Environ. Sci. Technol. 2009, 43, 643–649
Chlorinated and Parent Polycyclic Aromatic Hydrocarbons in Environmental Samples from an Electronic Waste Recycling Facility and a Chemical Industrial Complex in China J I N G M A , †,+ Y U I C H I H O R I I , + JINPING CHENG,† WENHUA WANG,† QIAN WU,+ TAKESHI OHURA,§ AND K U R U N T H A C H A L A M K A N N A N * ,+ School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, 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, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509, and Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
Received October 10, 2008. Revised manuscript received December 02, 2008. Accepted December 08, 2008.
Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are a class of halogenated contaminants found in the urban atmosphere; they have toxic potential similar to that of dioxins. Information on the sources of ClPAHs is limited. In this study, concentrations of 20 ClPAHs and 16 parent PAHs were measured in electronic wastes, workshop-floor dust, vegetation, and surface soil collected from the vicinity of an electronic waste (e-waste) recycling facility and in surface soil from a chemical industrial complex (comprising a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant), and agricultural areas in central and eastern China. High concentrations of ΣClPAHs were found in floor dust (mean, 103 ng/g dry wt), followed in order of decreasing concentration by leaves (87.5 ng/g dry wt), electronic shredder waste (59.1 ng/g dry wt), and soil (26.8 ng/g dry wt) from an e-waste recycling facility in Taizhou. The mean concentration of ΣClPAHs in soil from the chemical industrial complex (88 ng/g dry wt) was approximately 3-fold higher than the concentration in soil from e-waste recycling facilities. The soils from e-waste sites and industrial areas contained mean concentrations of ΣClPAHs 2 to 3 orders of magnitude higher than the concentrations in agricultural soils (ND-0.76 ng/ g), suggesting that e-waste recycling and chlorine-chemical industries are potential emission sources of ClPAHs. The profiles of ClPAHs in soil and dust were similar to a profile that has been reported previously for fly ash from municipal solid waste incinerators (6-ClBaP was the predominant compound), but the profiles in vegetation and electronic shredder waste were * Corresponding author phone: (518) 474-0015; fax: (518) 4732895; e-mail:
[email protected]. † Shanghai Jiao Tong University. + Wadsworth Center, State University of New York at Albany. § University of Shizuoka. 10.1021/es802878w CCC: $40.75
Published on Web 01/06/2009
2009 American Chemical Society
different from those found in fly ash. Concentrations of 16 parent PAHs were high (150-49 700 ng/g) in samples collected from the e-waste recycling facility. Significant correlation between ΣClPAH and ΣPAH concentrations suggests that direct chlorination of parent PAHs is the major pathway of formation of ClPAHs during e-waste recycling operations. Dioxin-like toxic equivalency quotients (TEQs) for ClPAHs and PAHs in samples were calculated on the basis of relative potencies reported for ClPAHs and PAHs. The highest mean TEQ concentrationsofClPAHs(518pg-TEQ/g)werefoundforworkshopfloor dust, followed by leaves (361 pg-TEQ/g), electronic shredder waste (308 pg-TEQ/g), soil from the chemical industrial complex (146 pg-TEQ/g), and soil from the sites of the e-waste recycling facility (92.3 pg-TEQ/g). With one exception, the floor dust samples, the TEQ concentrations of ClPAHs found in multiple environmental matrices in this study were higher than the TEQ concentrations of PCDD/Fs in the same samples reported in our earlier study.
Introduction Electronic waste (e-waste) recycling facilities have drawn the world’s attention as a new source of environmental contamination by polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) (1-4). Low-temperature incineration of organic materials (e.g., polyvinylchloride or PVC) during the recycling of e-wastes can release several toxic environmental pollutants. Chlorinated PAHs (ClPAHs) are substituted PAHs that are produced during the combustion of municipal solid wastes (5). ClPAHs are carcinogenic and mutagenic and possess toxic potentials similar to those of PCDD/Fs (5). As a class of ClPAHs, polychlorinated naphthalenes (PCNs) have been reported to occur in a wide variety of environmental and biological matrices (6-9). ClPAHs have been detected in environmental samples such as snow, tap water, sediment, urban air, road tunnel air, pulp-mill products, and fly ash (10-17). Nevertheless, prior to the present study, occurrence of ClPAHs in e-waste recycling facilities has not been investigated. Automobile emissions and municipal incineration facilities have been reported as major emission sources of ClPAHs (5, 16, 18). Wang et al. (18, 19) investigated the mechanism of formation of ClPAHs during the combustion of PVC. PVC accounts for a major fraction of materials found in e-wastes by volume (26%) (20). PVC is used in electronics as a housing material and as insulation for wires and other electronic parts (1, 3). The techniques employed in e-waste recycling in many countries are often primitive and hazardous and include manual disassembly, roasting (use of dry heat), and open burning at low temperatures, leading to environmental release of toxic pollutants (3, 4). We hypothesize that lowtech e-waste recycling is a source of ClPAHs in the environment. In this study, we analyzed multiple environmental matrices collected from an e-waste recycling facility, to investigate whether e-waste recycling is indeed a source of ClPAHs. Electronics shredder waste, workshop-floor dust, soil, and leaves were collected in and around a large-scale e-waste recycling facility located in Taizhou in eastern China. We also collected soil samples from a chemical industrial complex (including a PVC manufacturing plant and a chlor-alkali plant) in Shanghai. Furthermore, surface agricultural soils collected near seven cities in central and eastern China were analyzed, to enable an understanding of the sources and VOL. 43, NO. 3, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
643
FIGURE 1. Map of the study area and sampling locations in central and eastern China. The sampling sites each indicated with a bullet, are: surface agricultural soil from (1) Daqing in Heilongjiang Province; (2) Chifeng in Inner Mongolia; (3) Lanzhou in Gansu Province; (4) Luoyang in Henan Province; (5) Chengdu in Sichuan Province; (6) Haikou in Hainan Province; and (7) Dexing in Jiangxi Province. The two insets show the main study areas. Top, surface soil from Wujing chemical industrial complex and rural area in Shanghai; Bottom, surface soil, workshop-floor dust, electronic shredder waste, leaf from Fengjiang town, and surface soil from Wenling city in Taizhou District. profiles of ClPAH contamination in China (further details on the study area are provided in the Supporting Information and in our previous report (21)).
Materials and Methods Sample Collection and Target Compounds. Three types of sampling locations were selected for this study: e-waste recycling facilities, a chemical industrial complex, and agricultural areas (see Figure 1). Workshop-floor dust, electronic shredder waste, leaves from trees and shrubs, and surface soil (0-10 cm depth) were collected from a largescale e-waste recycling facility in Fengjiang town in Taizhou (samples from an urban area without an e-waste recycling facility in Wenling city, 25 km south of Fengjiang town, were used as reference for comparison) in September 2007 (Figure S1; Supporting Information) (21). Surface soil samples (0-10 cm depth) were collected in September 2007 from Wujing chemical industrial complex in Shanghai, and a rural area with no industries, 43 km northwest of Wujing town, was selected as a reference site (for details, see Figure S2 in the Supporting Information). Surface agricultural soils (0-10 cm depth) were collected from Daqing, Chifeng, Lanzhou, Luoyang, Chengdu, Haikou, and Dexing during 2006-2007. For each location, several samples were pooled, to yield a representative sample. All of the soil samples were collected using a clean stainless steel shovel at a depth of 0-10 cm. All collected samples were wrapped in solvent-cleaned aluminum foil and stored at -20 °C until analysis. Twenty individual ClPAHs, representing mono- through trichloroPAHs, were determined: 9-monochlorofluorene (9ClFle), 9-monochlorophenanthrene (9-ClPhe), 3,9-dichlorophenanthrene (3,9-Cl2Phe), 1,9-dichlorophenanthrene (1,9Cl2Phe), 9,10-dichlorophenanthrene (9,10-Cl2Phe), 3,9,10trichlorophenanthrene(3,9,10-Cl3Phe),2-monochloroanthracene (2-ClAnt), 9-monochloroanthracene (9- ClAnt), 9,10-dichloroanthracene (9,10-Cl2Ant), 3-monochlorofluoranthene (3ClFlu), 8-monochlorofluoranthene (8-ClFlu), 5,7-dichloro644
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 3, 2009
fluoranthene (5,7-Cl2Flu), 3,8-dichlorofluoranthene (3,8Cl2Flu),3,4-dichlorofluoranthene(3,4-Cl2Flu),1-monochloropyrene (1-ClPyr), 6-monochlorochrysene (6-ClChr), 6,12-dichlorochrysene (6,12-Cl2Chr), 7-monochlorobenz[a]anthracene (7ClBaA), 7,12-dichlorobenz[a]anthracene (7,12-Cl2BaA), and 6-monochlorobenzo[a]pyrene (6-ClBaP). The sum of concentrations of the 20 individual ClPAHs is referred to in this study as ΣClPAHs. The purities of ClPAH standards were >95% (confirmed by a gas chromatograph interfaced with mass spectrometer, GC/MS) (15, 22, 23). In addition, 16 U.S. Environmental Protection Agency’s (EPA) priority PAHs, naphthalene (Nap), acenaphthylene (Ael), acenaphthene (Ace), fluorene (Fle), phenanthrene (Phe), anthracene (Ant), fluoranthene (Flu), pyrene (Pyr), benz[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (IDP), benzo[g,h,i]perylene (BghiP), and dibenz[a,h]anthracene (DBahA), were determined. The sum of concentrations of the 16 parent PAHs is referred to as ΣPAHs. Sixteen PAHs and deuterated PAH standard mixtures, including naphthalene-d8, acenaphthene-d10, phenanthrened10, chrysene-d12, and pyrene-d12 were purchased from AccuStandard (New Haven, CT). Silica gel (grade 635, 60-100 mesh) was obtained from Aldrich (St. Louis, MO) and was activated at 130 °C for 6 h prior to use. Chemical Analysis. ClPAH and PAH congeners were analyzed following the method described elsewhere, with some modifications (15). Approximately 20 g of each airdried sample was homogenized with anhydrous sodium sulfate, followed by Soxhlet-extraction with dichloromethane (DCM) and n-hexane (3:1, v/v) for 16 h. Deuterated PAH standard was spiked onto each sample after extraction. The extracts were concentrated to 2 mL and then were fractionated using activated silica gel column (2 g) chromatography. The silica gel column was prewashed with 50 mL of n-hexane, and the target compounds were eluted with 20 mL of 20% DCM in n-hexane (F2) after passage of 7 mL of n-hexane (F1), and then 50 mL of DCM (F3), through the column. The fraction F2 contained ClPAHs and PAHs. This fraction was purified with a disposable filtration column (3 mL, packed with 20 µm frits; J. T. Baker, Phillipsburg, NJ, USA) 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; for silica gel, grade 644, 100-200 mesh, 150 Å, Sigma-Aldrich, St. Louis, MO). The column was precleaned by passage of 50 mL of toluene and then 10 mL of hexane. After loading the extract, the column was eluted with 50 mL of 20% DCM in n-hexane (F2-1), and the column was reversed and eluted with 100 mL of toluene (F2-2). The fraction F2-2 that contained ClPAHs and PAHs was concentrated to 100 µL. The fractions F1, F3, and F2-1 were concentrated and stored at 4 °C in the dark. Concentrations of ClPAHs and PAHs were determined by GC/MS (Agilent 6890GC and 5973MSD; Agilent Technologies, Foster City, CA). 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). Aliquots of 2 µL were injected in splitless mode, at 280 °C for ClPAHs and at 260 °C for PAHs. The column oven temperature was programmed from 80 (1 min) to 140 °C at a rate of 15 °C/min and then to 300 at 5 °C/min; this temperature was held for 5 min for ClPAH analysis. For PAH analysis, the temperature was ramped from 60 (2 min) to 130 °C at a rate of 10 °C/min, and then to 270 at 5 °C/min, and then finally to 300 °C (5 min) at 10 °C/min. The MS was operated in an electron impact (70 eV) selected ion monitoring (SIM). Quality Assurance/Quality Control. Procedural blanks were analyzed with every 10 samples, to monitor for contamination or interferences. None of the target ClPAHs were detected in procedural blanks. The limit of quantification (LOQ) was set to be the lowest concentration of the
TABLE 1. Limit of Quantification and Mean and Ranges of Concentrationsa (ng/g dry wt) for Individual ClPAHs in Electronic Shredder Waste, Leaves, Floor-Dust, and Soil Samples from an e-Waste Recycling Facility, a Chemical Industrial Complex, and from Other Locations e-waste recycling facility
compound
LOQ
electronic shredder waste n)5
9-ClFle 9-ClPhe 2-ClAnt 9-ClAnt 3,9-Cl2Phe b 9,10-Cl2Ant/ 1,9-Cl2Phe 9,10-Cl2Phe 3-ClFlu 8-ClFlu 1-ClPyr 3,9,10-Cl3Phe 5,7-Cl2Flu 3,8-Cl2Flu 3,4-Cl2Flu 6-ClChr 7-ClBaA 6,12-Cl2Chr 7,12-Cl2BaA 6-ClBaP ΣClPAHs
0.12 0.09 0.36 0.17 0.20 0.21
ND ND ND ND 0.94 (ND-1.65) ND
0.06 0.13 0.14 0.15 0.14 0.17 0.18 0.18 0.15 0.27 0.13 0.13 0.27
ND (0.46-0.65) (8.23-20.4) (7.48-26.7) (4.19-6.39) ND ND ND ND 10.6 (4.00-21.3) ND ND 13.5 (5.84-25.3) 59.1 (32.3-101)
0.52 13.2 14.9 5.43
industrial complex
ND ND ND ND ND ND
ND ND ND ND 0.37 (ND-4.49) ND
ND ND ND ND ND ND
ND ND ND ND ND ND
ND ND ND ND ND ND ND ND ND ND ND ND ND ND
0.13 (ND-0.56) 0.73 (ND-2.50) 0.01 (ND-
