ClPAH concentrations. As shown in Figure 4C−D, the comparison of predicted and measured total concentrations of PM10- and PM2.5-associated ClPAHs showed weak coefficients of determination. Information

on physical−chemical properties of ClPAHs is scarce and more detailed parameters are necessary for the development of reliable models to predict atmospheric concentrations of these compounds.26 Furthermore, the formation process of ClPAHs might be different from that of their corresponding parent PAHs; some ClPAHs are probably formed by secondary reactions with other precursors present in the atmosphere.20 These factors may affect formation of ClPAHs from parent PAHs. Toxic Equivalency Quotients of ClPAHs and Parent PAHs. The AhR-mediated activities of 18 ClPAHs and their corresponding parent PAHs have been reported previously.16 On the basis of these relative potency values, we calculated TEQ concentrations of ClPAHs and parent PAHs associated with PM10 and PM2.5 using the following equation: TEQ =

∑ [Ci]REPBaPi/60

where Ci is the concentration of individual ClPAH and parent PAH, REPBaPi is the potency of individual ClPAHs and corresponding parent PAHs relative to BaP (based on EC50). The calculated mean dioxin-like TEQ concentrations of ClPAHs (TEQClPAH) were 2.14 and 1.24 pg-TEQ/m3 for PM10-ClPAHs and PM2.5-ClPAHs, respectively. The TEQs of corresponding parent PAHs (TEQPAH) in PM10 and PM2.5 were 7130 and 5620 pg-TEQ/m3 (Table S8). 7-ClBaA and 6-ClBaP collectively accounted for the preponderance of the total TEQClPAH in PM samples, which is similar to the pattern reported for samples from an e-waste recycling facility in our previous study.18 BaA and BaP accounted for more than 95% of the total TEQPAH. In summary, this is the first study to report ClPAH concentrations in airborne PM10 and PM2.5 in suburban air. We found that mono- and dichloro substituted PAH congeners were ubiquitous and predominant in atmospheric fine particulate matter. The ∑ClPAHs concentrations in nighttime PM samples were higher than those in daytime PM samples. 6-ClBaP, 1-ClPyr, 7-ClBaA, and 3-ClFlu have strong environmental 7620



Article

Figure 4. Comparison of predicted (using multilinear regression models) and measured concentrations of (A) PM10-PAHs, (B) PM2.5-PAHs, (C) PM10-ClPAHs, and (D) PM2.5-ClPAHs for the period October 2011−March 2012 in a suburban area in Shanghai, China.

■

stabilities in air regardless of the particle size. Further research on the physical−chemical properties of ClPAHs is needed to better understand the behavior, sources, and toxic effects of ClPAHs in air.

■

(1) Walgraeve, C.; Demeestere, K.; Dewulf, J.; Zimmermann, R.; Van Langenhove, H. Oxygenated polycyclic aromatic hydrocarbons in atmospheric particulate matter: Molecular characterization and occurrence. Atmos. Environ. 2010, 44, 1831−1846. (2) Cheung, H. C.; Wang, T.; Baumann, K.; Guo, H. Influence of regional pollution outflow on the concentrations of fine particulate matter and visibility in the coastal area of southern China. Atmos. Environ. 2005, 39, 6463−6474. (3) Andreae, M. O.; Jones, C. D.; Cox, P. M. Strong present-day aerosol cooling implies a hot future. Nature 2005, 435, 1187−1190. (4) Billet, S.; Garcon, G.; Dagher, Z.; Verdin, A.; Ledoux, F.; Cazier, F.; Courcot, D.; Aboukais, A.; Shirali, P. Ambient particulate matter (PM2.5): Physicochemical characterization and metabolic activation of the organic fraction in human lung epithelial cells (A549). Environ. Res. 2007, 105, 212−223. (5) Harrison, R. M.; Yin, J. X. Particulate matter in the atmosphere: Which particle properties are important for its effects on health? Sci. Total Environ. 2000, 249, 85−101. (6) Abou Chakra, O. R.; Joyeux, M.; Nerriere, E.; Strub, M. P.; ZmirouNavier, D. Genotoxicity of organic extracts of urban airborne particulate matter: An assessment within a personal exposure study. Chemosphere 2007, 66, 1375−1381. (7) Particulate Matter Air Pollution: How it Harms Health; Fact sheet EURO/04/05; World Health Organization in Europe: Berlin, Copenhagen, Rome, 14 April 2005; www.chaseireland.org/ Documents/WHOParticulateMatter.pdf.

ASSOCIATED CONTENT

S Supporting Information *

Additional data tables as mentioned in the text. This information is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*Phone: +86-21-66137801; fax:+86-21-66137787; e-mail: [email protected] (M.W.). Phone: +518-474-0015; fax: +518-473-2895; e-mail: [email protected] (K.K.). Notes

The authors declare no competing financial interest.

■

REFERENCES

ACKNOWLEDGMENTS

This work was financially supported by the National Natural Science Foundation of China (21007039, 21210102027, 11025526, and 41073073). 7621



Article

gas-particle partitioning, and origin. Environ. Sci. Technol. 2008, 42, 3296−3302. (27) Ohura, T.; Kitazawa, A.; Amagai, T.; Makino, M. Occurrence, profiles, and photostabilities of chlorinated polycyclic aromatic hydrocarbons associated with particulates in urban air. Environ. Sci. Technol. 2005, 39, 85−91. (28) Ohura, T.; Kitazawa, A.; Amagai, T.; Shinomiya, M. Relationships between chlorinated polycyclic aromatic hydrocarbons and dioxins in urban air and incinerators. Organohalogen Compd. 2007, 69, 2902− 2905. (29) Ohura, T.; Sawada, K. I.; Amagai, T.; Shinomiya, M. Discovery of novel halogenated polycyclic aromatic hydrocarbons in urban particulate matters: Occurrence, photostability, and AhR activity. Environ. Sci. Technol. 2009, 43, 2269−2275. (30) Wang, X.; Bi, X.; Sheng, G.; Fu, J. Chemical composition and sources of PM10 and PM2.5 aerosols in Guangzhou, China. Environ. Monit. Assess. 2006, 119, 425−439. (31) Chang, Y. China needs a tighter PM2.5 limit and a change in priorities. Environ. Sci. Technol. 2012, 46, 7069−7070. (32) Overview of EPA’s revisions to the Air Quality Standards for Particle Pollution (Particulate Matter); U.S. EPA; http://www.epa.gov/pm/ 2012/decfsoverview.pdf. (33) Perez, N.; Pey, J.; Querol, X.; Alastuey, A.; Lopez, J. M.; Viana, M. Partitioning of major and trace components in PM10−PM2.5−PM1 at an urban site in Southern Europe. Atmos. Environ. 2008, 42, 1677−1691. (34) Gomiscek, B.; Hauck, H.; Stopper, S.; Preining, O. Spatial and temporal variations of PM1, PM2.5, PM10 and particle number concentration during the AUPHEP-project. Atmos. Environ. 2004, 38, 3917−3934. (35) Pio, C.; Cerqueira, M.; Harrison, R. M.; Nunes, T.; Mirante, F.; Alves, C.; Oliveira, C.; de la Campa, A. S.; Artíñano, B.; Matos, M. OC/ EC ratio observations in Europe: Re-thinking the approach for apportionment between primary and secondary organic carbon. Atmos. Environ. 2011, 45, 6121−6132. (36) Castro, L. M.; Pio, C. A.; Harrison, R. M.; Smith, D. J. T. Carbonaceous aerosol in urban and rural European atmospheres: Estimation of secondary organic carbon concentrations. Atmos. Environ. 1999, 33, 2771−2781. (37) Yang, Y. J.; Tan, J. G; Zheng, Y. F.; Cheng, S. H. Study of the atmospheric stabilities and the thickness of atmospheric mixed layer during recent 15 years in Shanghai. Sci. Meteorol. Sin. 2006, 26, 536−541. (38) Ohura, T.; Amagai, T.; Makino, M. Behavior and prediction of photochemical degradation of chlorinated polycyclic aromatic hydrocarbons in cyclohexane. Chemosphere 2008, 70, 2110−2117. (39) Oh, J. E.; Chang, Y. S.; Kim, E. J.; Lee, D. W. Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in different sizes of airborne particles. Atmos. Environ. 2002, 36, 5109− 5117. (40) Nilsson, U. L.; Colmsjö, A. L. Formation of chlorinated polycyclic aromatic hydrocarbons in different chlorination reactions. Chemosphere 1990, 21, 939−951. (41) Johnsen, S.; Gribbestad, I. S.; Jonasen, S. Formation of chlorinated PAH - A possible health hazard from water chlorination reactions. Sci. Total Environ. 1989, 81/82, 231−238. (42) Nilsson, U. L.; Colmsjö, A. L. Reactivity of polycyclic aromatic hydrocarbons in different chlorination reactions. Chemosphere 1989, 18, 2201−2211. (43) Sugiyama, H.; Katagiri, Y.; Kaneko, M.; Watanabe, T.; Hirayama, T. Chlorination of pyrene in soil components with sodium chloride under xenon irradiation. Chemosphere 1999, 38, 1937−1945. (44) Lu, T.; Huang, Z.; Cheung, C. S.; Ma, J. Size distribution of EC, OC and particle-phase PAHs emissions from a diesel engine fueled with three fuels. Sci. Total Environ. 2012, 438, 33−41. (45) Gray, H. A.; Cass, G. R. Source contributions to atmospheric fine carbon particle concentrations. Atmos. Environ. 1998, 32, 3805−3825. (46) Turpin, B. J.; Cary, R. A.; Huntzicker, J. J. An in-situ, time-resolved analyzed for aerosol organic and elemental carbon. Aerosol Sci. Technol. 1990, 12, 161−171.

(8) Akyüz, M.; Cabuk, H. Meteorological variations of PM2.5/PM10 concentrations and particle-associated polycyclic aromatic hydrocarbons in the atmospheric environment of Zonguldak, Turkey. J. Hazard. Mater. 2009, 170, 13−21. (9) Skarek, M.; Janosek, J.; Cupr, P.; Kohoutek, J.; Novotna-Rychetska, A.; Holoubek, I. Evaluation of genotoxic and non-genotoxic effects of organic air pollution using in vitro bioassays. Environ. Int. 2007, 33, 859−866. (10) Gilli, G.; Pignata, C.; Schiliro, T.; Bono, R.; La Rosa, A.; Traversi, D. The mutagenic hazards of environmental PM2.5 in Turin. Environ. Res. 2007, 103, 168−175. (11) Ohyama, M.; Otake, T.; Adachi, S.; Kobayashi, T.; Morinaga, K. A comparison of the production of reactive oxygen species by suspended particulate matter and diesel exhaust particles with macrophages. Inhalat. Toxicol. 2007, 19, 157−160. (12) Lundstedt, S.; White, P. A.; Lemieux, C. L.; Lynes, K. D.; Lambert, L. B.; Oberg, L.; Haglund, P.; Tysklind, M. Sources, fate, and toxic hazards of oxygenated polycyclic aromatic hydrocarbons (PAHs) at PAH-contaminated sites. Ambio 2007, 36, 475−485. (13) Li, Y.; Zhu, T.; Zhao, J. C.; Xu, B. Y. Interactive enhancements of ascorbic acid and iron in hydroxyl radical generation in quinone redox cycling. Environ. Sci. Technol. 2012, 46, 10302−10309. (14) Aristizábal, B. H.; Gonzalez, C. M.; Morales, L.; Abalos, M.; Abad, E. Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city. Chemosphere 2011, 85, 170−178. (15) Ohura, T. Environmental behavior, sources, and effects of chlorinated polycyclic aromatic hydrocarbons. Sci. World J. 2007, 7, 372−380. (16) Ohura, T.; Morita, M.; Makino, M.; Amagai, T.; Shimoi, K. Aryl hydrocarbon receptor-mediated effects of chlorinated polycyclic aromatic hydrocarbons. Chem. Res. Toxicol. 2007, 20, 1237−1241. (17) Horii, Y.; Khim, J. S.; Higley, E. B.; Giesy, J. P.; Ohura, T.; Kannan, K. Relative potencies of individual chlorinated and brominated polycyclic aromatic hydrocarbons for induction of aryl hydrocarbon receptor-mediated responses. Environ. Sci. Technol. 2009, 43, 2159− 2165. (18) Ma, J.; Horii, Y.; Cheng, J. P.; Wang, W. H.; Wu, Q.; Ohura, T.; Kannan, K. Chlorinated and parent polycyclic aromatic hydrocarbons in environmental samples from an electronic waste recycling facility and a chemical industrial complex in China. Environ. Sci. Technol. 2009, 43, 643−649. (19) Horii, Y.; Ohura, T.; Yamashita, N.; Kannan, K. Chlorinated polycyclic aromatic hydrocarbons in sediments from industrial areas in Japan and the United States. Arch. Environ. Contam. Toxicol. 2009, 57, 651−660. (20) Horii, Y.; Ok, G.; Ohura, T.; Kannan, K. Occurrence and profiles of chlorinated and brominated polycyclic aromatic hydrocarbons in waste incinerators. Environ. Sci. Technol. 2008, 42, 1904−1909. (21) Sun, J. L.; Ni, H. G.; Zeng, H. Occurrence of chlorinated and brominated polycyclic aromatic hydrocarbons in surface sediments in Shenzhen, South China and its relationship to urbanization. J. Environ. Monit. 2011, 13, 2775−2781. (22) Shiraishi, H.; Pilkington, N. H.; Otsuki, A.; Fuwa, K. Occurrence of chlorinated polynuclear aromatic hydrocarbons in tap water. Environ. Sci. Technol. 1985, 19, 585−590. (23) Ieda, T.; Ochiai, N.; Miyawaki, T.; Ohura, T.; Horii, Y. Environmental analysis of chlorinated and brominated polycyclic aromatic hydrocarbons by comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry. J. Chromatogr. A 2011, 1218, 3224−3232. (24) Nilsson, U. L.; Oestman, C. E. Chlorinated polycyclic aromatic hydrocarbons: Method of analysis and their occurrence in urban air. Environ. Sci. Technol. 1993, 27, 1826−1831. (25) Kitazawa, A.; Amagai, T.; Ohura, T. Temporal trends and relationships of particulate chlorinated polycyclic aromatic hydrocarbons and their parent compounds in urban air. Environ. Sci. Technol. 2006, 40, 4592−4598. (26) Ohura, T.; Fujima, S.; Amagai, T.; Shinomiya, M. Chlorinated polycyclic aromatic hydrocarbons in the atmosphere: Seasonal levels, 7622



Article

(47) Kim, Y. P.; Moon, K. C.; Lee, J. H.; Baik, N. J. Concentrations of carbonaceous species in particles at Seoul and Cheju in Korea. Atmos. Environ. 1999, 33, 2751−2758. (48) Demircioglu, E.; Sofuoglu, A.; Odabasi, M. Atmospheric concentrations and phase partitioning of polycyclic aromatic hydrocarbons in Izmir, Turkey. Clean: Soil, Air, Water 2011, 39, 319−327. (49) Larsen, R.; Baker, J. Source apportionment of polycyclic aromatic hydrocarbons in the urban atmosphere: A comparison of three methods. Environ. Sci. Technol. 2003, 37, 1873−1881.

7623
