PBDEs in sediments of the Beijiang River, China: Levels, distribution, and influence of total organic carbon

Chemosphere 76 (2009) 226–231

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PBDEs in sediments of the Beijiang River, China: Levels, distribution, and influence of total organic carbon Laiguo Chen a,*, Yumei Huang a,b, Xiaochun Peng a, Zhencheng Xu a, Sukun Zhang a, Minzhong Ren a, Zhixiang Ye b, Xinhua Wang c a

Center for Research on Urban Environment, South China Institute of Environmental Sciences (SCIES), Ministry of Environmental Protection (MEP), Guangzhou 510655, China Department of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China c Chinese Research Academy of Environmental Sciences, Beijing 100012, China b

a r t i c l e

i n f o

Article history: Received 12 January 2009 Received in revised form 10 March 2009 Accepted 13 March 2009 Available online 22 April 2009 Keywords: Polybrominated diphenyl ethers (PBDEs) Sediment Distribution Total organic carbon The Beijiang River

a b s t r a c t Forty surface and twenty-two deeper sediment samples were collected from the Beijiang River and analyzed to acquire information about the levels, distribution, possible sources and influencing factors of polybrominated diphenyl ethers (PBDEs) in the Beijiang River. Our results showed that the most abundant BDE congeners in surface sediments were BDE47, 99 and 209, with a median value of 0.044, 0.03, and 5.22 ng g 1, respectively. The levels of BDE209 in our samples were much higher relative to those of the other BDE congeners and made up more than 90% of the PBDEs levels in almost all samples. Disregarding BDE209, of the remaining 9 BDE congeners the most abundant ones were BDE47 and 99, which contributed 35.7% and 24.6%, respectively, to the median of the 9 congeners. The contribution of the Beijiang River to the PBDE pollution burden of the Pearl River Delta (PRD) was small in comparison to that of the Dongjiang River and the Guangzhou section of the Zhujiang River. PBDEs in the Beijiang River mainly came from use of deca-BDE and penta-BDE with a minor contribution of octa-BDE. The poor correlation between PBDE and TOC may indicate that PBDEs concentrations in the sediments of the Beijiang River were controlled not only by TOC contents, but also by a combined effect of transport, mixing, depositional mechanisms associated with PBDEs, uncontaminated sediments, or fresh input of PBDEs. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction Polybrominated diphenyl ethers (PBDEs), constituents of three commercial mixtures designated as penta-BDE, octa-BDE, and deca-BDE, have been widely used as flame retardant additives among others in plastics, foams, textiles, electronic components, building materials. As flame retardant additives are not chemically bound to the products, PBDEs may be released into the environment during production, use and disposal of PBDEs-containing products (de Wit, 2002). PBDEs are similar to polychlorinated biphenyls (PCBs) in structure and environmental behavior, and the penta-mix is being considered as a potential persistent organic pollutant (POP) (Wilford et al., 2005). Due to serious environmental concerns, production of the penta- and octa-PBDE formulations ceased in the European Union and North America in 2004 (Hale et al., 2006). Rapidly increasing levels have been found in environmental media, humans, and biota (Hites, 2004). In China, since the first domestic study on PBDE pollution in 2003 (Yang et al., 2003), more and more publications on PBDE pollution in air, water, biota and sediment have been reported in the literature (Mai et al., 2005; * Corresponding author. Tel.: +86 20 85545516; fax: +86 20 85546725. E-mail address: [email protected] (L. Chen). 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.03.033

Wang et al., 2005; Chen et al., 2006a,b, 2008; Jin et al., 2008). As the largest electronic and telecommunication equipment manufacturing base in China, PBDE pollution in the Pearl River Delta (PRD) is of grave concern. Some published studies on sediments and the atmosphere in this region indicated high levels of PBDE pollution (Mai et al., 2005; Chen et al., 2006a,b). Up to now, studies on sediments in this region have been carried out mainly in the Dongjiang River, Zhujiang River, Xijiang River, the PRD estuary, and the coastal areas (Mai et al., 2005), whereas the PBDE pollution in the Beijiang River area has not been studied at all. The distribution of POPs can be influenced by several factors, including their source contributions, relative concentrations, phases of their carrier during transport, and the degree of partitioning to suspended particles. Due to their hydrophobicity, POPs can be adsorbed or absorbed by different organic phases, which are found as coatings on particle surfaces or inside aggregates (Xing, 1997; Pignatello, 1998). They adhere to particles correlating with organic carbon and black carbon contents (Xing, 1997; Gustafsson et al., 1997; Accardi-Dey and Gschwend, 2002; Hung et al., 2006). As a result, equilibrium partitioning models for organic contaminants require optimal prediction for both organic carbon and black carbon contents (Gustafsson et al., 1997; Jonker and Smedes, 2000; Cornelissen et al., 2005).

L. Chen et al. / Chemosphere 76 (2009) 226–231

The Beijiang River, with a runoff volume of 4.82  1010 m3 year 1, is the second largest branch of the Zhujiang River. To better delineate the content level and fate of PBDEs in the PRD we investigated the concentrations, distribution, possible sources, and possible influencing factor of PBDEs in sediment of the Beijiang River. This is a part of our effort to control POPs levels in the PRD. 2. Materials and methods 2.1. Sample collection Forty surface and twenty-two deeper sediment samples were collected from the Beijiang River and its main branches in March 2006 (Fig. 1). Sediments were collected using a Van Veen stainless steel grab sampler. For sandy sediments, only surface samples were collected. For muddy sediments, the top 3–5 cm layer of sediments was scooped using a precleaned stainless steel scoop into polyethylene zip bag as surface samples, while the left sediments in the sampler were collected as deeper samples. All samples were transported on ice to the laboratory and stored at 20 °C until further analysis. 2.2. Analytical procedure Detailed analytical procedure and instrumental analysis conditions are given elsewhere (Mai et al., 2005). Briefly, the sediments were spiked with 13C-PCB141 and were Soxhlet extracted with a one to one mixture of acetone and hexane for 72 h. Activated copper granules were added during extraction to remove elemental sulfur. Concentrated extracts were cleaned and fractionated on acid/basic multilayer silica gel columns with 70 mL of methylene

227

chloride:hexane (1:1). The final extracts containing PBDEs were concentrated to 200 lL, and a known amount of an internal standard (13C-PCB208) was added. Sample analysis was performed with a Model 6890 gas chromatograph (GC) coupled with a Model 5975 mass spectrometer (MS) (Agilent, USA) using electron capture negative ionization (ECNI) in the selective ion monitor (SIM) mode with methane as reagent gas. The detection limit was defined as a signal/noise ratio >3, with 0.5–2.0 pg for the BDE28-183 on a DB-XLB capillary column (30 m  0.25 mm i.d., 0.25 lm film thickness), and 50 pg for BDE209 on another capillary column (CP-Sil 13 CB 12.5 m  0.25 mm i.d., 0.2 lm film thickness). 2.3. TOC measurement The analytical procedure of the TOC measurement in the sediment samples has been reported elsewhere (Gustafsson et al., 1997; Ran et al., 2002; Chen et al., 2005). Briefly, about 3 g of a freeze-dried, pulverized and sieved sediment sample was treated with 10% HCl to remove inorganic carbon, washed with deionized water three times, and dried overnight at 60 °C. The TOC content was determined with an elemental analyzer (Vario EL III Elementar, Germany). 2.4. Quality assurance/quality control (QA/QC) Eleven PBDE congeners were analyzed in all samples, including tri- to hepta-BDEs (BDE28, 47, 66, 85, 99, 100, 138, 153, 154, and 183) and deca-BDE (BDE209). However, BDE85 could not be quantified because of chromatographic interferences in some samples. Procedure blanks, duplicate samples and spiked blanks (standards

Fig. 1. Map of sampling sites.

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L. Chen et al. / Chemosphere 76 (2009) 226–231

spike into solvent) were analyzed. Only negligible trace concentrations, much below those in sediment samples of BDE28, 47, 99, and 209 were detected in the procedure blanks. They were subtracted from the concentrations found in the sediment samples. Differences between duplicate samples were typically less than 20%. The PBDE recoveries from spiked blanks ranged from 73.5% to 86.7%. In addition, 13C-PCB141 as surrogate standard was added to each of the sediment samples to monitor procedural performance and matrix effects. The surrogate recoveries in all samples were 68.2–126.8% for 13C-PCB141. The data reported here have not been corrected for surrogate recoveries. Acetanilide was used as external standard for TOC analysis. Each sample was analyzed twice, differences between the duplicate samples were typically less than 10%. 3. Results and discussion 3.1. Concentration level Table 1 presents a summary of the PBDE data in surface sediment samples. PBDEs were detected in all 40 surface samples. P The concentration of 9PBDEs (including BDE28, 47, 66, 99, 100, 138, 153, 154, 183) and BDE209 in 38 samples ranged from

Table 1 Summary of PBDEs concentrations (ng g Sampling site B1s B2s B3s B4s B5s B6s B7s B8s B9s B10s B11s B12s B13s B14s B15s B16s B17s B18s B19s B20s B21s B22s B23s B24s B25s B26s B27s B28s B29s B30s B31s B32s B33s B34s B35s B36s B37s B38s B39s B40s Median Min Max a b

b

1

0.019 to 0.91 ng g 1 with an average of 0.20 ng g 1 for the former, and from 0.23 to 103.5 ng g 1 with an average of 11.66 ng g 1 for P the latter. Extremely high concentrations of 9PBDEs and BDE209 were observed in the outfall of the Shaoguan smelter (B4s) (58.46, 1558 ng g 1) and the Shijiao (B40s) (186.3, 383.4 ng g 1) sampling sites, presumably due to the impact of point source inputs. The high concentrations in Shijiao may result from discharge of the adjacent Longtang town in Qingyuan, a wellknown e-waste dismantling region. The reasons for high concentrations in the Shaoguan smelter remain unclear, requiring additional study. Similar to the trends found in surface sediments, the concentraP tion of 9PBDEs and BDE209 in 20 deeper samples ranged from 0.025 to 0.38 ng g 1 and from 0.21 to 132.3 ng g 1, respectively, P with extremely high concentrations of 9PBDEs and BDE209 in the outfall of the Shaoguan smelter (B4d) (16.63, 263.0 ng g 1) and Shijiao (B40d) (133.8, 179.0 ng g 1) sampling sites (Table 2). P As Fig. 2 shows, the concentration ratio of 9PBDEs and BDE209 between surface sediments and deeper sediments differs greatly, with a range from 0.24 to 33.77. At most (>50%) sampling sites, the PBDEs concentrations in surface sediments were higher than deeper ones, especially at site B17 with a ratio of 33.77 for BDE209, which may be due to an increased usage of PBDEs

dw) and TOC (%) contents in surface sediments from the Beijiang River.a

28

47

66

100

99

154

153

138

183

209

P

0.008 0.005 0.022 3.24 0.032 0.004 0.033 0.002 0.004 0.016 0.016 0.075 0.026 0.003 0.005 0.003 0.008 0.005 0.009 0.015 0.004 0.002 0.017 0.004 0.05 0.004 0.006 0.006 0.006 0.003 0.003 0.042 0.002 0.009 0.01 0.007 0.018 0.014 0.072 21.2 0.008 0.002 21.2

0.067 0.031 0.15 15.56 0.15 0.029 0.18 0.005 0.037 0.10 0.10 0.20 0.17 0.041 0.035 0.024 0.064 0.039 0.022 0.054 0.015 0.038 0.045 0.037 0.21 0.017 0.054 0.033 0.035 0.009 0.018 0.14 0.011 0.017 0.049 0.052 0.069 0.043 0.33 70.6 0.044 0.005 70.6

0.007 n.d. 0.02 3.57 0.02 0.005 0.03 n.d. 0.005 0.014 0.015 0.03 0.019 0.003 0.005 n.d. 0.008 0.005 0.003 0.01 n.d. n.d. 0.007 0.004 0.057 n.d. 0.008 0.005 0.004 n.d. n.d. 0.038 n.d. n.d. 0.007 0.007 0.012 0.007 0.10 24.8 0.007 n.d. 24.8

0.013 n.d. 0.022 1.47 0.031 n.d. 0.021 n.d. n.d. 0.015 0.017 0.024 0.023 0.005 0.007 n.d. 0.011 0.008 n.d. n.d. n.d. n.d. n.d. 0.008 0.015 n.d. 0.008 n.d. n.d. n.d. n.d. 0.009 n.d. n.d. 0.007 n.d. 0.008 n.d. 0.019 2.33 0.006 n.d. 2.33

0.051 0.02 0.13 16.0 0.16 0.025 0.16 0.003 0.023 0.077 0.076 0.12 0.14 0.036 0.030 0.014 0.044 0.031 0.011 0.029 0.01 0.015 0.023 0.025 0.14 0.008 0.041 0.016 0.019 0.007 0.011 0.09 0.007 0.008 0.029 0.048 0.037 0.043 0.23 45.2 0.03 0.003 45.2

0.01 n.d. 0.026 1.74 0.04 0.007 0.034 n.d. 0.009 0.024 0.025 0.036 0.029 n.d. 0.009 n.d. 0.015 n.d. n.d. 0.008 n.d. n.d. n.d. 0.008 0.018 n.d. 0.013 n.d. n.d. n.d. n.d. 0.01 n.d. n.d. 0.007 n.d. 0.01 n.d. 0.029 3.35 0.008 n.d. 3.35

0.02 0.008 0.042 5.72 0.067 0.012 0.02 n.d. n.d. 0.033 0.035 0.008 0.043 0.009 0.012 n.d. 0.02 0.009 n.d. 0.018 n.d. n.d. n.d. 0.017 0.043 n.d. 0.027 0.007 0.008 n.d. n.d. 0.035 n.d. n.d. 0.011 n.d. 0.014 n.d. 0.08 14.5 0.01 n.d. 14.5

n.d. n.d. n.d. 0.58 0.015 n.d. n.d. n.d. 0.011 n.d. n.d. 0.015 0.007 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.015 1.88 n.d. n.d. 1.88

0.032 0.007 0.048 10.6 0.098 n.d. 0.076 0.011 0.01 0.031 0.029 0.053 0.035 n.d. 0.011 n.d. 0.02 n.d. 0.016 0.027 n.d. n.d. 0.010 0.013 0.017 n.d. 0.02 n.d. n.d. n.d. n.d. 0.012 n.d. n.d. 0.011 n.d. 0.01 n.d. 0.029 2.52 0.011 n.d. 10.6

10.4 6.18 31.0 1558 20.1 5.58 53.7 1.46 1.99 8.13 10.4 10.6 22.5 0.97 4.64 0.97 103.5 2.84 6.88 4.85 1.21 0.23 4.17 10.4 11.1 1.54 10.5 3.74 3.83 1.20 1.32 8.23 3.74 0.99 35.6 0.84 4.85 0.94 32.1 383.4 5.22 0.23 1558

0.21 0.071 0.46 58.5 0.61 0.082 0.55 0.02 0.10 0.31 0.31 0.56 0.49 0.097 0.11 0.041 0.19 0.097 0.062 0.16 0.028 0.055 0.10 0.12 0.55 0.028 0.17 0.068 0.072 0.019 0.033 0.38 0.02 0.034 0.13 0.11 0.18 0.11 0.91 186.3 0.11 0.019 186.3

n.d., not detected. Surface sediments in the Beijiang River.

9PBDEs

TOC 1.18 2.05 2.24 – 2.63 1.11 2.18 0.11 2.06 – 1.99 2.46 2.21 2.24 1.12 0.52 1.56 1.22 0.45 0.39 – 1.73 1.02 1.00 1.14 0.40 1.41 1.38 0.70 0.64 0.49 0.59 0.15 0.43 1.07 4.29 0.96 – 0.91 – – – –

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L. Chen et al. / Chemosphere 76 (2009) 226–231

products in this area or degradation of PBDEs in the deeper sediments. However, at some sampling sites, the concentrations in surface sediments were lower likely due to dilution by the overlying water or input of uncontaminated sediments.

34

3.3. Correlation between TOC and PBDEs level The sediment TOC in this study area (1.29 ± 0.82%) was intermediate between those found in surface sediments in other rivers (1.77 ± 1.05%) and in the estuary (1.15 ± 0.32%) of this region (Mai et al., 2005). Significant correlations between some POPs (including PCBs and pesticides) and TOC content were found for sediments of Kyeonggi Bay, Korea and the Danshui River, Taiwan (Lee et al., 2001; Hung et al., 2006, 2007). A modeling study suggested that PBDEs largely adhere to organic carbon in soils and sediments (Gouin and Harner, 2003). However, we found low correlations between the concentrations of BDE66 (r = 0.14), BDE100 (r = 0.27), BDE99 (r = 0.15), BDE154 P (r = 0.26), BDE153 (r = 0.14), BDE183 (r = 0.34), 9PBDEs (r = 0.34), or BDE209 (r = 0.10) and TOC contents, with several samples excluded (Samples B4s, B4d, B40s and B40d were excluded be-

Table 2 Summary of PBDEs concentrations (ng g

1

PBDEs

Cs/Cd concentration ratio

BDE209

3.2. Concentration comparison

8 6 4 2

B40

B36

B35

B34

B32

B31

B29

B26

B25

B24

B23

B18

B17

B13

B12

B11

B9

B10

B7

B6

B4

0 B2

Sedimentary PBDEs concentrations have been reported for various regions around the world. As Table 3 shows, except for the two presumed point source sediments from outfall of the ShaoP guan smelter and Shijiao, the 9PBDEs levels in this study fall in the low end of the worldwide range, whereas BDE209 levels are in the middle range. Compared to reported PBDEs concentration P in the PRD (Mai et al., 2005), the concentrations of 9PBDEs and BDE209 in our study are comparable to those found in the Xijiang River, and much lower than those in the Dongjiang River and the Zhujiang River. These last two rivers run through important electrical manufacturing regions including Huizhou, Shenzhen and Dongguan, and highly urbanized and populated Guangzhou. The Beijiang River on the other hand runs through relatively undeveloped regions including Shaoguan and Qingyuan.

9

33

Sampling site P

Fig. 2. Ratios of 9PBDEs and BDE209 between surface and deeper sediments from the Beijiang River (Cs-concentration in surface sediments, Cd-concentration in deeper sediments).

cause these samples were likely impacted by point source inputs, samples B10s, B21s, B38s and B29d were excluded for lack of TOC content data). We also found negative correlations of r = 0.26 and r = 0.04 for BDE28 and BDE47, respectively. Note that BDE138 was not included in our correlation analysis due to its infrequent detection. Poor correlations between the PBDEs concentrations and TOC were also observed in the South China Sea sediments (Mai et al., 2005). This may be attributed to the combined effect of transport, mixing, and depositional mechanisms associated with PBDEs and uncontaminated sediments of the study area (Mai et al., 2005), though continuous input of fresh PBDEs may be another possible reason. 3.4. PBDE congener pattern and potential sources BDE209 constitutes more than 90% of the total PBDEs in 56 out of 62 sediment samples. The predominance of BDE209 in sediments has also been found in various regions around world (Eljarrat et al., 2004; Mai et al., 2005; Verslycke et al., 2005; Chen et al.,

dw) and TOC (%) contents in deeper sediments from the Beijiang River.a

Sampling siteb

28

47

66

100

99

154

153

138

183

209

P

TOC

B2d B4d B6d B7d B9d B10d B11d B12d B13d B17d B18d B23d B24d B25d B26d B29d B31d B32d B34d B35d B36d B40d Median Min Max

0.007 0.67 0.005 0.032 0.008 0.003 0.009 0.017 0.011 0.006 0.003 0.007 0.003 0.006 0.003 0.006 0.005 0.018 0.006 0.019 0.002 16.16 0.007 0.002 16.16

0.04 4.18 0.031 0.12 0.056 0.021 0.053 0.10 0.028 0.033 0.017 0.042 0.013 0.048 0.017 0.016 0.025 0.07 0.009 0.079 0.015 50.67 0.036 0.009 50.67

n.d. 1.02 0.003 0.025 0.007 n.d. 0.006 0.012 0.004 0.004 n.d. 0.006 n.d. 0.006 n.d. n.d. 0.004 0.017 n.d. 0.016 n.d. 16.98 0.004 n.d. 16.98

n.d. 0.37 n.d. 0.016 0.01 n.d. 0.009 0.021 n.d. 0.006 n.d. 0.007 n.d. 0.01 n.d. n.d. n.d. n.d. n.d. 0.011 n.d. 1.62 n.d. n.d. 1.62

0.025 4.02 0.020 0.10 0.056 0.019 0.046 0.069 0.016 0.024 0.010 0.024 0.009 0.039 0.012 0.010 0.015 0.043 0.003 0.053 0.007 31.79 0.024 0.003 31.79

n.d. 0.44 n.d. 0.018 0.01 n.d. n.d. 0.032 n.d. 0.009 n.d. n.d. n.d. 0.013 n.d. n.d. n.d. 0.007 n.d. 0.010 n.d. 2.55 n.d. n.d. 2.55

0.008 1.83 0.011 0.039 0.025 n.d. n.d. 0.042 n.d. 0.014 0.007 0.010 0.006 0.022 n.d. n.d. 0.008 0.021 n.d. 0.025 n.d. 10.45 0.009 n.d. 10.45

n.d. 0.17 n.d. n.d. n.d. n.d. n.d. 0.008 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 1.44 n.d. n.d. 1.44

n.d. 3.93 0.007 0.032 0.023 n.d. 0.017 0.043 n.d. 0.032 0.013 n.d. 0.018 0.012 n.d. n.d. 0.008 0.028 0.014 0.018 n.d. 2.16 0.013 n.d. 3.93

5.26 263.0 3.35 11.3 7.94 4.82 5.49 33.86 2.28 3.06 9.32 8.23 5.46 4.47 6.47 0.99 3.06 14.65 0.30 132.3 0.21 179.0 5.46 0.21 263.0

0.081 16.63 0.078 0.38 0.20 0.043 0.14 0.34 0.058 0.13 0.05 0.096 0.049 0.16 0.033 0.032 0.065 0.21 0.032 0.23 0.025 133.8 0.089 0.025 133.8

2.41 – 2.00 2.11 1.69 1.39 1.82 2.14 0.28 0.99 0.53 1.06 0.53 1.16 0.52 – 0.83 0.34 0.42 0.97 2.44 – – – –

a b

n.d., not detected. Deeper sediments in the Beijiang River.

9PBDEs

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Table 3 Comparison of PBDEs levels in surface sediments from other regions around the worlda (ng g 1). P Region Number of congenersb PBDEsb

BDE209

Reference

Niagara River, North America San Francisco estuary, USA Scheldt estuary, Netherlands rivers and coasts, Portugal Cinca River, Spain Ebro River, Spain Tokyo Bay, Japan Qingdao near-shore, China Yangtze River Delta, China Dongjiang River, China Zhujiang River, China Xijiang River, China Beijiang River, China

– – 240–1650 – 2.1–39.9 – 0.89–85(20.53) – 0.16-94.6(13.4) 21.3–7340(1440) 26.3–3580(890) 1.9–77.4(16.1) 0.23–103.5 (11.66)

Samara et al. (2006) Hoenicke et al. (2007) Verslycke et al. (2005) Lacorte et al. (2003) Eljarrat et al. (2004) Lacorte et al. (2006) Minh et al. (2007) Yang et al. (2003) Chen et al. (2006b) Mai et al. (2005) Mai et al. (2005) Mai et al. (2005) This study

a b

9 5 9 17 6 13 8 21 12 9 9 9 9

0.72–148 0.2–211.8 14–22 0.5–20 0.3–34.1 0.01–10.6 0.051–3.6(0.94) 0.1–5.5(1.4) n.d.-0.55(0.15) 2.2–94.7(27.3) 1.1–49.3(12.9) 0.1–0.6(0.36) 0.019-0.91 (0.20)

Values in parentheses are average concentrations. BDE209 excluded.

2006b). This is probably due to the dominance of commercial decaBDE mixtures accounting for most of the PBDE mixture production and usage around the world (Hale et al., 2002). In Asia, the market demand for PBDEs was 24 650 metric tons in 2001, and within this figure, 23 000 metric tons were deca-BDE, and 150 and 1500 metric tons were penta-BDE and octa-BDE, respectively (Hites, 2004). In China, the domestic production and demand of PBDEs are enormous and have increased yearly, and the predominantly used product deca-BDE amounting to 30 000 metric tons in 2005, followed by octa-BDE and penta-BDE (Zou et al., 2007).

Both BDE47 and BDE99 were detected in all sediment samples. P As the most abundant congeners among the 9PBDEs (Fig. 3), the median values of BDE47 and BDE99 contributed 35.7% and 24.6%, P respectively, to the total 9PBDEs.These were followed by BDE183 (8.6%), BDE153 (8.2%), BDE28 (6.3%), BDE154 (6.2%), BDE66 (5.7%), BDE100 (4.6%). BDE138 was detected in only seven samples. The compositional pattern of BDE47, 99, 53, 154 and 100 found in the sediments is similar to that of the major components of the commercial penta-BDE product 70-5DE (Fig. 3), indicating penta-BDE as the principal source. Note that BDE183 is a marker congener of octa-BDE products (Song et al., 2004). Hence

100%

BDE138 80%

BDE153

Composition

BDE154 60%

BDE99 BDE100

40%

BDE66 BDE47

20%

B2s

B1s

0%

B3s B4s B5s B6s B7s B8s B9s B10s B11s B12s B13s B14s B15s B16s B17s B18s B19s B20s B21s B22s B23s B24s B25s B26s B27s B28s B29s B30s B31s B32s B33s B34s B35s B36s B37s B38s B39s B40s Median 70-5DE

BDE28

Sampling site

Fig. 3. Percentage contributions of 8 BDE congeners in surface sediments from the Beijiang River.

Table 4 Spearman’s rank correlation coefficients between different BDE congeners.

47 66 100 99 154 153 138 183 209 P PBDEs P10 a 9PBDEs a

28

47

66

100

99

154

153

138

183

209

P

0.869 0.911 0.743 0.826 0.764 0.708 0.509 0.750 0.724 0.730 0.874

0.957 0.871 0.966 0.867 0.834 0.540 0.794 0.736 0.749 0.976

0.837 0.938 0.880 0.838 0.527 0.800 0.772 0.783 0.963

0.886 0.917 0.879 0.558 0.850 0.819 0.826 0.902

0.864 0.855 0.534 0.768 0.720 0.736 0.970

0.873 0.627 0.907 0.853 0.855 0.922

0.431 0.793 0.838 0.843 0.878

0.550 0.460 0.460 0.565

0.867 0.868 0.856

0.998 0.809

0.819

BDE209 excluded.

10PBDEs

L. Chen et al. / Chemosphere 76 (2009) 226–231

P

the relatively high portion of BDE183 in 9PBDEs indicates the likely additional input from octa-BDE products. We found good correlations among the PBDEs (including 28, 47, 66, 100, 99, 154, 153) except for BDE138, with a Spearman’s rank correlation coefficient (rs) ranging from 0.708 to 0.966 (Table 4), indicating a common source and similar environmental behavior. P The particularly high rs values between BDE47 and 9PBDEs suggested that BDE47 could be readily used as an indicator to evaluate lower brominated PBDE contamination levels in the Beijiang River area. The strong correlation of BDE209 and the sum of BDE P ( 10PBDEs) further proved the predominance of BDE209 in the sediments. 4. Conclusions PBDEs were detected in all sediments of the Beijiang River, suggesting ubiquitous contamination by these chemicals. The predominance of BDE209 in sediments is in accordance with the predominance of deca-BDE commercial mixtures for most of the PBDE mixture usage in the Beijiang River area, with penta-BDE commercial mixture as another commonly used formula. In addiP tion, octa-BDE is also used in this area. The levels of 9PBDEs were at the low end, those of BDE209 in the middle compared to values reported in other regions of the world. Notably, both the levels of P 9PBDEs and BDE209 in this study were lower than those of the Zhujiang River and Dongjiang River in the same region, and contributed little to PBDE pollution of the PRD. Poor correlations between PBDE and TOC may indicate that TOC content and other factors jointly control PBDE partitioning in the sediments of the Beijiang River. Acknowledgements This study was financially supported by the National Science Foundation of China (No. 40803035), Special Scientific Research Funds for Environment Protection Commonweal Section, and the Guangdong Natural Science Foundation (No. 7300845). We thank Dr. Sun Ke of Beijing Normal University for her help analyzing TOC data of sediment and Dr. Mei Ding of Los Alamos National Laboratory (USA) for her help in revising this paper. References Accardi-Dey, A., Gschwend, P.M., 2002. Assessing the combined roles of natural organic matter and black carbon as sorbents in sediments. Environ. Sci. Technol. 36, 21–29. Chen, L.G., Mai, B.X., Bi, X.H., Chen, S.J., Wang, X.M., Ran, Y., Luo, X.J., Sheng, G.Y., Fu, J.M., Zeng, E.Y., 2006a. Concentration levels, compositional profiles and gasparticle partitioning of polybrominated diphenyl ethers in the atmosphere of an urban city in south China. Environ. Sci. Technol. 40, 1190–1196. Chen, S.J., Gao, X.J., Mai, B.X., Chen, Z.M., Luo, X.J., Sheng, G.Y., Fu, J.M., Zeng, E.Y., 2006b. Polybrominated diphenyl ethers in surface sediments of the Yangtze River delta: levels, distribution and potential hydrodynamic influence. Environ. Pollut. 144, 951–957. Chen, L.G., Mai, B.X., Xu, Z.C., Han, J.L., Peng, X.C., Sheng, G.Y., Fu, J.M., 2008. Comparison of PCBs and PBDEs concentrations and compositions in Guangzhou atmosphere in summer. Acta Sci. Circum. 28, 150–159 (Chinese). Chen, L.G., Ran, Y., Xing, B.S., Mai, B.X., He, J.H., Wei, X.G., Fu, J.M., Sheng, G.Y., 2005. Contents and sources of polycyclic aromatic hydrocarbons and organochlorine pesticides in vegetable soils of Guangzhou, China. Chemosphere 60, 879–890. Cornelissen, G., Gustafsson, O., Bucheli, T.D., Jonker, M.T., Koelmans, A.A., Van Noort, P.C.M., 2005. Extensive sorption of organic compounds to black carbon, coal, and kerogen in sediments and soils: mechanisms and consequences for distribution, bioaccumulation, and biodegradation. Environ. Sci. Technol. 39, 6881–6895.

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