Bull Environ Contam Toxicol (2015) 94:503–510 DOI 10.1007/s00128-015-1479-7
Characterization and Distribution of Heavy Metals, Polybrominated Diphenyl Ethers and Perfluoroalkyl Substances in Surface Sediment from the Dayan River, South China Hai Zheng • Guocheng Hu • Zhencheng Xu Huashou Li • Lijuan Zhang • Jing Zheng • Laiguo Chen • Dechun He
•
Received: 22 July 2013 / Accepted: 22 January 2015 / Published online: 10 February 2015 Ó Springer Science+Business Media New York 2015
Abstract In this study, surface sediment samples were collected from 11 sites in the Dayan River near an electronic waste site in Qingyuan. Heavy metals, polychlorinated biphenyls (PBDEs) and perfluoroalkyl substances (PFASs) were detected. The concentrations of Cu, Zn, Pb and Cd ranged from 12.1 to 641, 47.1 to 891, 39.2 to 641, 0.12 to 2.07 mg/kg dw, respectively. Total PBDEs ranged between 0.052 and 126.64 ng/g dw. BDE-47 and BDE-99 were the predominant PBDEs. The concentrations of PFASs in sediments ranged between 0.01 and 3.72 ng/g dw. The perfluorooctane sulfonate was predominantly PFASs. The strong positive correlations among Cu, Zn, perfluorooctanoic acid and PBDEs indicate that these contaminants were associated with each other and may share a common anthropogenic source in the sediments of the Dayan River. Keywords Heavy metals PBDEs PFASs Electronic waste Sediments South China China has become the largest disposal site of e-waste in the world. It has been estimated that 50 %–80 % of global e-wastes are legally or illegally imported to Asia, with 90 % of this e-waste sent to China, while 50 %–70 % of the e-waste generated in the United States is exported to China (Puckett et al. 2002). Greenpeace International (Greenpeace International 2007) reported that more than H. Zheng H. Li Institute of Tropical and Subtropical Ecology, South China Agricultural University, Guangzhou 510642, China G. Hu (&) Z. Xu L. Zhang J. Zheng L. Chen D. He South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655, China e-mail: [email protected]
4,000 t of e-waste are discarded in China every hour. Martin et al. (2004) estimated that approximately 145 million electronic devices (television sets, computers, electric fans, etc.) were ‘‘recycled’’ in Guangdong Province in 2002. The recovery of valuable metals, such as Au, Ag, Al, and Cu, is the main purpose of e-waste recycling. Therefore, heavy metals are major components of e-waste-released contaminants. Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants, have routinely been used in a variety of commercial and household products, especially in electronic equipment and other appliances, for more than 30 years (BSEF 2000). Perfluorinated compounds (PFASs), are a unique class of surfactants that have been used as components of surfactants, lubricants, paints, polishes, fire-retardants and water repellents for leather, paper, and textiles for over 50 years (Key et al. 1997; Prevedouros et al. 2006). In 2009, PBDEs and PFASs were added to the list of banned chemicals on the Stockholm Convention on Persistent Organic Pollutants because of their persistence, long-range atmospheric transport, widespread distribution, potential for bioaccumulation, and possible adverse effects on wildlife and humans (Ma et al. 2012; Li et al. 2012). It is reported that as much as 70,600 t of PBDEs are annually imported into China in the form of e-waste (Ni et al. 2010). Paul et al. (2009) estimated the worldwide production of perfluorooctane sulfonyl fluoride to be 96,000 t in 1970–2002, with an estimated global release of 45,250 t to air and water in 1970–2012 from direct and indirect sources. It has been reported that wastewater treatment plants and landfill leachates are sources of perfluorinated compounds (Chen et al. 2010; Busch et al. 2010). Many recent reports have demonstrated the pollution in e-waste sites. These reports found POPs (PBDEs, PCBs
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and PAHs) and heavy metals in dust, road and farmland soils, vegetables, aquatic species, domestic fowl, and human hair (Luo et al. 2009, 2011; Wu et al. 2008; Zheng et al. 2011; Wang et al. 2011; Pang et al. 2012; Li et al. 2011). Sediments act as a sink for organic pollutants in aquatic environments. Organic pollutants derived from various human activities are particularly important in urban river sediments (Fu et al. 2003). Luo et al. (2007) found that sediments were highly contaminated by e-waste recycling in Guiyu in Guangdong Province. However, there are no reports about PFASs in sediments near e-waste sites. In light of the above background, the major objectives of this study are to identify the concentrations of heavy metals, PBDEs and PFASs in surface sediment from the Dayan River near an e-waste site and to identify the congener patterns of PBDEs and PFASs. Another objective is to discuss the relationship between heavy metals, PBDEs and PFASs.
Materials and Methods The e-waste region is located in the town of Longtang, Qingyuan County, Guangdong Province, and is approximately 50 km north of Guangzhou (Fig. 1). This region houses more than 1,300 dismantling and recycling workshops, covering an area of approximately 100 km2. It is estimated that more than 80,000 workers are engaged in recycling activities and that approximately 1.7 million tonnes of e-wastes are dismantled annually in this region (Fang and Huang 2006).The recycling operations consist of dismantling electronic equipment, peeling and melting plastic, burning wires to recover copper, melting circuit boards over open fires and using acidic chemical strippers to recover gold and other metals. Acidic chemicals can be dumped into the river without any restrictions. The study area is located in southern China along the Beijiang River, which is one of the largest rivers in Guangdong Province. All sediment sampling sites are
Fig. 1 A sketch map of the sampling areas in the Dayan River
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located near the city of Qingyuan. Sediment samples were collected from 11 selected sites in the Dayan River and are identified as S1–S11 going from upstream to downstream. The samples were obtained from the following locations: S1: Jiangkou town, S2: Yuanhe village, S3: Xinma village, S4: Dazui village, S5: Dayanhe bridge, S6: Longtouchong, S7: Guangqing bridge, S8: Drain outlet of Guangqing bridge, S9: Huangtang village, S10: Xiaohetang village, S11: Xinzhan reservoir. S1–S4 are located in upstream of the town of Longtang, S5–S7 are near Longtang along the Dayan River, S8–S10 are downstream of Longtang, and S11 is in a reservoir located in a small branch of the Dayan River. Sediment samples were collected using a Van Veen stainless steel grab sampler in every site from Dayan River and Xinzhan reservoir. Eleven surface sediment samples (5 cm layer) were scooped using a precleaned stainless steel scoop into solvent-rinsed aluminum containers. Sediment samples were preserved at -20°C until analysis. The target compounds were heavy metals, PFASs and PBDEs. All the samples were collected in 2010. Samples were air dried at room temperature and sieved through a 2-mm nylon sieve to remove coarse debris. The sediments were then ground with a mortar and pestle until all particles passed a 200-mesh nylon sieve. The total heavy metal content of the prepared soil was determined by HCl–HNO3–HF–HClO4 extraction; 20 % of the samples were used as parallels for quality control. The results met the accuracy requirements in the Technical Specification for Soil Environmental Monitoring HJ/T 166-2004 (SEPAC 2004). Details about the procedures for PBDE extraction and purification can be found in Mai et al. (2005). First, sediment samples were ground to powders, and Soxhlet was extracted with acetone/hexane (1:1, v/v) for 48 h. Then, surrogates (BDE-77, BDE-118, and 13C-PCB-141) for recovery estimation were spiked prior to extraction. An aliquot of the extract was used for gravimetric lipid determination. The remainder was subjected to gel
Bull Environ Contam Toxicol (2015) 94:503–510
permeation chromatography (GPC) and eluted with dichloromethane/hexane (1:1, v/v) for lipid removal. The fraction from 90 to 280 mL, which contained the target compounds, was concentrated for further clean-up on a 2 g silica gel solid phase extraction column that was preactivated at 130°C for 15 h before use. The fraction containing PBDEs was obtained by elution with 6.5 mL of hexane/ dichloromethane (60:40, v/v) and redissolved in 50 lL of isooctane. Internal standard (13C-PCB-208) was spiked before instrumental analysis. The samples were analysed on an Agilent 6890 series gas chromatograph coupled to an Agilent 5973 mass spectrometer (GC-5973 Agilent, USA) using negative chemical ionisation (NCI) under a selected ion monitoring mode. An MS capillary column (J&W 122-1232, USA) was used for the determination of PBDE congeners. Methane was used as a chemical ionisation moderating gas and helium as the carrier gas at a flow rate of 1 mL/min. The ion source and interface temperatures were set to 150 and 300°C, respectively. The GC oven temperature program was carried out as follows: held initial temperature 110°C for 1 min, increased to 180°C at 8°C/min, and then to 240°C at 2°C/min, held for 5 min, and then increased to 280°C at 2°C/min, held for 8 min, and then increased to 300°C at 10°C/min and held for 5 min. A 1 lL injection was performed in the pulse splitless mode, with a purge time of 1 min and an injector temperature of 265°C. PBDEs (except BDE-209) were monitored with the m/z responses of 79/81 (bromide ions). BDE-209 used m/z responses of 486.6/484.6 and 496.6/ 494.6, respectively. Three field blanks were prepared using anhydrous sodium sulphate powder as a surrogate for sediment. A procedural blank was processed for every 11 samples. The surrogate recovery in all samples were 103 % ± 20.34 % for BDE-77, 105 % ± 18.51 % for BDE-118 and 102 % ± 8.91 % for 13C-PCB-141. The reported data were not recovery corrected. For PFAS analysis, sediment samples were freeze dried, ground, and homogenised by sieving through a stainless steel 60-mesh sieve and stored in polypropylene (PP) containers at -20°C until extraction. One gram of sediment sample was weighted in a PP centrifuge tube. After the addition of 40 lL of a 50 ng/mL solution of a surrogate standard solution (13C-PFOS and13C-PFOA), the samples were incubated for 30 min, and 8 mL of methanol was added, followed by thorough mixing using a vortex mixer. Samples were then extracted in an ultrasonic bath for 30 min at 60°C and then thoroughly mixed and shaken at 200 r/min for 16 h. Finally, they were centrifuged at 2,500 r/min for 5 min. The supernatant was transferred to a new vial and evaporated to 1 mL under N2. Then, 1 mL of the target analyte was transferred to 50 mL Milli-Q water
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for SPE clean-up. All samples were then extracted using an Oasis WAX cartridge. The target analyte was eluted with 4 mL MeOH and 4 mL 0.5 % NH4OH/MeOH. Then, the target analyte was concentrated to 1 mL under a stream of high purity nitrogen. Analysis of the PFASs was conducted using an HPLC–MS/MS. The separation of the analytes was performed using an Agilent HP1200 liquid chromatograph (HP1200 Agilent, USA) that was interfaced with an API 4000 Q TRAP spectrometer (API4000 Applied Biosystems Sciex, USA) and operated under the electrospray negative mode. A phenomenex C8 column [2.0 mm i.d., 50 mm length; Luna C8 (2)] was used as a chromatographic column. The mobile phase was 10 mM ammonium acetate-MeOH, starting at 30 % MeOH. Detailed instrumental parameters were presented by Taniyasu et al. (2005). Polytetrafluorethylene (PTFE) materials had been removed from the equipment or replaced by stainless steel or PEEK vessels. Polypropylene (PP) or glass tubes and containers were rinsed with methanol and water before use. The perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) standards (1 ng) were treated following the same procedure as the samples, and PFASs were well recovered, with recoveries ranging between 104 % and 117 %. The results indicated that the SPE extraction was sufficient to support quantitative extraction. The sediment samples (1 g, n = 6) were spiked with 2 ng of target standards, aged for 0.5 h, and passed through the whole procedure. The recoveries were in the range of 74.3 %–123 %, and the reproducibility was satisfactory. However, the concentrations of PFASs in the samples were not corrected for the recovery percentages. Linearity was evaluated using eight different concentration points covering a range of 50–20, 000 ng/L. Each concentration was spiked with 5 ng of 13C-PFOS and 13C-PFOA as the internal standards. Analyses and quantifications were performed using Analyst 1.4.1 software (API 4000; Applied Biosystems/MDS SCIEX, US). Curves were prepared using a quadratic ‘‘1/x2’’ weighted regression, where the calibrations showed strong linearity with correlation coefficients [0.99. The limits of detection (LODs) were determined on the basis of a signalto-noise ratio of 3 (S/N = 3) or greater, and the LOD was 0.01 ng/g for PFOS and 0.02 ng/g for PFOA. The eightpoint standard calibration was conducted before and after each analysis. Additionally, 1 lg/L PFASs was injected during the analysis for calibration verification and to ensure sensitivity stability. Statistical analysis was performed using SPSS software version 13.0 (SPSS Inc., Chicago, IL). A Pearson correlation matrix was applied to identify the relationship between the seven analytes. Figures were generated using Origin 8.5.
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Results and Discussion The total metal concentrations (Cu, Zn, Pb, Cd) of sediments from different locations in Dayan River are as shown in Table 1. The results are expressed as milligrams of metal per kilogram of dry sediment and as the mean value of three replicates. The concentration of Cu ranges from 12.2 to 641 mg/kg and that of Zn ranges from 47.0 to 891 mg/kg. The concentration of Pb ranges from 39.2 to 641 mg/kg and that of Cd ranges from 0.12 to 2.07 mg/kg. Sediment S8 had the highest concentrations of two heavy metals (Cu: 641; Zn: 891). The highest concentrations of Pb (164) and Cd (2.07) were found in S11 and S1, respectively, while high levels of Cu (206), Zn (172), and Pb (94.9) were found in S9, S2 and S4, respectively. The other samples were comparatively clean and had low levels of heavy metals. The heavy metal concentrations in all sediment samples (except S2) from the Dayan River were higher than the background values in Guangdong Province soils (China Environmental Monitoring Station 1990). Because there is no standard for river sediment quality in China, we assessed the quality of surface sediment samples base on the standard for marine sediment quality. According to the Chinese marine sediment quality criteria (National Standard of PR China 2002), first class quality is suitable for fisheries, nature reserves, endangered species reserves, and swimming; second class quality can be used for industry and tourism sites; and third class quality can only be used
for harbours. According to this standard, the concentrations of heavy metals at the S2, S4, S7 locations were qualified as first class (Table 1). At S8, the concentrations of Cu and Zn exceeded the third class criteria, while the concentrations of Pb and Cd exceeded the second and first class criteria, respectively. At S9, the concentrations of Zn, Pb and Cd exceeded the first class criteria, while that of Cu exceeded the third class criteria. As for the rest of the sediment samples, the concentrations of two or three heavy metals exceeded the first class criteria. P The concentrations of PBDEs in the sediment samP ples are shown in Fig. 2. PBDEs refers to the sum of all targeted PBDE congeners, including BDEs 28, 47, 66, 85, 99, 100, 138, 153, 154 and 183. All 11 samples contained P P detectable concentrations of PBDEs. The PBDE concentrations ranged between 0.05 and 127 ng/g dw. The P highest PBDE concentration in the Dayan River appeared at S8, which was located downstream of a sewage drainage outlet at the Guangqing Bridge and had a concentration up to 127 ng/g dw. Following were those at P sites S9 and S6, with concentrations of PBDEs of 7.69 and 4.67 ng/g dw, respectively. The concentrations of P PBDEs in the other eight samples ranged between 0.52 and 1.46 ng/g dw. The concentrations of PBDEs in S6– S10, which are located in the middle and downstream parts of the Dayan River and are close to Longtang, are greater than those in the upstream part of the River (S1–S5). This indicates that PBDEs may come from the release of pollutants from e-waste recycling.
Table 1 Concentrations of heavy metals in sediment samples from the Dayan River (mg/kg dw) Sampling location
Cu
Zn
Pb
Cd
S1
47.32 ± 1.61
213.66 ± 1.66
43.44 ± 1.04
2.07 ± 0.04
S2
12.16 ± 1.1
47.05 ± 8.06
58.70 ± 1.07
0.13 ± 0.01
S3
37.77 ± 0.49
117.38 ± 5.51
78.40 ± 0.3
1.16 ± 0.04
S4
17.07 ± 0.66
70.96 ± 3.18
57.98 ± 1.25
0.12 ± 0.01
S5
23.11 ± 1.53
90.10 ± 5.9
42.21 ± 2.57
0.64 ± 0.02
S6
60.96 ± 2.68
116.60 ± 4.6
66.34 ± 7.5
0.96 ± 0.03
S7
15.04 ± 0.08
50.62 ± 2.73
39.21 ± 2.04
0.24 ± 0.01
S8
640.96 ± 10.26
891.06 ± 55.58
148.11 ± 7.83
1.12 ± 0.02
S9 S10
206.22 ± 5.56 41.13 ± 2.25
172.06 ± 6.88 155.39 ± 1.59
94.87 ± 2.13 50.41 ± 2.38
0.82 ± 0.06 0.48 ± 0.01
S11
35.62 ± 1.3
145.93 ± 21.61
164.28 ± 2.71
0.76 ± 0.01
I class
35
150
60
0.5
II class
100
350
130
1.5
III class
200
600
250
5
17
47.3
36
0.056
Standard of marine sediment qualitya
Background of soils in Guangdong Provinceb a
National Standard of PR China (2002) (GB 18668-2002)
b
China Environmental Monitoring Station (1990)
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507
130 125 120 7 6 5 4 3 2 1 0 S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11
Sampling locations Fig. 2 Concentrations of Dayan River (ng/g dw)
P PBDEs in sediment samples from the
The relative abundance of PBDEs in the Dayan River sediments were as follows: BDE-47 [ -99 [ -154 [ -66 [ -153 [ -28 [ -183 [ -100 [ -85 [ -138 (Fig. 3). The contributions of BDE-47 (11.8 %–40.7 %), BDE-99 (7.64 %–43.6 %), BDE-154 (2.52 %–31.9 %) and BDE-66 (4.57 %–29.3 %) were 10 % more than the average. In all sediment samples (except S4), BDE-47 had a higher contribution than the other PBDEs. The contributions of BDE66 in S4–S7 were higher than those in the other sediment locations. The contribution of BDE-99 increased downstream, while that of BDE-154 decreased. Among the triP to hepta-BDE congeners ( PBDEs), BDE-47 and BDE-99 were the predominant compounds. The relative abundances of BDE-47 and BDE-99 were generally 50 % greater than P those of PBDEs, similar to the compositions of major penta-BDE commercial mixtures (Sjo¨din et al. 1998). BDE-66, BDE-153, and BDE-154, which include three congeners that are usually found in the technical P pentaBDE mixture, accounted for 64.8 %–87.9 % of PBDEs, for which the mean value of all samples was 79.4 %. BDE-
S1
Sampling location
S2
BDE28 BDE47 BDE66 BDE85 BDE99 BDE100 BDE138 BDE153 BDE154 BDE183
S3 S4 S5 S6 S7 S8 S9 S10 S11
183 and BDE-138, which are two major components in the octa-BDE mixture, accounted for only 2.81 %–15.6 % of P PBDEs, with a mean value of 7.14 %. The concentrations of PFASs in the sediment samples are shown in Fig. 4. Generally, the total concentrations of PFASs in the sediments of the Dayan River ranged between 0.01 and 3.72 ng/g dw. The highest PFASs in the Dayan River appeared at S9, with a concentration up to 3.72 ng/g dw. The second- and third-ranked PFASs, with concentrations of 2.09 and 0.42 ng/g dw, were found at sites S8 and S10, respectively. The concentrations of PFASs in the other 8 samples ranged between 0.01 and 0.21 ng/g dw. As showed in Fig. 1, S8, S9 and S10 are located downstream of Longtang, which is at the centre of the recycling regions in Guangdong. PFASs released by the process of e-waste dismantling reached the surface and polluted rivers through dry and wet deposition and were then finally adsorbed by the sediment. The closer the sediment sample locations to Longtang, the higher the levels of PFASs tended to be in the sediments of the Dayan River. PFOS was the dominant PFAS contaminant at all sampling sites except S2 and S4. At the other 9 sites, PFOS contributed 52.3 %–99.0 % of the total PFASs in the analytes. However, relatively low contributions of PFOA were determined in all analytes, ranging from 0.03 % to 47.7 %. Sedimentary PBDE concentrations have been reported in various regions in China. As Table 2 shows, except for S8 (sediment from the outfall of the Guangqing Bridge), the levels of PBDEs in this study were low, which is consistent with studies in the Xiamen area and Beijiang River; however, they were much lower than those in the Guiyu River, the Zhujiang River, and the Dongjiang River. The Zhujiang River and the Dongjiang River run through
4.0
Concentration of PFASs (ng/g dw)
Concentaion of PBDEs (ng/g dw)
135
PFOA
3.5
PFOS
3.0 2.5 2.0
0.5
0.0 S1
10
20
30
40
50
60
70
80
90 100
S2
S3
S4
S5
S6
S7
S8
S9
S10 S11
Sampling location
Percentage contributions (%) Fig. 3 Percentage contributions of PBDEs in sediment samples
Fig. 4 Concentrations of PFASs in sediment samples from the Dayan River (ng/g dw)
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Table 2 Comparison of heavy metals, PBDEs and PFASs concentrations in sediments Location
N
Yangtze River Delta
PBDEs
PFOS
PFOA
References
13
n.d.–0.55
n.a.
n.a.
Chen et al. (2006)
Xiamen area
8
0.25–6.42
n.a.
n.a.
Li et al. (2010)
River of Guiyu, Guangdong
5
51.3–365 (156)
n.a.
n.a.
Luo et al. (2007)
Beijiang River, Guangdong
10
Zhujiang River, China Dongjiang River, China Liao River, Liaoning
9 9 14
0.02–186
n.a.
n.a.
Chen et al. (2009)
1.1–49.3 (12.9)
n.a.
n.a.
Mai et al. (2005)
0.04–0.48 (0.15)
0.06–0.31 (0.15)
Yang et al. (2011)
2.2–94.7 (27.3)
Mai et al. (2005)
n.a.
Daliao River system Liaoning
9
n.a.
\0.12–0.37 (0.20)
\0.08–0.17 (0.13)
Bao et al. (2009)
Huangpu River, Shanghai
9
n.a.
\0.12–0.46 (0.11)
0.20–0.64 (0.43)
Bao et al. (2010)
Taihu Lake, China
18
n.a.
0.06–0.31 (0.15)
\0.02–0.52 (0.16)
Yang et al. (2011)
Pearl River, Guangzhou Dayan River
13 11
n.a. 0.05–126.64 (12.86)
\0.12–3.1 (0.58) 0.01–3.72 (0.61)
0.09–0.29 (0.21) n.d.–0.08 (0.02)
Bao et al.(2010) Present study
n.d. not detected n.a. not applicable
important electrical manufacturing regions including Huizhou, Shenzhen, Dongguan, and near Guangzhou, which is a highly urbanised and populated city. The Dayan River is a branch of the Beijiang River, which runs through relatively undeveloped regions in Qingyuan. The PBDE pollution in sediments from Guangdong seemed to be more serious than that in other areas in China. Compared with the sediment PFASs determined in water bodies around China, it was clear that the sediment PFOS contamination in the Dayan River, which is up to 3.72 ng/g dw, was at a relatively higher level that those so far reported in China (Table 2). An even higher level of PFOS was found in the highly urbanised and populated centre of Guangzhou, which is possibly influenced by the discharge of municipal wastewater from the city (Bao et al. 2010). Although PFOS in the Dayan River is only 0.08 ng/ g, those detected in the Daliao River system and the Liao River are even lower. As demonstrated in Table 3, PFOS was the dominant PFAS contaminant in sediments from the Dayan River and the Pearl River system in southern China (Guangdong province), while PFOA was the main PFAS contaminant in sediments from central China (Taihu Lake,
Table 3 Correlation coefficients between heavy metals in sediments from the Dayan River
Cu Zn Pb Cd
** Correlation is significant at the 0.01 level
PFOA
* Correlation is significant at the 0.05 level
PBDEs
123
PFOS
Huangpu River) and northern China (Liao river, Daliao river system). The Dayan River and the Pearl River had similar concentrations of PFOS and PFOA. Sediments act as a sink for organic pollutants in the aquatic environment derived from various human activities (Fu et al. 2003). To reveal the correlation between the variables, statistical analysis was carried out on the whole data set of the chemical concentrations in the sediment samples. The correlation coefficient matrix between heavy metals, PBDEs and PFASs is shown in Table 3. The strong positive correlations among Cu, Zn, PFOA and PBDEs indicate that these contaminants are associated with each other and may share a common anthropogenic and natural source in the sediments of the Dayan River. There may be co-migration of Zn, Cu and PBDEs in the water system, which indicates that these contaminants come from e-waste recycling in Longtang. The correlation coefficients between Pb and Cu, Zn, PBDEs were [0.5, showing significant positive relationships. Non-significant positive correlations were observed between Cd and other contaminants. In this study, surface sediment samples were collected from 11 sites in the Dayan River near an e-waste site in
Cu
Zn
Pb
Cd
PFOA
1
0.967** 1
0.596 0.589
0.262 0.369
0.711* 0.77*
1
PFOS 0.343 0.302
P PBDEs 0.951** 0.969**
0.149
0.349
0.041
0.536
1
0.007
-0.204
0.188
1
0.219
0.764*
1
0.442 1
Bull Environ Contam Toxicol (2015) 94:503–510
Qingyuan. Heavy metal, polychlorinated biphenyls and perfluoroalkyl substances were detected. The concentrations of Cu, Zn, Pb and Cd ranged from 12.2 to 641, 47.0 to 891, 39.2 to 641, and 0.12 to 2.07 mg/kg dw, respectively. The P PBDE concentration ranged between 0.05 and 127 ng/g dw. BDE-47 and BDE-99 were the predominant PBDEs. The concentrations of PFASs in sediments ranged between 0.01 and 3.72 ng/g dw. PFOS was the predominant PFAS. The strong positive correlations among Cu, Zn, PFOA and PBDEs indicate that these contaminants were associated with each other and may share a common anthropogenic and natural source in the sediments of the Dayan River. Acknowledgments The authors gratefully acknowledge the financial support of the Ministry of Environmental Protection (No. 201009026), the National Natural Science Foundation of China (Nos. 21107028, 30200030), and the Natural Science Foundation of Educational Department of Guangdong government (No. 20070506), and National High Technology Research and Development Program of China (863 Program, No. 2013AA102402).
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509 Li Q, Yang C, Luo Z, Zhang X (2010) Occurrence and levels of polybrominated diphenyl ethers (PBDEs) in recent sediments and marine organisms from Xiamen offshore areas, China. Mar Pollut Bull 60:464–469 Li Y, Lin T, Chen Y, Hue LM, Guo ZG, Zhang G (2012) Polybrominated diphenyl ethers (PBDEs) in sediments of the coastal East China Sea: occurrence, distribution and mass inventory. Environ Pollut 171:155–161 Luo Q, Cai ZW, Wong MH (2007) Polybrominated diphenyl ethers in fish and sediment from river polluted by electronic waste. Sci Total Environ 383:115–127 Luo Y, Luo XJ, Lin Z, Chen SJ, Liu J, Mai BX, Yang ZY (2009) Polybrominated diphenyl ethers in road and farmland soils from an e-waste recycling region in Southern China: concentrations, source profiles, and potential dispersion and deposition. Sci Total Environ 407:1105–1113 Luo CI, Liu CP, Wang Y, Liu X, Li FB, Zhang G, Li XD (2011) Heavy metal contamination in soils and vegetables near an e-waste processing site, south China. J Hazard Mater 186: 481–490 Ma J, Qiu X, Zhang J, Duan XL, Zhu T (2012) State of polybrominated diphenyl ethers in China: an overview. Chemosphere 88:769–778 Mai B, Chen S, Luo X (2005) Distribution of polybrominated diphenyl ethers in sediments of the Pearl River Delta and adjacent South China Sea. Environ Sci Technol 39:3521–3527 Martin M, Lam PK, Richardson BJ (2004) An Asian quandary: where have all of the PBDEs gone? Mar Pollut Bull 49:375–382 National Standard of PR China (2002) Marine sediment quality (GB 18668-2002). Standards Press of China, Beijing (in Chinese) Ni HG, Zeng H, Tao S, Zeng EY (2010) Environmental and human exposure to persistent halogenated compounds derived from e-waste in China. Environ Toxicol Chem 29:1237–1247 Pang JX, Sun BQ, Li HZ, Mehlera WT, You J (2012) Influence of bioturbation on bioavailability and toxicity of PAHs in sedimen from an electronic waste recycling site in South China. Ecotoxicol Environ Saf 84:227–233 Paul AG, Jones KC, Sweetman AJ (2009) A first global production, emission, and environmental inventory for perfluorooctane sulfonate. Environ Sci Technol 43:386–392 Prevedouros K, Cousins I, Buck R, Korzeniowski S (2006) Sources, fate and transport of perfluorocarboxylates. Environ Sci Technol 40:32–44 Puckett J, Byster L, Westervelt S, Gutierrez R, Davis S, Hussain A (2002) Exporting harm: the high-tech trashing of Asia. Basel action network, Silicon valley toxics coalition. Available at http://ban.org/E-waste/technotrashfinalcomp.pdf Sjo¨din A, Jakobsson E, Kierkegaardb A, Marsha G, Sellstro¨mb U (1998) Gas chromatographic identification and quantification of polybrominated diphenyl ethers in a commercial product, Bromkal 70-5DE. J Chromatogr A 822:83–89 State Environmental Protection Administration of Chin (SEPAC) (2004) The technical specification for soil environmental monitoring. HJ/T 166-2004. Environmental Press of China, Beijing (in Chinese) Taniyasu S, Kannan K, So MK, Gulkowskad A, Sinclairb E, Okazawaa T, Yamashitaa N (2005) Analysis of fluorotelomer alcohols, fluorotelomer acids, and short-and long-chain perfluorinated acids in water and biota. J Chromatogr A 1093:89–97 Wang Y, Luo CL, Li J, Yin H, Li XD, Zhang G (2011) Characterization of PBDEs in soils and vegetations near an e-waste recycling site in South China. Environ Pollut 159:2443–2448 Wu JP, Luo XJ, Zhan Y, Luo Y, Chen SJ, Mai BX, Yang ZY (2008) Bioaccumulation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in wild aquatic species
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Characterization and Distribution of Heavy Metals, Polybrominated Diphenyl Ethers and Perfluoroalkyl Substances in Surface Sediment from the Dayan River, South China Hai Zheng • Guocheng Hu • Zhencheng Xu Huashou Li • Lijuan Zhang • Jing Zheng • Laiguo Chen • Dechun He
•
Received: 22 July 2013 / Accepted: 22 January 2015 / Published online: 10 February 2015 Ó Springer Science+Business Media New York 2015
Abstract In this study, surface sediment samples were collected from 11 sites in the Dayan River near an electronic waste site in Qingyuan. Heavy metals, polychlorinated biphenyls (PBDEs) and perfluoroalkyl substances (PFASs) were detected. The concentrations of Cu, Zn, Pb and Cd ranged from 12.1 to 641, 47.1 to 891, 39.2 to 641, 0.12 to 2.07 mg/kg dw, respectively. Total PBDEs ranged between 0.052 and 126.64 ng/g dw. BDE-47 and BDE-99 were the predominant PBDEs. The concentrations of PFASs in sediments ranged between 0.01 and 3.72 ng/g dw. The perfluorooctane sulfonate was predominantly PFASs. The strong positive correlations among Cu, Zn, perfluorooctanoic acid and PBDEs indicate that these contaminants were associated with each other and may share a common anthropogenic source in the sediments of the Dayan River. Keywords Heavy metals PBDEs PFASs Electronic waste Sediments South China China has become the largest disposal site of e-waste in the world. It has been estimated that 50 %–80 % of global e-wastes are legally or illegally imported to Asia, with 90 % of this e-waste sent to China, while 50 %–70 % of the e-waste generated in the United States is exported to China (Puckett et al. 2002). Greenpeace International (Greenpeace International 2007) reported that more than H. Zheng H. Li Institute of Tropical and Subtropical Ecology, South China Agricultural University, Guangzhou 510642, China G. Hu (&) Z. Xu L. Zhang J. Zheng L. Chen D. He South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655, China e-mail: [email protected]
4,000 t of e-waste are discarded in China every hour. Martin et al. (2004) estimated that approximately 145 million electronic devices (television sets, computers, electric fans, etc.) were ‘‘recycled’’ in Guangdong Province in 2002. The recovery of valuable metals, such as Au, Ag, Al, and Cu, is the main purpose of e-waste recycling. Therefore, heavy metals are major components of e-waste-released contaminants. Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants, have routinely been used in a variety of commercial and household products, especially in electronic equipment and other appliances, for more than 30 years (BSEF 2000). Perfluorinated compounds (PFASs), are a unique class of surfactants that have been used as components of surfactants, lubricants, paints, polishes, fire-retardants and water repellents for leather, paper, and textiles for over 50 years (Key et al. 1997; Prevedouros et al. 2006). In 2009, PBDEs and PFASs were added to the list of banned chemicals on the Stockholm Convention on Persistent Organic Pollutants because of their persistence, long-range atmospheric transport, widespread distribution, potential for bioaccumulation, and possible adverse effects on wildlife and humans (Ma et al. 2012; Li et al. 2012). It is reported that as much as 70,600 t of PBDEs are annually imported into China in the form of e-waste (Ni et al. 2010). Paul et al. (2009) estimated the worldwide production of perfluorooctane sulfonyl fluoride to be 96,000 t in 1970–2002, with an estimated global release of 45,250 t to air and water in 1970–2012 from direct and indirect sources. It has been reported that wastewater treatment plants and landfill leachates are sources of perfluorinated compounds (Chen et al. 2010; Busch et al. 2010). Many recent reports have demonstrated the pollution in e-waste sites. These reports found POPs (PBDEs, PCBs
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and PAHs) and heavy metals in dust, road and farmland soils, vegetables, aquatic species, domestic fowl, and human hair (Luo et al. 2009, 2011; Wu et al. 2008; Zheng et al. 2011; Wang et al. 2011; Pang et al. 2012; Li et al. 2011). Sediments act as a sink for organic pollutants in aquatic environments. Organic pollutants derived from various human activities are particularly important in urban river sediments (Fu et al. 2003). Luo et al. (2007) found that sediments were highly contaminated by e-waste recycling in Guiyu in Guangdong Province. However, there are no reports about PFASs in sediments near e-waste sites. In light of the above background, the major objectives of this study are to identify the concentrations of heavy metals, PBDEs and PFASs in surface sediment from the Dayan River near an e-waste site and to identify the congener patterns of PBDEs and PFASs. Another objective is to discuss the relationship between heavy metals, PBDEs and PFASs.
Materials and Methods The e-waste region is located in the town of Longtang, Qingyuan County, Guangdong Province, and is approximately 50 km north of Guangzhou (Fig. 1). This region houses more than 1,300 dismantling and recycling workshops, covering an area of approximately 100 km2. It is estimated that more than 80,000 workers are engaged in recycling activities and that approximately 1.7 million tonnes of e-wastes are dismantled annually in this region (Fang and Huang 2006).The recycling operations consist of dismantling electronic equipment, peeling and melting plastic, burning wires to recover copper, melting circuit boards over open fires and using acidic chemical strippers to recover gold and other metals. Acidic chemicals can be dumped into the river without any restrictions. The study area is located in southern China along the Beijiang River, which is one of the largest rivers in Guangdong Province. All sediment sampling sites are
Fig. 1 A sketch map of the sampling areas in the Dayan River
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located near the city of Qingyuan. Sediment samples were collected from 11 selected sites in the Dayan River and are identified as S1–S11 going from upstream to downstream. The samples were obtained from the following locations: S1: Jiangkou town, S2: Yuanhe village, S3: Xinma village, S4: Dazui village, S5: Dayanhe bridge, S6: Longtouchong, S7: Guangqing bridge, S8: Drain outlet of Guangqing bridge, S9: Huangtang village, S10: Xiaohetang village, S11: Xinzhan reservoir. S1–S4 are located in upstream of the town of Longtang, S5–S7 are near Longtang along the Dayan River, S8–S10 are downstream of Longtang, and S11 is in a reservoir located in a small branch of the Dayan River. Sediment samples were collected using a Van Veen stainless steel grab sampler in every site from Dayan River and Xinzhan reservoir. Eleven surface sediment samples (5 cm layer) were scooped using a precleaned stainless steel scoop into solvent-rinsed aluminum containers. Sediment samples were preserved at -20°C until analysis. The target compounds were heavy metals, PFASs and PBDEs. All the samples were collected in 2010. Samples were air dried at room temperature and sieved through a 2-mm nylon sieve to remove coarse debris. The sediments were then ground with a mortar and pestle until all particles passed a 200-mesh nylon sieve. The total heavy metal content of the prepared soil was determined by HCl–HNO3–HF–HClO4 extraction; 20 % of the samples were used as parallels for quality control. The results met the accuracy requirements in the Technical Specification for Soil Environmental Monitoring HJ/T 166-2004 (SEPAC 2004). Details about the procedures for PBDE extraction and purification can be found in Mai et al. (2005). First, sediment samples were ground to powders, and Soxhlet was extracted with acetone/hexane (1:1, v/v) for 48 h. Then, surrogates (BDE-77, BDE-118, and 13C-PCB-141) for recovery estimation were spiked prior to extraction. An aliquot of the extract was used for gravimetric lipid determination. The remainder was subjected to gel
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permeation chromatography (GPC) and eluted with dichloromethane/hexane (1:1, v/v) for lipid removal. The fraction from 90 to 280 mL, which contained the target compounds, was concentrated for further clean-up on a 2 g silica gel solid phase extraction column that was preactivated at 130°C for 15 h before use. The fraction containing PBDEs was obtained by elution with 6.5 mL of hexane/ dichloromethane (60:40, v/v) and redissolved in 50 lL of isooctane. Internal standard (13C-PCB-208) was spiked before instrumental analysis. The samples were analysed on an Agilent 6890 series gas chromatograph coupled to an Agilent 5973 mass spectrometer (GC-5973 Agilent, USA) using negative chemical ionisation (NCI) under a selected ion monitoring mode. An MS capillary column (J&W 122-1232, USA) was used for the determination of PBDE congeners. Methane was used as a chemical ionisation moderating gas and helium as the carrier gas at a flow rate of 1 mL/min. The ion source and interface temperatures were set to 150 and 300°C, respectively. The GC oven temperature program was carried out as follows: held initial temperature 110°C for 1 min, increased to 180°C at 8°C/min, and then to 240°C at 2°C/min, held for 5 min, and then increased to 280°C at 2°C/min, held for 8 min, and then increased to 300°C at 10°C/min and held for 5 min. A 1 lL injection was performed in the pulse splitless mode, with a purge time of 1 min and an injector temperature of 265°C. PBDEs (except BDE-209) were monitored with the m/z responses of 79/81 (bromide ions). BDE-209 used m/z responses of 486.6/484.6 and 496.6/ 494.6, respectively. Three field blanks were prepared using anhydrous sodium sulphate powder as a surrogate for sediment. A procedural blank was processed for every 11 samples. The surrogate recovery in all samples were 103 % ± 20.34 % for BDE-77, 105 % ± 18.51 % for BDE-118 and 102 % ± 8.91 % for 13C-PCB-141. The reported data were not recovery corrected. For PFAS analysis, sediment samples were freeze dried, ground, and homogenised by sieving through a stainless steel 60-mesh sieve and stored in polypropylene (PP) containers at -20°C until extraction. One gram of sediment sample was weighted in a PP centrifuge tube. After the addition of 40 lL of a 50 ng/mL solution of a surrogate standard solution (13C-PFOS and13C-PFOA), the samples were incubated for 30 min, and 8 mL of methanol was added, followed by thorough mixing using a vortex mixer. Samples were then extracted in an ultrasonic bath for 30 min at 60°C and then thoroughly mixed and shaken at 200 r/min for 16 h. Finally, they were centrifuged at 2,500 r/min for 5 min. The supernatant was transferred to a new vial and evaporated to 1 mL under N2. Then, 1 mL of the target analyte was transferred to 50 mL Milli-Q water
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for SPE clean-up. All samples were then extracted using an Oasis WAX cartridge. The target analyte was eluted with 4 mL MeOH and 4 mL 0.5 % NH4OH/MeOH. Then, the target analyte was concentrated to 1 mL under a stream of high purity nitrogen. Analysis of the PFASs was conducted using an HPLC–MS/MS. The separation of the analytes was performed using an Agilent HP1200 liquid chromatograph (HP1200 Agilent, USA) that was interfaced with an API 4000 Q TRAP spectrometer (API4000 Applied Biosystems Sciex, USA) and operated under the electrospray negative mode. A phenomenex C8 column [2.0 mm i.d., 50 mm length; Luna C8 (2)] was used as a chromatographic column. The mobile phase was 10 mM ammonium acetate-MeOH, starting at 30 % MeOH. Detailed instrumental parameters were presented by Taniyasu et al. (2005). Polytetrafluorethylene (PTFE) materials had been removed from the equipment or replaced by stainless steel or PEEK vessels. Polypropylene (PP) or glass tubes and containers were rinsed with methanol and water before use. The perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) standards (1 ng) were treated following the same procedure as the samples, and PFASs were well recovered, with recoveries ranging between 104 % and 117 %. The results indicated that the SPE extraction was sufficient to support quantitative extraction. The sediment samples (1 g, n = 6) were spiked with 2 ng of target standards, aged for 0.5 h, and passed through the whole procedure. The recoveries were in the range of 74.3 %–123 %, and the reproducibility was satisfactory. However, the concentrations of PFASs in the samples were not corrected for the recovery percentages. Linearity was evaluated using eight different concentration points covering a range of 50–20, 000 ng/L. Each concentration was spiked with 5 ng of 13C-PFOS and 13C-PFOA as the internal standards. Analyses and quantifications were performed using Analyst 1.4.1 software (API 4000; Applied Biosystems/MDS SCIEX, US). Curves were prepared using a quadratic ‘‘1/x2’’ weighted regression, where the calibrations showed strong linearity with correlation coefficients [0.99. The limits of detection (LODs) were determined on the basis of a signalto-noise ratio of 3 (S/N = 3) or greater, and the LOD was 0.01 ng/g for PFOS and 0.02 ng/g for PFOA. The eightpoint standard calibration was conducted before and after each analysis. Additionally, 1 lg/L PFASs was injected during the analysis for calibration verification and to ensure sensitivity stability. Statistical analysis was performed using SPSS software version 13.0 (SPSS Inc., Chicago, IL). A Pearson correlation matrix was applied to identify the relationship between the seven analytes. Figures were generated using Origin 8.5.
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Results and Discussion The total metal concentrations (Cu, Zn, Pb, Cd) of sediments from different locations in Dayan River are as shown in Table 1. The results are expressed as milligrams of metal per kilogram of dry sediment and as the mean value of three replicates. The concentration of Cu ranges from 12.2 to 641 mg/kg and that of Zn ranges from 47.0 to 891 mg/kg. The concentration of Pb ranges from 39.2 to 641 mg/kg and that of Cd ranges from 0.12 to 2.07 mg/kg. Sediment S8 had the highest concentrations of two heavy metals (Cu: 641; Zn: 891). The highest concentrations of Pb (164) and Cd (2.07) were found in S11 and S1, respectively, while high levels of Cu (206), Zn (172), and Pb (94.9) were found in S9, S2 and S4, respectively. The other samples were comparatively clean and had low levels of heavy metals. The heavy metal concentrations in all sediment samples (except S2) from the Dayan River were higher than the background values in Guangdong Province soils (China Environmental Monitoring Station 1990). Because there is no standard for river sediment quality in China, we assessed the quality of surface sediment samples base on the standard for marine sediment quality. According to the Chinese marine sediment quality criteria (National Standard of PR China 2002), first class quality is suitable for fisheries, nature reserves, endangered species reserves, and swimming; second class quality can be used for industry and tourism sites; and third class quality can only be used
for harbours. According to this standard, the concentrations of heavy metals at the S2, S4, S7 locations were qualified as first class (Table 1). At S8, the concentrations of Cu and Zn exceeded the third class criteria, while the concentrations of Pb and Cd exceeded the second and first class criteria, respectively. At S9, the concentrations of Zn, Pb and Cd exceeded the first class criteria, while that of Cu exceeded the third class criteria. As for the rest of the sediment samples, the concentrations of two or three heavy metals exceeded the first class criteria. P The concentrations of PBDEs in the sediment samP ples are shown in Fig. 2. PBDEs refers to the sum of all targeted PBDE congeners, including BDEs 28, 47, 66, 85, 99, 100, 138, 153, 154 and 183. All 11 samples contained P P detectable concentrations of PBDEs. The PBDE concentrations ranged between 0.05 and 127 ng/g dw. The P highest PBDE concentration in the Dayan River appeared at S8, which was located downstream of a sewage drainage outlet at the Guangqing Bridge and had a concentration up to 127 ng/g dw. Following were those at P sites S9 and S6, with concentrations of PBDEs of 7.69 and 4.67 ng/g dw, respectively. The concentrations of P PBDEs in the other eight samples ranged between 0.52 and 1.46 ng/g dw. The concentrations of PBDEs in S6– S10, which are located in the middle and downstream parts of the Dayan River and are close to Longtang, are greater than those in the upstream part of the River (S1–S5). This indicates that PBDEs may come from the release of pollutants from e-waste recycling.
Table 1 Concentrations of heavy metals in sediment samples from the Dayan River (mg/kg dw) Sampling location
Cu
Zn
Pb
Cd
S1
47.32 ± 1.61
213.66 ± 1.66
43.44 ± 1.04
2.07 ± 0.04
S2
12.16 ± 1.1
47.05 ± 8.06
58.70 ± 1.07
0.13 ± 0.01
S3
37.77 ± 0.49
117.38 ± 5.51
78.40 ± 0.3
1.16 ± 0.04
S4
17.07 ± 0.66
70.96 ± 3.18
57.98 ± 1.25
0.12 ± 0.01
S5
23.11 ± 1.53
90.10 ± 5.9
42.21 ± 2.57
0.64 ± 0.02
S6
60.96 ± 2.68
116.60 ± 4.6
66.34 ± 7.5
0.96 ± 0.03
S7
15.04 ± 0.08
50.62 ± 2.73
39.21 ± 2.04
0.24 ± 0.01
S8
640.96 ± 10.26
891.06 ± 55.58
148.11 ± 7.83
1.12 ± 0.02
S9 S10
206.22 ± 5.56 41.13 ± 2.25
172.06 ± 6.88 155.39 ± 1.59
94.87 ± 2.13 50.41 ± 2.38
0.82 ± 0.06 0.48 ± 0.01
S11
35.62 ± 1.3
145.93 ± 21.61
164.28 ± 2.71
0.76 ± 0.01
I class
35
150
60
0.5
II class
100
350
130
1.5
III class
200
600
250
5
17
47.3
36
0.056
Standard of marine sediment qualitya
Background of soils in Guangdong Provinceb a
National Standard of PR China (2002) (GB 18668-2002)
b
China Environmental Monitoring Station (1990)
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507
130 125 120 7 6 5 4 3 2 1 0 S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11
Sampling locations Fig. 2 Concentrations of Dayan River (ng/g dw)
P PBDEs in sediment samples from the
The relative abundance of PBDEs in the Dayan River sediments were as follows: BDE-47 [ -99 [ -154 [ -66 [ -153 [ -28 [ -183 [ -100 [ -85 [ -138 (Fig. 3). The contributions of BDE-47 (11.8 %–40.7 %), BDE-99 (7.64 %–43.6 %), BDE-154 (2.52 %–31.9 %) and BDE-66 (4.57 %–29.3 %) were 10 % more than the average. In all sediment samples (except S4), BDE-47 had a higher contribution than the other PBDEs. The contributions of BDE66 in S4–S7 were higher than those in the other sediment locations. The contribution of BDE-99 increased downstream, while that of BDE-154 decreased. Among the triP to hepta-BDE congeners ( PBDEs), BDE-47 and BDE-99 were the predominant compounds. The relative abundances of BDE-47 and BDE-99 were generally 50 % greater than P those of PBDEs, similar to the compositions of major penta-BDE commercial mixtures (Sjo¨din et al. 1998). BDE-66, BDE-153, and BDE-154, which include three congeners that are usually found in the technical P pentaBDE mixture, accounted for 64.8 %–87.9 % of PBDEs, for which the mean value of all samples was 79.4 %. BDE-
S1
Sampling location
S2
BDE28 BDE47 BDE66 BDE85 BDE99 BDE100 BDE138 BDE153 BDE154 BDE183
S3 S4 S5 S6 S7 S8 S9 S10 S11
183 and BDE-138, which are two major components in the octa-BDE mixture, accounted for only 2.81 %–15.6 % of P PBDEs, with a mean value of 7.14 %. The concentrations of PFASs in the sediment samples are shown in Fig. 4. Generally, the total concentrations of PFASs in the sediments of the Dayan River ranged between 0.01 and 3.72 ng/g dw. The highest PFASs in the Dayan River appeared at S9, with a concentration up to 3.72 ng/g dw. The second- and third-ranked PFASs, with concentrations of 2.09 and 0.42 ng/g dw, were found at sites S8 and S10, respectively. The concentrations of PFASs in the other 8 samples ranged between 0.01 and 0.21 ng/g dw. As showed in Fig. 1, S8, S9 and S10 are located downstream of Longtang, which is at the centre of the recycling regions in Guangdong. PFASs released by the process of e-waste dismantling reached the surface and polluted rivers through dry and wet deposition and were then finally adsorbed by the sediment. The closer the sediment sample locations to Longtang, the higher the levels of PFASs tended to be in the sediments of the Dayan River. PFOS was the dominant PFAS contaminant at all sampling sites except S2 and S4. At the other 9 sites, PFOS contributed 52.3 %–99.0 % of the total PFASs in the analytes. However, relatively low contributions of PFOA were determined in all analytes, ranging from 0.03 % to 47.7 %. Sedimentary PBDE concentrations have been reported in various regions in China. As Table 2 shows, except for S8 (sediment from the outfall of the Guangqing Bridge), the levels of PBDEs in this study were low, which is consistent with studies in the Xiamen area and Beijiang River; however, they were much lower than those in the Guiyu River, the Zhujiang River, and the Dongjiang River. The Zhujiang River and the Dongjiang River run through
4.0
Concentration of PFASs (ng/g dw)
Concentaion of PBDEs (ng/g dw)
135
PFOA
3.5
PFOS
3.0 2.5 2.0
0.5
0.0 S1
10
20
30
40
50
60
70
80
90 100
S2
S3
S4
S5
S6
S7
S8
S9
S10 S11
Sampling location
Percentage contributions (%) Fig. 3 Percentage contributions of PBDEs in sediment samples
Fig. 4 Concentrations of PFASs in sediment samples from the Dayan River (ng/g dw)
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Table 2 Comparison of heavy metals, PBDEs and PFASs concentrations in sediments Location
N
Yangtze River Delta
PBDEs
PFOS
PFOA
References
13
n.d.–0.55
n.a.
n.a.
Chen et al. (2006)
Xiamen area
8
0.25–6.42
n.a.
n.a.
Li et al. (2010)
River of Guiyu, Guangdong
5
51.3–365 (156)
n.a.
n.a.
Luo et al. (2007)
Beijiang River, Guangdong
10
Zhujiang River, China Dongjiang River, China Liao River, Liaoning
9 9 14
0.02–186
n.a.
n.a.
Chen et al. (2009)
1.1–49.3 (12.9)
n.a.
n.a.
Mai et al. (2005)
0.04–0.48 (0.15)
0.06–0.31 (0.15)
Yang et al. (2011)
2.2–94.7 (27.3)
Mai et al. (2005)
n.a.
Daliao River system Liaoning
9
n.a.
\0.12–0.37 (0.20)
\0.08–0.17 (0.13)
Bao et al. (2009)
Huangpu River, Shanghai
9
n.a.
\0.12–0.46 (0.11)
0.20–0.64 (0.43)
Bao et al. (2010)
Taihu Lake, China
18
n.a.
0.06–0.31 (0.15)
\0.02–0.52 (0.16)
Yang et al. (2011)
Pearl River, Guangzhou Dayan River
13 11
n.a. 0.05–126.64 (12.86)
\0.12–3.1 (0.58) 0.01–3.72 (0.61)
0.09–0.29 (0.21) n.d.–0.08 (0.02)
Bao et al.(2010) Present study
n.d. not detected n.a. not applicable
important electrical manufacturing regions including Huizhou, Shenzhen, Dongguan, and near Guangzhou, which is a highly urbanised and populated city. The Dayan River is a branch of the Beijiang River, which runs through relatively undeveloped regions in Qingyuan. The PBDE pollution in sediments from Guangdong seemed to be more serious than that in other areas in China. Compared with the sediment PFASs determined in water bodies around China, it was clear that the sediment PFOS contamination in the Dayan River, which is up to 3.72 ng/g dw, was at a relatively higher level that those so far reported in China (Table 2). An even higher level of PFOS was found in the highly urbanised and populated centre of Guangzhou, which is possibly influenced by the discharge of municipal wastewater from the city (Bao et al. 2010). Although PFOS in the Dayan River is only 0.08 ng/ g, those detected in the Daliao River system and the Liao River are even lower. As demonstrated in Table 3, PFOS was the dominant PFAS contaminant in sediments from the Dayan River and the Pearl River system in southern China (Guangdong province), while PFOA was the main PFAS contaminant in sediments from central China (Taihu Lake,
Table 3 Correlation coefficients between heavy metals in sediments from the Dayan River
Cu Zn Pb Cd
** Correlation is significant at the 0.01 level
PFOA
* Correlation is significant at the 0.05 level
PBDEs
123
PFOS
Huangpu River) and northern China (Liao river, Daliao river system). The Dayan River and the Pearl River had similar concentrations of PFOS and PFOA. Sediments act as a sink for organic pollutants in the aquatic environment derived from various human activities (Fu et al. 2003). To reveal the correlation between the variables, statistical analysis was carried out on the whole data set of the chemical concentrations in the sediment samples. The correlation coefficient matrix between heavy metals, PBDEs and PFASs is shown in Table 3. The strong positive correlations among Cu, Zn, PFOA and PBDEs indicate that these contaminants are associated with each other and may share a common anthropogenic and natural source in the sediments of the Dayan River. There may be co-migration of Zn, Cu and PBDEs in the water system, which indicates that these contaminants come from e-waste recycling in Longtang. The correlation coefficients between Pb and Cu, Zn, PBDEs were [0.5, showing significant positive relationships. Non-significant positive correlations were observed between Cd and other contaminants. In this study, surface sediment samples were collected from 11 sites in the Dayan River near an e-waste site in
Cu
Zn
Pb
Cd
PFOA
1
0.967** 1
0.596 0.589
0.262 0.369
0.711* 0.77*
1
PFOS 0.343 0.302
P PBDEs 0.951** 0.969**
0.149
0.349
0.041
0.536
1
0.007
-0.204
0.188
1
0.219
0.764*
1
0.442 1
Bull Environ Contam Toxicol (2015) 94:503–510
Qingyuan. Heavy metal, polychlorinated biphenyls and perfluoroalkyl substances were detected. The concentrations of Cu, Zn, Pb and Cd ranged from 12.2 to 641, 47.0 to 891, 39.2 to 641, and 0.12 to 2.07 mg/kg dw, respectively. The P PBDE concentration ranged between 0.05 and 127 ng/g dw. BDE-47 and BDE-99 were the predominant PBDEs. The concentrations of PFASs in sediments ranged between 0.01 and 3.72 ng/g dw. PFOS was the predominant PFAS. The strong positive correlations among Cu, Zn, PFOA and PBDEs indicate that these contaminants were associated with each other and may share a common anthropogenic and natural source in the sediments of the Dayan River. Acknowledgments The authors gratefully acknowledge the financial support of the Ministry of Environmental Protection (No. 201009026), the National Natural Science Foundation of China (Nos. 21107028, 30200030), and the Natural Science Foundation of Educational Department of Guangdong government (No. 20070506), and National High Technology Research and Development Program of China (863 Program, No. 2013AA102402).
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