Science of the Total Environment 524–525 (2015) 1–7

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Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv

Spatial distribution and partition of perfluoroalkyl acids (PFAAs) in rivers of the Pearl River Delta, southern China Baolin Liu a,b,c, Hong Zhang a,⁎, Liuwei Xie a, Juying Li d, Xinxuan Wang c, Liang Zhao a, Yanping Wang c, Bo Yang d a

College of Physical Science and Technology, Shenzhen University, Shenzhen 518060, China College of Chemistry, Changchun Normal University, Changchun 130032, China College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, Tianjin 300222, China d College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060, China b c

H I G H L I G H T S • • • •

PFBS, PFOS and PFOA were the three prominent PFAAs in the rivers. Distribution of PFAAs showed a high pollution in the Pearl River. There were different sources between short-chain PFAAs and long-chain PFAAs. The adsorbances of PFAAs increase with the increase of the alkyl chains.

a r t i c l e

i n f o

Article history: Received 9 January 2015 Received in revised form 1 April 2015 Accepted 1 April 2015 Available online 15 April 2015 Editor: Adrian Covaci Keywords: Perfluoroalkyl acids The Pearl River Delta Source appointment Kd Koc

a b s t r a c t This study investigated the occurrence of perfluoroalkyl acids (PFAAs) in surface water from 67 sampling sites along rivers of the Pearl River Delta in southern China. Sixteen PFAAs, including perfluoroalkyl carboxylic acids (PFCAs, C5–14, C16 and C18) and perfluoroalkyl sulfonic acids (PFSAs, C4, C6, C8 and C10) were determined by high performance liquid chromatography–negative electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). Total PFAA concentrations (∑ PFAAs) in the surface water ranged from 1.53 to 33.5 ng·L − 1 with an average of 7.58 ng·L − 1 . Perfluorobutane sulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) were the three most abundant PFAAs and on average accounted for 28%, 16% and 10% of ∑ PFAAs, respectively. Higher concentrations of ∑ PFAAs were found in the samples collected from Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River flowing the cities which had very well-developed manufacturing industries. PCA model was employed to quantitatively calculate the contributions of extracted sources. Factor 1 (72.48% of the total variance) had high loading for perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), PFBS and PFOS. For factor 2 (10.93% of the total variance), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUdA) got high loading. The sorption of PFCAs on suspended particulate matter (SPM) increased by approximately 0.1 log units for each additional CF2 moiety and that on sediment was approximately 0.8 log units lower than the SPM logKd values. In addition, the differences in the partition coefficients were influenced by the structure discrepancy of absorbents and influx of fresh river water. These data are essential for modeling the transport and environmental fate of PFAAs. © 2015 Elsevier B.V. All rights reserved.

1. Introduction Perfluoroalkyl acids (PFAAs) have been widely used in various consumers and industrial products requiring surface protection during the past 50 years, as have outstanding properties, such as interfacial activity, water and oil repellency, resistance to acid and high temperatures

⁎ Corresponding author. E-mail address: [email protected] (H. Zhang).

http://dx.doi.org/10.1016/j.scitotenv.2015.04.004 0048-9697/© 2015 Elsevier B.V. All rights reserved.

(Kissa, 2001). PFAAs such as perfluoroalkyl carboxylic acids (PFCAs, − F(CF2)nCO− 2 ) and perfluoroalkane sulfonic acids (PFSAs, F(CF2)nSO3 ) are persistent against environmental biodegradation processes (Schultz et al., 2003) and have led to their widespread occurrence in river and ocean water (Yamashita et al., 2005, 2008; Zushi and Masunaga, 2009; Suja et al., 2009; Ahrens, 2011; Wang et al., 2013), wildlife (Giesy and Kannan, 2001; Taniyasu et al., 2003; Senthil Kumar et al., 2009; Ahrens et al., 2011; Houde, et al., 2011), sediments (Zushi et al., 2010; Bao et al., 2010; Zareitalabad et al., 2013), soils (Zareitalabad et al., 2013; Kim et al., 2014), atmosphere (Shoeib et al., 2006; Dreyer et al., 2009;

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Chaemfa et al., 2010) and the human body (Taniyasu et al., 2003; Harada et al., 2007; Bao et al., 2011; Polanska et al., 2012). As a result, contamination by PFAAs has come to the forefront of environmental research. Restrictions have been introduced for the production and use of PFAAs since 2000. In 2009, Annex B of the Stockholm Convention on Persistent Organic Pollutants (POPs) included the perfluorooctane sulfonate (PFOS) and its parent compound, perfluorooctyl sulfonyl fluoride (PFOSF) (UNEP, 2009). However, these chemicals are still used especially in some developing countries such as China (So et al., 2007; Sun et al., 2011; Wang et al., 2011; Yang et al., 2011) which plays a very important role in the global manufacture of PFAAs before 2008 (Ministry of Environmental Protection of China, 2008). Fluorochemical manufacturing facilities are extensively distributed in China, including Liaoning, Tianjin, Shanghai, Zhejiang, Fujian and Guangdong (Cai et al., 2012; Wang et al., 2012b, 2014). There were a number of surveys on PFAAs distribution in central and northern China (Sun et al., 2011; Yang et al., 2011; Wang et al., 2012a, 2012b, 2013, 2014; Meng et al., 2013). While there were many PFC surveys concentrated on the Pearl River in sourthern China (So et al., 2007; Bao et al., 2010; Zhang et al., 2013), it was relatively rare in other rivers in the Pearl River Delta (PRD) such as Dongjiang River, Xijiang River and Beijiang River. Therefore, distribution characteristics of PFAAs in rivers in the PRD are imperative for improving our ability to better understand the distribution of PFAAs and evaluate the level of anthropogenic participation in the pollution caused by PFAAs in the PRD. The PRD, which is located in southern China, is one of the most economically developed regions of China. The Pearl River, Dongjiang River, Xijiang River and Beijiang River which are used for public drinking water supply for millions of people run through the PRD. However, rapid industrialization and urbanization related to manufacture, application and disposal of polyfluorinated alkyl substances (PFASs) have been arising in the PRD in the past decades, which has resulted serious PFAA contamination in the rivers (So et al., 2007; Bao et al., 2010; Zhang et al., 2013). The objectives of this study were to survey the level and spatial distribution of PFAAs in rivers of the PRD, the partition coefficients between water and suspended particulate matter (SPM) and between water and sediment and to understand the sources of PFAAs. 2. Materials and methods 2.1. Chemicals and reagents The target analytes included a mixture of 16 PFAAs (i.e. C5–C14-, C16and C18-PFCAs and C4-, C6-, C8- and C10-PFSAs). The target analytes and 8 internal standards (IS) (i.e. 13C labeled C6-, C8–C12-PFCAs and C8PFSAs and 18 O labeled C6-PFSAs) (Table S1) were purchased from Wellington Laboratories. Methanol (HPLC grade) from J.T. Baker Technologies (USA) and Milli-Q water (electrical resistivity 18.2 MΩ·cm) were used throughout the study. Formic acid (96%), ammonia hydroxide (25%) and ammonium acetate were of HPLC grade, and purchased from Dikma Technologies (USA). Oasis WAX (6 mL, 150 mg, 30 μm) cartridges used for solid phase extraction were purchased from Waters Corporation (USA). 2.2. Sample collection Water samples (n = 67) were collected from rivers in the PRD, including the Pearl River (n = 10), Xijiang River (n = 25), Beijing River (n = 6), and Dongjiang River (n = 26) in August 2013 (Fig. 1). The geographic location of each water sample was listed in Table S2. At each sampling site, 2 L of surface water was collected for the analysis of PFAAs and particulate organic carbon using methanol pre-cleaned polypropylene (PP) bottles. All the water samples were passed through 0.45 μm filters purchased from Whatman Corporation (UK) and refrigerated at 4 °C in the dark for further treatment. Surface sediment

samples (0–5 cm) were collected from 51 sampling sites in accordance with the locations sampling water samples. They were stored in PP bags which were pre-cleaned with methanol and frozen at −20 °C immediately on arriving at the laboratory. The sediments were homogenized and freeze dried in a stainless steel container immediately, and then ground and passed through a 100-mesh sieve, finally kept in PP bags under ambient temperature until the extraction. 2.3. Sample preparation The filtered water samples were extracted using WAX cartridges which were preconditioned with eluting with 2 mL of methanol followed by 2 mL ultra-pure water as previously reported (Taniyasu et al., 2008). A 1000 mL water sample spiked with 5 mL 1 ng·mL−1 IS mix was loaded onto the cartridge at a rate of 2 drops per second. The cartridges were then washed with 2 mL of 2% methane acid, 2 mL of methane acid-methanol (the volume ratio of 1:1) and 2 mL methanol. The target analytes were eluted with 4 mL of 9% ammonia–methanol solution and collected in a 10 mL PP centrifuge tube rinsed with methanol. The eluate was then concentrated to 1 mL under a nitrogen stream and passed through a nylon membrane Millex filter unit (pore diameter 0.2 μm, Millipore, Billerica, MA) before injecting into LC–MS/MS. Sediment samples and the SPMs remaining on the filters were extracted making use of the method as previously described by Higgins et al. (2005). Briefly, 5 mL 1 ng·mL−1 IS mix and 10 mL methanol were dispensed onto a 1.0 g (dry weight equivalent) sediment or SPM sample in a 15 mL centrifuge tube. Each sample was vibrated for 60 min, then centrifuged at 10,000 r·min−1 for 10 min, followed by sonicating for 10 min at 60 °C. After centrifugation, the pellet was extracted twice more as described and the supernatants were combined. The extracts were concentrated to dryness under a gentle stream of nitrogen gas and then were added 8 mL 2% formic acid solution and 42 mL ultrapure water. The mixture was loaded onto the preconditioned Oasis WAX cartridge. Analytes were eluted and the extracts were combined as described above. The extracts were stored at 4 °C before injection to the LC–MS/MS. 2.4. Instrument analysis The final sample extracts were separated by injecting a 10 μL aliquot into a HP 1290 high performance liquid chromatography system (HPLC) (Agilent Technologies) with an Agilent poroshell 120 EC-C18 column (2.7 μm, 2.1 mm × 100 mm). The flow rate was 0.2 mL/min. The column temperature was set at 35 °C. The elution was conducted by mobile phase consisted of 5.0 mM aqueous ammonium acetate (mobile phase A) and 5.0 mM methanolic ammonium acetate (mobile phase B). The gradient elution was started at 90% A, decreased to 30% A at 3 min, and then continuously decreased to 0% A at 13 min before reverting to original conditions at 14 min and maintaining for 6 min. Analytes were determined by using an API 3000 tandem triple quadrupoles mass spectrometry (MS/MS) with negative electrospray ionization (ESI) and multiple reaction monitoring (MRM). The electrospray voltage was 4.5 kV. The ion source temperature was 450 °C. The flow rate of air curtain gas and the auxiliary flow rate were set to 9.0 and 5.0 L·min− 1, respectively. The mass spectrum parameters of target analytes and IS can be found in Table S3. 2.5. Quality control and quality assurance In order to avoid exogenous contamination, all laboratory vessels were PP products and rinsed four times with ultra-pure water and methanol alternately before use. The linear correlation coefficients (r2) of all PFAA homologues were 0.9907–0.9997 for 5–60 ng·mL−1. Along with each batch of 10 samples, one procedure blank was analyzed to assess potential sample contamination. Solvent blanks containing Milli-Q water and methanol (1:1 v/v) were analyzed with every 10 water samples for

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Fig. 1. Sampling sites in rivers of the Pearl River Delta (PRD), China.

monitoring the contamination from instrument. Procedural blanks (500 mL of Milli-Q water for water sample (n = 7) and 0.5 g quartz sand for SPM and sediment sample (n = 5)) were extracted in the same manner as the samples. Only PFOA (b 0.03–0.07 ng·L−1) was detected in the water blank, but this was below the limit of quantification (LOQ). The limit of detection (LOD) of the analytes was determined with a signal-to-noise ratio of 3:1, while LOQ was determined with a signal-to-noise ratio of 10:1. The results lower than LOQ were reported as half of the LOQ, while those lower than LOD were reported as ND (not detected) and zero was assigned for statistical analysis. The LOQ was 0.023–0.158 ng·L−1 for water samples and 0.013–3.175 ng·g−1 for SPM and sediment samples, respectively (Table 1). The spiked recoveries of the 16 PFAAs ranged from 49.1% (PFTeDA) to 134.9% (PFODA) with variation coefficients of 0.5%–26.6% for water samples and were in the range of 61.6% (PFODA) to 127.3% (PFDA) with variation coefficients of 1.2%–23.4% for SPM and sediment samples. All the statistical analyses were performed using SPSS 19.0 and Origin 8.6 for windows.

3. Results and discussion 3.1. Levels and spatial distributions of PFAAs in the Peal River Fifteen PFAAs were quantified in rivers of PRD, i.e. C5–C14, C16, C18PFCAs, and C4-, C6-, C8-PFSAs (Table S2). PFDS was not detected in all samples (Fig. S1). The ∑ PFAA concentrations ranged from 1.53 ng·L−1 to 33.5 ng·L−1 with a mean value of 7.58 ng·L−1. Higher concentrations of ∑ PFAAs were found in the samples collected from Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River (Fig. S2a), which may be attributed to municipal or industrial discharges. For instance, well-developed manufacturing industries are mainly distributed in Foshan, Jiangmen and Dongguan. Guangzhou which the Pearl River flow through is considered as the largest industrial city in southern China. Lower concentrations of ∑ PFAAs were found in the samples collected from Zhaoqing section of Xijiang River and Huizhou section of Dongjiang River, which lie in the upstream of the surveyed

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Table 1 Recoveries and method detection limit of the target analytes in the investigate matrices. Compound

PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUdA PFDoA PFTrDA PFTeDA PFHxDA PFODA PFBS PFHxS PFOS PFDS

River water (n = 3)

River SPM and sediment (n = 3)

Recovery (%) ± SD

LOD (ng L−1)

LOQ (ng L−1)

Recovery (%) ± SD

LOD (ng g−1)

LOQ (ng g−1)

101.7 ± 5.3 96.1 ± 2.3 91.3 ± 6.5 101.4 ± 1.1 96.9 ± 2.0 93.8 ± 0.5 95.8 ± 2.1 95.1 ± 1.7 67.7 ± 10.1 49.1 ± 16.7 78.7 ± 26.6 134.9 ± 12.5 110.4 ± 2.5 94.1 ± 3.1 103.5 ± 2.6 113.6 ± 3.5

0.040 0.027 0.018 0.036 0.015 0.022 0.015 0.017 0.014 0.029 0.022 0.048 0.012 0.013 0.006 0.009

0.132 0.089 0.061 0.121 0.049 0.075 0.051 0.057 0.049 0.099 0.073 0.158 0.040 0.042 0.023 0.031

100.7 ± 3.4 99.1 ± 3.5 86.2 ± 12.1 92.5 ± 1.6 99.8 ± 3.5 127.3 ± 23.4 87.5 ± 12.1 123.5 ± 19.3 98.9 ± 12.1 96.3 ± 13.7 73.0 ± 23.1 61.6 ± 13.2 109.3 ± 12.1 117.7 ± 13.1 107.3 ± 1.2 115.2 ± 1.3

0.013 0.009 0.009 0.022 0.011 0.012 0.013 0.013 0.019 0.023 0.286 0.952 0.008 0.006 0.004 0.004

0.045 0.031 0.032 0.073 0.038 0.039 0.043 0.044 0.064 0.078 0.952 3.175 0.027 0.020 0.013 0.013

river. The levels of ∑ PFAAs were significantly lower in samples collected from nonindustrial areas by using multi-factor analysis of variance test (p b 0.05) (Table S2). Consequently, wastewater which contains pollutants such as PFAAs from industrial sources could affect the quality of receiving waters. An overall increasing trend of ∑ PFAAs along the flow direction of the river could be demonstrated in rivers of the PRD. PFBS, PFOA and PFOS with average values of 2.11 ng·L−1, 1.53 ng·L−1 and 1.08 ng·L−1 were the three predominated PFAAs found in the water samples (Fig. S1). PFBS was the most prevalent PFAA which was detected in all the river samples, which is different from previous reports suggesting that PFOS and PFOA are the two extensively detected PFAAs in rivers of China (So et al., 2007; Pan et al., 2011; Yang et al., 2011; Wang et al., 2013). The relatively higher concentration of PFBS compared with the Yangtze River (So et al., 2007) indicated the use of PFBS as a substitute for PFOS-based products in the PRD (Zhang et al., 2013). PFOA and PFOS were detected in 95% and 85% of the collected samples, respectively. PFOA ranged from bLOQ to 9.34 ng·L−1 and accounted for 1% to 37% of the ∑ PFAAs. Meanwhile, PFOS concentrations ranged from ND to 10.6 ng·L−1 and accounted for 0% to 38% of the ∑ PFAAs. The higher percentages of PFOS and PFOA appeared in samples collected from Guangzhou, Jiangmen and Dongguan sections that were placed to industrial areas as mentioned above (Fig. S2b and c). PFNA was the mostly detected long-chain PFAA (perfluoroalkyl chains longer than 8 carbons) accounting for 22% to 69% of ∑ PFAAs which is consistent to a previous report (Zushi et al., 2011). PFHxA had been widely detected in the water and sediment of urban rivers (Labadie and Chevreuil, 2011; Möller et al., 2010; Wang et al., 2011). In the Pearl River, PFHxA was detected in 75% of the samples, while in Xijiang River and Beijiang River, the detection rate of PFHxA was very low.

the total variance) had high loading for PFHxA, PFPeA, PFBS and PFOS. For factor 2 (10.93% of the total variance), PFNA and PFUdA got high loading. According to the reported sources of PFAAs, the extracted factors should be related to the actual source categories. PFOS and other PFSAs are mainly products in an electrochemical fluorination process (Hekster et al., 2003; de Voogt et al., 2006). The mist suppressant which contained PFSAs was applied to control hexavalent chromium emissions in electroplating industry (Kelly and Solem, 2008; Xiao et al., 2012). However, the products from telomerization of tetrafluoroethylene contain an ethylene. Fluorotelomer alcohol 8:2 (8:2-FTOH, C8F17C2C2H4OH) which could be degraded to PFOA and other shortchain PFCAs (Dinglasan et al., 2004; Wang et al., 2005a, 2005b) is a pivotal substance for telomer production. In addition, PFOA has been widely used in food-packing processes (Xiao et al., 2012). In Pearl River Delta, there were a large number of factories, among which 15– 20% were electroplating factories and food-packing process industrial facilities (Ministry of Environmental Protection of China., 2013). Thus factor 1 could be identified as electroplating industry and foodpacking process industry emission source. The ratio of PFAAs to PFOA or PFOS could be applied to identify the sources of PFAAs (Simcik and Dorweiler, 2005; Wang et al., 2012a). The PFHxA/PFOA ratios in this study were mostly less than 1.0 except Foshan section of the Pearl River, indicating potential point sources of PFHxA. Similarly, the ratios of PFBS/PFOS were almost higher than 1.0, which could be likely due to the global phase-out of PFOS and PFOA and the use of PFBS and other short-chain PFCAs as substitutes for PFOS-based and PFOA-

3.2. Source appointment The principal component analysis (PCA) model is a widely used receptor model for apportioning pollutants such as PFAAs, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in atmospheric and aquatic environments (Bzdusek et al., 2006; Shi et al., 2009, 2012; Xu et al., 2013). In this study, PCA model was used to identify the sources of PFAAs. A 67× 10 dataset was introduced into PCA model. The character 67 was assigned to be the number of water samples and 10 was the number of PFAAs. The other 6 individual PFAAs including PFDoA, PFTrDA, PFTeDA, PFHxDA, PFODA and PFDS were excluded because of their low detection rates. Statistical analysis results are presented in Fig. 2, in which the source contributions were obtained. PFAAs could be grouped into a two-component model that accounted for 84% of all the data variation. The eigenvalues of two factors were greater than one after varimax rotation. Factor 1 (72.48% of

Fig. 2. Graphical display of PCA.

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Table 2 Partition coefficients between suspended particulate matter (SPM) and dissolved phase (logKd), and sediment and overlaying dissolved phase (logK′d), and organic carbon normalized partition coefficient between SPM and dissolved phase (logKoc), and sediment and overlaying dissolved phase (logK′oc) for individual PFAAs. Compound

PFPeA PFHxA PFOA PFNA PFDA PFUdA PFODA PFHxS PFOS

SPM-derived

Sediment-derived

Log Kd(cm3·g−1)

Log Koc(cm3·g−1)

Log K′d(cm3·g−1)

Log K′oc(cm3·g−1)

3.69 ± 0.71(n = 58) 3.41 ± 0.67(n = 45) 3.46 ± 0.72(n = 59) 3.77 ± 0.53(n = 51) n.a. n.a. 5.50 ± 0.20(n = 2) 3.95 ± 0.60(n = 18) 3.72 ± 0.67(n = 39)

4.43 ± 0.81 4.46 ± 0.63 4.54 ± 0.68 4.72 ± 0.53 n.a. n.a. 6.04 ± 0.12 4.64 ± 0.62 4.76 ± 0.63

2.96 ± 0.61(n = 49) 2.87 ± 0.55(n = 38) 2.67 ± 0.48(n = 40) 2.88 ± 0.21(n = 37) 2.99 ± 0.22(n = 36) 3.16 ± 0.25(n = 32) n.a. 3.61 ± 0.40(n = 26) 3.11 ± 1.17(n = 45)

4.94 ± 0.68 4.80 ± 0.58 4.67 ± 0.55 4.88 ± 0.30 4.99 ± 0.31 5.13 ± 0.27 n.a. 5.65 ± 0.56 5.07 ± 1.17

n.a. = not available; Kd = CSPM/Cw; Koc = Kd × 100/foc; K′d = Cs/Cw; K′oc = K′d × 100/foc; CSPM = PFAA concentration on SPM; Cs = PFAA concentration in sediment; Cw = PFAA concentration in the dissolved phase; foc = organic carbon fraction.

based production (D′Eon et al., 2006; Zhang et al., 2013). Similar results have been observed in European rivers such as Rheine River in Germany (Möller et al., 2010). Higher ratios of PFBS/PFOS were concentrated in samples of Foshan section and the concentrations of PFBS and PFOS in Guangzhou section were significantly higher than other rivers. According to Yearbook Guangzhou and Foshan, 2012, a number of industries such as clothing, electronics, food-packing factories have been built in the 1980s and we also found them in the sampling process. Hence, factor 1 could mainly explain anthropogenic point sources which are mainly distributed in Foshan and Guangzhou of the PRD. Because telomerization can only yield even-numbered, linear perfluoroalkyl chains, PFNA and PFUdA had significantly different sources from short-chain PFCAs. It was reported that precursors of PFAAs (e.g. fluorotelomer alcohols (FTOHs), fluorooctane sulfonamides (FOSAs), and fluorooctane sulfonamidoethanols (FOSEs)) used for paint and ink additives, leather and paper products, etc. (Loewen et al., 2005) could be degraded to long-chain PFAAs in the atmosphere (Ellis et al., 2004; Martin et al., 2005; D′Eon et al., 2006). They could get into the rivers through dry or wet deposition. Thus factor 2 could be identified as atmospheric sources. The correlations of individual PFC concentrations could explain the impact of atmospheric deposition. A positive correlation between PFNA and PFOA with a slope ~ 1 in snow samples which were only contaminated atmospherically by 8:2 PTOH was found by Young et al. (2007). The correlations between PFNA and PFOA with a slope of ~ 0.4 in the Atlantic Ocean and ~ 0.2 in Northern Europe can be partly explained by atmospheric deposition (Ahrens et al., 2009a, 2010b). In this survey, PFNA and PFOA were correlated with a slope of ~ 0.15, which indicated that a small part of PFOA and PFNA originated from atmospheric deposition. Simcik and Dorweiler (2005) found that a high ratio of PFHpA to PFOA indicated a good tracer of atmospheric deposition. In this study, PFHpA/PFOA ratios at all the sampling sites were lower than 1, which suggested that PFAAs in rivers of the PRD originated from direct emissions rather than atmospheric deposition. 3.3. Partition coefficient of PFAAs between SPM and dissolved phase The distribution of PFAAs between the SPM and dissolved phase is characterized by a partition coefficient (Kd), which was defined as a ratio of solute concentrations in SPM (CSPM) and water phases (Cw) according to Eq. (1). The organic carbon normalized partition coefficient (Koc) was calculated with the organic carbon fraction (foc) according to Eq. (2). K d ¼ C SPM =C w

ð1Þ

K oc ¼ K d  100=f oc :

ð2Þ

The partition coefficients are shown in Table 2. The sorption of individual PFAAs on SPM was obviously influenced by the perfluoroalkyl

chain length. For example, the log Koc value increased from 4.43 cm3·g−1 for PFPeA to 4.72 cm3·g−1 for PFNA. The log Koc increased by approximate 0.1 log units for PFCAs with each additional CF2 moiety. Furthermore, in addition to the side chain length, functional groups (i.e. sulfonate and carboxylic acid) were also found to influence the distribution of PFAAs on SPM. The log Koc for PFSAs was approximate 0.2 log units higher than PFCAs which had the same carbon chain length. The results are not in agreement with a previous study which showed that the partition coefficient of PFSAs was 0.71–0.76 log units higher than PFCAs with the same carbon chain length (Ahrens et al., 2010a). The SPM property, water chemistry (e.g., pH, Ca2+, salinity) may influence the sorption of PFAAs (Ahrens et al., 2009b, 2010a; You et al., 2010).

3.4. Partition coefficient of PFAAs between sediment and dissolved phase The data on sediment from the same sampling location as a water sample were used to calculate the partition coefficients of PFAAs between sediment and dissolved phase. The partition coefficient (log K′d) and organic carbon normalized partition coefficient (log K′oc) were calculated using the same formula as SPM in the previous section, in which the PFAA concentration in sediment (Cs) was used of the CSPM. The partition coefficients for PFAAs on sediments are shown in Table 2. The average log K′oc values generally increased for PFCA homologues with increasing carbon chain length except PFPeA and PFHxA, where a slight decline in log K′oc values was found. This is consistent with field finding from Haihe River (Li et al., 2011). The log K′d of 3.11 ± 1.17 for PFOS in this study is much higher than the field log K′d in literatures, i.e. 1.2–1.6 (Becker et al., 2008), 2.1 ± 0.1 (Ahrens et al., 2010a) and 2.53 ± 0.35 (Kwadijk et al., 2010). For PFOA, the average value of log K′d (2.67 ± 0.48) is also higher than the previous reports, i.e. 0.04 ± 0.03 (Ahrens et al., 2010a), 0.18–0.48 (Becker et al., 2008) and 1.83 ± 0.40 (Kwadijk et al., 2010). The reason for difference of log K′d may be due to the different sediment characteristics between the studied areas (Li et al., 2011). The log K′d values for PFCA on sediment were approximately 0.8 log units lower than the log Kd values on SPM. Similarly, the log K′d values for PFSA on sediment were approximately 0.5 log units lower than the log Kd values on SPM. The differences between the partition coefficients on sediment and SPM could be explained by the following reasons. First, the structure discrepancy between sediment and SPM which have different adsorption capacities for PFAAs exerted influence on this variability. Second, the influx of fresh water might result in the disequilibrium of distribution between SPM and dissolved phase, leading to higher concentrations of PFAAs on SPM and log Kd values (Ahrens et al., 2010a). These results are consistent with patterns observed in a previous study (Maruya et al., 1996).

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4. Conclusion This study provided baseline data of PFAA pollution in rivers of the PRD, sourthern China. PFBS, PFOA and PFOS were the predominant PFAAs detected in this study. Higher levels of ∑ PFAAs were found in the water samples collected Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River flowing the cities, suggesting the existences of potential sources in this area. PCA model concluded that short-chain PFAAs (C ≤ 7) and long-chain PFAAs (C ≥ 8) had different sources in the surface water. Among the different PFAA homologues, the average log Koc values generally increased with increasing perfluoroalkyl chain length. The log Kd values for PFAAs with the same carbon chain length on sediment were lower than that on SPM. However, particle/water and sediment/water interactions are very complex and largely controlled by the organic carbon. Overall, these data could help improve understanding the fate of PFAAs and are essential for modeling behaviors of transportation and transformation for PFAAs in water environment. Acknowledgment This study was supported by the National Natural Science Foundation of China (Nos. 11275130, 21177089 21407108 and 31200407) and Science and Technology Research Project of the Education Department of Jilin Province, China (No. 2014518). Appendix A. Supplementary data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.scitotenv.2015.04.004. References Ahrens, L., 2011. Polyfluoroalkyl compounds in the aquatic environment: a review of their occurrence and fate. J. Environ. Monit. 13, 20–31. Ahrens, L., Barber, J.L., Xie, Z., Ebinghaus, R., 2009a. Longitudinal and latitudinal distribution of perfluoroalkyl compounds in the surface water of the Atlantic Ocean. Environ. Sci. Technol. 43, 3122–3127. Ahrens, L., Yamashita, N., Yeung, L.W.Y., Taniyasu, S., Horii, Y., Lam, P.K.S., Ebinghaus, R., 2009b. Partitioning behaviour of per- and polyfluoroalkyl compounds between pore water and sediment in two sediment cores from Tokyo Bay, Japan. Environ. Sci. Technol. 43, 6969–6975. Ahrens, L., Taniyasu, S., Yeung, L.W.Y., Yamashita, N., Lam, P.K.S., Ebinghaus, L., 2010a. Distribution of polyfluoroalkyl compounds in water, suspended particulate matter and sediment from Tokyo Bay, Japan. Chemosphere 79, 266–272. Ahrens, L., Xie, Z., Ebinghaus, R., 2010b. Distribution of perfluoroalkyl compounds in seawater from Northern Europe, Atlantic Ocean, and Southern Ocean. Chemosphere 78, 1011–1016. Ahrens, L., Herzke, D., Huber, S., Bustnes, J.O., Bangjord, G., Ebinghaus, R., 2011. Temporal trends and pattern of polyfluoroalkyl compounds in tawny owl (Strix aluco) eggs from Norway, 1986–2009. Environ. Sci. Technol. 45, 8090–8097. Bao, J., Liu, W., Liu, L., Jin, Y., Ran, X., Zhang, Z., 2010. Perfluorinated compounds in urban river sediments from Guangzhou and Shanghai of China. Chemosphere 80, 123–130. Bao, J., Liu, W., Liu, L., Jin, Y., Dai, J., Ran, X., Zhang, Z., Tsuda, S., 2011. Perfluorinated compounds in the environment and the blood of residents living near fluorochemical plants in Fuxin. China. Environ. Sci. Technol. 45, 8080–8975. Becker, A.M., Gerstmann, S., Frank, H., 2008. Perfluorooctanoic acid and perfluorooctane sulfonate in the sediment of the Roter Main river, Bayreuth, Germany. Environ. Pollut. 156, 818–820. Bzdusek, P.A., Christensen, E.R., Lee, C.M., Pakdeesusuk, U., Freedman, D.L., 2006. PCB congeners and dechlorination in sediments of Lake Hartwell, South Carolina, determined from cores collected in 1987 and 1998. Environ. Sci. Technol. 40, 109–119. Cai, M., Zhao, Z., Yang, H., Yin, Z., Hong, Q., Sturm, R., Ebinghaus, R., Ahrens, L., Cai, M., He, J., Xie, Z., 2012. Spatial distribution of per- and polyfluoroalkyl compounds in coastal waters from the East to South China Sea. Environ. Pollut. 161, 162–169. Chaemfa, C., Barber, J.L., Huber, S., Breivik, K., Jones, K.C., 2010. Screening for PFOS and PFOA in European air using passive samplers. J. Environ. Monit. 12, 1100–1109. D′Eon, J.C., Hurley, M.D., Wallington, T.J., Mabury, S.A., 2006. Atmospheric chemistry of N-methyl perfluorobutane sulfonamidoethanol, C4F9SO2N(CH3)CH2CH2OH: kinetics and mechanism of reaction with OH. Environ. Sci. Technol. 40, 1862–1868. de Voogt, P., Berger, U., de Coen, W., de Wolf, W., Heimstad, E., McLachlan, M., van Leeuwen, S., van Roon, A., 2006. Perfluorinated organic compounds in the European environment (Perforce). Report to the EU. University of Amsterdam, Amsterdam, The Netherlands, pp. 1–126. Dinglasan, M.J.A., Ye, Y., Edwards, E.A., Mabury, S.A., 2004. Fluorotelomer alcohol biodegradation yields poly- and perfluorinated acids. Environ. Sci. Technol. 38, 2857–2864.

Dreyer, A., Weinberg, I., Temme, C., Ebinghaus, R., 2009. Polyfluorinated compounds in the atmosphere of the Atlantic and Southern oceans: evidence for a global distribution. Environ. Sci. Technol. 43, 6507–6514. Ellis, D.A., Martin, J.W., De Silva, A.O., Mabury, S.A., Hurley, M.D., Sulbaek Andersen, M.P., Wallington, T.J., 2004. Degradation of fluorotelomer alcohols: a likely atmospheric source of perfluorinated carboxylic acids. Environ. Sci. Technol. 38, 3316–3321. Giesy, J.P., Kannan, K., 2001. Global distribution of perfluorooctane sulfonate in wildlife. Environ. Sci. Technol. 35, 1339–1342. Harada, K., Koizumi, A., Saito, N., Inoue, K., Yoshinaga, T., Date, C., Fujii, S., Hachiya, N., Hirosawa, I., Koda, S., Kusaka, Y., Murata, K., Omae, K., Shimbo, S., Takenaka, K., Takeshita, T., Todoriki, H., Wada, Y., Watanabe, T., Ikeda, M., 2007. Historical and geographical aspects of the increasing perfluorooctanoate and perfluorooctane sulfonate contamination in human serum in Japan. Chemosphere 66, 293–301. Hekster, F.M., Laane, R.W.P.M., de Voogt, P., 2003. Environmental and toxicity effects of perfluoroalkylated substances. Rev. Environ. Contam. Toxicol. 179, 99–121. Higgins, C.P., Field, J.A., Criddle, C.S., Luthy, R.G., 2005. Quantitative determination of perfluorochemicals in sediments and domestic sludge. Environ. Sci. Technol. 39, 3946–3956. Houde, M., De Silva, A.O., Muir, D.C.G., Letcher, R.J., 2011. Monitoring of perfluorinated compounds in aquatic biota: an updated review. Environ. Sci. Technol. 45, 7962–7973. Kelly, J., Solem, L., 2008. Identification of a major source of perfluorooctane sulfonate (PFOS) at a wastewater treatment plant in Brainerd, Minnesota. Environ. Epidemiol. 19, 303–304. Kim, E., Park, Y., Park, J., Kim, J., 2014. Distributions of new Stockholm convention POPs in soils across South Korea. Sci. Total Environ. 476–477, 327–335. Kissa, E., 2001. Fluorinated Surfactants and Repellents vol. 97. Marcel Dekker. Kwadijk, C.J.A.F., Korytar, P., Koelmans, A.A., 2010. Distribution of perfluorinated compounds in aquatic systems in the Netherlands. Environ. Sci. Technol. 44, 3746–3751. Labadie, P., Chevreuil, M., 2011. Partitioning behaviour of perfluorinated alkyl contaminants between water, sediment and fish in the Orge River (nearby Paris, France). Environ. Pollut. 159, 391–397. Li, F., Sun, H., Hao, Z., He, N., Zhao, L., Zhang, T., Sun, T., 2011. Perfluorinated compounds in Haihe River and Dagu Drainage Canal in Tianjin, China. Chemosphere 84, 265–271. Loewen, M., Halldorson, T., Wang, F., Tomi, G., 2005. Fluorotelomer carboxylic acids and PFOS in rainwater from an urban center in Canada. Environ. Sci. Technol. 39, 2944–2951. Martin, J.W., Ellis, D.A., Mabury, S.A., Hurley, M.D., Wallington, T.J., 2005. Atmospheric chemistry of perfluoroalkanesulfonamides: kinetic and product studies of the OH radical and Cl atom initiated oxidation of N-ethyl perfluorobutanesulfonamide. Environ. Sci. Technol. 40, 864–872. Maruya, K.A., Risebrough, R.W., Horne, A.J., 1996. Partitioning of polynuclear aromatic hydrocarbons between sediments from San Francisco Bay and their porewaters. Environ. Sci. Technol. 30, 2942–2947. Meng, J., Wang, T., Wang, P., Giesy, J.P., Lu, Y., 2013. Perfluorinated compounds and organochlorine pesticides in soils around Huaihe River: a heavily contaminated watershed in Central China. Environ. Sci. Pollut. Res. 20, 3956–3974. Ministry of Environmental Protection of China, 2008. Preliminary Information on Risk Management Evaluation of PFOS's in China. http://chm.pops.int/Portals/0/ Repository/comments_draftRME2008/UNEP-POPS-POPRC-DRME-08-CHISCCP. English.PDF. Ministry of Environmental Protection of China, 2013. Environmental Statistics Year book of China. Möller, A., Ahrens, L., Surm, R., Westerveld, J., van der Wielen, R., Ebinghaus, F., de Voogt, P., 2010. Distribution and sources of polyfluoroalkyl substances (PFAS) in the River Rhine watershed. Environ. Pollut. 158, 3243–3250. Pan, Y., Shi, Y., Wang, J., Jin, X., Cai, Y., 2011. Pilot investigation of perfluorinated compounds in river water, sediment, soil and fish in Tianjin, China. Bull. Environ. Contam. Toxicol. 87, 152–157. Polanska, K., Jurewicz, J., Hanke, W., 2012. Exposure to environmental and lifestyle factors and attention-deficit/hyperactivity disorder in children — a review of epidemiological studies. Int. J. Occup. Med. Environ. Health 25, 330–355. Schultz, M.M., Barofsky, D.F., Field, J.A., 2003. Fluorinated alkyl surfactants. Environ. Eng. Sci. 20, 487–501. Senthil Kumar, K., Zushi, Y., Masunaga, S., Gilligan, M., Pride, C., Sajwan, K.S., 2009. Perfluorinated organic contaminants in sediment and aquatic wildlife, including sharks, from Georgia, USA. Mar. Pollut. Bull. 58, 621–629. Shi, G., Feng, Y., Wu, J., Li, X., Wang, Y., Xue, Y., Zhu, T., 2009. Source identification of polycyclic aromatic hydrocarbons in urban particulate matter of TangShan, China. Aerosol. Air Qual. Res. 9, 309–315. Shi, G., Tian, Y., Guo, C., Feng, Y., Xu, J., Zhang, Y., 2012. Sediment–pore water partition of PAH source contributions to the Yellow River using two receptor models. J. Soil Sediment. 12, 1154–1163. Shoeib, M., Harner, T., Vlahos, P., 2006. Perfluorinated chemicals in the Arctic atmosphere. Environ. Sci. Technol. 40, 7577–7583. Simcik, M.F., Dorweiler, K.J., 2005. Ratio of perfluorochemical concentrations as a tracer of atmospheric deposition to surface waters. Environ. Sci. Technol. 39, 8678–8683. So, M.K., Miyake, Y., Yeung, W.Y., Ho, Y.M., Taniyasu, S., Rostkowski, P., Yamashita, N., Zhou, B.S., Shi, X.J., Wang, J.X., Giesy, J.P., Yu, H., Lam, P.K.S., 2007. Perfluorinated compounds in the Pearl River and Yangtze River of China. Chemosphere 68, 2085–2095. Suja, F., Pramanik, B.K., Zain, S.M., 2009. Contamination, bioaccumulation and toxic effects of perfluorinated chemicals (PFCs) in the water environment: a review paper. Water Sci. Technol. 60, 1533–1544. Sun, H., Li, F., Zhang, T., Zhang, X., He, N., Song, Q., Zhao, L., Sun, L., Sun, T., 2011. Perfluorinated compounds in surface waters and WWTPs in Shenyang, China: Mass flows and source analysis. Water Res. 45, 4483–4490.

B. Liu et al. / Science of the Total Environment 524–525 (2015) 1–7 Taniyasu, S., Kannan, K., Horii, Y., Hanari, N., Yamashita, N., 2003. A survey of perfluorooctane sulfonate and related perfluorinated organic compounds in water, fish, birds, and humans from Japan. Environ. Sci. Technol. 37, 2634–2639. Taniyasu, S., Kannan, K., Yeung, L.W.Y., Kwok, K.Y., Lam, P.K.S., Yamashita, N., 2008. Analysis of trifluoroacetic acid and other short-chain perfluorinated acids (C2–C4) in precipitation by liquid chromatography–tandem mass spectrometry: comparison to patterns of long-chain perfluorinated acids (C5–C18). Anal. Chim. Acta 619, 221–230. UNEP, 2009. The 9 New POPs Under the Stockholm Convention. http://chm.pops.int/ Programmes/NewPOPs/The9newPOPs/tabid/672/language/en-US/Default.aspx (accessed Feb. 27, 2011). Wang, N., Szostek, B., Folsom, P.W., Sulecki, L.M., Capka, V., Buck, R.C., Berti, W.R., Gannon, J.T., 2005a. Aerobic biotransformation of 14 C-labeled 8-2 telomer B alcohol by activated sludge from a domestic sewage treatment plant 39, 531–538. Wang, N., Szostek, B., Buck, R.C., Folsom, P.W., Sulecki, L.M., Capka, V., Berti, W.R., Gannon, J.T., 2005b. Fluorotelomer alcohol biodegradation: direct evidence that perfluorinated carbon chains breakdown. Environ. Sci. Technol. 39, 7516–7528. Wang, T., Lu, Y., Chen, C., Naile, J.E., Khim, J.S., Park, J., Luo, W., Jiao, W., Hu, W., Giesy, J.P., 2011. Perfluorinated compounds in estuarine and coastal areas of north Bohai Sea, China. Mar. Pollut. Bull. 62, 1905–1914. Wang, T., Khim, J.S., Chen, C., Naile, J.E., Lu, Y., Kannan, K., Park, J., Luo, W., Jiao, W., Hu, W., Giesy, J.P., 2012a. Perfluorinated compounds in surface waters from Northern China: comparison to level of industrialization. Environ. Int. 42, 37–46. Wang, T., Lu, Y., Chen, C., Naile, J.E., Khim, J.S., Giesy, J.P., 2012b. Perfluorinated compounds in a coastal industrial area of Tianjin, China. Environ. Geochem. Health 34, 301–311. Wang, B., Cao, M., Zhu, H., Chen, J., Wang, L., Liu, G., Gu, X., Lu, X., 2013. Distribution of perfluorinated compounds in surface water from Hanjiang River in Wuhan, China. Chemosphere 93, 468–473. Wang, P., Lu, Y., Wang, T., Fu, Y., Zhu, Z., Liu, S., Xie, S., Xiao, Y., Giesy, J.P., 2014. Occurrence and transport of 17 perfluoroalkyl acids in 12 coastal rivers in south Bohai coastal region of China with concentrated fluoropolymer facilities. Environ. Pollut. 190, 115–122. Xiao, F., Halbach, T.R., Simcik, M.F., Gullver, J.S., 2012. Input characterization of perfluoroalkyl substances in wastewater treatment plants: source discrimination by exploratory data analysis. Water Res. 46, 3101–3109.

7

Xu, J., Tian, Y., Zhang, Y., Guo, C., Shi, G., Zhang, C., Feng, Y., 2013. Source appointment of perfluorinated compounds (PFCs) in sediments: Using three multivariate factor analysis receptor models. J. Hazard. Mater. 260, 483–488. Yamashita, N., Kannan, K., Taniyasu, S., Horii, Y., Petrick, G., Gamo, T., 2005. A global survey of perfluorinated acids in oceans. Mar. Pollut. Bull. 51, 658–668. Yamashita, N., Taniyasu, S., Petrick, G., Wei, S., Gamo, T., Lam, P.K.S., Kannan, K., 2008. Perfluorinated acids as novel chemical tracers of global circulation of ocean waters. Chemosphere 70, 1247–1255. Yang, L., Zhu, L., Liu, Z., 2011. Occurrence and partition of perfluorinated compounds in water and sediment from Liao River and Taihu Lake, China. Chemosphere 83, 806–814. You, C., Jia, C.X., Pan, G., 2010. Effect of salinity and sediment characteristics on the sorption and desorption of perfluorooctane sulfonate at sediment–water interface. Environ. Pollut. 158, 1343–1347. Young, C.J., Furdui, V.L., Franklin, J., Koerner, R.M., Muir, D.C.G., Mabury, S.A., 2007. Perfluorinated acids in Arctic snow: new evidence for atmospheric formation. Environ. Sci. Technol. 41, 3455–3461. Zareitalabad, P., Siemens, J., Hamer, M., Amelung, W., 2013. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in surface waters, sediments, soils and wastewater — a review on concentrations and distribution coefficients. Chemosphere 91, 725–732. Zhang, Y., Lai, S., Zhao, Z., Liu, F., Chen, H., Zou, S., Xie, Z., Ebinghaus, R., 2013. Spatial distribution of perfluoroalkyl acids in the Pearl River of Southern China. Chemosphere 93, 1519–1525. Zushi, Y., Masunaga, S., 2009. Identifying the nonpoint source of perfluorinated compounds using a geographic information system based approach. Environ. Toxicol. Chem. 28, 691–700. Zushi, Y., Tamada, M., Kanai, Y., Masunaga, S., 2010. Time trends of perfluorinated compounds from the sediment core of Tokyo Bay, Japan (1950s–2004). Environ. Pollut. 158, 756–763. Zushi, Y., Ye, F., Motegi, M., Nojiri, K., Hosono, S., Suzuki, T., Kosugi, Y., Yaguchi, K., Masunaga, S., 2011. Spatially detailed survey on pollution by multiple perfluorinated compounds in the Tokyo Bay basin of Japan. Environ. Sci. Technol. 45, 2887–2893.