Perfluorinated compounds in sediments from the Daliao River system of northeast China

Chemosphere 77 (2009) 652–657

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Perfluorinated compounds in sediments from the Daliao River system of northeast China Jia Bao a, Yihe Jin a,*, Wei Liu a, Xiaorong Ran b, Zhixu Zhang b a

School of Environmental and Biological Science and Technology, Dalian University of Technology, Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, Dalian 116024, China b Life Sciences and Chemical Analysis, Agilent Technologies Co., Ltd., No. 3 Wang Jing North Road, Chao Yang District, Beijing 100102, China

a r t i c l e

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Article history: Received 8 February 2009 Received in revised form 3 July 2009 Accepted 10 August 2009 Available online 6 September 2009 Keywords: Perfluorooctane sulfonate (PFOS) Perfluorooctanoic acid (PFOA) River sediment Vertical variation

a b s t r a c t Perfluorinated compounds (PFCs) have received much attention on their distributions in various matrixes of different areas globally, however, little is known about their existences in river sediments of China. In this study, eight target PFCs including perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorododecanoic acid (PFDoA) and perfluorotetradecanoic acid (PFTA) were determined based upon the upper 10 cm surface sediment samples collected from eleven sites covering three main streams of the Daliao River system in northeast China, which received huge amount of industrial and domestic wastewater annually from the neighbouring areas. Analytical results indicated that total concentrations of PFCs were determined in the range of 0.29–1.03 ng g 1 dry weight in sediments from this river system. As the dominant PFCs contaminants in sediment samples, concentrations of PFOS and PFOA were ranged between
1. Introduction Perfluorinated compounds (PFCs) have been employed universally in both industrial and domestic products, such as surface protectors of textile, leather, carpet, and paper repelling water and oil, fire fighting foams, photolithography, electronic chemicals, floor polishes, photographic film, denture cleaners, shampoos, carpet spot cleaners, and pesticides, since its initial commercialization over half a century ago (OECD, 2002). The extremely stable chemical structures of PFCs contribute to their unusual physical–chemical properties involving extraordinary resistance to environmental and biological degradation, repellence to water and oil, as well as thermal stability (Kissa, 2001). The widespread applications of PFCs coupled with their unique characteristics make them ubiquitously distributed in various types of biotic and abiotic matrices (Giesy and Kannan, 2001; Hansen et al., 2001; Moody et al., 2002; Houde et al., 2006). In addition, their existences have posed

* Corresponding author. Address: School of Environmental and Biological Science and Technology, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, China. Tel./fax: +86 411 84708084. E-mail address: [email protected] (Y. Jin). 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.08.018

certain environmental risks to the corresponding ecosystems, in terms of their bioaccumulation (Martin et al., 2004) and diverse toxicities (Lau et al., 2004). The research on this realm so far have revealed the main pathways of PFCs into the environment that related to the emissions from the manufacturing processes (Prevendouros et al., 2006), the precursor transformations (Dinglasan et al., 2004), and the effluents of treated wastewater (Sinclair and Kannan, 2006; Becker et al., 2008a). In recent years, much attention from the field of environmental sciences has been mostly paid on the PFCs in aqueous environments (Mclachlan et al., 2007; Ju et al., 2008; Murakami et al., 2008), biota (Giesy and Kannan, 2001; Houde et al., 2006) and populations with non-occupational exposures (Hansen et al., 2001; Jin et al., 2007) in different areas. Accordingly, some research have been carried on the distributions of PFCs in Chinese environments since 2004 (So et al., 2004; Jin et al., 2007; Ju et al., 2008; Li et al., 2008a,b; Yeung et al., 2008), yet little is known about the PFCs in sediments of water bodies within Chinese regions. Previous studies showed that the PFCs in water bodies can accumulate in bottom sediment via sorption (Higgins and Luthy, 2006; Becker et al., 2008b), subsequently transferred into the aquatic organisms due to their good bioavailability (Higgins et al., 2007).

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In many cases, occurrences of PFCs in water bodies were originated from the effluents of wastewater treatment plants (WWTP) served for the urbanized or industrialized areas due to incomplete PFCs treatments (Sinclair and Kannan, 2006; Becker et al., 2008a). Hence the water bodies that received those effluents might result in accumulations of PFCs in the bottom sediments, and thereby influence the surrounding aquatic ecosystems (Martin et al., 2004; Nakata et al., 2006). Up to date, several studies on PFCs in river sediments have been implemented in USA (Higgins et al., 2005), Japan (Nakata et al., 2006; Senthilkumar et al., 2007), and Germany (Becker et al., 2008b), indicated the levels of PFCs in river sediments ranging from the levels of mid-pg g 1 to low-ng g 1. The Daliao River system is situated in the south of northeast China with a catchment area of 27 000 km2 and a catchment population of more than 20 million, consisting of Hun River, Taizi River and Daliao River. (Fig. 1) The watershed covers series of highly dense and industrialized regions in northeast China, namely the central Liaoning city cluster, which is also an important industrial base of China specializing in machinery, electronics, metal refining, and petroleum and chemical industries. As a main tributary of the Liao River system, which is recognized as one of the most contaminated water bodies throughout China (Du, 2004), the Daliao River system received about 2 billion tons of industrial and domestic wastewater annually from the neighbouring areas (Du, 2004; Cai, 2006). Ministry of Environmental Protection of China (2008) outlined that China had began large-scale production of perfluorooctane sulfonate (PFOS) since 2003. The total production of PFOS within China was less than 50 tons before 2004, whereas Chinese annual production of this PFC had grown rapidly due to the sharp increase in domestic applications as well as overseas demands resulting from the restrictions on production of PFOS in developed countries since 2005. Statistically, in the year of 2006, 15 Chinese enterprises in total produced more than 200 tons of perfluorooctane sulfonyl fluoride (PFOSF), being the precursor of PFOS, about 100 tons of which was exported to Brazil, EU and Japan. According to Stock et al. (2007), study on vertical variations of PFCs concentrations in sediments with depth was able to illustrate potential trends in sediment PFCs contaminations, which might draw a picture for the historical variations of local PFCs contaminations through the temporal analysis on sediments. The goals of this study were to determine the spatial distributions of PFCs in sediments from the Daliao River system including its three main streams as mentioned above, and to show the potential trends in PFCs contaminations of sediments with depth in this river system, based upon the analyses on the vertical variations of PFCs concentrations in sectioned sediment core samples. This

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study presented the first investigation on the spatial distributions and vertical variations with depth of sediment PFCs contaminations in the Daliao River system of northeast China. 2. Materials and methods 2.1. Chemicals and equipments Standards of potassium nonafluoro-1-butanesulfonate (PFBS, 98%) and hepatadecafluoropelargonic acid (PFNA, 95%) were purchased from Tokyo Chemical Industry (Tokyo, Japan). Potassium perfluorohexane sulfonate (PFHxS, 98%) was purchased from Interchim (Montlucon, France). Potassium heptadecafluorooctane sulfonate (PFOS, 98%) was purchased from Fluka (Steinheim, Germany). Pentadecafluorooctanoic acid (PFOA, 95%) was purchased from Wako Pure Chemical Industries (Osaka, Japan). Nonadecafluorodecanoic acid (PFDA, 96%) and perfluorododecanoic acid (PFDoA, 97%) were purchased from Acros Organics (Geel, Belgium). Perfluorotetradecanoic acid (PFTA, 97%) was purchased from Aldrich (Steinheim, Germany). Tetrabutylammonium hydrogensulfate (TBAHS) of HPLC grade and sodium carbonate (99%) were obtained from Acros Organics (Geel, Belgium). HPLC grade ammonium acetate was obtained from Dikma Technology (Richmond, VA). HPLC grade methyl tert-butyl ether (MTBE), methanol, and acetonitrile were purchased from Tedia (Fairfield, OH). Milli-Q water was cleaned using Waters Oasis HLB Plus cartridges (Milford, MA) to remove the potential residue of PFCs. Mixed stock PFCs standard solution was prepared in methanol. All reagents were used as received. All the equipments involved in the sample collection, preparation, and analysis were pre-cleaned with methanol and cleaned Milli-Q water. No Teflon and glass equipments were used during the whole study. 2.2. Sampling area and collection The Daliao River system covers three main streams as mentioned above, which flow through Liaoning Province of northeast China southwestwards from the mountain areas in the northeast. Geographically, the Hun River is 415 km in length with a catchment area of 11 500 km2, while the Taizi River is 413 km in length with a catchment area of 13 900 km2. The two rivers converge to form the Daliao River, which ultimately flows into the Liaodong Bay of the Bohai Sea through a 97 km long watercourse with a catchment area of 1926 km2. In April of 2008, samplings for this study were performed at 11 sites in the Daliao River system (Fig. 1). Of which, sites H1–H4 were located in the Hun River, sites T1–T4 were located in the Taizi River, and sites D1–D3 were situated in the Daliao River. All the sampling locations were placed at least 5 m off the riverbanks. Five individual surface sediments (0–10 cm) were collected with a hand piston sediment sampler (£ = 6 cm) at each site, and then stored in polypropylene (PP) tubes. The sampler was pre-cleaned with methanol and Milli-Q water before each sampling. Duplicated samples from sites H2, T4 and D1 were sectioned into 1 cm per slice in situ, and gathered into 250 mL PP bottles. 2.3. Sample preparation and analysis

Fig. 1. Sediment sampling area and sites in the Daliao River system, China.

When arriving at the laboratory, samples were transferred into PP boxes and air-dried. Individual samples from each location or depth were mixed and homogenized with a porcelain mortar and pestle, and then sieved with a 0.83 mm mesh, finally stored at 600 mL PP bottles under ambient temperature until the extraction. Sediment samples were extracted based upon the method that employed by Stock et al. (2007). Briefly, 5 g of sediment sample

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was weighed into a 50 mL PP centrifuge tube, and then moistened by adding 2 mL cleaned Milli-Q water with vortexing. 2 mL of 0.25 M sodium carbonate buffer and 1 mL of 0.5 M TBAHS were added for extraction by vortexing. Subsequently, 5 mL of MTBE was added and shaken for 20 min. After centrifuging for 30 min at 3500 rpm, the supernatant of MTBE was collected. The remanent aqueous mixture was rinsed with 5 mL of MTBE, followed by shaking and centrifuging, the supernatant was combined with the first one in a 15 mL PP centrifuge tube. The MTBE solvent was evaporated to dryness under a gentle flow of high purity nitrogen, and reconstituted in 1 mL mixture of methanol and 10 mM ammonium acetate (2:3, v/v). The solution was filtered through a 0.22 lm nylon filter, and then transferred into a 1 mL PP snap top vial with polyethylene (PE) cap. The extracts of sediment samples were analysed via high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). Chromatography was performed by an Agilent 1100 HPLC system (Agilent Technologies, Palo Alto, CA). A 25 lL aliquot of extract was injected onto a 2.1  100 mm (3.5 lm) Agilent Eclipse Plus C18 column (Agilent Technologies, Palo Alto, CA) with 10 mM ammonium acetate and acetonitrile as mobile phases initialising with 40% acetonitrile at a flow rate of 250 lL min 1 and column temperature of 40 °C. The gradient was increased to 90% acetonitrile at 9 min and then held for 2 min. In addition, a post time of 8 min was run for equilibration during injection interval. The HPLC system was interfaced to an Agilent 6410 Triple Quadrupole (QQQ) mass spectrometer (Agilent Technologies, Santa Clara, CA) operated with electrospray ionization (ESI) in negative mode. The gas temperature and ion spray voltage were maintained at 350 °C and 4000 V. Ions were monitored with a multiple reaction monitoring (MRM) mode, and the parameters involving parent and product ions, and collision energies of each target analyte were detailed in Table 1.

2.4. Quantification and confirmation During the analysis of analytes, procedural blanks were prepared for every seven samples to check the possible contaminations occurred in the extraction. Solvent blanks containing MilliQ water and acetonitrile (3:2, v/v) were prepared to run after every seven samples for monitoring the instrumental background. Duplicate samples and calibration check standards were run after every six samples to assure the precision and accuracy of each run. The concentrations of extracts were quantified via six-point matrixmatched calibration curves drawn by external standards in the range of 0.05–10 ng mL 1. The regression coefficients (r2) of calibration curves for all target analytes were higher than 0.995. The limit of detection (LOD) was defined as the peak of analyte that needed to yield a signal-to-noise (S/N) ratio of 3:1, while the limit of quantification (LOQ) was defined as the peak of analyte that needed to yield a signal-to-noise (S/N) ratio of 10:1 or the lowest point at calibration curve calculated to be with 30% of its actual value. All the analytical results that lower than the LOQs were calcu-

lated using half of the LOQs, while those lower than the LODs were treated as zero. Both recovery and reproducibility of the extraction were validated by spiking 10 ng of each PFC standard onto 5 g sediment samples from the 9 to 10 cm section of site H2 via seven replicated analyses (Table 1). In the blank sediment, only PFOA with concentration that below LOQ was detected, and the other seven PFCs were not determined. The native PFOA concentration was calculated using half of its LOQ and the native concentrations of the other target analytes were treated as zero in the spike and recovery experiments. Recoveries were determined in the range from 81 ± 2% to 108 ± 3%, and relative standard deviation (RSD) for each analyte was lower than 5%.

3. Results and discussion 3.1. Spatial distributions of sediment PFCs in the Daliao River system P As the Table 2, total concentrations of PFCs ( PFCs) in sediments from the Daliao River system were ranged between 0.29 and 1.03 ng g 1 dry weight (dw), and total concentrations of perfluP P orosulfonates ( PFSAs) and perfluorocarboxylates ( PFCAs) at P each sampling site were comparable mutually. In general, PFCs of sites H1 and H2 that situated in the upstream of the Hun River were around twofold higher than those of sites H3 and H4 that located in the midstream and downstream of the river. In the Taizi P River, comparable PFCs were observed in the three sites of T1, T2 and T4 that situated in the main stream of the river, while about P twofold lower PFC was detected at site T3 of a small tributary to P the river. The highest PFC in the Daliao River was determined at P site D2, which were slightly higher than PFCs of the other two sites in this river. Of all the sampling sites, site H2 presented the P highest PFC up to 1.03 ng g 1 dw. Geographically, this site was located in the section of the Hun River that downstream Shenyang City (Fig. 1), which is the central city of northeast China. PFOS and PFOA of total PFCs for analysis were the dominant contaminants detected in sediments from this river system, overall, levels of PFOS contaminations were ranged between below LOQ and 0.37 ng g 1 dw and those of PFOA were varied from below LOQ to 0.17 ng g 1 dw. Both the highest levels of PFOS and PFOA were also observed in site H2. In addition, concentrations of PFOS were higher than those of PFOA at all the sampling sites but site T3. Whereas concentrations of the other six analytes involving PFBS, PFHxS, PFNA, PFDA, PFDoA and PFTA at most of the sampling sites in this watershed were lower than their LOQs. Compared to other research findings, concentrations of PFOS in sediment samples from the Daliao River system were comparable to those from the tidal flat areas of Ariake Sea, Japan (0.09– 0.14 ng g 1) (Nakata et al., 2006) and the Roter Main River, Germany (0.07–0.31 ng g 1) (Becker et al., 2008b), but lower than those from the four rivers by the San Francisco Bay, USA (
Table 1 Validation and MS/MS parameters of the method. Analytes

% Recovery (± SD)

LOD (ng g

PFBS PFHxS PFOS PFOA PFNA PFDA PFDoA PFTA

83 ± 3 81 ± 2 85 ± 4 108 ± 2 92 ± 2 101 ± 3 91 ± 3 81 ± 4

0.04 0.08 0.07 0.05 0.07 0.03 0.06 0.13

1

)

LOQ (ng g 0.10 0.13 0.12 0.08 0.10 0.09 0.09 0.17

1

)

Parent ions

Product ions

Collision energies

299 399 499 413 463 513 613 713

99, 80 99, 80 99, 80 369, 169 419, 219 469, 269 569, 369 669, 469

30, 40 50, 50 55, 60 5, 15 5, 10 5, 15 5, 10 8, 10

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J. Bao et al. / Chemosphere 77 (2009) 652–657 Table 2 Concentrations of PFCs in sediments from the Daliao River system (ng g

1

dw).

Site

PFBS

PFHxS

PFOS

PFOA

PFNA

PFDA

PFDoA

PFTA

P PFSA

P PFCA

P PFC

Hun River H1 H2 H3 H4

0.19 <0.10 <0.10 <0.10

<0.13 <0.13 n.d. n.d.

0.17 0.37 0.13 0.17

0.13 0.17 0.11 <0.08

<0.10 <0.10 <0.10 <0.10

<0.09 0.10 n.d. n.d.

0.10 0.14 <0.09 <0.09

<0.17 <0.17 n.d. n.d.

0.43 0.48 0.18 0.22

0.42 0.54 0.21 0.14

0.85 1.03 0.39 0.36

Taizi River T1 T2 T3 T4

0.12 <0.10 <0.10 <0.10

n.d. <0.13 n.d. <0.13

0.29 0.36 <0.12 0.17

0.12 0.09 0.09 0.14

<0.10 <0.10 <0.10 <0.10

<0.09 <0.09 n.d. <0.09

<0.09 <0.09 <0.09 <0.09

<0.17 <0.17 n.d. <0.17

0.42 0.47 0.11 0.28

0.34 0.32 0.18 0.37

0.76 0.79 0.29 0.65

Daliao River D1 <0.10 D2 <0.10 D3 <0.10

n.d. <0.13 n.d.

0.14 0.28 0.20

0.11 0.13 0.10

<0.10 <0.10 <0.10

<0.09 <0.09 <0.09

<0.09 <0.09 <0.09

n.d. n.d. n.d.

0.19 0.40 0.25

0.25 0.27 0.24

0.44 0.66 0.49

n.d. = not determined.

ble to those of the four rivers by the San Francisco Bay, USA (0.16– 0.23 ng g 1) (Higgins et al., 2005), whereas lower than those of the Ariake Sea, Japan (0.84–1.10 ng g 1) (Nakata et al., 2006). Additionally, concentrations of PFHxS and PFNA in sediment samples were comparable to that reported for the four rivers by the San Francisco Bay, USA (0–
1 cm sections in sites H2, T4 and D1 were 2.3-, 1.2- and 2.5-fold, respectively, higher than the averages of 10 cm mixtures, and the P PFCs of 1–2 cm sections in these three locations were 2.1-, 1.3and 1.5-fold, respectively, higher than the averages. In the first slice of site H2, PFOS concentration was up to 0.97 ng g 1 dw, which presented about a 1.6-fold increase compared to the average of 10 cm mixture, and a 3.7-fold rise compared to the concentration of the fifth slice. PFOA concentration of 0.30 ng g 1 dw showed about a 0.8-fold increase in comparison with the average, and a 6.4-fold rise in comparison with that of the fifth slice. Moreover, PFHxS and PFNA concentrations of 0.34 and 0.17 ng g 1 dw, respectively, were also determined in this layer, which were higher than their averages of 10 cm mixture that below LOQs. According to Lin et al. (2006), an average daily flow of municipal wastewaters up to 650 000 tons was discharged from south of Shenyang City into the river section that less than 3 km upstream site H2, which would be a potential source for PFCs contaminations at this site. In addition, possible seasonal variations of PFCs concentrations in municipal sewages between dry and wet season (Yu et al., 2009) could cause concentrations of PFDA, PFDoA and PFTA in the second slice higher than those in the first slice. Dilution of river water in wet season might be another conceivable reason for this difference. In site T4, PFOS concentration of 0.29 ng g 1 dw in the first layer was around 1.7-fold higher than the average of 10 cm mixture, and twofold higher than that in the fifth layer, while PFOA concentration of 0.17 ng g 1 dw was about 1.2-fold higher than the average of 10 cm mixture, and 1.9-fold higher than that in the fifth layer. PFCs contaminations of this site with small vertical variations along depth might result from fewer amounts of effluents from villages in the vicinity. Contrary to the two sites above, PFOA was the dominant PFC contaminant of site D1 with a concentration of 0.35 ng g 1 dw in the first slice, which was calculated as about 3.2-fold higher than the average of 10 cm mixture, and 8.6-fold higher than that of

Fig. 2. Vertical variations of PFCs in sediment cores from sites H2, T4 and D1.

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the fifth slice. PFOS concentration of 0.16 ng g 1 dw in this slice was merely 1.2-fold higher than both the average and that of the fifth slice. Remarkably, PFCAs including PFNA, PFDA, PFDoA and PFTA with concentrations above LOQs were also detected in this slice, while these PFCs were generally below their LOQs or not determined in the other slices of this sediment core. As Fig. 1, site D1 was located at the confluence of the Hun River and Taizi River. According to a regional report from Asian Development Bank (2005), as a major centre for textiles and apparel production in northeast China, a projected 400-ha textile industrial park specialized in textiles, fabrics and apparel has been built up at west region of Haicheng Town, which situated in the downstream catchment of the Taizi River, since 2005. The differences among PFOA concentrations and occurrences of PFCAs in the first slice of this site might be attributable to the industrial wastewaters from this town-based textile industrial park in booming development but lacking of wastewater treatments (Asian Development Bank, 2005), as PFCAs were proved to have a link with effluents from the textile industries (Boulanger et al., 2005). The present study revealed the spatial distributions and vertical variations with depth of sediment PFCs contaminations in the Daliao River system of northeast China. The analytical results concerned in this study were the averages of mixed and homogenized individual sediment samples from each sampling location or depth, while the limitation might relate to the lack of replicated measurements of each sample. Based upon the analyses on vertical variations of PFCs contaminations with depth in sediment core samples, two implications could be summarized as below. In one side, mixtures of 10 cm sediment core samples could just present the overall sediment PFCs contaminations of sampling locations, as a result, the contaminations that more severe than the averages existed in certain depths locally might be underestimated or even neglected attributed to the dilution of deeper sediment cores with low PFCs concentrations mentioned above, if the averages relied on. In the other side, because the environmental risk evaluations on sediment PFCs within China are still inadequate in recent times, it is suggested that prospective environmental investigations on PFCs contaminations of sediments from Chinese water bodies would take further actions on the vertical distributions of PFCs contaminations via the temporal analysis in order to provide comprehensive information for legislative initiatives or even controls for local PFCs contaminations. Additionally, PFCs levels of sediments from different depths also require focusing on their potential toxicities to surrounding aquatic environments. Acknowledgement This work is funded by the National Nature Science Foundation of China (No. 20837004 and No. 30471435). Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.chemosphere.2009.08.018. Reference Asian Development Bank, 2005. PRC: Town-based urbanization strategy study. Development Proposals for Demonstration Towns, 4, 7–29. . Becker, A.M., Gerstmann, S., Frank, H., 2008a. Perfluorooctane surfactants in waste waters, the major source of river pollution. Chemosphere 72, 115–121. Becker, A.M., Gerstmann, S., Frank, H., 2008b. Perfluorooctanoic acid and perfluorooctane sulfonate in the sediment of the Roter Main River, Bayreuth, Germany. Environ. Pollut. 156, 818–820. Boulanger, B., Vargo, J.D., Schnoor, J.L., Hornbuckle, K.C., 2005. Evaluation of perfluorooctane surfactants in a wastewater treatment system and in a

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