- Email: [email protected]
Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment
Chemosphere xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment Jung Keun Oh a,⇑, Kensuke Kotani a, Satoshi Managaki b, Shigeki Masunaga a a b
Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama 240-8501, Japan Faculty of Environmental Science, Musashino University, Tokyo 135-8181, Japan
h i g h l i g h t s HBCD diastereomeric pattern differed depending on the pollution source. The highest level of total HBCDs for surface sediment samples in the world was detected. Enantiomer selectivity for HBCDs was found in the sediment samples. PBCD derived from HBCD was detected in both water and sediment samples. Correlation between the HBCD and PBCD concentration in aquatic samples was confirmed.
a r t i c l e
i n f o
Article history: Received 14 October 2013 Received in revised form 20 January 2014 Accepted 21 January 2014 Available online xxxx Keywords: Hexabromocyclododecane Pentabromocyclododecene Diastereomer profile Enantiomer fraction Surface water Surface sediment
a b s t r a c t Hexabromocyclododecane (HBCD) and its lower brominated derivatives were measured in both surface water and sediment samples from three Japanese rivers; Tsurumi River, Yodo River, and Kuzuryu River. P The concentration level of HBCD (sum of a-, b-, and c-HBCD) was in the order of Kuzuryu > Yodo > Tsurumi P HBCD concentration Rivers, reflective of the different emission sources for each basin. The highest 1 (7800 ng g dw) was detected in the sediment sample from the Kuzuryu River that receives effluents from textile industries, which use HBCD in flame retardant finishes. A different diastereomeric pattern of a-, b-, and c-HBCD of each river was investigated, indicating the level of HBCD in these rivers is directly influenced by emission source. Enantiomer fractions of HBCDs in water and sediment samples were also determined. Racemic mixtures were observed in the water samples, whereas enantiomeric enrichment of ( ) c-HBCD and (+) a-HBCD was observed in the sediment samples. Some lower brominated HBCD derivatives such as pentabromocyclododecenes were detected in both the water and sediment samples, and their concentration ranged from below the detection limit to 15 ng L 1 and 20 ng g 1 dw, respectively. Ó 2014 Published by Elsevier Ltd.
1. Introduction Hexabromocyclododecane (HBCD) is a brominated flame retardant (BFR) used in polystyrene foams, e.g., expanded polystyrene (EPS) and extruded polystyrene (XPS) foam, and in textiles (Marvin et al., 2006). It is manufactured worldwide because of its remarkable flame retardant properties and good blending with polymers. Global use and production of HBCD exceeds 0.16 Mt year 1 (BSEF, 2009), and approximately 3.0 kt was used in Japan in 2010 (METI, 2010). It is noted that, in Japan, about 80% of HBCD is used in polystyrene foams, and the rest is mostly used for textiles (METI, 2008). ⇑ Corresponding author. Address: Graduate School of Environment and Information Sciences Yokohama National University 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. Tel.: +81 45 339 4346; fax: +81 45 339 4373. E-mail address: [email protected] (J.K. Oh).
HBCD is an additive BFR that is not covalently bonded to polymers, which means that there is high risk of it being released to the environment during use, disposal, and recycling of materials that contain HBCD (Tomy et al., 2005; POPRC, 2011). Owing to evidence of its persistence, bioaccumulation in environmental compartments, and toxic properties (Tomy et al., 2011; Li et al., 2012; Zhang et al., 2013), HBCD has recently determined to be listed for global elimination after the sixth meeting of the Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants (C&EN, 2013). Generally, it is widely known that HBCD has a high soil–water partition coefficient (log Koc = 4.66 for HBCD by applying the QSAR equation (EU RAR, 2008)), high log Kow (5.6, (Covaci et al., 2006)), low water solubility (65.6 lg L 1, sum of solubility of the three major diastereomers), and low vapor pressure (6.27 10 5 Pa at 21 °C, (CMABFRIP, 1997)). Theoretically, HBCD has 16
http://dx.doi.org/10.1016/j.chemosphere.2014.01.074 0045-6535/Ó 2014 Published by Elsevier Ltd.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
2
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
stereoisomers, including six diastereomeric pairs of enantiomers and four meso forms (Heeb et al., 2005). The technical HBCD mixture is mainly composed of three enantiomeric pairs of diastereomers (approximately 75–89% c-isomer, 10–13% a-isomer, and <0.5–12% b-isomer) (Becher, 2005). The three main diastereomers (a-, b-, and c-HBCD) have different values of polarity, dipole moment, and water solubility, which may cause different stabilities and biological uptake rates in the environment (Hakk et al., 2012). Moreover, the difference in hydrophobicity of the individual diastereomers (log Kow of a-, b-, and c-HBCD are 5.07, 5.12, and 5.47, respectively) (KEMI, 2005) may lead to different levels of persistence, biological magnification, and toxicity. Peled et al. (1995) observed an interconversion of HBCD diastereomers during heating processes at temperatures above 160 °C. The degradation and biotransformation products of HBCD have been detected in various environmental matrixes and in biota. The breakable carbon–bromine bond, unlike the carbon–fluorine or carbon–chlorine bond, can be expected to generate significant degradation or biotransformation in biological systems (Tomy et al., 2011). Barontini et al. (2001) reported that 7 isomers of pentabromocyclododecenes (PBCDs) identified as thermal degradation products of HBCDs. Harrad et al. (2009) reported that photolytically mediated loss of HBr from HBCD leads to the formation of PBCD and tetrabromocyclododecadiene (TBCD) isomers in English lakes. Anaerobic degradation products of HBCD, tetrabromocyclododecene (TBCDe) and dibromocyclododecadiene (DBCDi), which are formed by the debromination of vicinal dibromides, have also been reported in sediment microcosms in laboratory studies (Davis et al., 2006; Lo et al., 2012). Moreover, many kinds of metabolites of HBCD have been identified in biotic samples, such as chicken eggs (Hiebl and Vetter, 2007), Pollack (Esslinger et al., 2011), and Wistar rats (Brandsma et al., 2009). Enantiomeric patterns of HBCDs have been identified in some environmental and biota samples (Janak et al., 2005; Guerra et al., 2008; Koeppen et al., 2010; Esslinger et al., 2011; Gao et al., 2011; Li et al., 2012; Vorkamp et al., 2012). Despite the increasing number of studies on HBCD, few have attempted to characterize and identify its degradation products and enantiomeric patterns in environmental compartments. As there is evidence that some degradation products have higher binding affinities for human transthyretin receptor than their parent HBCDs or even thyroxin (Weber et al., 2009), further studies are needed to examine which transformation products are mainly formed in biotic and abiotic environments. In the previous study (Managaki et al., 2012), it was investigated the distribution of HBCD in sediment from Tsurumi River, Yodo River, and Kuzuryu River. The aim of this study is not only to clarify the behavior of diastereomers of HBCD, but also to identify their lower brominated derivatives in the water and sediment samples collected from these rivers, Japan, with different HBCD emission sources in each basin.
2. Materials and methods 2.1. Standards and reagents Native, deuterated (d18-), and 13C12-labeled a-, b-, and c-HBCD (50 lg mL 1) and native PBCD (50 lg mL 1) in toluene were provided by Wellington Laboratories (Guelph, Canada). LC-MS grade methanol and acetonitrile, and pesticide analysis grade dichloromethane (DCM) and n-hexane were purchased from Wako Pure Chemical Industry. (Tokyo, Japan). All the other reagents, such as 44% sulfuric acid-impregnated silica gel, Wakogel S-1, copper (powder), and sodium sulfate (anhydrous) were purchased from Wako Pure Chemical Industry.
2.2. Description of sampling sites Fig. 1 shows the sampling locations of this study. Tsurumi River, regulated by the Japanese government (Minister of Land, Infrastructure, Transport and Tourism), flows through Tokyo and Kanagawa prefectures, ranked as two of the most highly populated areas in Japan. Its basin is a typical residential area with over 1.8 million people and has the highest population density in Japan. A total of 7 municipal wastewater treatment plants are located in the river basin, and a large amount of effluent from these plants is discharged into the river. In spite of continuous efforts to improve the river water quality, it is still ranked as one of the worst in Japan because of the rapid urbanization in the basin. Yodo River is the only river flowing out of Lake Biwa, the largest lake in Japan. It flows through Shiga, Kyoto, and Osaka prefectures. Approximately 11 million people live in the basin. The river has the most tributaries (965) in Japan. The flow of the river consists mainly of effluents from industries, including EPS and XPS production, and household wastewater. Kuzuryu River flows through Fukui prefecture, and 0.66 million people live in the basin. Many dyeing and textile processing factories (644, 4% of total number in Japan, 2010) are located along the river. Moreover, a large amount of textiles (366 kt, 15% of total volume in Japan, 2010) is produced in this prefecture. Wastewater from textile factories may have released their effluents into the river. Surface water and sediment samples were collected at 17 sites from the three rivers; Tsurumi River (T-1–T-4, n = 4), Yodo River (Y-1–Y-6, n = 6) and Kuzuryu River (K-1–K-7, n = 7). Samples from Tsurumi River were taken in October, 2011, while samples from Yodo River and Kuzuryu River were collected in December, 2011. 1 L of water was collected at each site using a grab sampler. The water samples were transported to the laboratory and stored at 4 °C in the dark until pre-treatment. Sediments were sampled using an Ekman–Birge sediment sampler at the same sites, simultaneously with the water samples. The sediment samples were put in brown glass bottles and immediately brought to the laboratory for storage at 25 °C prior to analysis. 2.3. Extraction and cleanup 2.3.1. Water The water samples were analyzed according to the method reported by Suzuki and Hasegawa (2006). Each water sample (1 L) was spiked with 50 ng each of 13C12-labeled a-, b-, and c-HBCD (1 mg L 1 in acetone, 50 lL) as internal standards. This standard solution was mixed well using test tube mixer, and kept in a refrigerator for 6 h before spiking to the sample. Before this standard was spiked to the sample, it was mixed one more time for 20 s using test tube mixer. After conditioning the solid-phase extraction disk (Empore Disk Styrenedivinylbenzene (SDB-XD, 47 mm) 3 M, USA) with 10 mL each of methanol and purified water, the sample was passed through at a flow rate of 30 mL min 1. After passing the water sample to the SPE disk, 7 mL of acetone was injected to the same SPE disk to escape the loss. Therefore, filtered water sample and 7 mL of acetone were combined and analyzed. After drying in an oven at 45 °C for 1 h, the disk was eluted with 4 mL of acetone followed by 3 mL of DCM. The eluate was evaporated under the flow of N2 and then reconstituted in 1 mL of methanol including 50 ng of d18-c-HBCD. 2.3.2. Sediment Sample information of each sampling point is shown in Table SM-1 in Supplementary Material (SM). All the sediment samples were homogenized, freeze-dried, and sieved through a 2 mm sieve prior to analysis. Subsequently, 2 g of the sample was weighed accurately, placed in a stainless-steel cell, and mixed with
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
3
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
T-4 T-3 T-2 T-1 K-1 K-2 K-3 K-4
K-5
K-7
K-6
Y-6 Y-4 Y-2
Y-5
Y-3
Y-1
Fig. 1. Map of the study area in Japan and location of sampling sites: (a) Tsurumi River in Kanagawa prefecture, (b) Yodo River in Osaka prefecture, and (c) Kuzuryu River in Fukui prefecture.
2 g of Cu powder to remove sulfuric adulteration before extraction. Each sample was spiked with 50 ng each of 13C12-labeled a-, b-, and c-HBCD as internal standards. Extraction was carried out using an accelerated solvent extraction instrument system (ASE 200, Dionex) with DCM and n-hexane (80:20 v/v) at 100 °C and 10.3 MPa. Approximately 40 mL of the extract was collected and subsequently concentrated to 5 mL under the flow of N2. The cleanup procedure was performed using a chromatography column packed with 8 g of 44% sulfuric-coated silica gel, 2 g of neutral baked silica gel, and 0.5 cm of sodium sulfate. The analyte was eluted with 30 mL of DCM and n-hexane (50:50 v/v). The eluate was evaporated to dryness under the flow of N2 and redissolved in 1 mL of methanol containing 50 ng of d18-c-HBCD to calculate the recovery rates of a-, b-, and c-HBCD. The final extract was passed through a nylon membrane (0.20 lm, Millipore) for the removal of fine particles prior to LC-MS/MS analysis. 2.4. LC-MS/MS analysis 2.4.1. Diastereomer analysis A high pressure liquid chromatograph (Waters 2695; Milford, MA, USA) coupled to a triple-quadrupole mass spectrometer (Micromass Quattro Ultima triple-quadrupole MS; Micromass, Milford, MA, USA) were used for the determination of HBCDs and lower brominated derivatives. A ZORBAX Eclipse XDB-C18 column (150 mm 2.1 mm id, 3.5 lm particle size, Agilent Technology, Santa Clara, CA) was used to determine HBCD and its degradation products. The mobile-phase A (20:50:30 water:methanol:acetonitrile) and B (70:30 methanol:acetonitrile) at a flow rate of 200 lL min 1 were applied. The MS/MS analysis was performed using negative electrospray ionization (ESI) with multiple reaction monitoring (MRM) mode. The a-, b-, and c-HBCD isomers and PBCD were determined by MRM transition of m/z 640.7 > 79.0 and m/z 560.8 > 79.0, respectively. Concentrations in the sediment samples were calculated using relative response factors for each of the target compounds. 2.4.2. Enantiomer analysis Separation of a-, b-, and c-HBCDs was conducted by a Chiral Nucleodex b-PM column (200 mm 4.0 mm id, 5 lm particle size, Macherey–Nagel, Düren, Germany) with Nucleodex beta-PM guard
cartridge (Guerra et al., 2008). The mobile-phase A (30:70 methanol:water) and B (30:70 methanol:acetonitrile) at a flow rate of 200 lL min 1 were used to identify each enantiomer of HBCD. Specific instrumental parameters were equal to that of diastereomer analysis. The specific MS/MS detection conditions were optimized and details are shown in Table SM-2. 2.5. Quality assurance and quality control The NIST standard reference material (SRM1944, New York/ New Jersey Waterway Sediment) was analyzed to confirm analytical performance, and good precision (relative standard deviation below 20%) of the applied method (Table SM-3) was verified in comparison with the indicative values (Keller et al., 2010). A 5-points Calibration (0.02, 0.1, 0.5, 1, 5 ng lL 1 in methanol) was analyzed to confirm the linearity of the MS response, and a fine Calibration curve was obtained with R2 > 0.99 (Fig. SM-1). The recovery of 13C12-labeled a-, b-, and c-HBCD for all the samples ranged between 63–111%, 62–109%, and 66–98% for water, and 68–108%, 95–123%, and 62–118%, respectively (Fig. SM-2). Procedural blank tests were conducted with each experiment batch to confirm the contamination caused by glassware and laboratory atmosphere.
3. Results and discussion 3.1. Concentration levels in water and sediment P The distributions of HBCDs (sum of a-, b-, and c-HBCD) in water and sediment from the three rivers are shown in Table 1. The sum concentration of HBCD (a-, b-, and c-HBCD) was detected in most of the surface water samples and all of the sediment samples and ranged from 2.5 to 2100 ng L 1 and from 5.7 to 7800 ng g 1 dw, respectively. Interestingly, noticeably high conP centrations of HBCDs were detected in the water and sediment samples collected from Kuzuryu River (180–2100 ng L 1 and 97–7800 ng g 1 dw, respectively) that receives textile industry effluents. In this study, much higher concentration of HBCDs was detected in sediment sample (K-7, 7800 ng g 1) of HBCD production sites. To our knowledge, this sediment level of HBCDs is the
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
4
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
Table 1 Concentrations of HBCDs and PBCD in surface waters and sediments from three rivers in Japan. River
a
Location
Water samples (ng L
1
)
Sediment samples (ng g
a-HBCD
b-HBCD
c-HBCD
P
HBCDs
1
dw)
PBCD
a-HBCD
b-HBCD
c-HBCD
P HBCDs
PBCD
Tsurumi
T-1 T-2 T-3 T-4
37 7.7 3.3 3.3
3.0 0.87 0.23 0.28
17 5.2 3.2 3.4
57 14 6.6 7.0
n.d.a n.d. n.d. n.d.
8.4 2.7 4.0 2.4
1.5 0.54 0.46 0.32
13 7.4 6.5 2.9
22 11 11 5.7
n.d. n.d. n.d. n.d.
Yodo
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6
5.0 1.4 0.69 1.6 3.3 4.2
0.34 0.22 0.12 0.13 0.088 0.057
14 2.7 1.7 3.9 6.1 11
19 4.3 2.5 5.6 9.5 15
n.d. n.d. n.d. n.d. n.d. n.d.
3.9 1.7 5.9 28 6.1 35
0.70 0.32 0.88 3.2 0.80 4.9
11 7.7 16 61 25 86
15 9.7 23 92 32 130
0.45 2.6 5.5 1.1 0.70 2.6
Kuzuryu
K-1 K-2 K-3 K-4 K-5 K-6 K-7
62 100 380 29 110 180 82
0.72 0.80 42 1.3 3.3 2.9 6.2
140 190 1700 140 320 630 380
210 290 2100 180 430 820 470
3.0 2.4 15 2.3 3.1 4.9 3.6
170 30 17 180 60 25 630
32 5.0 3.1 33 16 4.6 180
790 120 77 780 470 88 7000
980 150 97 990 550 120 7800
12 3.0 3.2 11 6.9 2.7 20
n.d.: not detected.
highest in the world (Table SM-4). Relatively low concentrations of P HBCDs were observed in the samples from Tsurumi River (6.6– 57 ng L 1 and 5.7–22 ng g 1 dw, respectively) that receives mainly domestic/municipal wastewater as a possible source of HBCD. To our knowledge, there is no industrial activity that uses HBCD in the Tsurumi River basin. The detection of HBCD in this basin may reflect widespread use of HBCD in domestic applications (Harrad P et al., 2009). From Yodo River, the concentration levels of HBCDs in water and sediment of the three rivers were determined from its basin (2.5–19 ng L 1 and 9.7–130 ng g 1 dw, respectively) that flows through an industrial area where polystyrene insulation boards are manufactured. Consequently, we find that concentration levels of HBCD in water and sediment samples from the three rivers differ significantly in accordance with the provisionally established HBCD emission sources. 3.2. Trend of HBCD pollution in rivers We have looked for disparities between this study and a previous study (Managaki et al., 2012) that collected sediment samples from almost the same locations. For Tsurumi River, higher concentrations of HBCD in sediment were observed in this study (mean value of 12 ng g 1 dw) compared to the previous study (mean value of 2.7 ng g 1 dw). Even though there is no known direct emission source of HBCD near Tsurumi River basin, there are potential indirect emission sources. In Japan, in the manufacture of flame-retarded textiles, an impregnation technique is commonly used, by which the flame retardant chemical is easily separated from the textile (Kajiwara et al., 2009). Significant levels of HBCD in indoor air and dust have been observed in Japan (Takigami et al., 2009) and can be linked with this hypothesis. Moreover, the accumulating stock of products containing HBCD in houses and offices might be another contributing factor to increasing HBCD concentrations in indoor dust. In this regard, it is important to conduct continuous investigations of HBCD in Tsurumi River. In the case of the Yodo River, there is no significant change of concentration between this study (mean value of 50 ng g 1 dw) and the previous study (mean value of 57 ng g 1 dw), while decreasing concentration trends were observed in this study (mean value of 480 ng g 1 dw) compared to the previous study (mean value of 1400 ng g 1) in the Kuzuryu River, excluding the sampling point (K-7) whose sampling location was different from the previous study. The Japanese Textiles and Furniture Association and Japan EPS/XPS Industry
Association have been making voluntary efforts to reduce environmental emissions of HBCD (Voluntary Emission Control Action Programme) by replacing HBCD with alternative flame retardants since February 2008 (UNEP-POPRC, 2011). According to the Chemical Substances Control Law of Japan, the HBCD shipping volume for resin had been constant, while the fiber shipping volume of HBCD had been steadily decreasing for 8 year (2004–2011). These activities may have contributed to the reduction of concentration levels in the near-source areas such as Yodo and Kuzuryu Rivers. 3.3. Diastereomer profiles and emission sources The relative diastereomeric patterns of HBCDs in the water and sediment samples are summarized in Fig. 2. In this study, c-HBCD was the predominant diastereomer in all water (30–82%, mean 65%) and sediment samples (56–89%, mean 73%), and the indicated diastereomeric compositions of HBCD in all samples were influenced by the technical mixture of HBCD. Moreover, we calculated the ratio of c- to a-HBCD to discuss how HBCD diastereomers are distributed in the aquatic environment. Interestingly, this ratio of the water samples (2.72 ± 1.32) was smaller than the theoretical ratio of the technical mixture (ranging from 5.77 to 8.90) and even that of the sediment samples (3.88 ± 2.47). These ratios of HBCDs in the water and sediment samples of our study are similar to those (2.89 ± 1.41 and 5.69 ± 1.52, respectively) in the English lakes (Harrad et al., 2009). The higher water solubility of a-HBCD might explain this result (Hunziker et al., 2004; Law et al., 2006). Zhao et al. (2010) reported that a-HBCD was the most stable stereoisomer compared with b-HBCD and c-HBCD by density functional theory calculation. High proportions of a-HBCD were detected in Tsurumi River (47–64% in water and 25–42% in sediment samples), which were greater than those in the technical HBCD mixture. As there is no industrial activity involving HBCD in Tsurumi River basin (Managaki et al., 2012), this concentration level may suggest that HBCD in house curtains and electric applications is released to the river via indoor/outdoor air and domestic wastewater. Honda et al. (2010) found relatively high proportions of a-HBCD (average P of 58% of HBCDs) in 8 dust samples from Japanese houses and offices. Moreover, Kajiwara et al. (2009) reported an enriched proportion of a-HBCD (13–46%) in Japanese textile products indicating that c-HBCD might be isomerized to a-HBCD by heating processes. In comparison with the samples from Tsurumi River, c-HBCD was more predominant in both water (64–82%) and sediment samples
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx α-HBCD
β-HBCD
5
γ-HBCD
Composition (%)
100 80 60 40 20 0 T-1
T-2
T-3
T-4
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 K-1 K-2 K-3 K-4 K-5 K-6 K-7
T-1
T-2
T-3
T-4
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 K-1 K-2 K-3 K-4 K-5 K-6 K-7
Composition (%)
100 80 60 40 20 0 Fig. 2. Percentage distribution of HBCD diastereomers to
(66–89%) from Yodo and Kuzuryu Rivers, but still it was slightly less than in the technical HBCD mixture. Many textile processing plants and some EPS/XPS manufacturers are located in the Kuzuryu and Yodo River basins, respectively. Thermal rearrangement of c-HBCD into a-HBCD has been reported for commercial HBCD at temperatures above 160 °C in the XPS production process, resulting in 78% of a-HBCD, 13% of b-HBCD, and 9% of c-HBCD (Barontini et al., 2001). According to a report from Johokiko (2008) from Japan, a temperature of 160–190 °C is required in the manufacture of flame retarded textiles. However, our data showed less thermally transformed HBCD patterns in those rivers than that of Barontini et al. (2001). Moreover, the diastereomeric patterns of HBCDs in the Kuzuryu and Yodo River was different from that in Tsurumi River, suggesting that HBCD diastereomer compositions in effluents discharged directly from industries and in effluents from municipal wastewater treatment plants are different. The composition of HBCD diastereomers is influenced by several factors such as different HBCD industries, manufacturers of technical HBCD, and thermal/bio transformation processes in environmental compartments (Li et al., 2013).
3.4. Enantiomer fraction of HBCD There has been a burgeoning interest in looking at enantiomerspecific distribution of HBCD in riverine samples (Guerra et al., 2008, 2009; Feng et al., 2012). Enantiomer fractions (EFs) of a-, b-, and c-HBCD in the water and sediment samples were determined (Fig. 3) in order to understand the extent of biological processes in the aquatic environment of the study area. EF values corrected by 13C12-labeled HBCDs were used for all samples to offset the matrix effects such as mobile-phase and column bleed in the LC–ESI–MS analysis (Dodder et al., 2006; Marvin et al., 2007). The EFs obtained from the samples were compared to those of the technical formulation (p < 0.05, t test), presuming that HBCD formulations are racemic (Li et al., 2012). In the enantiomer analysis, corrected EFs of HBCD were obtained only from Kuzuryu River samples, whereas almost all the enantiomer peaks in the other two rivers’ (Tsurumi River, Yodo River) samples did not satisfy the criteria to be identified as a target pollutant (below limit of determination). The corrected EFs in the water of Kuzuryu River for aHBCD (mean ± standard deviation: 0.500 ± 0.014) and c-HBCD (0.497 ± 0.020) indicated no enantioselectivity. These results are similar to those from the English lakes (Harrad et al., 2009). On
P HBCDs in surface waters (top) and sediments (bottom).
the other hand, EF values for all sediment samples were determined. It is notable that the EFs of the sediments were statistically significantly different from that of the technical HBCD mixture, suggesting the occurrence of enantioselective transformation. Enrichment of ( ) c-HBCD was observed in Tsurumi River and Yodo River (0.357 ± 0.023 and 0.472 ± 0.014, respectively), while abundant (+) a-HBCD and ( ) c-HBCD (0.526 ± 0.007 and 0.463 ± 0.032, respectively) were observed in Kuzuryu River. These results suggest that enantioselectivity occurs in river sediment. Our results for c-HBCD were very similar to those from the Pearl River Delta, China, (Feng et al., 2012) and for a-HBCD similar to those from the rivers in the city of Tianjin, north China (Zhang et al., 2013). Our results indicate that different biological processes in aquatic sediments at different locations may have diverse effects on the HBCD EF values of the three rivers, as described by Feng et al. (2012).
3.5. Lower brominated derivatives The occurrence of transformation products and metabolites of HBCD is known in several environmental compartments. In the present study, 4 kinds of PBCD isomers were identified as lower brominated derivatives of HBCD in the water samples from Kuzuryu River and in the sediment samples from Yodo River and
Fig. 3. Enantiomer fraction of HBCDs in surface waters and sediment from three rivers in Japan (*p < 0.05).
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
6
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
Fig. 4. Linear correlation between the concentration of PBCD and total HBCD in river water from Kuzuryu River (left) and sediment from Yodo and Kuzuryu River (right).
Kuzuryu River as summarized in Table 1. PBCD, which can be regarded as a degradation product of HBCD via loss of HBr (Harrad et al., 2009), was monitored in the m/z 560.8 > 79 transition trace, using the same analytical condition as for the HBCD diastereomers. In this study, only one isomer of PBCD was quantified using the response factor for the PBCD native standard, even though we confirmed 4 kinds of PBCD isomers in the samples. Concentration levels of PBCD ranged from 2.4 to 15 ng L 1 in Kuzuryu River water and from 0.45 to 20 ng g 1 dw in Yodo River and Kuzuryu River sediment, respectively. These PBCD levels were higher than those observed in the sediment collected from the English lakes (Harrad et al., 2009). In this study, there was no additional discovery about sequential loss of two HBr monitored in the m/z 480.4 > 79 transition trace. The PBCD content in the technical HBCD mixture was analyzed P to be 0.43% (average ratio against HBCDs) and was lower than in the river water (0.91% PBCD in Kuzuryu River) and sediment samples (1.64% PBCD in Yodo River and Kuzuryu River). These percentage values were determined in comparison to the MS reP sponse of HBCDs in the technical HBCD mixture. PBCD may be regarded as a degradation product from thermal processes of HBCD synthesis (Barontini et al., 2001). This suggests that processed products or industrial processes using technical HBCD can be sources of PBCD to the aquatic environment. In our study, significant correlation was found between the concentration of P PBCD and HBCDs for the water and sediment samples (p < 0.01, 5% of significance level) where PBCD was detected P (Fig. 4). Interestingly, the ratios of PBCD to HBCDs were higher in the environmental samples than in the technical HBCD mixture, suggesting PBCD may increase through various transformation reactions in the aquatic environment. PBCD has previously been reported to occur in biotic samples (Hiebl and Vetter, 2007) and in the recycling process of electronic waste (Zhong et al., 2010). Although lower brominated HBCD derivatives other than PBCD were not detected in our environmental samples, we confirmed three other lower brominated derivatives in the technical HBCD mixture: one hydrodebromination product such as 0.07% of tetrabromocyclododecadienes (transition of 480 > 79, TBCDs), and two debromo-elimination products such as 0.02% of tetrabromocyclododecene (transition of 482 > 79, TBCDe) and 0.03% of dibromocyclododecadiene (transition of 322 > 79, DBCDi). These percentages were mass signal responses against total HBCD concentration in the technical HBCD mixture. Barontini et al. (2001) reported that some isomers of PBCD and TBCD are possibly present as byproducts of HBCD synthesis and some of those impurities can be released into various environmental compartments. It is possible that these lower brominated HBCD derivatives are attributable to the impurities in commercial formulations. The results of this study leave more to be investigated and answered because of the limited access to diastereomeric composition and unknown impurities in commercial HBCD mixtures.
4. Conclusions HBCD diastereomers, enantiomers, and their lower brominated derivatives were analyzed in water and sediment samples from three rivers in Japan. The following results were obtained: (1) diastereomeric patterns and the concentration of HBCDs in the three rivers is different, indicating the different emission sources have influence on the behavior of HBCDs for each basin; (2) the corrected EFs of HBCD showed no enantioselectivity in the water samples from Yodo River and Kuzuryu River, whereas a preference for ( ) c-HBCD was observed in the sediment samples of all three rivers, suggesting the degradation of HBCD in river sediment; and (3) pentabromocyclododecene was detected as a lower brominated derivative of HBCD in the sediments from the Yodo and the Kuzuryu River. However, the compounds were also found in the technical HBCD mixture in lower composition than in the environment, indicating we need more information about diastereomeric pattern and impurities about various commercial HBCDs. Moreover, in order to conduct better risk assessment of HBCD and its degradation products, we need more information about several unexplained aspects such as the degradation and transformation processes in aquatic environments, the stereoisomer-specific processes during industrial applications of HBCD, and the toxicity of degradation products of HBCD. Acknowledgements The sampling in this study was supported by the Leadership Program in Sustainable Living with Environmental Risks at Yokohama National University funded by the Strategic Funds for the Promotion of Science and Technology. Moreover, this study was supported by the Environment Research and Technology Development Fund of the Ministry of the Environment, Japan (Grant No. C-1003; ‘‘Environmental Risk Minimization Method Based on Lifecycle Risk Assessment and Alternative Assessment for Persistent Organic Pollutants, such as HBCD, in Products’’) and by the River Fund in charge of River Foundation, Japan.
Appendix A. Supplementary material Supplementary material associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2014.01.074. References Barontini, F., Cozzani, V., Petarca, L., 2001. Thermal stability and decomposition products of hexabromocyclododecane. Ind. Eng. Chem. Res. 40, 3270–3280. Becher, G., 2005. The stereochemistry of 1,2,5,6,9,10-hexabromocyclododecane and its graphic representation. Chemosphere 58, 989–991.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx Brandsma, S.H., Van der Ven, L.T.M., De Boer, J., Leonards, P.E.G., 2009. Identification of hydroxylated metabolites of hexabromocyclododecane in wildlife and 28days exposed Wistar rats. Environ. Sci. Technol. 43, 6058–6063. BSEF, Bromine Science and Environmental Forum, 2009. HBCD Factsheet. (accessed June, 2012). Chemical and Engineering News (C&EN), 13 May 2013 Global Ban for Flame Retardant. (accessed 30.5.13). Chemical Manufacturers Association Brominated Flame Retardant Industry Panel [CMABFRIP], 1997. Octabromodiphenyl oxide (OBDPO): determination of noctanol/water partition coefficient. Wildlife International Ltd., Project Number 439C–112, July 23, 1997. Covaci, A., Gerecke, A., Law, R.J., Voorspoels, S., Kohler, M., Heeb, N.V., Leslie, H., Allchin, C.R., De Boer, J., 2006. Hexabromocyclododecanes (HBCDs) in the environment and humans: a review. Environ. Sci. Technol. 40, 3679–3688. Davis, J.W., Gonsior, S.J., Markham, D.A., Friederich, U., Hunziker, R.W., Ariano, J.M., 2006. Biodegradation and product identification of [14C]hexabromocyclododecane in wastewater sludge and freshwater aquatic sediment. Environ. Sci. Technol. 40, 5395–5401. Dodder, N.G., Peck, A.M., Kucklick, J.R., Sander, L.C., 2006. Analysis of hexabromocyclododecane diastereomers and enantiomers by liquid chromatography/tandem mass spectrometry: chromatographic selectivity and ionization matrix effects. J. Chromatogr. A 1135, 36–42. Esslinger, S., Becker, R., Maul, R., Nehls, I., 2011. Hexabromocyclododecane enantiomers: microsomal degradation and patterns of hydroxylated metabolites. Environ. Sci. Technol. 45, 3938–3944. EU RAR, European Union Risk Assessment Report, 2008. (accessed 16.12.13). Feng, A.-H., Chen, S.-J., Chen, M.-Y., He, M.-J., Luo, X.-J., Mai, B.-X., 2012. Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) in riverine and estuarine sediments of the Pearl River Delta in southern China, with emphasis on spatial variability in diastereoisomer- and enantiomerspecific distribution of HBCD. Mar. Pollut. Bull. 64, 919–925. Gao, S., Wang, J., Yu, Z., Guo, Q., Sheng, G., Fu, J., 2011. Hexabromocyclododecanes in surface soils from e-waste recycling areas and industrial areas in South China: concentrations, diastereoisomer- and enantiomer-specific profiles, and inventory. Environ. Sci. Technol. 45, 2093–2099. Guerra, P., Eljarrat, E., Barceló, D., 2008. Enantiomeric specific determination of hexabromocyclododecane by liquid chromatography–quadrupole linear ion trap mass spectrometry in sediment samples. J. Chromatogr. A 1203, 81–87. Guerra, P., Cal, A.D.L., Marsh, G., Eljarrat, E., Barceló, D., 2009. Transfer of hexabromocyclododecane from industrial effluents to sediments and biota: case study in Cinca river (Spain). J. hydrol. 369, 360–367. Hakk, H., Szabo, D.T., Huwe, J., Diliberto, J., Birnbaum, L.S., 2012. Novel and distinct metabolites identified following a single oral dose of a- or chexabromocyclododecane in mice. Environ. Sci. Technol. 46, 13494–13503. Harrad, S., Abdallah, M.A.-E., Rose, N.L., Turner, S.D., Davidson, T.A., 2009. Currentuse brominated flame retardants in water, sediment, and fish from English lakes. Environ. Sci. Technol. 43, 9077–9083. Heeb, N.V., Schweizer, W.B., Kohler, M., Gerecke, A.C., 2005. Structure elucidation of hexabromocyclododecanes – a class of compounds with a complex stereochemistry. Chemosphere 61, 65–73. Hiebl, J., Vetter, W., 2007. Detection of hexabromocyclododecane and its metabolite pentabromocyclododecene in chicken egg and fish from the official food control. J. Agric. Food Chem. 55, 3319–3324. Honda, M., Suzuki, G., Kajiwara, N., Takigami, H., Takasuga, T., 2010. Hexabromocyclododecanes in dust from public facilities and business places in Japan, In: 5th International Symposium on Brominated Flame Retardants. Hunziker, R.W., Gonsior, S., MacGregor, J.A., Desjardins, D., Ariano, J., Friederich, U., 2004. Fate and effect of hexabromocyclododecane in the environment. Organohalogen Compd. 66, 2300–2305. Janak, K., Covaci, A., Voorspoels, S., Becher, G., 2005. Hexabromocyclododecane in marine species from the Western Scheldt estuary: diastereoisomer- and enantiomer-specific accumulation. Environ. Sci. Technol. 39, 1987–1994. Johokiko, 2008. Nannenzai ni yoru nannenzairyou no nannenkakikou to saishin Jireisyu, Yokyo, Japan, pp. 331–340 (in Japanese). Kajiwara, N., Sueoka, M., Ohiwa, T., Takigami, H., 2009. Determination of flameretardant hexabromocyclododecane diastereomers in textiles. Chemosphere 74, 1485–1489. Keller, J.M., Kucklick, J.R., Leigh, S.D., Schantz, M.M., 2010. Progress update on certifying HBCD in NIST standard reference materials (SRMS). Organohalogen Compd. 72, 518–521.
7
KEMI, 2005. National Chemicals Inspectorate (KEMI). Draft of the EU Risk Assessment Report on Hexabromocyclododecane, Sundbyberg, Sweden. Koeppen, R., Becker, R., Esslinger, S., Nehls, I., 2010. Enantiomer-specific analysis of hexabromocyclododecane in fish from Etnefjorden (Norway). Chemosphere 80, 1241–1245. Law, K., Halldorson, T., Danell, R., Stern, G., Gewurtz, S., Alaee, M., Marvin, C., Whittle, M., Tomy, G., 2006. Bioaccumulation and trophic transfer of some brominated flame retardants in a Lake Winnipeg (Canada) food web. Environ. Toxicol. Chem. 25, 2177–2186. Li, H., Mo, L., Yu, Z., Sheng, G., Fu, J., 2012. Levels, isomer profiles and chiral signatures of particle-bound hexabromocyclododecanes in ambient air around Shanghai, China. Environ. Pollut. 165, 140–146. Li, H., Shang, H., Wang, P., Wang, Y., Zhang, H., Zhang, Q., Jiang, G., 2013. Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China. J. Environ. Sci. 25, 69–76. Lo, K.W., Saha-Roy, S.C., Jans, U., 2012. Investigation of the reaction of hexabromocyclododecane with polysulfide and bisulfide in methanol/water solutions. Chemosphere 87, 158–162. Managaki, S., Enomoto, I., Masunaga, S., 2012. Sources and distribution of hexabromocyclododecanes (HBCDs) in Japanese river sediment. J. Environ. Monit. 14, 901–907. Marvin, C.H., Macinnis, G., Alaee, M., Arsenault, G., Tomy, G.T., 2007. Factors influencing enantiomeric fractions of hexabromocyclododecane measured using liquid chromatography/tandem mass spectrometry. Rapid Commun. Mass Spectrom. 21, 1925–1930. Marvin, C.H., Tomy, G.T., Alaee, M., Macinnis, G., 2006. Distribution of hexabromocyclododecane in Detroit River suspended sediments. Chemosphere 64, 268–275. METI, 2008. Ministry of Economy, Trade and Industry (METI), Japan. Announcement (No. 241) through Official Gazettes on Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc., Japanese. METI, 2010. Ministry of Economy, Trade and Industry (METI), Japan. (accessed 15.4.13). Peled, M., Scharia, R., Sondock, D., 1995. Thermal rearrangement of hexabromocyclododecane (HBCD). In: Desmurs, J.R., Gerard, B., Goldstein, M.J. (Eds.), Advances in Organobromine Chemistry II. Elsevier, Amsterdam, The Netherlands, pp. 92–99. POPs Review Committee (POPRC), 2011. Draft Risk Management Evaluation on Hexabromocyclododecane. . Suzuki, S., Hasegawa, A., 2006. Determination of hexabromocyclododecane diastereoisomers and tetrabromobisphenol A in water and sediment by liquid chromatography/mass spectrometry. Anal. Sci. 22, 469–474. Takigami, H., Suzuki, G., Hirai, Y., Sakai, S., 2009. Brominated flame retardants and other polyhalogenated compounds in indoor air and dust from two houses in Japan. Chemosphere 76, 270–277. Tomy, G.T., Halldorson, T., Danell, R., Law, K., Arsenault, G., Alaee, M., MacInnis, G., Marvin, C.H., 2005. Refinements to the diastereoisomer-specific method for the analysis of hexabromocyclododecane. Rapid Commun. Mass Spectrom. 19, 2819–2826. Tomy, G.T., Palace, V., Marvin, C., Stapleton, H.M., Covaci, A., Harrad, S., 2011. Biotransformation of HBCD in biological systems can confound temporal-trend studies. Environ. Sci. Technol. 45, 364–365. UNEP-POPRC, United Nations Environment Programme-Persistent Organic Pollutants Review Committee, 2011. Risk management evaluation (UNEP/ POPS/POPRC.7/19/Add.1). . Vorkamp, K., Bester, K., Rigét, F.F., 2012. Species-specific time trends and enantiomer fractions of hexabromocyclododecane (HBCD) in biota from East Greenland. Environ. Sci. Technol. 46, 10549–10555. Weber, M., Durmaz, V., Becker, R., Esslinger, S., 2009. Predictive identification of pentabromocyclododecene (PBCD) isomers with high binding affinity to hTTR. Organohalogen Compd. 71, 247–252. Zhang, Y., Ruan, Y., Sun, H., Zhao, L., Gan, Z., 2013. Hexabromocyclododecanes in surface sediments and a sediment core from Rivers and Harbor in the northern Chinese city of Tianjin. Chemosphere 90, 1610–1616. Zhao, Y.-Y., Zhang, X.-H., Sojinu, O.S.S., 2010. Thermodynamics and photochemical properties of alpha, beta, and gamma-hexabromocyclododecanes: a theoretical study. Chemosphere 80, 150–156. Zhong, Y., Peng, P., Yu, Z., Deng, H., 2010. Effects of metals on the transformation of hexabromocyclododecane (HBCD) in solvents: implications for solvent-based recycling of brominated flame retardants. Chemosphere 81, 72–78.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
Contents lists available at ScienceDirect
Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment Jung Keun Oh a,⇑, Kensuke Kotani a, Satoshi Managaki b, Shigeki Masunaga a a b
Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama 240-8501, Japan Faculty of Environmental Science, Musashino University, Tokyo 135-8181, Japan
h i g h l i g h t s HBCD diastereomeric pattern differed depending on the pollution source. The highest level of total HBCDs for surface sediment samples in the world was detected. Enantiomer selectivity for HBCDs was found in the sediment samples. PBCD derived from HBCD was detected in both water and sediment samples. Correlation between the HBCD and PBCD concentration in aquatic samples was confirmed.
a r t i c l e
i n f o
Article history: Received 14 October 2013 Received in revised form 20 January 2014 Accepted 21 January 2014 Available online xxxx Keywords: Hexabromocyclododecane Pentabromocyclododecene Diastereomer profile Enantiomer fraction Surface water Surface sediment
a b s t r a c t Hexabromocyclododecane (HBCD) and its lower brominated derivatives were measured in both surface water and sediment samples from three Japanese rivers; Tsurumi River, Yodo River, and Kuzuryu River. P The concentration level of HBCD (sum of a-, b-, and c-HBCD) was in the order of Kuzuryu > Yodo > Tsurumi P HBCD concentration Rivers, reflective of the different emission sources for each basin. The highest 1 (7800 ng g dw) was detected in the sediment sample from the Kuzuryu River that receives effluents from textile industries, which use HBCD in flame retardant finishes. A different diastereomeric pattern of a-, b-, and c-HBCD of each river was investigated, indicating the level of HBCD in these rivers is directly influenced by emission source. Enantiomer fractions of HBCDs in water and sediment samples were also determined. Racemic mixtures were observed in the water samples, whereas enantiomeric enrichment of ( ) c-HBCD and (+) a-HBCD was observed in the sediment samples. Some lower brominated HBCD derivatives such as pentabromocyclododecenes were detected in both the water and sediment samples, and their concentration ranged from below the detection limit to 15 ng L 1 and 20 ng g 1 dw, respectively. Ó 2014 Published by Elsevier Ltd.
1. Introduction Hexabromocyclododecane (HBCD) is a brominated flame retardant (BFR) used in polystyrene foams, e.g., expanded polystyrene (EPS) and extruded polystyrene (XPS) foam, and in textiles (Marvin et al., 2006). It is manufactured worldwide because of its remarkable flame retardant properties and good blending with polymers. Global use and production of HBCD exceeds 0.16 Mt year 1 (BSEF, 2009), and approximately 3.0 kt was used in Japan in 2010 (METI, 2010). It is noted that, in Japan, about 80% of HBCD is used in polystyrene foams, and the rest is mostly used for textiles (METI, 2008). ⇑ Corresponding author. Address: Graduate School of Environment and Information Sciences Yokohama National University 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan. Tel.: +81 45 339 4346; fax: +81 45 339 4373. E-mail address: [email protected] (J.K. Oh).
HBCD is an additive BFR that is not covalently bonded to polymers, which means that there is high risk of it being released to the environment during use, disposal, and recycling of materials that contain HBCD (Tomy et al., 2005; POPRC, 2011). Owing to evidence of its persistence, bioaccumulation in environmental compartments, and toxic properties (Tomy et al., 2011; Li et al., 2012; Zhang et al., 2013), HBCD has recently determined to be listed for global elimination after the sixth meeting of the Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants (C&EN, 2013). Generally, it is widely known that HBCD has a high soil–water partition coefficient (log Koc = 4.66 for HBCD by applying the QSAR equation (EU RAR, 2008)), high log Kow (5.6, (Covaci et al., 2006)), low water solubility (65.6 lg L 1, sum of solubility of the three major diastereomers), and low vapor pressure (6.27 10 5 Pa at 21 °C, (CMABFRIP, 1997)). Theoretically, HBCD has 16
http://dx.doi.org/10.1016/j.chemosphere.2014.01.074 0045-6535/Ó 2014 Published by Elsevier Ltd.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
2
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
stereoisomers, including six diastereomeric pairs of enantiomers and four meso forms (Heeb et al., 2005). The technical HBCD mixture is mainly composed of three enantiomeric pairs of diastereomers (approximately 75–89% c-isomer, 10–13% a-isomer, and <0.5–12% b-isomer) (Becher, 2005). The three main diastereomers (a-, b-, and c-HBCD) have different values of polarity, dipole moment, and water solubility, which may cause different stabilities and biological uptake rates in the environment (Hakk et al., 2012). Moreover, the difference in hydrophobicity of the individual diastereomers (log Kow of a-, b-, and c-HBCD are 5.07, 5.12, and 5.47, respectively) (KEMI, 2005) may lead to different levels of persistence, biological magnification, and toxicity. Peled et al. (1995) observed an interconversion of HBCD diastereomers during heating processes at temperatures above 160 °C. The degradation and biotransformation products of HBCD have been detected in various environmental matrixes and in biota. The breakable carbon–bromine bond, unlike the carbon–fluorine or carbon–chlorine bond, can be expected to generate significant degradation or biotransformation in biological systems (Tomy et al., 2011). Barontini et al. (2001) reported that 7 isomers of pentabromocyclododecenes (PBCDs) identified as thermal degradation products of HBCDs. Harrad et al. (2009) reported that photolytically mediated loss of HBr from HBCD leads to the formation of PBCD and tetrabromocyclododecadiene (TBCD) isomers in English lakes. Anaerobic degradation products of HBCD, tetrabromocyclododecene (TBCDe) and dibromocyclododecadiene (DBCDi), which are formed by the debromination of vicinal dibromides, have also been reported in sediment microcosms in laboratory studies (Davis et al., 2006; Lo et al., 2012). Moreover, many kinds of metabolites of HBCD have been identified in biotic samples, such as chicken eggs (Hiebl and Vetter, 2007), Pollack (Esslinger et al., 2011), and Wistar rats (Brandsma et al., 2009). Enantiomeric patterns of HBCDs have been identified in some environmental and biota samples (Janak et al., 2005; Guerra et al., 2008; Koeppen et al., 2010; Esslinger et al., 2011; Gao et al., 2011; Li et al., 2012; Vorkamp et al., 2012). Despite the increasing number of studies on HBCD, few have attempted to characterize and identify its degradation products and enantiomeric patterns in environmental compartments. As there is evidence that some degradation products have higher binding affinities for human transthyretin receptor than their parent HBCDs or even thyroxin (Weber et al., 2009), further studies are needed to examine which transformation products are mainly formed in biotic and abiotic environments. In the previous study (Managaki et al., 2012), it was investigated the distribution of HBCD in sediment from Tsurumi River, Yodo River, and Kuzuryu River. The aim of this study is not only to clarify the behavior of diastereomers of HBCD, but also to identify their lower brominated derivatives in the water and sediment samples collected from these rivers, Japan, with different HBCD emission sources in each basin.
2. Materials and methods 2.1. Standards and reagents Native, deuterated (d18-), and 13C12-labeled a-, b-, and c-HBCD (50 lg mL 1) and native PBCD (50 lg mL 1) in toluene were provided by Wellington Laboratories (Guelph, Canada). LC-MS grade methanol and acetonitrile, and pesticide analysis grade dichloromethane (DCM) and n-hexane were purchased from Wako Pure Chemical Industry. (Tokyo, Japan). All the other reagents, such as 44% sulfuric acid-impregnated silica gel, Wakogel S-1, copper (powder), and sodium sulfate (anhydrous) were purchased from Wako Pure Chemical Industry.
2.2. Description of sampling sites Fig. 1 shows the sampling locations of this study. Tsurumi River, regulated by the Japanese government (Minister of Land, Infrastructure, Transport and Tourism), flows through Tokyo and Kanagawa prefectures, ranked as two of the most highly populated areas in Japan. Its basin is a typical residential area with over 1.8 million people and has the highest population density in Japan. A total of 7 municipal wastewater treatment plants are located in the river basin, and a large amount of effluent from these plants is discharged into the river. In spite of continuous efforts to improve the river water quality, it is still ranked as one of the worst in Japan because of the rapid urbanization in the basin. Yodo River is the only river flowing out of Lake Biwa, the largest lake in Japan. It flows through Shiga, Kyoto, and Osaka prefectures. Approximately 11 million people live in the basin. The river has the most tributaries (965) in Japan. The flow of the river consists mainly of effluents from industries, including EPS and XPS production, and household wastewater. Kuzuryu River flows through Fukui prefecture, and 0.66 million people live in the basin. Many dyeing and textile processing factories (644, 4% of total number in Japan, 2010) are located along the river. Moreover, a large amount of textiles (366 kt, 15% of total volume in Japan, 2010) is produced in this prefecture. Wastewater from textile factories may have released their effluents into the river. Surface water and sediment samples were collected at 17 sites from the three rivers; Tsurumi River (T-1–T-4, n = 4), Yodo River (Y-1–Y-6, n = 6) and Kuzuryu River (K-1–K-7, n = 7). Samples from Tsurumi River were taken in October, 2011, while samples from Yodo River and Kuzuryu River were collected in December, 2011. 1 L of water was collected at each site using a grab sampler. The water samples were transported to the laboratory and stored at 4 °C in the dark until pre-treatment. Sediments were sampled using an Ekman–Birge sediment sampler at the same sites, simultaneously with the water samples. The sediment samples were put in brown glass bottles and immediately brought to the laboratory for storage at 25 °C prior to analysis. 2.3. Extraction and cleanup 2.3.1. Water The water samples were analyzed according to the method reported by Suzuki and Hasegawa (2006). Each water sample (1 L) was spiked with 50 ng each of 13C12-labeled a-, b-, and c-HBCD (1 mg L 1 in acetone, 50 lL) as internal standards. This standard solution was mixed well using test tube mixer, and kept in a refrigerator for 6 h before spiking to the sample. Before this standard was spiked to the sample, it was mixed one more time for 20 s using test tube mixer. After conditioning the solid-phase extraction disk (Empore Disk Styrenedivinylbenzene (SDB-XD, 47 mm) 3 M, USA) with 10 mL each of methanol and purified water, the sample was passed through at a flow rate of 30 mL min 1. After passing the water sample to the SPE disk, 7 mL of acetone was injected to the same SPE disk to escape the loss. Therefore, filtered water sample and 7 mL of acetone were combined and analyzed. After drying in an oven at 45 °C for 1 h, the disk was eluted with 4 mL of acetone followed by 3 mL of DCM. The eluate was evaporated under the flow of N2 and then reconstituted in 1 mL of methanol including 50 ng of d18-c-HBCD. 2.3.2. Sediment Sample information of each sampling point is shown in Table SM-1 in Supplementary Material (SM). All the sediment samples were homogenized, freeze-dried, and sieved through a 2 mm sieve prior to analysis. Subsequently, 2 g of the sample was weighed accurately, placed in a stainless-steel cell, and mixed with
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
3
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
T-4 T-3 T-2 T-1 K-1 K-2 K-3 K-4
K-5
K-7
K-6
Y-6 Y-4 Y-2
Y-5
Y-3
Y-1
Fig. 1. Map of the study area in Japan and location of sampling sites: (a) Tsurumi River in Kanagawa prefecture, (b) Yodo River in Osaka prefecture, and (c) Kuzuryu River in Fukui prefecture.
2 g of Cu powder to remove sulfuric adulteration before extraction. Each sample was spiked with 50 ng each of 13C12-labeled a-, b-, and c-HBCD as internal standards. Extraction was carried out using an accelerated solvent extraction instrument system (ASE 200, Dionex) with DCM and n-hexane (80:20 v/v) at 100 °C and 10.3 MPa. Approximately 40 mL of the extract was collected and subsequently concentrated to 5 mL under the flow of N2. The cleanup procedure was performed using a chromatography column packed with 8 g of 44% sulfuric-coated silica gel, 2 g of neutral baked silica gel, and 0.5 cm of sodium sulfate. The analyte was eluted with 30 mL of DCM and n-hexane (50:50 v/v). The eluate was evaporated to dryness under the flow of N2 and redissolved in 1 mL of methanol containing 50 ng of d18-c-HBCD to calculate the recovery rates of a-, b-, and c-HBCD. The final extract was passed through a nylon membrane (0.20 lm, Millipore) for the removal of fine particles prior to LC-MS/MS analysis. 2.4. LC-MS/MS analysis 2.4.1. Diastereomer analysis A high pressure liquid chromatograph (Waters 2695; Milford, MA, USA) coupled to a triple-quadrupole mass spectrometer (Micromass Quattro Ultima triple-quadrupole MS; Micromass, Milford, MA, USA) were used for the determination of HBCDs and lower brominated derivatives. A ZORBAX Eclipse XDB-C18 column (150 mm 2.1 mm id, 3.5 lm particle size, Agilent Technology, Santa Clara, CA) was used to determine HBCD and its degradation products. The mobile-phase A (20:50:30 water:methanol:acetonitrile) and B (70:30 methanol:acetonitrile) at a flow rate of 200 lL min 1 were applied. The MS/MS analysis was performed using negative electrospray ionization (ESI) with multiple reaction monitoring (MRM) mode. The a-, b-, and c-HBCD isomers and PBCD were determined by MRM transition of m/z 640.7 > 79.0 and m/z 560.8 > 79.0, respectively. Concentrations in the sediment samples were calculated using relative response factors for each of the target compounds. 2.4.2. Enantiomer analysis Separation of a-, b-, and c-HBCDs was conducted by a Chiral Nucleodex b-PM column (200 mm 4.0 mm id, 5 lm particle size, Macherey–Nagel, Düren, Germany) with Nucleodex beta-PM guard
cartridge (Guerra et al., 2008). The mobile-phase A (30:70 methanol:water) and B (30:70 methanol:acetonitrile) at a flow rate of 200 lL min 1 were used to identify each enantiomer of HBCD. Specific instrumental parameters were equal to that of diastereomer analysis. The specific MS/MS detection conditions were optimized and details are shown in Table SM-2. 2.5. Quality assurance and quality control The NIST standard reference material (SRM1944, New York/ New Jersey Waterway Sediment) was analyzed to confirm analytical performance, and good precision (relative standard deviation below 20%) of the applied method (Table SM-3) was verified in comparison with the indicative values (Keller et al., 2010). A 5-points Calibration (0.02, 0.1, 0.5, 1, 5 ng lL 1 in methanol) was analyzed to confirm the linearity of the MS response, and a fine Calibration curve was obtained with R2 > 0.99 (Fig. SM-1). The recovery of 13C12-labeled a-, b-, and c-HBCD for all the samples ranged between 63–111%, 62–109%, and 66–98% for water, and 68–108%, 95–123%, and 62–118%, respectively (Fig. SM-2). Procedural blank tests were conducted with each experiment batch to confirm the contamination caused by glassware and laboratory atmosphere.
3. Results and discussion 3.1. Concentration levels in water and sediment P The distributions of HBCDs (sum of a-, b-, and c-HBCD) in water and sediment from the three rivers are shown in Table 1. The sum concentration of HBCD (a-, b-, and c-HBCD) was detected in most of the surface water samples and all of the sediment samples and ranged from 2.5 to 2100 ng L 1 and from 5.7 to 7800 ng g 1 dw, respectively. Interestingly, noticeably high conP centrations of HBCDs were detected in the water and sediment samples collected from Kuzuryu River (180–2100 ng L 1 and 97–7800 ng g 1 dw, respectively) that receives textile industry effluents. In this study, much higher concentration of HBCDs was detected in sediment sample (K-7, 7800 ng g 1) of HBCD production sites. To our knowledge, this sediment level of HBCDs is the
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
4
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
Table 1 Concentrations of HBCDs and PBCD in surface waters and sediments from three rivers in Japan. River
a
Location
Water samples (ng L
1
)
Sediment samples (ng g
a-HBCD
b-HBCD
c-HBCD
P
HBCDs
1
dw)
PBCD
a-HBCD
b-HBCD
c-HBCD
P HBCDs
PBCD
Tsurumi
T-1 T-2 T-3 T-4
37 7.7 3.3 3.3
3.0 0.87 0.23 0.28
17 5.2 3.2 3.4
57 14 6.6 7.0
n.d.a n.d. n.d. n.d.
8.4 2.7 4.0 2.4
1.5 0.54 0.46 0.32
13 7.4 6.5 2.9
22 11 11 5.7
n.d. n.d. n.d. n.d.
Yodo
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6
5.0 1.4 0.69 1.6 3.3 4.2
0.34 0.22 0.12 0.13 0.088 0.057
14 2.7 1.7 3.9 6.1 11
19 4.3 2.5 5.6 9.5 15
n.d. n.d. n.d. n.d. n.d. n.d.
3.9 1.7 5.9 28 6.1 35
0.70 0.32 0.88 3.2 0.80 4.9
11 7.7 16 61 25 86
15 9.7 23 92 32 130
0.45 2.6 5.5 1.1 0.70 2.6
Kuzuryu
K-1 K-2 K-3 K-4 K-5 K-6 K-7
62 100 380 29 110 180 82
0.72 0.80 42 1.3 3.3 2.9 6.2
140 190 1700 140 320 630 380
210 290 2100 180 430 820 470
3.0 2.4 15 2.3 3.1 4.9 3.6
170 30 17 180 60 25 630
32 5.0 3.1 33 16 4.6 180
790 120 77 780 470 88 7000
980 150 97 990 550 120 7800
12 3.0 3.2 11 6.9 2.7 20
n.d.: not detected.
highest in the world (Table SM-4). Relatively low concentrations of P HBCDs were observed in the samples from Tsurumi River (6.6– 57 ng L 1 and 5.7–22 ng g 1 dw, respectively) that receives mainly domestic/municipal wastewater as a possible source of HBCD. To our knowledge, there is no industrial activity that uses HBCD in the Tsurumi River basin. The detection of HBCD in this basin may reflect widespread use of HBCD in domestic applications (Harrad P et al., 2009). From Yodo River, the concentration levels of HBCDs in water and sediment of the three rivers were determined from its basin (2.5–19 ng L 1 and 9.7–130 ng g 1 dw, respectively) that flows through an industrial area where polystyrene insulation boards are manufactured. Consequently, we find that concentration levels of HBCD in water and sediment samples from the three rivers differ significantly in accordance with the provisionally established HBCD emission sources. 3.2. Trend of HBCD pollution in rivers We have looked for disparities between this study and a previous study (Managaki et al., 2012) that collected sediment samples from almost the same locations. For Tsurumi River, higher concentrations of HBCD in sediment were observed in this study (mean value of 12 ng g 1 dw) compared to the previous study (mean value of 2.7 ng g 1 dw). Even though there is no known direct emission source of HBCD near Tsurumi River basin, there are potential indirect emission sources. In Japan, in the manufacture of flame-retarded textiles, an impregnation technique is commonly used, by which the flame retardant chemical is easily separated from the textile (Kajiwara et al., 2009). Significant levels of HBCD in indoor air and dust have been observed in Japan (Takigami et al., 2009) and can be linked with this hypothesis. Moreover, the accumulating stock of products containing HBCD in houses and offices might be another contributing factor to increasing HBCD concentrations in indoor dust. In this regard, it is important to conduct continuous investigations of HBCD in Tsurumi River. In the case of the Yodo River, there is no significant change of concentration between this study (mean value of 50 ng g 1 dw) and the previous study (mean value of 57 ng g 1 dw), while decreasing concentration trends were observed in this study (mean value of 480 ng g 1 dw) compared to the previous study (mean value of 1400 ng g 1) in the Kuzuryu River, excluding the sampling point (K-7) whose sampling location was different from the previous study. The Japanese Textiles and Furniture Association and Japan EPS/XPS Industry
Association have been making voluntary efforts to reduce environmental emissions of HBCD (Voluntary Emission Control Action Programme) by replacing HBCD with alternative flame retardants since February 2008 (UNEP-POPRC, 2011). According to the Chemical Substances Control Law of Japan, the HBCD shipping volume for resin had been constant, while the fiber shipping volume of HBCD had been steadily decreasing for 8 year (2004–2011). These activities may have contributed to the reduction of concentration levels in the near-source areas such as Yodo and Kuzuryu Rivers. 3.3. Diastereomer profiles and emission sources The relative diastereomeric patterns of HBCDs in the water and sediment samples are summarized in Fig. 2. In this study, c-HBCD was the predominant diastereomer in all water (30–82%, mean 65%) and sediment samples (56–89%, mean 73%), and the indicated diastereomeric compositions of HBCD in all samples were influenced by the technical mixture of HBCD. Moreover, we calculated the ratio of c- to a-HBCD to discuss how HBCD diastereomers are distributed in the aquatic environment. Interestingly, this ratio of the water samples (2.72 ± 1.32) was smaller than the theoretical ratio of the technical mixture (ranging from 5.77 to 8.90) and even that of the sediment samples (3.88 ± 2.47). These ratios of HBCDs in the water and sediment samples of our study are similar to those (2.89 ± 1.41 and 5.69 ± 1.52, respectively) in the English lakes (Harrad et al., 2009). The higher water solubility of a-HBCD might explain this result (Hunziker et al., 2004; Law et al., 2006). Zhao et al. (2010) reported that a-HBCD was the most stable stereoisomer compared with b-HBCD and c-HBCD by density functional theory calculation. High proportions of a-HBCD were detected in Tsurumi River (47–64% in water and 25–42% in sediment samples), which were greater than those in the technical HBCD mixture. As there is no industrial activity involving HBCD in Tsurumi River basin (Managaki et al., 2012), this concentration level may suggest that HBCD in house curtains and electric applications is released to the river via indoor/outdoor air and domestic wastewater. Honda et al. (2010) found relatively high proportions of a-HBCD (average P of 58% of HBCDs) in 8 dust samples from Japanese houses and offices. Moreover, Kajiwara et al. (2009) reported an enriched proportion of a-HBCD (13–46%) in Japanese textile products indicating that c-HBCD might be isomerized to a-HBCD by heating processes. In comparison with the samples from Tsurumi River, c-HBCD was more predominant in both water (64–82%) and sediment samples
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx α-HBCD
β-HBCD
5
γ-HBCD
Composition (%)
100 80 60 40 20 0 T-1
T-2
T-3
T-4
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 K-1 K-2 K-3 K-4 K-5 K-6 K-7
T-1
T-2
T-3
T-4
Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 K-1 K-2 K-3 K-4 K-5 K-6 K-7
Composition (%)
100 80 60 40 20 0 Fig. 2. Percentage distribution of HBCD diastereomers to
(66–89%) from Yodo and Kuzuryu Rivers, but still it was slightly less than in the technical HBCD mixture. Many textile processing plants and some EPS/XPS manufacturers are located in the Kuzuryu and Yodo River basins, respectively. Thermal rearrangement of c-HBCD into a-HBCD has been reported for commercial HBCD at temperatures above 160 °C in the XPS production process, resulting in 78% of a-HBCD, 13% of b-HBCD, and 9% of c-HBCD (Barontini et al., 2001). According to a report from Johokiko (2008) from Japan, a temperature of 160–190 °C is required in the manufacture of flame retarded textiles. However, our data showed less thermally transformed HBCD patterns in those rivers than that of Barontini et al. (2001). Moreover, the diastereomeric patterns of HBCDs in the Kuzuryu and Yodo River was different from that in Tsurumi River, suggesting that HBCD diastereomer compositions in effluents discharged directly from industries and in effluents from municipal wastewater treatment plants are different. The composition of HBCD diastereomers is influenced by several factors such as different HBCD industries, manufacturers of technical HBCD, and thermal/bio transformation processes in environmental compartments (Li et al., 2013).
3.4. Enantiomer fraction of HBCD There has been a burgeoning interest in looking at enantiomerspecific distribution of HBCD in riverine samples (Guerra et al., 2008, 2009; Feng et al., 2012). Enantiomer fractions (EFs) of a-, b-, and c-HBCD in the water and sediment samples were determined (Fig. 3) in order to understand the extent of biological processes in the aquatic environment of the study area. EF values corrected by 13C12-labeled HBCDs were used for all samples to offset the matrix effects such as mobile-phase and column bleed in the LC–ESI–MS analysis (Dodder et al., 2006; Marvin et al., 2007). The EFs obtained from the samples were compared to those of the technical formulation (p < 0.05, t test), presuming that HBCD formulations are racemic (Li et al., 2012). In the enantiomer analysis, corrected EFs of HBCD were obtained only from Kuzuryu River samples, whereas almost all the enantiomer peaks in the other two rivers’ (Tsurumi River, Yodo River) samples did not satisfy the criteria to be identified as a target pollutant (below limit of determination). The corrected EFs in the water of Kuzuryu River for aHBCD (mean ± standard deviation: 0.500 ± 0.014) and c-HBCD (0.497 ± 0.020) indicated no enantioselectivity. These results are similar to those from the English lakes (Harrad et al., 2009). On
P HBCDs in surface waters (top) and sediments (bottom).
the other hand, EF values for all sediment samples were determined. It is notable that the EFs of the sediments were statistically significantly different from that of the technical HBCD mixture, suggesting the occurrence of enantioselective transformation. Enrichment of ( ) c-HBCD was observed in Tsurumi River and Yodo River (0.357 ± 0.023 and 0.472 ± 0.014, respectively), while abundant (+) a-HBCD and ( ) c-HBCD (0.526 ± 0.007 and 0.463 ± 0.032, respectively) were observed in Kuzuryu River. These results suggest that enantioselectivity occurs in river sediment. Our results for c-HBCD were very similar to those from the Pearl River Delta, China, (Feng et al., 2012) and for a-HBCD similar to those from the rivers in the city of Tianjin, north China (Zhang et al., 2013). Our results indicate that different biological processes in aquatic sediments at different locations may have diverse effects on the HBCD EF values of the three rivers, as described by Feng et al. (2012).
3.5. Lower brominated derivatives The occurrence of transformation products and metabolites of HBCD is known in several environmental compartments. In the present study, 4 kinds of PBCD isomers were identified as lower brominated derivatives of HBCD in the water samples from Kuzuryu River and in the sediment samples from Yodo River and
Fig. 3. Enantiomer fraction of HBCDs in surface waters and sediment from three rivers in Japan (*p < 0.05).
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
6
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx
Fig. 4. Linear correlation between the concentration of PBCD and total HBCD in river water from Kuzuryu River (left) and sediment from Yodo and Kuzuryu River (right).
Kuzuryu River as summarized in Table 1. PBCD, which can be regarded as a degradation product of HBCD via loss of HBr (Harrad et al., 2009), was monitored in the m/z 560.8 > 79 transition trace, using the same analytical condition as for the HBCD diastereomers. In this study, only one isomer of PBCD was quantified using the response factor for the PBCD native standard, even though we confirmed 4 kinds of PBCD isomers in the samples. Concentration levels of PBCD ranged from 2.4 to 15 ng L 1 in Kuzuryu River water and from 0.45 to 20 ng g 1 dw in Yodo River and Kuzuryu River sediment, respectively. These PBCD levels were higher than those observed in the sediment collected from the English lakes (Harrad et al., 2009). In this study, there was no additional discovery about sequential loss of two HBr monitored in the m/z 480.4 > 79 transition trace. The PBCD content in the technical HBCD mixture was analyzed P to be 0.43% (average ratio against HBCDs) and was lower than in the river water (0.91% PBCD in Kuzuryu River) and sediment samples (1.64% PBCD in Yodo River and Kuzuryu River). These percentage values were determined in comparison to the MS reP sponse of HBCDs in the technical HBCD mixture. PBCD may be regarded as a degradation product from thermal processes of HBCD synthesis (Barontini et al., 2001). This suggests that processed products or industrial processes using technical HBCD can be sources of PBCD to the aquatic environment. In our study, significant correlation was found between the concentration of P PBCD and HBCDs for the water and sediment samples (p < 0.01, 5% of significance level) where PBCD was detected P (Fig. 4). Interestingly, the ratios of PBCD to HBCDs were higher in the environmental samples than in the technical HBCD mixture, suggesting PBCD may increase through various transformation reactions in the aquatic environment. PBCD has previously been reported to occur in biotic samples (Hiebl and Vetter, 2007) and in the recycling process of electronic waste (Zhong et al., 2010). Although lower brominated HBCD derivatives other than PBCD were not detected in our environmental samples, we confirmed three other lower brominated derivatives in the technical HBCD mixture: one hydrodebromination product such as 0.07% of tetrabromocyclododecadienes (transition of 480 > 79, TBCDs), and two debromo-elimination products such as 0.02% of tetrabromocyclododecene (transition of 482 > 79, TBCDe) and 0.03% of dibromocyclododecadiene (transition of 322 > 79, DBCDi). These percentages were mass signal responses against total HBCD concentration in the technical HBCD mixture. Barontini et al. (2001) reported that some isomers of PBCD and TBCD are possibly present as byproducts of HBCD synthesis and some of those impurities can be released into various environmental compartments. It is possible that these lower brominated HBCD derivatives are attributable to the impurities in commercial formulations. The results of this study leave more to be investigated and answered because of the limited access to diastereomeric composition and unknown impurities in commercial HBCD mixtures.
4. Conclusions HBCD diastereomers, enantiomers, and their lower brominated derivatives were analyzed in water and sediment samples from three rivers in Japan. The following results were obtained: (1) diastereomeric patterns and the concentration of HBCDs in the three rivers is different, indicating the different emission sources have influence on the behavior of HBCDs for each basin; (2) the corrected EFs of HBCD showed no enantioselectivity in the water samples from Yodo River and Kuzuryu River, whereas a preference for ( ) c-HBCD was observed in the sediment samples of all three rivers, suggesting the degradation of HBCD in river sediment; and (3) pentabromocyclododecene was detected as a lower brominated derivative of HBCD in the sediments from the Yodo and the Kuzuryu River. However, the compounds were also found in the technical HBCD mixture in lower composition than in the environment, indicating we need more information about diastereomeric pattern and impurities about various commercial HBCDs. Moreover, in order to conduct better risk assessment of HBCD and its degradation products, we need more information about several unexplained aspects such as the degradation and transformation processes in aquatic environments, the stereoisomer-specific processes during industrial applications of HBCD, and the toxicity of degradation products of HBCD. Acknowledgements The sampling in this study was supported by the Leadership Program in Sustainable Living with Environmental Risks at Yokohama National University funded by the Strategic Funds for the Promotion of Science and Technology. Moreover, this study was supported by the Environment Research and Technology Development Fund of the Ministry of the Environment, Japan (Grant No. C-1003; ‘‘Environmental Risk Minimization Method Based on Lifecycle Risk Assessment and Alternative Assessment for Persistent Organic Pollutants, such as HBCD, in Products’’) and by the River Fund in charge of River Foundation, Japan.
Appendix A. Supplementary material Supplementary material associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2014.01.074. References Barontini, F., Cozzani, V., Petarca, L., 2001. Thermal stability and decomposition products of hexabromocyclododecane. Ind. Eng. Chem. Res. 40, 3270–3280. Becher, G., 2005. The stereochemistry of 1,2,5,6,9,10-hexabromocyclododecane and its graphic representation. Chemosphere 58, 989–991.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074
J.K. Oh et al. / Chemosphere xxx (2014) xxx–xxx Brandsma, S.H., Van der Ven, L.T.M., De Boer, J., Leonards, P.E.G., 2009. Identification of hydroxylated metabolites of hexabromocyclododecane in wildlife and 28days exposed Wistar rats. Environ. Sci. Technol. 43, 6058–6063. BSEF, Bromine Science and Environmental Forum, 2009. HBCD Factsheet.
7
KEMI, 2005. National Chemicals Inspectorate (KEMI). Draft of the EU Risk Assessment Report on Hexabromocyclododecane, Sundbyberg, Sweden. Koeppen, R., Becker, R., Esslinger, S., Nehls, I., 2010. Enantiomer-specific analysis of hexabromocyclododecane in fish from Etnefjorden (Norway). Chemosphere 80, 1241–1245. Law, K., Halldorson, T., Danell, R., Stern, G., Gewurtz, S., Alaee, M., Marvin, C., Whittle, M., Tomy, G., 2006. Bioaccumulation and trophic transfer of some brominated flame retardants in a Lake Winnipeg (Canada) food web. Environ. Toxicol. Chem. 25, 2177–2186. Li, H., Mo, L., Yu, Z., Sheng, G., Fu, J., 2012. Levels, isomer profiles and chiral signatures of particle-bound hexabromocyclododecanes in ambient air around Shanghai, China. Environ. Pollut. 165, 140–146. Li, H., Shang, H., Wang, P., Wang, Y., Zhang, H., Zhang, Q., Jiang, G., 2013. Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China. J. Environ. Sci. 25, 69–76. Lo, K.W., Saha-Roy, S.C., Jans, U., 2012. Investigation of the reaction of hexabromocyclododecane with polysulfide and bisulfide in methanol/water solutions. Chemosphere 87, 158–162. Managaki, S., Enomoto, I., Masunaga, S., 2012. Sources and distribution of hexabromocyclododecanes (HBCDs) in Japanese river sediment. J. Environ. Monit. 14, 901–907. Marvin, C.H., Macinnis, G., Alaee, M., Arsenault, G., Tomy, G.T., 2007. Factors influencing enantiomeric fractions of hexabromocyclododecane measured using liquid chromatography/tandem mass spectrometry. Rapid Commun. Mass Spectrom. 21, 1925–1930. Marvin, C.H., Tomy, G.T., Alaee, M., Macinnis, G., 2006. Distribution of hexabromocyclododecane in Detroit River suspended sediments. Chemosphere 64, 268–275. METI, 2008. Ministry of Economy, Trade and Industry (METI), Japan. Announcement (No. 241) through Official Gazettes on Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc., Japanese. METI, 2010. Ministry of Economy, Trade and Industry (METI), Japan.
Please cite this article in press as: Oh, J.K., et al. Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.074