Polybrominated Diphenyl Ethers in Sediments of the Daliao River Estuary, China: Levels, Distribution and Their Inﬂuencing Factors

Chemosphere 82 (2011) 1262–1267

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Polybrominated diphenyl ethers in sediments of the Daliao River Estuary, China: Levels, distribution and their inﬂuencing factors

Xiaofeng Zhao a,c, Haijun Zhang a, Yuwen Ni a, Xianbo Lu a, Xueping Zhang a, Fan Su a, Jingfeng Fan b ⇑ Daoming Guan b, Jiping Chen a, a Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China b National Marine Environmental Monitoring Center, Linghe Street 42, Dalian 116023, China c Graduate University of Chinese Academy of Sciences, Beijing 100049, China article info abstract

Article history: The concentrations, compositional profiles, possible sources of polybrominated diphenyl ethers (PBDEs) Received 11 June 2010 in sediments of the Daliao River Estuary as well as the factors influencing the distribution of PBDEs were Received in revised form 7 November 2010 investigated. The total concentrations of PBDEs ranged from 0.13 to 1.98 ng gÀ1 d.w. BDE209 was the Accepted 7 December 2010 dominating congener in all sediment samples, indicating the pollution of PBDEs in the Daliao River Estu- Available online 3 January 2011 ary mainly came from the use of deca-BDE commercial mixtures. The intrusion of sea waters promoted the deposition of the colloid-associated PBDEs in the estuary. There were significantly negative correla- Keywords: tions between PBDE concentration in sediment with pH value and salinity in the bottom water. The Polybrominated diphenyl ether (PBDE) higher river flow in the flood season (summer) obviously accelerated the transport of PBDEs, and thereby Daliao River Estuary Hydrodynamic conditions increased the risk of PBDE contamination to the deep ocean. Moreover, a positive correlation between Total organic content (TOC) TOC and PBDE distributions was observed, suggesting that TOC regulated the distributions of PBDEs in sediments of Daliao River Estuary. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction 2009). Various hydrophobic organic contaminants such as PBDEs released via riverine inputs and atmospheric deposition tend to Polybrominated diphenyl ethers (PBDEs) are additive flame- be trapped in estuarine sediments. The danger is that these hydro- retardants and widely used in industrial and domestic electronic phobic compounds in sediments can accumulate in organisms and equipment, textiles and flexible foam (de Wit, 2002; Alaee et al., transfer along the food chain (Hung et al., 2006). At the same time, 2003). They can enter various compartments including aquatic the estuary also acts as a transit zone in which contaminants can environment during their production, use and disposal processes be transported from rivers to deeper oceans, and thus cause more (Voorspoels et al., 2003). Because of their persistence, long-range serious pollutions (Men et al., 2009). atmospheric transport, tendency to bioaccumulate and potential Daliao River runs through many important large- or medium- adverse effect on ecosystem and humans (de Wit, 2002; Evandri sized industrial cities of northeast of China, and eventually flows et al., 2003; Keum and Li, 2005), Tetra-hepta BDEs have been des- into the Liaodong Bay of Bohai Sea. As the rapid development of ignated as new persistent organic pollutants (POPs) at the fourth the economy in this area, Daliao River water system is now expe- meeting of the Conference of the Parties (COP4) of the Stockholm riencing a serious pollution stress from various anthropogenic dis- Convention in May 2009 (UNEP, 2009). Monitoring of the PBDE le- charges. Before the year of 2000, most of industrial and domestic vel and transfer in the environment has become a part of the con- wastewaters in this river basin were not treated or not effectively tents of national implementation plan for the Stockholm treated, and they were directly discharged into the water system. It Convention on POPs. was estimated that about 2074 million tons of industrial and The estuary is a special coastal zone, which is one of the most domestic wastewater had been discharged into the Daliao River productive and resourceful ecosystems on the earth and is critical catchments in 2004 (Tan et al., 2009). Bohai Sea is a large semi-en- to the life history and development of various aquatic species closed coastal bay with a narrow strait to the open sea. The half-ex- (Chapman and Wang, 2001). However, the estuary is also an area change time of the sea water in the Liaodong Bay of Bohai Sea was strongly influenced by anthropogenic activities (Men et al., estimated to be about 3 years (Wei et al., 2002). The poor water exchange has been recognized as one of the important factors for the

⇑ Corresponding author. Tel./fax: +86 411 84379562. high accumulation of pollutants in this aquatic environment E-mail address: [email protected] (J. Chen). (Zhang et al., 2006).

Since 1978, the Environment Monitoring Network in Bohai Sea by sieving through a stainless steel 60-mesh sieve and then stored has been started up by the State Oceanic Administration of China. in pre-cleaned brown glass bottles at À4 °C for further analysis. The routine environmental monitoring of the network focuses on the dissolved inorganic nitrogen, dissolved inorganic phosphate, 2.3. Sample extraction and analysis chemical oxygen demand, heavy metals and oil pollution (Zhang et al., 2006). In the last two decades, some surveys on the distribu- Calibration standard mixtures containing 27 labeled and their tions of several POPs in the Liaohe River water system have been corresponding native isomers (including BDE3, 7, 15, 17, 28, 47, performed (Zhang et al., 2008, 2010; Guo et al., 2009; Men et al., 49, 66, 71, 77, 85, 99, 100, 119, 126, 138, 153, 154, 156,183, 184, 2009; Tan et al., 2009). Recently, Zhang et al. (2009) reviewed that 191, 196, 197, 206, 207, 209), 10 13C-labeled standards (BDE3, the residues of 6 classes of POPs, including polycyclic aromatic 15, 28, 47, 99, 153, 154, 183, 209 and 138) were purchased from hydrocarbons (PAHs), dichlorodiphenyltrichloroethanes (DDTs), Wellington Laboratories Inc. (Ontario, Canada). Toluene, hexane hexachlorocyclohexanes (HCHs), polychlorinated biphenyls (PCBs), and dichloromethane used for the extraction and cleanup proce- polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in dures were pesticide analysis grade (J. T. Baker, USA), and the other the sediments and mollusks of Bohai Sea. However, surveys on the solvents and reagents were of analytical grade. distributions of PBDEs in this area are still sparse. Twenty-seven PBDE congeners were involved in the analytical The primary aim of this study was to present the detailed data work. PBDEs were analyzed using the following methods described regarding the concentration magnitude and the spatial distribution previously (Marvin et al., 2007), with minor modifications. About of PBDEs in sediments from the Daliao River Estuary. Moreover, in 10 g freeze-dried sediment samples were spiked with nine 13C-la- order to demonstrate the potential factors controlling the distribu- beled surrogate standards (BDE3, 15, 28, 47, 99, 153, 154, 183 and tion of PBDEs in the estuary sediments, we also investigated the 209), and extraction was performed using classical Soxhlet method influence of hydrodynamic condition in different seasons on the with toluene for about 16 h. Activated copper granules were added transport of PBDEs, and the possible regulation of total organic car- to the extraction flasks during the extraction to remove elemental bon (TOC) to the PBDE distribution. sulfur. The extract was cleaned and fractionated on a multi-layer silica gel column filled from bottom with 2 g anhydrous sodium sulfate, 1 g activated silica gel, 3 g sodium hydroxide/silica (3%, 2. Materials and methods w/w), 1 g activated silica gel, 8 g sulfuric acid/silica (44%, w/w), 1 g activated silica gel, 2 g silver nitrate silica (10%, w/w), 2 g anhy- 2.1. Hydrographic characteristics of Daliao River drous sodium sulfate. The column was eluted with 80 mL hexane: dichloromethane (DCM) (1: 1, v/v). The collected solution was con- Because dominated by a semi-moist monsoon climate, the Da- centrated to about 2 mL and was further cleaned with a basic alu- liao River has a large seasonal variation in discharge and sediment mina column (4.5 g), then eluted with 75 mL hexane: DCM (1: 1, v/ load: the highest discharge typically occurring in July–September. v). Finally, extracts were concentrated, evaporated to dryness un- The discharge amounts of water and sediment of Daliao River are 8 3 À1 6 À1 der a nitrogen stream, and spiked with known amounts at 42 Â 10 m year and 9 Â 10 ton year , respectively (Song 1 13 (100 ng mLÀ ) of recovery standard ( C-BDE138) prior to instru- et al., 1997). In addition, the Daliao River Estuary is also influenced mental analysis. by tidal currents that can reach up to 94 km upstream from the riv- The target compounds were determined by an Autospec Ultima er mouth during the dry season. The study on the transport and high resolution mass spectrometer (Micromass, UK) coupled with a dispersion of suspended sediments from the Liaohe River Estuary Hewlett–Packard (PaloAlto, CA, USA) 6890 Plus gas chromatograph showed that seaward transport of sediments was related to the ti- (HRGC–HRMS). A DB-5HT (15 m Â 0.25 mm Â 0.10 lm film thick- dal cycle and the seasonal river flow cycle. During the spring tides ness; J&W Scientific, USA) capillary was used for the separation and the high river flow in flood season, the maximum transport of of mono- to deca-BDE congeners. Samples were injected in a split- sediments occurred (Wang and Bao, 1996). Therefore, the transport less mode at an injector temperature of 270 °C and at an initial col- and re-distribution of sediment-associated PBDEs in the Daliao umn temperature of 110 °C. After 1 min, the column temperature River Estuary should be strongly influenced by these factors. was programmed at 40 °C minÀ1 to 200 °C, then at 10 °C minÀ1 up to 330 °C and held for 10 min. All data were obtained in the se- 13 2.2. Sample collection and storage lected ion monitoring (SIM) mode using C12 isotope dilution analysis for qualitative and quantitative analysis. The ion source The rainfall in the Daliao River Basin mainly occurs in summer, was operated at 250 °C, the electron energy was 37 eV, ionization and concentrates from June to September, accounting for 80% of current was 0.5 mA, ion accelerating voltage was 8 kV and the annual precipitation. To assess the effect of hydrodynamic condi- mass spectrometer was tuned to a mass resolution of 8000 under tions on the distributions of PBDEs, sediment samples were col- positive EI conditions. The separation of 27 PBDE congeners on a lected from the upstream of Daliao River mouth to the open sea 15 m DB-5HT column was shown in Fig. S1 of Supporting before, during and after the rainfall season. The sampling was con- Information. ducted respectively in spring (May), summer (August) and autumn (November) 2007. Samples in winter were not obtained due to the 2.4. Other parameters analysis icing of river water. To avoid site deviations in each seasonal sampling, sampling sites were chosen based on their distinguishable The TOC in sediment sample was analyzed by the method de- locations and were positioned by a global positioning system scribed by Yu and Zhong (2007). Briefly, about 0.15 g of freezed, (GPS) and terrestrial surrounding. The spatial distribution of sam- ground and sieved sediment samples was treated with 1 M HCl pling locations was given in Fig. 1. The sediment samples were col- to removed inorganic carbon, washed with deionized water for lected by using a grab sampler at a 0–5 cm depth. Five separate three times, and dried for 24 h at 60 °C. The TOC analysis was per- samples from each site were taken, and then mixed together as formed on an elemental analyzer (Elementar Vario Macro CHN, one sample for the specific sampling site. After being put into Germany). Physicochemical properties of site-specific water sam- pre-cleaned self-sealing aluminum/polyethylene bags with zip- ples were also determined, including pH, salinity and suspended pers, all collected samples were transported with ice to the labora- particulate matter (SPM). These measurements were carried out tory. Sediment samples were freeze-dried, ground, homogenized basing on the methods of HY003.4-91 (China). 1264 X. Zhao et al. / Chemosphere 82 (2011) 1262–1267

Fig. 1. Map showing the sediment sampling locations in Daliao River Estuary, Northeast China.

2.5. Quality assurance/quality control (QA/QC) ary, China (0.3–21.8 ng gÀ1)(Mai et al., 2005), San Francisco estuary, USA (0.2–211.8 ng gÀ1)(Hoenicke et al., 2007), and Scheldt The resolution and sensitivity tests of HRGC–HRMS were car- estuary, Netherlands (14–22 ng gÀ1)(Verslycke et al., 2005). The ried out on time. Minimum limits of detection (LODM) and mini- concentrations of BDE209 in our work were comparable to those À1 mum limits of quantification (LOQM) were obtained by for sediments from the river estuary in Tianjin (0–5 ng g )(Wang measuring the minimum concentration of the calibration standard et al., 2007), but lower than those from the Pearl River Estuary, Chi- solutions (CS1). The standard deviation was calculated based on na (0.7–111.9 ng gÀ1)(Mai et al., 2005), river and estuaries, Japan five parallel injections. Take threefold of the standard deviation (<25–11 600 ng gÀ1)(Environmental Agency of Japan, 1988). as LODM for the apparatus and tenfold of the standard deviation as LOQM. The overall recovery of the analytical method was moni- 13 3.2. Congener profile of PBDEs and potential sources tored using the C12-labeled PBDEs as surrogate standards. The surrogate recoveries in all the samples ranged from 54% to 118%. A spiked procedural blank was conducted in parallel with every The relative contributions of individual PBDE congeners in sed- 11 sediment samples. No interferences of PBDE congeners were iments from the Daliao River Estuary were presented in Fig. 2. The found in blanks. The final concentrations of PBDEs were corrected contribution of BDE209 to the total PBDEs ranged from 74.5% to by recoveries. 94.8%, with the average value of 87.9%. This suggested that deca- BDE formulation was the predominant commercial PBDE products used in the study area. And it agreed with the fact that technical 2.6. Statistical analysis deca-BDE mixtures were the dominant PBDE formulation used in China (Mai et al., 2005; Zou et al., 2007). Statistical tests were performed using Origin 8.0 (Windows BDE47, BDE99 and BDE183 were also found in all sediment software package). The normality of all data was assessed by a samples. Their mean percentages (and ranges) were as follows: Shapiro–Wilk test. Since some variables did not present a normal BDE47, 1.67% (0.60–5.42%); BDE99, 0.92% (0.23–3.05%) and distribution, concentrations of PBDEs for different seasons were BDE183, 0.62% (0.14–2.52%). BDE47 and BDE99 are the main com- compared using the non-parametric Mann–Whitney test. A proba- ponents in penta-BDE mixtures (Hites, 2004), while BDE183 is con- bility of 0.05 or lower was considered significant. Correlation anal- sidered as a marker compound for the commercial octa-mix PBDE ysis was determined with the Pearson correlation coefficient (R). formulations (Law et al., 2006). Therefore, the higher levels of penta-BDEs and octa-BDEs in sediments of the Daliao River Estuary 3. Results and discussion may result from the applications of technical penta- and octa- BDE formulations. However, as shown in Fig. S2, the penta-BDE 3.1. Contamination level of PBDEs in sediments profiles in sediments from the Daliao River Estuary were obvious different from those in commercial mixtures produced in Europe The detailed concentration data of total PBDEs were given in and USA, such as DE-71 and Bromkal 70-5DE (La Guardia et al., Tables S1–3. Of the 27 PBDE congeners measured, at least ten com- 2006). This suggested that penta-BDE mixtures used in the study pounds (BDE15, 28, 47, 49, 66, 99, 100, 153, 183 and 209) were de- area may be produced in China. Moreover, it was found that low- tected in all sediment samples from the Daliao River Estuary. The brominated BDEs in collected sediments were higher compared total concentrations of PBDEs ranged from 0.13 to 1.98 ng gÀ1 d.w., with the composition of commercial PBDE mixtures. The relative with a mean value of 0.63 ng gÀ1 d.w. BDE209 was the dominating high levels of low-brominated BDEs possibly partly came from congener in all sediment samples, and its concentrations in each degradation of the higher-brominated BDEs by microbes (Gerecke sediment sample were about one orderP of magnitude higher than et al., 2005; He et al., 2006) or by sunlight during transport the sum of other PBDE congeners ( PBDEs) (Tables S1–3). (Söderström et al., 2004). To evaluate the pollution levels of PBDE contaminants in the Pearson correlation analysis for the main PBDE congeners in all Daliao River Estuary, PBDE concentrations in sediments were com- samples was carried out (Table S5). Except BDE15, good correla- pared withP those reported for several other river estuaries tions were observed for all PBDE congeners. The result suggested (Table S4). PBDEs in the present study were similar to those that atmospheric deposition might be an important source of for sediments from the river estuary in Tianjin (0.05–0.5 ng gÀ1) BDE15. In addition, the debromination of higher brominated PBDE (Wang et al., 2007), and Korea coasts (0.05–0.90 ng gÀ1)(Moon congeners may be another source of BDE15 (Gerecke et al., 2005; et al., 2007), but lower than those for sediments in Pearl River Estu- He et al., 2006). X. Zhao et al. / Chemosphere 82 (2011) 1262–1267 1265

Fig. 2. Relative abundances (%) of PBDE congeners in sediments of the Daliao River Estuary. Vertical bars represent the error bars.

3.3. Spatial distributions of PBDEs and the influence of hydrodynamic strength as river waters mix with saline waters (Sicre et al., 1993). conditions Marine influx was the dominant factor in controlling pH values and salinity levels in the estuary. In this study, the bottom water sam- According to results of the significance analysis, the pollution ples were collected together with sediments samples. It was found levels of PBDEs and BDE209 showed no significant differences in that pH value and salinity of bottom water increased spatially from different seasons (P > 0.05). However, the spatial distributions of the inner to the outer estuary in each season except several sites in PBDEs along the sampling sites showed obvious seasonal varia- spring (Figs. S3 and 4). Meanwhile, the concentration of PBDEs in tions in the three seasons (Fig. 3). It was observed that the spatial sediments presented significant negative correlations (P < 0.05) distributions of PBDEs in the dry seasons (spring and autumn) dis- with pH value and salinity of bottom waters (Table S6) in all the played a similar trend. Concentrations of PBDEs in site 1 were low- three seasons. This suggested the intrusion of sea waters acceler- er, and reached the highest levels in sites 2 (1.98 ng gÀ1 d.w.) and 3 ated the deposition of colloid-associated PBDEs in the estuary. (1.78 ng gÀ1 d.w.), and then fluctuated from 0.12 ng gÀ1 d.w. to In the dry seasons, because of low river flow, tidal currents be- 0.67 ng gÀ1 d.w. However, PBDEs concentrations in summer come the major forcing in the Daliao River Estuary. The sea water (0.25–0.85 ng gÀ1 d.w.) had a more even spatial distribution than can intrude into the up-estuary region. Fine-grained particles in those in the dry seasons. outer estuary can also be removed and relocated to the middle Due to the higher hydrophobicity, PBDEs are prone to be bound and inner estuary regions. During this process, quick deposition oc- onto the organic suspended particulates. Their precipitation from curs due to increasing settling velocity of fine sediment particles, water phase in estuarine area is, to a large extent, governed by where flocculation is taking place in the region between the fresh physical and chemical transformations induced by increasing ionic water and salt water. It often results in the highest concentrations of sediment-associated pollutants in the deposition zone of the turbidity maximum zone (TME). This phenomenon known as the mid-estuarine maximum has been observed in the Tolka Estuary (Dablin, Ireland) (Buggy and Tobin, 2006). In this study, the highest concentrations of SPM and PBDEs were observed in sites 2 and 3 in the dry season (Figs. 3 and Fig. S5), suggesting that these sites may fall into the zone of mid-estuarine maximum. Moreover, the high correlation of PBDEs in sediments with SPM in bottom water (Table S6) in the dry season also consisted with the general knowl- edge that these contaminants in the water column are bound with suspended particulates. This may further indicate both intensive re-suspension of sediments and scavenging of these compounds from the water column in the dry seasons in the estuary (Kow- alewska et al., 2003). Summer is the rainy season in Daliao River watershed. Higher river flow rate resulting from strong rainfall can weaken the tide action, and significantly accelerated the transportation of SPM- associated contaminants to the deeper sea. As shown in Fig. 3, the concentrations of PBDEs in sites 2 and 3 decreased by 2–3 Fig. 3. Seasonal and spatial distribution of PBDEs in sediments from the Daliao times compared with the surveying data in spring, and the mean River Estuary. concentration of PBDEs in the sea sediments (sites 6–14) in 1266 X. Zhao et al. / Chemosphere 82 (2011) 1262–1267

to the open sea in the ﬂood seasons. In addition, a signiﬁcant correlation was found between the PBDE levels and the TOC contents, suggesting that TOC played an important role in the re-distributions of PBDEs in sediments of Daliao River Estuary.

Acknowledgments

We appreciated Eric Reiner, Manager, DTO at Ontario Ministry of the Environment for providing the analysis method of PBDEs (Environment Ontario Laboratory Services Branch Method BDE- 3430). This work was financially supported by National Basic Re- search Program of China (Grant No. 2009CB421602), Research and Demonstration of National Monitoring Technology System of Aquatic Environment of China (Grant no. 2009ZX07527-004), and National Natural Science Foundation of China (Grant No. 40676060). Fig. 4. Relationship between concentrations of total PBDEs and TOC in sediment samples from the Daliao River Estuary. Appendix A. Supplementary material summer was significantly higher than that in spring. This process The detailed concentration data of PBDE congeners from all increased the risk of PBDE contamination to the deep ocean. season and locations (Tables S1-3); Comparison of PBDE concentrations (Table S4); Pearson correlation analysis (Tables S5 and 6); 3.4. Relationship between TOC and PBDEs the complete separation of the 27 PBDE congeners by HRGC- HRMS (Fig. S1); the comparison of the profile of penta-BDEs It is well-known that organic matter (OM) in sediments is the (Fig. S2); pH values, salinity and SPM contents (Figs. S3–5); and principal factor controlling the sorption of organic compounds the correlation between the concentrations of individual PBDE (Cornelissen et al., 2005). Therefore, TOC might be strongly corre- congeners and TOC (Fig. S6). Supplementary data associated with lated with PBDEs in sediments. In the present work, the values of this article can be found, in the online version, at doi:10.1016/ TOC in these sediments varied from 0.14% to 1.56%, with the aver- j.chemosphere.2010.12.032. age value of 0.71%. A regression analysis between the total PBDEs and the TOC was References conducted. As shown in Fig. 4, the total concentration of PBDEs were significantly correlated with the TOC content (R = 0.53, Alaee, M., Arias, P., Sjödin, A., Bergman, Å., 2003. An overview of commercially used brominated flame retardants, their applications, their use patterns in different P < 0.01), implying that organic matter played an important role countries/regions and possible modes of release. Environ. Int. 29, 683–689. in the transport and re-distribution of PBDEs in the Daliao River Buggy, C.J., Tobin, J.M., 2006. Seasonal and spatial distributions of tributyltin in Estuary. The similar relationships between the total PBDEs and surface sediment of the Tolka Estuary, Dublin. Irel. Environ. Pollut. 143, 294– 303. TOC contents were also found in the Macao coastal sediments by Chapman, M.P., Wang, F.Y., 2001. Assessing sediment contamination in estuaries. Mai et al. (2005). Environ. Toxicol. Chem. 20, 3–22. The significant correlations with TOC at the 0.01 level were also Cornelissen, G., Gustafsson, ö., Bucheli, T.D., Jonker, M.T.O., Koelmans, A.A., van Noort, P.C.M., 2005. Extensive sorption of organic compounds to black carbon, found for BDE 28, BDE 47, BDE 49, BDE 66, BDE 99, BDE 100, coal, and kerogen in sediments and soils: mechanisms and consequences for BDE154, BDE 183, and BDE 209, except BDE 153 at the 0.05 level distribution, bioaccumulation, and biodegradation. Environ. Sci. Technol. 39, (Fig. S6). Such correlations may ascribe to the similar sources or 6881–6895. de Wit, C.A., 2002. An overview of brominated flame retardants in the environment. transport behaviors of both PBDEs and organic carbon (Hung Chemosphere 46, 583–624. et al., 2006). However, there was no significant correlation be- Environmental Agency of Japan., 1991. Chemicals in the environment Report on tween BDE15 and TOC (Fig. S6). BDE15 has the higher volatility environmental survey and wildlife monitoring of chemicals in FY 1988 and and thus the atmosphere deposition should be the main resource 1989 Environmental Agency Japan. Tokyo, Japan: Department of Environmental Health, Office of Health Studies. of BDE15 in aquatic environment. Therefore, the poor correlation Evandri, M.G., Costa, L.G., Bolle, P., 2003. Evaluation of brominated diphenyl ether- between BDE15 and TOC contents may be attributed to the consid- 99 toxicity with Raphidocelis subcapitata and Daphnia magna. Environ. Toxicol. erable input of BDE15 from the atmosphere source. Chem. 22, 2167–2172. Gerecke, A.C., Hartmann, P.C., Heeb, N.V., Kohler, H.P.E., Giger, W., Schmid, P., Zennegg, M., Kohler, M., 2005. Anaerobic degradation of decabromodiphenyl ether. Environ. Sci. Technol. 39, 1078–1083. 4. Conclusions Guo, W., He, M.C., Yang, Z.F., Lin, C.Y., Quan, X.C., Men, B., 2009. Distribution, partitioning and sources of polycyclic aromatic hydrocarbons in Daliao River The paper showed the results of PBDE pollution in sediment water system in dry season. China J. Hazard. Mater. 164, 1379–1385. He, J.Z., Robrock, K.R., Alvarez-Cohen, L., 2006. Microbial reductive debromination of samples from Daliao River Estuary. In comparison with the re- polybrominated diphenyl ethers (PBDEs). Environ. Sci. Technol. 40, 4429–4434. ported data about PBDEs in sediments of other estuaries and coasts Hites, R.A., 2004. Polybrominated diphenyl ethers in the environment and in in the world, the pollution levels of PBDEs in the present work people: a meta-analysis of concentrations. Environ. Sci. Technol. 38, 945–956. were relatively low. The deca-BDE formulation was the predomi- Hoenicke, R., Oros, D.R., Oram, J.J., Taberski, K.M., 2007. Adapting an ambient monitoring program to the challenge of managing emerging pollutants in the nant commercial PBDE products used in the study area. The rela- San Francisco Estuary. Environ. Res. 105, 132–144. tionships of PBDEs in sediments with pH value, salinity and SPM Hung, C.C., Gong, G.C., Jiann, K.T., Yeager, K.M., Santschi, P.H., Wade, T.L., Sericano, contents in bottom water revealed that hydrodynamic conditions J.L., Hsieh, H.L., 2006. Relationship between carbonaceous materials and polychlorinated biphenyls (PCBs) in the sediments of the Danshui River and controlled the transfer and deposition behaviors of organic col- adjacent coastal areas, Taiwan. Chemosphere 65, 1452–1461. loid-associated PBDEs in the estuary. Due to the seasonal varia- Keum, Y.S., Li, Q.X., 2005. Reductive debromination of polybrominated diphenyl tions of hydrodynamic conditions, sediment-associated PBDEs ethers by zerovalent iron. Environ. Sci. Technol. 39, 2280–2286. Kowalewska, G., Konat-Stepowicz, J., Wawrzyniak-Wydrowska, B., Szymczak-Zyla, were re-suspended and then re-deposited within the riverway in M., 2003. Transfer of organic contaminants to the Baltic in the Odra Estuary. the dry season, while re-suspended and subsequently transported Mar. Pollut. Bull. 46, 703–718. X. Zhao et al. / Chemosphere 82 (2011) 1262–1267 1267

La Guardia, M.J., Hale, R.C., Harvey, E., 2006. Detailed polybrominated diphenyl United Nations Environment Programme (UNEP), 2009. Conference of the Parties of ether (PBDE) congener composition of the widely used penta-, octa-, and the Stockholm Convention on Persistent Organic Pollutants Fourth meeting. deca-PBDE technical flame-retardant mixtures. Environ. Sci. Technol. 40, UNEP/POPS/COP.4/1. 6247–6254. Verslycke, T.A., Vethaak, A.D., Arijs, K., Janssen, C.R., 2005. Flame retardants, Law, R.J., Allchin, C.R., de Boer, J., Covaci, A., Herzke, D., Lepom, P., Morris, S., surfactants and organotins in sediment and mysid shrimp of the Scheldt estuary Tronczynski, J., de Wit, C.A., 2006. Levels and trends of brominated flame (The Netherlands). Environ. Pollut. 136, 19–31. retardants in the European environment. Chemosphere 64, 187–208. Voorspoels, S., Covaci, A., Schepens, P., 2003. Polybrominated diphenyl ethers in Mai, B.X., Chen, S.J., Luo, X.J., Chen, L.G., Yang, Q.S., Sheng, G.Y., Peng, P.G., Fu, J.M., marine species from the Belgian North Sea and the Western Scheidt Estuary: Zeng, E.Y., 2005. Distribution of polybrominated diphenyl ethers in sediments levels, profiles, and distribution. Environ. Sci. Technol. 37, 4348–4357. of the Pearl River Delta and adjacent South China Sea. Environ. Sci. Technol. 39, Wang, Y.G., Bao, Y.G., 1996. Mechanisms control ling the transport and dispersionof 3521–3527. suspended sediments from the Liaohe Estuary. J Ocean. Huanghai Bohai Seas 14, Marvin, C., Williams, D., Kuntz, K., Klawunn, P., Backus, S., Kolic, T., Lucaciu, C., 33–40 (in Chinese). MacPherson, K., Reiner, E., 2007. Temporal trends in polychlorinated Wang, Y.W., Jiang, G.B., Lam, P.K.S., Li, A., 2007. Polybrominated diphenyl ether in dibenzo-p-dioxins and dibenzofurans, dioxin-like PCBs, and polybrominated the East Asian environment: a critical review. Environ. Int. 33, 963–973. diphenyl ethers in Niagara river suspended sediments. Chemosphere 67, Wei, H., Tian, T., Zhou, F., Zhao, L., 2002. Numerical study on the water exchange of 1808–1815. the Bohai Sea: simulation of the half-life time by dispersion model. J Ocean Men, B., He, M.C., Tan, L., Lin, C.Y., Quan, X.C., 2009. Distributions of polycyclic Univ. Qingdao 32, 519–525 (in Chinese). aromatic hydrocarbons in the Daliao River Estuary of Liaodong Bay, Bohai Sea Yu, W.Q., Zhong, S.J., 2007. Freeze-drying pretreatment improves organic carbon (China). Mar. Pollut. Bull. 58, 818–826. determinations of marine sediments. Acta Sci. Circum. 27, 861–867 (in Chinese). Moon, H.B., Kannan, K., Choi, M., Choi, H.G., 2007. Polybrominated diphenyl ethers Zhang, H.J., Ni, Y.W., Chen, J.P., Su, F., Lu, X.B., Zhao, L., Zhang, Q., Zhang, X.P., 2008. (PBDEs) in marine sediments from industrialized bays of Korea. Mar. Pollut. Polychlorinated dibenzo-p-dioxins and dibenzofurans in soils and sediments Bull. 54, 1402–1412. from Daliao River Basin, China. Chemosphere 73, 1640–1648. Sicre, M.A., Broyelle, I., Lorre, A., Saliot, A., 1993. Sources and transport of particulate Zhang, H.J., Zhao, X.F., Ni, Y.W., Lu, X.B., Chen, J.P., Su, F., Zhao, L., Zhang, N., 2010. hydrocarbons in the meso-tidal Changjiang Estuary. Estuar. Coast. Shelf Sci. 37, PCDD/Fs and PCBs in sediments of the Liaohe River, China: levels, distribution, 557–573. and possible sources. Chemosphere 79, 754–762. Song, Y.X., Zhan, X.W., Wang, Y.G., 1997. Modern sedimentation feature of north Zhang, P., Song, J., Yuan, H., 2009. Persistent organic pollutant residues in the estuarine region of the Liaodong Bay. Acta Ocean. Sin. 19, 145–149 (in Chinese). sediments and mollusks from the Bohai Sea coastal areas, North China: an Söderström, G., Sellström, U., de Wit, C.A., Tysklind, M., 2004. Photolytic overview. Environ. Int. 35, 632–646. debromination of decabromodiphenyl ether (BDE 209). Environ. Sci. Technol. Zhang, Z., Zhu, M., Wang, Z., Wang, J., 2006. Monitoring and managing pollution load 38, 127–132. in Bohai Sea, PR China. Ocean Coast. Manage. 49, 706–716. Tan, L., He, M.C., Men, B., Lin, C.Y., 2009. Distribution and sources of organochlorine Zou, M.Y., Ran, Y., Gong, J., Maw, B.X., Zeng, E.Y., 2007. Polybrominated diphenyl pesticides in water and sediments from the Daliao River Estuary of Liaodong ethers in watershed soils of the Pearl River Delta, China: occurrence, inventory, Bay, Bohai Sea (China). Estuar. Coast. Shelf Sci. 84, 119–127. and fate. Environ. Sci. Technol. 41, 8262–8267.