Chemosphere 133 (2015) 22–30

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Occurrence, profiles, and ecological risks of polybrominated diphenyl ethers (PBDEs) in river sediments of Shanghai, China Xue-Tong Wang a,⇑, Lei Chen a, Xi-Kui Wang b, Yuan Zhang a, Jun Zhou a, Si-Yue Xu a, Yan-Feng Sun a, Ming-Hong Wu a a b

Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China School of Light Chemistry and Environmental Engineering, Qilu University of Technology, Jinan 250353, China

h i g h l i g h t s  Fifty-five PBDE congeners were investigated in river sediments from Shanghai.  Deca-, tetra-, penta- and octaBDE were dominant homologues in sediments.  High levels of PBDEs were caused mainly by industrial activities.  Correspondence analysis indicated debromination products.  RQ indicated a high ecological risk to sediment dwelling organisms.

a r t i c l e

i n f o

Article history: Received 28 October 2014 Received in revised form 9 February 2015 Accepted 16 February 2015

Handling Editor: Myrto Petreas Keywords: Polybrominated diphenyl ethers (PBDEs) River sediment Correspondence analysis (CA) Debromination product Ecological risk

a b s t r a c t Fifty-two PBDE congeners in river sediments from Shanghai were analyzed in the present study. The concentrations of R51PBDEs (defined as the sum of 51 BDE congeners except BDE209) and BDE209 ranged from 0.231 to 119 ng g 1 and from nd to 189 ng g 1, respectively. The most abundant BDE congeners in surface sediments were BDE118, 207, 208, 99, 49, 75, 47, 71 and 209, with median values of 1.67, 1.81, 1.83, 1.87, 1.98, 2.52, 2.73, 4.62 and 45.7 ng g 1 dw, respectively. The concentrations of R52PBDEs were significantly correlated with total organic carbon (TOC) content in sediments (p < 0.05). Weak correlations between all PBDE homologues and TOC (r < 0.32) suggest that TOC had a little influence on sediment PBDE transport and distribution patterns in river sediments of Shanghai. Correspondence analysis (CA) showed that PBDEs in sediments in the studied area originated from commercial BDE formulations, combustion emission sources, and debromination of highly brominated PBDEs by aerobic/anaerobic microbes or sunlight. Risk assessment based on risk quotients (RQ) showed that PBDEs in all river sediments collected from Shanghai posed a high potential ecological risk (RQ > 1) to the sediment dwelling organisms, and pentaBDE, decaBDE and tetraBDE were the major ecological risk drivers. Ó 2015 Elsevier Ltd. All rights reserved.

1. Introduction Polybrominated diphenyl ethers (PBDEs) are persistent manmade aromatic chemicals with 209 possible PBDE congeners. Three commercial formulations: Penta-, Octa-, and DecaBDE were produced under a variety of product names (e.g., DE-71, Bromkal 70-5DE, DE-79, Bromkal 790-8DE, Saytex 102E, and Bromkal 820DE) (ATSDR, 2004; La Guardia et al., 2006). Commercial PentaBDE was used mainly in polyurethane foam. Commercial OctaBDE was predominantly used in casings for electronic products. Commercial PentaBDE, OctaBDE, and DecaBDE mixtures were ⇑ Corresponding author. Tel./fax: +86 021 66137734. E-mail address: [email protected] (X.-T. Wang). http://dx.doi.org/10.1016/j.chemosphere.2015.02.064 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved.

also used in nylon, textiles, adhesives and TV casings. Due to the widespread use of commercial PBDEs as additive fire retardants in a wide range of products, and as a result of their physicochemical properties, they have been found in various environmental media, such as water, sediment, indoor air and dust, outdoor air, soil, plants, biota, bird eggs, and human milk and blood (Ma et al., 2012; Ni et al., 2013; Law et al., 2014), resulting in increasing risk to human health. PBDEs are persistent, lipophilic and bioaccumulative, similar to other environmental pollutants such as organochlorine compounds (WHO, 1997), thereby presenting a potential ecological risk. Toxicological studies in animals have shown that liver, thyroid, and neurobehavioral development may be impaired by these contaminants (ATSDR, 2004). Commercial PentaBDE and OctaBDE

X.-T. Wang et al. / Chemosphere 133 (2015) 22–30

formulations were banned by the European Union in 2004, and California and Hawaii in 2006 (Hess, 2009). Tetra- to hepta-BDEs contained in Penta- and OctaBDE formulations were included in the Annex A of Stockholm Convention for Persistent Organic Pollutants (UNEP, 2011). The major sources of PBDEs to the environment are homes and household dust (Jones-Otazo et al., 2005; Stapleton et al., 2005), releases during the manufacturing and use of commercial products, and releases during the recycling and disposal of products containing PBDEs. Stack flue gases of combustion sources including waste incinerators, metallurgical processes, and power-heating systems are also important PBDE emitters to the atmosphere (Wang et al., 2010; Tu et al., 2011). Subsequently, PBDEs may be distributed throughout the environment by atmospheric transport (Strandberg et al., 2001), runoff, industrial point sources, and sewage outflows (Litten et al., 2003), leaching from aging consumer products, incineration of municipal waste, land application of sewage sludge as biosolids, industrial discharge, and accidental spills (Hale et al., 2001; ATSDR, 2004; USEPA, 2008). PBDEs have low vapor pressures, very low water solubility, and high octanol–water partition coefficients (log Kow ranges from 4.87 to 9.97 for tetra- to decaBDEs) (Environment Canada, 2006), which means that the sediment may act as an important and final sink for these organic contaminants, and thus it is also a long-term source of these contaminants to overlying water columns and biota (Fu et al., 2003). PBDEs in the environment may be photo-transformed by debromination processes during exposure to sunlight (Stapleton and Dodder, 2008). Recent studies found that PBDEs in sediments can end up in various forms and produce some toxic debromination products due to microbial activity in the environment (Lee and He, 2010). Accumulation of PBDEs in sediment was regarded as a serious environmental problem in the world (Mai et al., 2005). PBDEs in sediments can pose an ecological risk to aquatic biota (ATSDR, 2004). PBDEs have attracted attention recently due to their proven adverse effects on animals, humans and their increasing concentrations in various environmental media and biota (Ryan and Rawn, 2014; Tang et al., 2014). Therefore, sediment quality represents an important indicator for assessing water quality and potential effects of PBDEs on aquatic biota (Zhao et al., 2012). However, only very little data is available to date about the contamination of PBDEs in riverine sediment of Shanghai (Wu et al., 2013). Thus, the objectives of the present study were to investigate the contamination levels and spatial distribution of PBDEs in riverine sediments from Shanghai, to obtain detailed information on their homologue profiles and the potential sources, and to assess their ecological risks to aquatic life.

2. Materials and methods 2.1. Study area and sample collection As one significant national central city in China and a prosperous cosmopolitan city renowned in the world, Shanghai, located on silting alluviation plain of the Yangtze River delta, is adjacent to the East China Sea to the east, Hangzhou Bay to the south, Jiangsu and Zhejiang Provinces to the west. It is the most significant industrial and commercial hub in China, and also the national center in terms of economy, transport, technology, industry, finance, trade, convention, and shipping. There are developed water system and many rivers in Shanghai. Huangpu River is one of the branches of the Yangtze River, with 113 km long flowing through Shanghai. It is on average 400 m wide and 9 m deep. It takes its rise from the Taihu Lake in Jiangsu Province, runs eastwards through the Dianshan Lake in Qingpu District and then flows to Minhang District in Shanghai. The Huangpu River divides the

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city into two regions: Pudong (east) and Puxi (west). The main tributaries of Huangpu River included Suzhou, Yunzao, Chuanyang, Dianpu, Dazhi, Xietang, Yuanxiejing and Daliugang Rivers. Due to the rapid growth of industrial production, population and traffic density in Shanghai and the contiguous provinces, Shanghai is faced with serious environmental problems during the last few decades. It has suffered from water shortages, and the drinking water quality has deteriorated. In order to comprehensively understand PBDE contamination in riverine sediments of Shanghai watersheds. Surface sediments were collected in August 2013 from Huangpu River and its main tributaries (Fig. 1). Sixty-seven sampling locations (Fig. 1) were selected from Suzhou Rive (Sites 1–7), Wenzao River (Sites 8– 10), Youdun River (Sites 11–14), Dianpu River (Sites 15–20), Chuanyang River (Sites 21–23), Dazhi River (Sites 24–26), Jinhui River (Sites 27–29), Yexie River (Sites 30–32), the main stream of Huangpu River (Sites 33–47), upper reach of Huangpu River (UR1: Sites 48–58, and UR2: Sites 59–67, which originate from Zhejiang Province and Jiangsu Province, respectively). Sediments were collected using a stainless steel grab sampler. The top 5-cm layer of sediments was scooped using a precleaned stainless steel scoop, wrapped in a tinfoil and enclosed in ziplock bags to avoid pollutant losses. After transported on ice to the laboratory, sediments were stored at 20 °C. All the lyophilized sediments were ground, sieved (80 mesh), and stored in sealed brown glass bottles before further analysis. The total organic carbon (TOC) content of the soil samples was determined by potassium dichromate titrimetric method. 2.2. Chemicals and materials PBDE standard solutions including BDE-AAP-A-15X (containing BDE1, 2, 3, 7, 8, 10, 11, 12, 13, 15, 17, 25, 28, 30, 32, 33, 35, 37, 47, 49, 66, 71, 75, 77, 85, 99, 100, 116, 118, 119, 126, 138, 153, 154, 155, 166, 181, 183, and 190) and BDE-OND (containing BDE 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, and 209) were purchased from AccuStandard Inc (New Haven, CT, USA) and Wellington Laboratories Inc (Guelph, Ontario, Canada), respectively. Surrogate standards (13C12-BDE139 and 13C12-BDE209) and injection internal standard (13C12-PCB138) were obtained from Cambridge Isotope Laboratories Inc. (Andover, MA USA). Silica gel (100–200 mesh) (Qingdao Haiyang Chemical Co., Shandong, China) and neutral alumina (100–200 mesh) (Sinopharm Chemical Reagent Co., Shanghai, China) were activated at 130 °C for a minimum of 16 h prior to use, then neutral alumina was deactivated by ultrapure water (6%, w/w), acid silica gel (30%, w/w) was prepared by thoroughly mixing 100 g of silica gel with 44 g of concentrated sulfuric acid, and stored in a desiccator. Anhydrous sodium sulfate (Sinopharm Chemical Reagent Co., Shanghai, China) was baked at 450 °C for 5 h before use. All solvents (Sinopharm Chemical Reagent Co., Shanghai, China) used were of analytical grade and redistilled in an all-glass system before use. 2.3. Sample extraction and cleanup About 20 g of air-dried sediment samples mixed with 20 g of anhydrous sodium sulfate, spiked with 6 ng of 13C12-BDE139 and 15 ng 13C12-BDE209 as surrogate standards and equilibrated for 24 h, and then Soxhlet extracted with 200 mL of n-hexane/acetone (1:1, v/v) for 24 h with activated copper to remove elemental sulfur. The extracts were concentrated by K–D concentrator and solvent-exchanged to hexane. After being reduced to approximately 1 mL, the extract was cleaned by a column containing 10-g deactivated neutral alumina, 10-g acid silica gel and 2 cm anhydrous sodium sulfate from the bottom to top. The column was eluted

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X.-T. Wang et al. / Chemosphere 133 (2015) 22–30

Fig. 1. Plot of sediment sampling locations in Shanghai Rivers.

with 50 mL of n-hexane and 100 mL of n-hexane/dichloromethane mixture (1:1, v/v), respectively. The first fraction was discarded, and the second fraction containing PBDEs was concentrated, solvent-exchanged to n-hexane, and reduced to near dryness, and finally redissolved in 50 lL of isooctane containing 6 ng of 13 C12-PCB138 before GC/MS analysis. 2.4. Instrumental analysis, identification and quantification of PBDEs The analyses of PBDEs performed with an Agilent 6890N gas chromatograph-5975 mass selective detector (GC/MS) system. Separation was performed with two fused-silica capillary column (J&W Scientific, Folsom, USA), one (DB–5, 30 m  0.25 mm  0.25 lm film thickness) for di- to heptaBDEs, the other (DB–5HT, 15 m  0.25 mm  0.25 lm film thickness) for octa- to decaBDE. Helium was used as carrier gas at a constant flow of 0.9 mL min 1. One lL of each sample was injected in the pulse/ splitless mode at an injector temperature of 280 °C. The oven temperature program for di- to heptaBDEs was as follows: 90 °C (held for 1 min), to 200 °C at 20 °C min 1 (held for 10 min), then increased to 250 °C at a rate of 2 °C min 1 (held for 10 min), and finally increased to 310 °C at a rate of 10 °C min 1 (held for 20 min). The temperature program for other BDEs was as follows: initial temperature of 90 °C was held for 2 min, increased to 220 °C at a rate of 10 °C min 1, and then increased to 310 °C at a rate of 20 °C min 1, and held for 15 min. The MS was employed in the electron capture negative ionization mode (ECNI) with methane (99.995%) as reagent gas. The electron collision energy was 100 eV. The ion source, quadruple and transfer line temperatures were held at 250, 150 and 280 °C, respectively. The compounds were monitored at m/z 79 and 81 for di- through heptaBDE, m/z of 79, 81, 407, 409, 486, and 488 for octa-BDE, and m/z of 79, 81, 486, and 488 for nona- and decaBDE. For the surrogate standards

(13C12-BDE139 and 13C12-BDE209) and injection internal standard (13C12-PCB138), m/z 574.6 and 576.6, m/z 415.6, 494.6, and m/z 372 and 374 were monitored, respectively. Identification of PBDE congeners was based on the selected ions and the comparison of retention time between samples and the standard solution containing individual PBDEs. The most abundant isotope signal was used for quantification and the second one for the identification of possible interferences. Quantifications of PBDEs were carried out based on five level calibration curves (r2 > 0.99). Due to low sensitivity of GC–ECNI/MS for BDE1, 2, and 3, they were not analyzed in this study.

2.5. Quality assurance and quality control Glassware used was heated to 450 °C for 6 h to minimize the risk of contamination. Each 12 samples included procedural blank and duplicate samples. The procedural blanks, spiked blanks and sample duplicates were routinely analyzed with sediment samples and no interferences were detected in the procedural blanks. The procedure was checked for recovery efficiencies by analyzing clean soils (deep soils obtained from construction site away from industrial contamination) spiked with PBDE standards. The method detection limit (MDL) was calculated as three times the signalto-noise level in clean sample. MDLs of PBDEs ranged from 0.01 to 0.02 ng g 1 dry weight (dw) for di- to nonaBDEs and was 0.06 ng g 1 dw for BDE209, respectively. The recoveries of PBDEs spiked in clean soils ranged from 81.6% to 103%, and the relative standard deviations (n = 7) were less than 15%. The coefficient of variation of PBDEs in duplicate samples was less than 15%. The recoveries of 13C12-BDE139 and 13C12-BDE209 spiked in sediment samples ranged from 85.6% to 98.3%. All results were not corrected for recoveries and expressed on a dry weight basis.

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2.6. Statistical analysis

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3. Result and discussion

The spatial distribution of R51PBDEs and BDE209 in river sediments from Shanghai is depicted in Fig. 2. R51PBDEs and BDE209 concentrations in sediment samples from different rivers varied widely with the variation coefficients of 219% and 227%, respectively. The highest concentration was found at site 53 (119 ng g 1) for R51PBDEs, and sites 29 (189 ng g 1) and 36 (126 ng g 1) for BDE209. The sites 29 and 36 are located at industrial parks in Shanghai, and site 53 is near Jiashan county of Zhejiang province, where a large number of industries are concentrated, suggesting that the high PBDE burden may attribute to industrial activities for these sampling sites.

3.1. Levels and spatial distribution of PBDEs

3.2. Comparison with other studies

The 52 PBDE congeners were detected in sediment samples, indicating that PBDEs are widespread pollutants in aquatic environment in Shanghai. The descriptive statistics of concentrations of individual PBDE congeners with detection frequencies above 50%, sum of PBDE congeners except for BDE 209 (R51PBDEs), and sum of 52 PBDEs (R52PBDEs, sum of 52 PBDE congeners), and sum of 10 most frequently detected PBDE congeners (sum of BDE28, 47, 66, 85, 99, 100, 138, 153, 154, and 183, R10PBDEs) in sediment samples collected are given in Table 1. BDE118, 207, 208, 99, 49, 75, 47, 71 and 209 were main BDE congeners in surface sediments with median values of 1.67, 1.81, 1.83, 1.87, 1.98, 2.52, 2.73, 4.62 and 45.7 ng g 1 dw, respectively. The concentrations ranged from 0.231 to 119 ng g 1 for R51PBDEs and from nd to 189 ng g 1 for BDE209, with mean values of 3.02 and 2.18 ng g 1, respectively. The total concentrations of R10PBDEs in sediment samples were between 0.042 and 21.7 ng g 1 with a median value of 0.475 ng g 1.

In order to comprehensively assess the sediment pollution status by PBDEs, the total concentrations of sediment PBDEs in the freshwater ecosystems around the world were collected. The minimum, maximum, and mean values of total PBDE congeners and BDE209 collected were summarized in Table 2. Compared with other regions in China, the measured concentrations of RPBDEs (not including BDE209) and BDE209 in sediments from Shanghai in this study were lower than those found from Beijiang River (Chen et al., 2009), and Jiaojiang River (Yang et al., 2014); and similar to those from Baiyangdian Lake and Fuhe River (Hu et al., 2010), Taihu Lake (Zhou et al., 2012), Chaohu Lake (Wang et al., 2012). However, the levels of PBDEs were higher than those in Three Gorges Reservoir (Li et al., 2013) Cheng-Yu economic zone (Zhang et al., 2011), Qiantangjiang River (Fang, 2012) and Hai River basin (Li et al., 2013) in China. When comparing with concentrations measured in sediments from other countries reported in recent years, the concentration of RPBDEs (not including BDE209) and BDE209 in sediment from Shanghai was lower than those found from four major rivers (Lee et al., 2012) and Shihwa Lake (Moon et al., 2012) in Korea, and similar to the values from Goseong creek in Korea (Lee et al., 2014), Maggiore Lake in Italy (Mariani et al., 2008), Niagara River in Canada (Richman et al., 2013), and Ebro and Llobregat River basins in Spain (Barón et al., 2014). However, the levels of PBDEs were higher than those in Olkhon Island in Russia (Ok et al., 2013). From the comparison above it can be concluded that the river sediments in Shanghai are moderately contaminated by PBDEs compared with other areas around the world.

Statistical analyses including descriptive statistics, Spearman’s rank correlation and correspondence analysis (CA) were performed using Statistica 8.0 (StatSoft Inc., USA). Spatial distributions of PBDE concentrations in sediments were mapped out using MapInfo Professional 9.5 (MapInfo Corporation, USA). For samples with concentration below MDL, zero was used for the calculations.

Table 1 Concentrations of PBDE congeners and total PBDEs in sediments (ng g

1

).

BDE congener

Min

Max

Mean

Median

SD

DF (%)

BDE10 BDE30 BDE28 + 33 BDE75 BDE49 BDE71 BDE47 BDE100 BDE99 BDE116 BDE118 BDE153 BDE183 BDE202 BDE201 BDE204 BDE197 BDE198/199/200/203 BDE196 BDE205 BDE194 BDE195 BDE208 BDE207 BDE206 BDE209 R52BDEs R51BDEs R10BDEs TOC (%)

nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 0.231 0.231 0.042 1.05

1.92 1.71 0.308 22.2 4.45 65.4 7.03 0.55 20.1 2.50 1.47 0.458 0.438 0.255 0.360 0.706 0.228 0.170 0.646 0.616 0.274 1.45 1.95 2.51 0.509 189 214 119 21.7 8.19

0.082 0.072 0.028 0.904 0.283 2.41 0.344 0.073 0.713 0.207 0.275 0.045 0.065 0.039 0.032 0.045 0.018 0.010 0.042 0.085 0.049 0.124 0.278 0.286 0.093 13.2 20.4 7.20 1.37 4.44

0.035 0.024 0.013 0.165 0.072 0.366 0.098 0.025 0.084 0.041 0.134 0.016 0.030 0.024 0.019 0.022 Nd Nd 0.019 0.042 0.028 0.046 0.174 0.140 0.057 2.18 6.38 3.02 0.475 4.47

0.239 0.218 0.051 2.99 0.611 8.43 0.918 0.106 2.57 0.413 0.312 0.070 0.081 0.042 0.048 0.092 0.032 0.021 0.085 0.107 0.060 0.237 0.338 0.377 0.106 29.9 35.5 15.7 3.18 1.54

61.2 56.7 53.7 79.1 80.6 88.1 94.0 65.7 91.0 73.1 97.0 80.6 91.0 98.5 98.5 92.5 89.6 98.5 98.5 98.5 98.5 98.5 86.6 88.1 86.6 83.6

SD: standard deviation. DF: detection frequencies. nd: not detected. R10PBDEs: ten most frequently tested PBDEs, including BDE 28, 47, 66, 85, 99, 100, 138, 153, 154, and 183. R51PBDEs: fifty-one PBDEs, not including BDE209.

3.3. Compositional profiles and possible sources of PBDEs The PBDE homologue distribution patterns in river sediments from Shanghai are given in Table S1. DecaBDE, tetraBDE, pentaBDE and octaBDE had the highest relative concentrations in sediments, with median values of 34.0%, 23.8%, 8.48% and 3.23%, respectively, suggesting that the contributions of commercial BDE mixtures to the total PBDEs in river sediments were in the order: Deca- > Penta- > OctaBDE. The predominant congeners in commercial BDE mixtures are BDE47, 99, 100, and 153 for PentaBDE, BDE 153, 183, 196, 197, 203 and 207 for OctaBDE, and BDE206 and 209 for DecaBDE (La Guardia et al., 2006), respectively. These BDE congeners were detected at high detection frequencies and levels in river sediments in the study (Table 1), which are associated with contributions of commercial BDE formulations. To identify the potential possible sources of sediment PBDEs in the studied area, correspondence analysis (CA) was used to compare PBDE homologue profiles of sediment samples from Shanghai to those of the commercial PBDE mixtures and combustion sources. CA is a multivariate statistical analysis developed on the basis of R- and Q-type factor analyses. CA is a geometric technique for displaying the rows and columns of a two-way

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Fig. 2. Spatial distribution of PBDEs in riverine sediments from Shanghai.

Table 2 Comparisons of PBDE concentrations (ng/g dw) in sediment measured in this study with those in other locations around the world. Location

na

RPBDEsb (mean)

BDE209 (mean)

References

Shanghai rivers, China

52 10 10 8 8 19 16 8 26 20 27 10 8 27 23 17 19 7 7 40

0.205–119 (7.56) 0.04–21.7 (4.40) 0.02–186 0.05–5.03 (0.78) 0.13–6.39 (2.33) 0.20–6.45 (0.99) 0.44–12.0 (1.7) 0.067–5.28 (0.701) 0.39–34.4 (5.21) 0.06– 2.10d nd–0.146 (0.046c) 8.93–45.0 (22.3) 0.02–27.1 0.46–1760 (55)d 0.16–943 nd–18 0.50–13.9 (5.39)d 1.50–44.3 –37.3 0.164–0.670 (0.302)d

nd–189 (13.2)

This study

0.23–1558 4.35–19.3 (10.4) 11.8–293 (103) 0. 44–6.29 (1.35) 0.31–74.6 (6.5) 2.16–446 (70.8) 9.68–144 (37.5) nd–0.13 nd–0.503 (ndc) 423–3159 (1380) nd–24.5 0.34–1320 (41) 0.82–17800 nd–170 0.03–11.4 1.47–43.6 nd–28.9 0.050–0.438 (0.161)

Chen et al. (2009) Hu et al. (2010) Hu et al. (2010) Zhang et al. (2011) Wang et al. (2012) Fang (2012) Zhou et al. (2012) Zhao et al. (2012) Li et al. (2013) Yang et al. (2014) Mariani et al. (2008) Lee et al. (2012) Moon et al. (2012) Richman et al. (2013) Lee et al. (2014) Barón et al. (2014) Barón et al. (2014) Ok et al. (2013)

Beijiang River, China Baiyangdian Lake, China Fuhe River, China Cheng-Yu economic zone, China Chaohu Lake, China Qiantangjiang River, China Taihu Lake, China Hai River basin, China Three Gorges Reservoir, China Jiaojiang River, China Maggiore Lake, Italy Four major rivers, Korea Lake Shihwa, Korea Niagara River, Canada Goseong creek, Korea Llobregat River basin, Spain Ebro River basin, Spain Olkhon Island, Russia

nd: not detected. a Number of PBDEs congeners analyzed in sample. b The sum of all target PBDE congeners except for BDE 209. c Median concentration. d Total PBDE concentration including BDE 209.

contingency table as points in a low-dimensional space, such that the positions of the row and column points are consistent with their associations in the table. Its primary goal is to transform a table of numerical information into a graphical display that is contributed to interpretation. In this study, CA was performed based on the mole fractions of PBDE homologues in sediment samples, commercial BDE mixtures, and combustion sources. The data regarding the PBDE compositions in six commercial BDE mixtures

(two PentaBDE products (DE-71 and Bromkal 70-5DE), two OctaBDE products (DE-79 and Bromkal 79-8DE) and two DecaBDE products (Saytex 102E and Bromkal 82-0DE), and two combustion sources (municipal solid waste incinerator (MSWI) and coal-fired power plant (TPP)) were obtained from La Guardia et al. (2006) and Tu et al. (2011), respectively. Di- to decaBDE homologues in sediments, commercial PBDE mixtures, and combustion source samples were included in the CA. Relative

X.-T. Wang et al. / Chemosphere 133 (2015) 22–30

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Fig. 4. Box–Whisker plot of relative abundance of PBDE homologues in sediment samples. Fig. 3. 2D plot of row and column coordinates conducted by correspondence analysis.

compositions of PBDE homologues in commercial BDE formulations (La Guardia et al., 2006) and combustion emission sources (Tu et al., 2011) were recalculated based on mole fractions (Table S2). The CA ordination plot based on the mole fractions of PBDE homologues is shown in Fig. 3. The two dimensions represented two main factors, which explained the most original variables and with the cumulative contributions of 67.9% (39.7% and 28.2% of the total variance of the data set for Dimension 1 and 2, respectively). Sixty-seven sediment samples were classified into 5 groups, combined 19, 6, 14, 21, and 7 sediment samples, respectively. As shown in Fig. 3, 9 PBDE homologues can be categorized into four sets along Dimensions 1 and 2. Deca- and nonaBDE, octaand heptaBDE, tetra-, penta- and hexaBDE had common sources, which are predominant homologues of the Deca-, Octa-, and PentaBDE technical mixtures, respectively (La Guardia et al., 2006). DiBDE and triBDE also had similar source, and might come mainly from degradation of highly brominated BDEs by sunlight, fish and aerobic/anaerobic microbes (Benedict et al., 2007; Shih and Wang, 2009; Lee and He, 2010; Deng et al., 2011). The CA ordination plot shows that along Dimensions 1 and 2 the data points of PBDEs in group 1 including 19 sediments, commercial DecaBDE (102E, 82-0DE) and combustion sources (MSWI and TPP) concentrate in positive values, distinctly separate from those in group 3 including 14 sediments and commercial PentaBDE (DE71 and 70-5DE), which have negative values along Dimensions 1 and 2. By contrast, the data points of PBDEs in groups 2 (6 sediments and DE-79) and 5 (7 sediments) mainly concentrate in negative and positive values along Dimensions 1 and 2, respectively, distinctly separate from group 4 (21 sediments), which have positive and negative values along Dimensions 1 and 2, respectively. These results suggest that commercial DeBDE, OctaBDE and PentaBDE formulations had higher contributions to RPBDEs for sediments in Groups 1, 2 and 3, respectively. By contrast, 21 sediments in groups 4 were mainly from the usage of commercial DecaBDE and PentaBDE. While PBDEs in sediments in groups 5 might be mainly from the usage of commercial DecaBDE, OctaBDE and PentaBDE formulations. The PBDE homologue profiles of five major groups obtained from CA based on the mole fractions of PBDEs in the sediments are shown in Fig. 4. Sediment samples included in group 1 (n = 19) were characterized by a predominance of decaBDE and

tetraBDE, accounting for 44.9–98.1% (median 67.1%) and 0.12– 25.4% (median 12.8%), respectively. The dominant PBDE homologues in sediments in group 4 (n = 21) were decaBDE, tetraBDE and pentaBDE, accounting for 25.9–52.2% (median 36.0%), 11.6– 52.8% (median 30.4%) and 5.43–35.8% (median 10.1%). The relatively high levels of decaBDE in sediments in groups 1 and 4 are associated with contributions of technical DecaBDE mixtures (La Guardia et al., 2006) or/and combustion emission sources (Tu et al., 2011). This result can be explained by the fact that the increased use of the commercial DecaBDE mixture in China is likely an explanatory factor. Several coal-fired power plants and municipal solid waste incinerators in Shanghai might also have an important contribution to the PBDEs in these sediments. In addition, due to the high KOW of BDE209, it is preferentially partitioned to sediments. The recent studies indicated that BDE209 can be debrominated successively to nona- to monoBDEs by anaerobic microbes from river sediment (Huang et al., 2014) and to nona- to diBDEs by sunlight (Wei et al., 2013), and the debromination rates increased with increasing number of bromines (Wei et al., 2013; Huang et al., 2014). Compared with commercial DecaBDE, the relative abundances of decaBDE in sediments in group 1 were lower than those in commercial DecaBDE (Saytex 102E: 98.5% and Bromkal 82–0DE: 90.3%). The possible reason might be the debromination of BDE209 by aerobic/anaerobic microbes or sunlight. The second dominant homologue in group 4 was tetraBDE, these predominant homologue may be associated with contribution of commercial PentaBDE (La Guardia et al., 2006) and debromination of decaBDE by microbes or/and sunlight (Wei et al., 2013; Huang et al., 2014). Group 2 includes samples (n = 6) with a predominance of octaBDE and tetraBDE, accounting for 43.8–88.2% (median 64.4%) and 6.21–33.3% (median 13.5%), the predominant octaBDE is associated with contribution of OctaBDE technical mixtures (La Guardia et al., 2006). Compared with commercial OctaBDE, the relative abundances of octaBDE in these sediments were higher than those in commercial OctaBDE (DE-79: 35.0% and 79–0DE: 21.1%), which might also be due to the degradation of nonaBDE and decaBDE contained in commercial OctaBDE mixture. TetraBDE and pentaBDE predominated in sediments in group 3 (n = 14), accounting for 16.0–75.9% (median 48.6%) and 7.96–60.5% (median 18.5%), respectively. These predominant homologues are components of PentaBDE technical mixtures (La Guardia et al., 2006). The PBDE homologues in sediments in group 5 (n = 7) were predominant with decaBDE, octaBDE, tetraBDE and pentaBDE,

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accounting for 18.3–35.8% (median 28.8%), and 15.2–35.5% (median 25.0%), 15.8–36.5% (median 24.0%) and 4.67–11.7% (median: 8.16%), respectively. These predominant homologues might be indicative of combined contribution of three technical BDEs. Previous study has confirmed that OctaBDE mixture consisting of hexa- to nonaBDEs in microcosms established with soils and sediments might biodegrade into hexa- to monoBDEs, and the toxic tetraBDE were major degradation product (Lee and He, 2010). Microbial reductive debromination of higher brominated PBDEs to lower-brominated homologues was a possible source of the more toxic congeners (e.g., penta- and tetraBDEs) detected in the environment (Lee and He, 2010; Deng et al., 2011). TetraBDE was present only in commercial TetraBDE (DE-71: 33.9%, 70–5DE: 40.0%) (La Guardia et al., 2006) and combustion emission sources (MSWI: 4.48%, TPP: 3.02%) (Tu et al., 2011), however, tetraBDE were found in most sediment samples at relatively higher levels, which might be attributed to contribution of the debromination of higher brominated PBDEs to less-brominated congeners (Lee and He, 2010). BDE71, 75 and 118 were minor components in commercial PentaBDE at relative contents of 0.01%, 0.01% and 0.08–0.10%. In the present study, the relative contents of BDE71, 75 and 118 in sediments were higher than in PentaBDE formulation, which further corroborated that these BDE congeners might come from degradation of highly brominated PBDE or trace components of technical Deca-BDE mixtures (Eriksson et al., 2004; Gereke et al., 2005). BDE208 was very minor in the commercial DecaBDE (0.066–0.074%) and OctaBDE (DE-79: 0.15%) mixtures, but it was commonly detected in the combustion sources (MSWI: 2.86%, TPP: 2.59%) (Tu et al., 2011). Consequently, these PBDE congeners might derive from combustion sources, or from the degradation of commercial DecaBDE mixtures. In conclusion, the main sources of PBDEs in sediments in groups 1, 2 and 3 were commercial DecaBDE, OctaBDE and PentaBDE, respectively. For groups 4 and 5, the sediment PBDEs might come from a combination of commercial mixtures. In addition, combustion emission and debromination of commercial DecaBDE by aerobic/anaerobic microbes or sunlight had also contributions to PBDE contamination in river sediments from Shanghai in the study. 3.4. Correlation between PBDEs and TOC Spearman’s rank correlation was calculated for each PBDE homologues and total PBDEs (Table S3). In this work, TOC contents in these sediments varied from 1.05% to 8.19%, with an average value of 4.44% (Table 1). The high brominated homologues (nonaBDE and decaBDE) and R52PBDEs were significantly correlated with TOC contents (p < 0.05). These might be due to the higher octanol–water partition coefficients of high brominated homologues (Bhavsar et al., 2008). Similar findings were also found in previous studies (Zhao et al., 2012; Moon et al., 2012; Lee et al., 2014). No significant correlations were observed between low brominated homologues (di- to octaBDE) and sediment TOC (p > 0.05). Additionally, we also found weak correlations between all PBDE homologues and TOC (r < 0.32) in this study, indicating that TOC had a little influence on sediment PBDE transport and distribution patterns in the studied area. Significant correlations among BDE homologues except octaBDE were also observed, indicated their common source and similar environmental behavior (Zhou et al., 2012). 3.5. Ecological risk assessments of PBDEs in sediments Environmental health guidelines for PBDE in sediment have not yet been stipulated in China. Environment Canada has developed Federal Environmental Quality Guidelines (FEQGs) for PBDEs

Fig. 5. The RQ of each PBDE homologues based on FseQG set by Environment Canada.

(Environment Canada, 2013). In this study, Federal Sediment Quality Guidelines (FSeQGs) for the protection of sediment dwelling animals as well as pelagic animals which bioaccumulate PBDEs from sediments were used for the assessment of ecological risk of PBDEs in river sediments. The FSeQGs normalized to 1% organic carbon for triBDE, tetraBDE, pentaBDE, hexaBDE, octaBDE and decaBDE in sediment were 44, 39, 0.4, 440, 5600 and 19 ng g 1 dw, respectively (Environment Canada, 2013). Risk quotient (RQ) approach is widely used in risk assessment studies of heavy metallic and organic pollutants (Khairy et al., 2009; Liu et al., 2015). The RQ was determined by dividing the measured concentrations of chemicals in sediments by their respective sediment quality guidelines. In the present study, the RQ for each PBDE homologues was calculated based on the FSeQGs set by Environment Canada. The concentrations of PBDE homologues in sediment samples were normalized to 1% organic carbon before RQ calculation. To better elucidate the risk levels, the RQ were classified into three risk levels: 0.01 6 RQ < 0.1, low risk; 0.1 6 RQ < 1, medium risk; and RQ P 1, high risk to sediment dwelling organisms (EC, 1996; Sanchez-Bayo et al., 2002; Liu et al., 2015). As shown in Fig. 5, the RQs of hexaBDE and octaBDE in sediments were below 1 at all sampling sites. For pentaBDE, decaBDE, tetraBDE and triBDE, the RQs were larger than 1 in 100%, 83.6%, 68.7% and 7.5% of sediment samples, respectively, which indicated that PBDEs in river sediment from Shanghai posed a potential high ecological risk at all sampling sites and pentaBDE, decaBDE and tetraBDE were the major ecological risk drivers for sediment dwelling organisms. More attention should be paid to this aquatic environment. However, it should be noted that conservative application factors have been used due to lack of toxicity data for media for which FEQGs were developed, thus, there is considerable uncertainty in the toxicity thresholds (Environment Canada, 2013). Therefore, the actual impact of PBDEs in sediments might be overestimated by the calculated RQs in this study. 4. Conclusions In the present study, the concentrations, compositional profiles, potential sources and ecological risk to aquatic life of PBDEs in river sediments of Shanghai were investigated. The concentrations of PBDEs in river sediments from Shanghai are at medium levels compared with other areas around the world. PBDEs in sediments in the studied area might originate from commercial BDE mixtures, combustion emission and debromination of highly brominated

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