Marine Pollution Bulletin 80 (2014) 338–343

Contents lists available at ScienceDirect

Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul

Baseline

Spatial distribution and ecological risk of polychlorinated biphenyls in sediments from Qinzhou Bay, Beibu Gulf of South China Jinlian Zhang a, Yuanyuan Li a, Yinghui Wang a,⇑, Yuanyuan Zhang a, Dan Zhang a, Ruijie Zhang a,b, Jun Li b, Gan Zhang b a b

School of Environment Studies, Guangxi University, Nanning 530004, China State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

a r t i c l e

i n f o

Keywords: Polychlorinated biphenyls Surface sediment Qinzhou Bay Beibu Gulf of South China

a b s t r a c t The residual level of polychlorinated biphenyls (PCBs) was determined in the surface sediments collected from the Qinzhou Bay, Beibu Gulf of Southern China. The results showed that the total concentration of PCBs ranged from 1.62 to 62.63 ng/g dry wt, with a mean of 9.87 ng/g dry wt. Generally, the average PCBs concentrations in three sample groups descended in this order: inner bay > outer bay > rivers. On a mean level, with respect to the PCBs homologue profiles, the analysis suggested that tetrachlorinated biphenyls was the most abundant PCB, followed by hexachlorinated biphenyls, pentachlorinated biphenyls. PCB profiles varied according to the nature of the site and its proximity to the sources. PCA with multiple linear regression analysis indicated that Aroclor products contributed to the PCBs in Qinzhou Bay. Risk assessments conducted on the levels indicated that PCBs in sediments of Qinzhou Bay posed no significant risk to human health. Ó 2013 Elsevier Ltd. All rights reserved.

Polychlorinated biphenyls (PCBs) represent an important group of synthetic organic chemicals those are widely used in industry during the past decades as dielectric fluids in transformers and capacitors and heat exchange fluids. They are characterized as semi-volatile, toxic, persistence, apt to bio-accumulate and longrange transportation and being found ubiquitous in various environmental matrixes (Wania and Mackay, 1996). Consequently, PCBs are banned globally under the Stockholm Convention on Persistent Organic Pollutants (UNEP/UNDP, 2001). However, although being banned since the early 1970s, PCBs are still detected to date and they could still pose a serious threat to the environmental, humans and wildlife. Sediments are major natural sinks and environmental reservoirs for PCBs in the aquatic environment because of the low water solubility (Zhang et al., 2007a; Li et al., 2010). Meanwhile, with the sediment re-suspension, PCBs can re-enter the aquatic environment, circulate in water body and potentially develop and cause a secondary pollution (Wang et al., 2008). Beibu Gulf has become one of the most important economic development areas in China for its bountiful resources and strategic location to both China and Southeast Asian Countries. As a semi-enclosed bay surrounded by land territories of China and Vietnam and the Hainan Island, the Beibu Gulf, has a weak selfpurification capability (Ye, 2007; Yu and Mu, 2006). In recent years, ⇑ Corresponding author. Address: No. 100 Daxue Avenue, Xixiangtang District, Nanning, Guangxi Autonomous Region, China. Tel./fax: +86 771 3270672. E-mail address: [email protected] (Y. Wang). 0025-326X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.marpolbul.2013.12.028

industrialization and urbanization have changed the natural ecosystem structure and environmental quality of the estuary region. Qinzhou Bay, as one of the main bays in the Beibu Gulf, has the large-size petroleum refinery and pulp paper mill and the development of industrial plants located in the industrial estate. The objectives of the present study are: (1) to investigate the spatial distribution and PCBs profiles in surface sediments of river and marine systems, focusing at the Qinzhou Bay; (2) to identify the possible sources of PCBs by integrating some statistical analysis including principal components analysis (PCA) and multiple linear regression analysis (MLRA); (3) to evaluate the eco-toxicological risks of contaminated sediment. Field sampling was performed in July 2010. A total of 40 samples were divided into three groups: rivers (13 samples), the inner bay (13 samples) and the outer bay (14 samples). The study area and sampling sites were presented in Fig. 1. The samples were collected using a stainless steel grab sampler and placed in glass jars which were pre-washed by methylene chloride, and then the jars were placed in an ice box and transferred to the laboratory for storage at 20 °C until analysis. Sample preparation and analysis methods of PCBs had been described elsewhere detailed (Kang et al., 2000a,b; Mai et al., 2002). All freeze-dried samples were ground, sieved, homogenized and stored in the desiccators prior to chemical analysis. The freezedried sediments were extracted using ASE (accelerated solvent extractor, DIONEX) with dichloromethane. Then, the samples were mixed with activated copper granules and soxhlet extracted for

339

J. Zhang et al. / Marine Pollution Bulletin 80 (2014) 338–343

Fig. 1. Locations of sampling sites, distributions of PCBs in sediments of Beibu Gulf and its tributary rivers.

72 h by using n-hexane/acetone (1:1, v/v) mixture in a soxhlet apparatus. Surrogate recovery standard of 2,4,5,6-Tetrachloro-mxylene was also added in the samples prior to extraction. The extracted solutions were rotary evaporated to 1–2 mL and then eluted by 100 mL hexane and dichloromethane (7:3, v/v) through a multi-layer silica gel column which was employed to remove any interfering substances, including pesticides (Sterzenbach et al., 1997; Kang et al., 1999). During concentration of the solvent, dichloromethane was exchanged with hexane. The extract was concentrated and purified by a 10 mm i.d. silica column packed, from the bottom to top, with 6 cm silver nitrate silica gel, 10 cm deactivated silica gel, 12 cm sulfuric acid silica, and 1 cm anhydrous sodium sulfate. Pentachloronitrobenzene was added to the extract prior to instrumental analysis as the internal standard and the final volume of the sample was adjusted to 1 mL. The samples was analyzed with a Hewlett–Packard (HP) 6890 gas chromatograph (GC), which was equipped with an electron capture detector (ECD) and a DB-5 fused silica capillary column (60 m  0.25 mm i.d. with 0.25 lm film thickness). An increase in temperature was programmed from an initial temperature of 90 °C at 6 °C min 1 to 180 °C; then at 1 °C min 1 to 240 °C; finally at 6 °C min 1 to 290 °C. The injection temperature was 280 °C and the detector temperature was 300 °C. Nitrogen was employed as the carrier gas at a flow rate of 2.5 mL min 1 in the constant flow mode. The injection volume was 1 lL in the split-less mode. A mixture of standards was obtained from Supelco and it contained the equal mass ratios of equal mass ratios of Aroclors 1242, 1248, 1254 and 1260. These Aroclors were previously characterized with individual PCB congeners using an internal standard method (Eganhouse and Gossett, 1991). Any PCBs in the samples was identified on the basis of their retention time and the pattern P of Chromatogram. PCB was defined as the sum of the PCBs concentrations in the samples. The total organic carbon (TOC) in the sediments was determined using a Vario EL-III Elemental Analyzer. The dried and homogenized sediment samples were first acidified with 10% (v/ v) HCl to remove carbonates, then dried at 60 °C before the TOC analysis. Quality assurance and quality control procedures included analyses of matrix spikes, duplicates and laboratory blanks (Wade and

Cantillo, 1994). The duplicated measurements for blank, blank spike and matrix spike were conducted in this study and the sediment samples were only conducted as a single measurement. The recoveries for PCB congeners ranged from 97% to 119% on average, and the relative standard deviation ranged from 0.6% to 1.1%. The method detection limits for each analyte was determined following procedures outlined in the EPA method detailed in 40 CFR Part 136, Appendix B. The calculated detection limit varied between 0.4 and 1.4 ng/g dry weight (dry wt.). Descriptive statistics of PCBs concentrations and spatial distribution were shown in Fig. 1 and Table 1. In surface sediments of the Qinzhou Bay, the total polychlorinated biphenyls concentraP tions ( PCBs) ranged from 1.62 ng/g dry wt. to 62.63 ng/g dry wt., with a mean of 9.87 ng/g dry wt. Generally, the mean concentration of PCBs decreased in the following trend: the inner bay (Maowei Sea) > the outer bay (Qinzhou Bay) > the rivers. The overall PCBs concentrations in the inner bay were higher than those in the outer bay, and decreased gradually

Table 1 The concentration of PCBs in the sediments of the Beibu Gulf. Outer bay

a

Site

P PCBsa (ng/g)

QZ 1 QZ 2 QZ 3 QZ 4 QZ 5 QZ 6 QZ 7 QZ 8 QZ 9 QZ 10 QZ 11 QZ 12 QH SN1

3.14 7.98 2.88 7.75 4.38 4.03 2.26 3.25 4.46 3.85 3.36 21.46 62.63 6.86

Mean (ng/g) SD

9.87 11.14

Inner bay P Site PCBsa (ng/g)

Site

P PCBsa (ng/g)

M M M M M M M M M M M M M

QJ1 QJ2 DF1 DF2 DF3 DF4 ML1 ML2 JG1 JG2 JG3 JG4 JG5

17.63 18.34 7.46 18.61 5.74 8.61 4.45 8.69 4.61 1.62 4.73 7.70 1.79

1 2 3 4 5 6 7 8 9 10 11 12 13

12.71 7.93 3.79 4.51 27.92 11.24 2.31 3.04 4.16 9.20 7.24 24.89 27.48

PCB represent the sum of 35 monitoring congeners.

Rivers

340

J. Zhang et al. / Marine Pollution Bulletin 80 (2014) 338–343

towards the open sea, which suggested that terrestrial pollution was a main contaminant source. There were higher PCBs concentrations in the eastern coast than those in the western coast, which could have resulted from the development of urbanization and industrialization of the eastern zone. As shown in Fig. 1, the surface sediment concentrations of PCBs in outer bay were in the range of 2.26–62.63 ng/g dry wt, with a mean of 9.88 ng/g dry wt. The highest PCBs concentration was found at QH, where many cargo ships moored, loading, and unloading raw chemical materials and crude oil products. That might be a reason for the highest concentration at QH. The second P highest value of the PCBs in the outer bay was presented at sampling site QZ12(21.46 ng/g dry wt), located near to the Xiniujiao Industrial Park in Southern Qinzhou City, and that might account for the high concentration. The lowest PCBs concentration was observed at QZ7 located in the central of the outer bay, where there were very few human. This might be the main reason that caused the differences between QZ7 and other sample points in the outer bay (Barakat et al., 2011). The sediment concentration in the inner bay was relatively higher than other two areas, with the higher PCBs were monitored at M5, M13 and M12 (27.924 ng/g dry wt, 27.48 ng/g dry wt and 24.89 ng/g dry wt, respectively). It could be due to the topography and physiognomy of being a pocket semi-closed bay, the shipping activity and the higher terrestrial input such as the industrial sewage and the farm wastewater. M5 was in the center of inner bay, suggesting that the higher organic matter due to the topography of gradual silation was a source of PCB pollution. Another high concentration site was M13 which located near a hatchery. And this fish farm might contribute to the PCBs pollution. M12 lay by the Qinzhou Port Economic Development Industrial Park, which was a big hub of industries, such as petrochemical, asphalt, pulp paper and metallurgy. So this Qinzhou Port Economic Development Industrial Park could contribute to the high concentration of PCBs at M12.

The accumulated PCBs in the river were in the range of 1.62– 18.61 ng/g dry wt. The concentration in DF2 was much higher than other sites in DaFeng River. The values at DF2 were within the same order of magnitude of those reported in aquaculture feeds collected from the Pearl River Delta (Guo et al., 2009). High PCB concentrations were also observed in fish feeds all over the world including Europe (75.6–1153 ng/g dry wt) (Jacobs et al., 2002), Canada (mean 270 ng/g dry wt) (Kelly et al., 2008) and America (mean 84.8 ng/g dry wt) (Serrano et al., 2008). As mentioned earlier, surface sediment around mariculture was enriched with PCBs, therefore, fish feed was expected to be the importance source of PCBs in the sediment at mariculture. Qin River was polluted severely from indiscriminate discharges of domestic and industrial wastewater. The wastewater was discharged to the sea through the pipe belong to the municipal waste water treating plant (WWTP) of the Qinzhou City at QJ1 (Liu et al., 2010), which possibly led to the high PCB concentration. Compared with other coastal sediments around the world P (Fig. 2), the PCBs in surface sediments of Qinzhou Bay (1.62– 62.63 ng/g dry wt) in the present study was in a low to moderate level. The concentrations of PCBs in sediment samples from Qinzhou Bay were close to those found in the Daya Bay, China (Zhou et al., 2001), Tokyo Bay, Japan (Kobayashi et al., 2010)and Houston Ship Channel, America (Lakshmanan et al., 2010). Slightly higher concentrations of PCBs were observed in the coast of Korea (Hong et al., 2006), coast of Singapore (Wurl and Obbard, 2005) and Alexandria Harbor, Egypt (Barakat et al., 2002), while higher concentrations were encountered in the Green Bay, America (Cacela et al., 2002) and Pearl River Delta, China (Kang et al., 2000a,b). The concentrations of PCBs in sediment samples from the Qinzhou Bay were much higher than those presented in Shandong Peninsula, China (Pan et al., 2010), James Ross Island, Antarctica (Klanova et al., 2008), Mekong River delta, Vietnam (Carvalho et al., 2008) and Chukchi Sea, Russia (Hong et al., 2012).

Fig. 2. Concentration ranges and mean value (‘’) of PCBs in surface sediment (ng/g dry wt.) of Beibu Gulf and other regions around the world.

341

J. Zhang et al. / Marine Pollution Bulletin 80 (2014) 338–343 Table 2 The composition of PCB homologue profiles in sediments from the Qinzhou Bay and its adjacent rivers.

Maoling River Qin River Jingu River Dafeng River Maowei Sea Qinzhou Bay The whole area

3CB (%)

4CB (%)

5CB (%)

6CB (%)

7CB (%)

8CB (%)

10CB (%)

1.29 0.98 16.34 6.03 1.59 1.16 2.62

15.84 54.08 14.14 40.55 44.13 43.92 42.07

12.06 17.89 11.36 15.62 12.06 5.64 10.76

4.53 0.60 21.30 19.35 24.39 21.88 19.98

29.40 19.82 2.10 0.69 0.44 0.65 3.40

0.65 0.06 10.70 9.06 8.79 16.79 10.54

36.24 6.56 24.05 8.72 8.61 9.95 10.63

A relationship between the concentrations of PCBs and TOC was analyzed. Results revealed that there was no significant correlation P between the PCBs and TOC (R2 = 0.079, p = 0.078, n = 40),which agreed well with those results obtained for PCBs in mid- and down-stream segments of the Yellow River sediments (He et al., 2006) and in the Yangtze Estuary (Yang et al., 2002). A total of 35 PCB congeners were detected in this study and they were divided into 8 homologue groups according to the number of chlorine atom. Expect for the undetected di-PCBs, the descending order of the homologue proportions was: tetra-PCBs > hexaPCBs > penta-PCBs > octa-PCBs > deca-PCBs > hepta-PCBs > tri-PCBs (Table 2). The tetra- to hexa-chlorinated biphenyls occupied the largest portion, approximately 60% of all congeners, suggesting that potential local contamination was dominant (Wania and Mackay, 1996). Similarly, Zhang et al. (2007b) found tetra-, penta-, and hexa-chlorinated biphenyls were the dominant species in some agricultural soils from Southern Jiangsu, China. The highest proportion for tetra-polychlorinated biphenyls was detected in samples from the outer bay, the inner bay and the rivers, accounting for 42%, 44.1% and 37.1%, respectively. In contrast, the percentages of tri-PCBs were 1.1%, 1.59% and 5.73% for the outer bay, inner bay and rivers, respectively. Tri-chlorinated biphenyls occupied the least percentage in this study although it accounted for 90% of all produced PCBs in China. It could be explained by the fact that lower chlorinated PCBs were more readily volatized into the gas and they released from sediments because of their high water solubility, vapor pressure and biodegradability (Wania and Mackay, 1996). The spatial profiles of PCBs in sediments indicated that the profiles in the out bay and inner bay were similar but different from the river. This could be confirmed by the spatial trend and the percentages of PCB homologues. As to the compositional profiles of PCBs in sediment samples, tetra-PCBs were the most abundant throughout all study areas. In contrast, the most difference among the three sampling areas was hepta-chlorinated biphenyls. The

hepta-PCB concentrations were 0.9 ng/g dry wt for the rivers, 0.08 ng/g dry wt for the outer bay and 0.05 ng/g dry wt for the inner bay. In general, similar patterns were observed among all samples. As to the tetra-PCBs in sediments at each sampling location, the spatial trend was averaged from one area to the others, accounting P from 37% to 44% of PCBs in sediments, respectively. The pattern of individual congeners in sediment from the estuary showed that the input from point sources was possibly the major PCBs input to the Qinzhou Bay, but there were still other influences, such as atmospheric transport and deposition. Principal component analysis (PCA) was applied to integrate the P homologues normalized by PCBs into a smaller suite of orthogonal derived variables to ascertain whether or not multiple sources were contributing to the PCBs in the Qinzhou Bay. Composition percentages were arcsine transformed, centered, and scaled to unit variance before determining the principal components (PCs). The procedure provided a set of coefficients that would identify the most important congener by distinguishing samples in lower dimensions and ordinating into a graphic (Mardia et al., 1994). The relationship between PCB homologues and source composition (Aroclor 1016, 1242, 1248, 1254 and 1260) was determined (Fig. 3). The composition profiles of Aroclors were obtained from the USEPA website. This procedure could help in interpreting the result of PCA (designating extracted factor as a source or mixed sources) and in identifying whether each source’s composition with selected homologues represented the original characteristic. As shown in Fig. 3, high-chlorinated homologues such as hexaPCBs, hepta-PCBs and octa-PCBs had relatively higher portion of Aroclor 1260. Aroclor 1254 had higher portion of most penta-chlorinated biphenyls, however, Aroclor 1248 was predominated by tetra-PCBs. The PCA was carried out by using SPSS 16.0. And VARIMAX, the most commonly used orthogonal rotation method, was performed

Rotated Component Matrixa Component 1 triPCB

2

3

0.020

-0.210

tetraPCB

0.072

0.988

0.129

pentaPCB

-0.289

0.944

-0.010

hexaPCB

0.968

-0.075

-0.047

heptaPCB

-0.718

0.576

0.370

octaPCB

0.956

-0.126

-0.034

decaPCB

-0.636

-0.380

0.639

Extraction Method: Principal Component Analysis. Rotation Method: Varimax with Kaiser Normalization. a. Rotation converged in 4 iterations.

Fig. 3. Comparison of composition profiles and factor loading of PCA.

-0.969

342

J. Zhang et al. / Marine Pollution Bulletin 80 (2014) 338–343

in order to interpret each factor extracted. The aggregation demonstrated similar sources, while the scatter indicated multiple sources of PCBs in the surface sediments. Totally, 3 factors (96.79% of cumulative variance) were extracted, whose eigenvalue were higher than 1.0. Based on the composition profile in Fig. 3, Aroclor 1254 and 1260’s homologues were positively correlated with factor 1 (50.84% variance of the total). On the other hand, Aroclor 1242, 1248 and 1254 were highly positive-correlated with factor 2 (29.31% variance of the total). Of the three factors, tri-chlorinated biphenyls was the only positive-correlated with factor 3 (16.64% variance of the total). According to the result of PCA, PCBs in sediments from the Qinzhou Bay were mainly originated from the Aroclor products. Similar result had been reported for the soil samples around industrial complex (Park et al., 2009). Normally, soil and sediment were regarded as a final destination of pollutants. Therefore, they often contained high-chlorinated biphenyls. To evaluate the eco-toxicity of sediment contamination, many approaches had been developed, including the quality criterion such as Sediment Quality Guidelines by the Canadian Council of Ministers of the Environment (Canadian Council of Ministers of the Environment, 1999) and some other methods. The present data in this study were compared with North American sediment quality guidelines, (Long et al., 1995) and The Canada sediment quality guidelines (Canadian Council of Ministers of the Environment, 1999). Detected PCBs concentrations in all surface sediments were much lower than the ERM (180.0 ng/g) and PEL (227 ng/g), which indicated that there were insignificant potential adverse effects of PCBs on the benthic organisms in the studied area. The results showed the comparison of PCBs concentrations from the Qinzhou Bay with SQGs. Only 7% of the sampling sites in the outer bay and 23% of the sampling sites in the inner bay higher than the ERL (22.7 ng/g) and ISQG (34.1 ng/g), which suggested there probably existed occasional adverse biological effects. Acknowledgements This study was supported by Natural Science Foundation of Guangxi Province (2010GXNSFE013006), NSFC (41273139) and Science and Technology Program of The Oceanic Administration of Guangxi (5986). References Barakat, Assem O., Kim, Moonkoo, Qian, Yoarong, Wade, Terry L., 2002. Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt. Mar. Pollut. Bull. 44, 1421–1434. Barakat, A.O., Mostafa, A., Wade, T.L., et al., 2011. Distribution and characteristics of PAHs in sediments from the Mediterranean coastal environment of Egypt. Mar. Pollut. Bull. 62, 1969–1978. Cacela, Dave, Beltman, Douglas J., Lipton, Joshua, 2002. Polychlorinated biphenyl source attribution in Green Bay, Wisconsin, USA, using multivariate similarity among congener profiles in sediment samples. Environ. Toxicol. Chem. 21 (8), 1591–1599. Canadian Council of Ministers of the Environment, 1999. Canadian soil quality guidelines for the protection of environment and human health: polychlorinated biphenyls (total). In: Canadian Environmental Quality Guidelines, 1999, Canadian Council of Ministers of Environment, Winnipeg. Carvalho, F.P., Villeneuve, J.P., Cattini, C., Tolosa, I., Thuan, D.D., Nhan, D.D., 2008. Agrochemical and polychlorobyphenyl (PCB) residues in the Mekong River delta, Vietnam. Mar. Pollut. Bull. 56 (8), 1476–1485. Eganhouse, R.P., Gossett, R.W., 1991. Sources and magnitude of bias associated with determination of polychlorinated biphenyls in environmental samples. Anal. Chem. 63, 2130–2137. Guo, Y., Yu, H.Y., Zhang, B.Z., Zeng, E.Y., 2009. Persistent halogenated hydrocarbons in fish feeds manufactured in South China. J. Agric. Food Chem. 57, 3674–3680. He, M.C., Sun, Y., Li, X.R., Yang, Z.F., 2006. Distribution patterns of nitrobenzenes and polychlorinated biphenyls in water, suspended particulate matter and sediment from mid- and down-stream of Yellow River (China). Chemosphere 65 (3), 365– 374.

Hong, Hong, S.H., Yim, U.H., Shim, W.J., Li, D.H., Oh, J.R., 2006. Nationwide monitoring of polychlorinated biphenyls and organochlorine pesticides in sediments from coastal environment of Korea. Chemosphere 64, 1479–1488. Hong, Qingquan, Wang, Yun, Luo, Xiaojun, Chen, Shejun, Chen, Jigang, Cai, Minghong, Cai, Minggang, Mai, Bixian, 2012. Occurrence of polychlorinated biphenyls (PCBs) together with sediment properties in the surface sediments of the Bering Sea, Chukchi Sea and Canada Basin. Chemosphere 88, 1340–1345. Jacobs, M.N., Covaci, A., Schepens, P., 2002. Investigation of selected persistent organic pollutants in farmed Atlantic salmon (Salmo salar), salmon aquaculture feed, and fish oil components of the feed. Environ. Sci. Technol. 36, 2797–2805. Kang, Y.H., Sheng, G.Y., Fu, J.M., Mai, B.X., 1999. Study on the elimination of organochlorine pesticides and QA/QC for the determination of polychlorobiphenyls in sediment samples. Fenxi Huaxue 27, 1258–1263 (in Chinese with an English Abstract). Kang, Y., Sheng, G., Fu, J., Mai, B., Zhang, G., Lin, Z., Min, Y., 2000a. Polychlorinated biphenyls in surface sediments from the Pearl River Delta and Macau. Mar. Pollut. Bull. 40, 794–797. Kang, Y.h., Sheng, G.Y., Fu, J.M., et al., 2000b. Preliminary study on the distribution and characterization of polychlorinated biphenyls in some of surface sediments from Pearl River Delta. Environ. Chem. 19 (3), 262–269. Kelly, B.C., Fernandez, M.P., Ikonomou, M.G., Knapp, W., 2008. Persistent organic pollutants in aquafeed and Pacific salmon smolts from fish hatcheries in British Columbia, Canada. Aquaculture 285, 224–233. Klanova, J., Matykiewiczova, N., Macka, Z., Prosek, P., Laska, K., Klan, P., 2008. Persistent organic pollutants in soils and sediments from James Ross Island, Antarctica. Environ. Pollut. 152 (2), 416–423. Kobayashi, Jun, Serizawa, Shigeko, Sakurai, Takeo, Imaizumi, Yoshitaka, Suzukiand, Noriyuki, Horiguchi, Toshihiro, 2010. Spatial distribution and partitioning of polychlorinated biphenyls in Tokyo Bay, Japan. J. Environ. Monit. 12, 838–845. Lakshmanan, Divagar, Howell, Nathan L., Rifai, Hanadi S., Koenig, Larry, 2010. Spatial and temporal variation of polychlorinated biphenyls in the Houston Ship Channel. Chemosphere 80, 100–112. Li, J., Liu, X., Zhang, G., Li, X.D., 2010. Particle deposition fluxes of BDE-209, PAHs, DDTs and chlordane in the Pearl River Delta, South China. Sci. Total Environ. 408, 3664–3670. Liu, B.L., Qing, S.M., Zhang, Z.J., Liu, G.Q., Zhang, S.F., 2010. Pollution evolution for heavy metals in the sediments of Qinjiang River drain outlet. Sci. Technol. Inform. 29, 137–138 (in Chinese). Long, E.R., Macdonald, D.D., Smith, S.L., Calder, F.D., 1995. Incidence of adverse biological effects within ranges of chemical concentrations in marine and estuarine sediments. Environ. Manage. 19, 81–97. Mai, B., Fu, J., Sheng, G., Kang, Y., Lin, Z., Zhang, G., Min, Y., Zeng, E.Y., 2002. Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China. Environ. Pollut. 117, 457–474. Mardia, K.V., Kent, J.T., Bibby, J.M., 1994. Multivariate Analysis. Academic, New York, NY, USA. Pan, J., Yang, Y., Geng, C., Yeung, L.W.Y., Cao, X., Dai, T., 2010. Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans in marine and lacustrine sediments from the Shandong Peninsula, China. J. Hazard. Mater. 176, 274–279. Park, S.U., Kim, J.G., Masunaga, S., Kim, K.S., 2009. Source identification and concentration distribution of polychlorinated biphenyls in environmental media around industrial complexes. Bull. Environ. Contam. Toxicol. 83, 859– 864. Serrano, R., Barreda, M., Blanes, M.A., 2008. Investigating the presence of organochlorine pesticides and polychlorinated biphenyls in wild and farmed gilthead sea bream (Sparus aurata) from the Western Mediterranean sea. Mar. Pollut. Bull. 56, 963–972. Sterzenbach, D., Wenclawiak, B.W., Weigelt, V., 1997. Determination of chlorinated hydrocarbons in marine sediments at the part-pertrillion level with supercritical fluid extraction. Anal. Chem. 69, 831–836. UNEP/UNDP, 2001. United Nations Environment Programme, United Nations Development Programme, World Development Report 2001: Making New Technologies Work for Human Development. Geneva. . Wade, T.L., Cantillo, A.Y., 1994. Use of standards and reference materials in the measurement of chlorinated hydrocarbon residues – chemistry workbook. NOAA Technical Memo NOS ORCA 77 (National Status and Trends Program for Marine Environmental Quality). NOAA, Silver Springs, MD. Wang, Z., Yan, W., Chi, J., Zhang, G., 2008. Spatial and vertical distribution of organochlorine pesticides in sediments from Daya Bay, South China. Mar. Pollut. Bull. 56, 1578–1585. Wania, F., Mackay, D., 1996. Tracking the distribution of persistent organic pollutants: control strategies for these contaminants will require a better understanding of how they move around the globe. Environ. Sci. Technol. 30 (9), 390A–396A. Wurl, O., Obbard, J.P., 2005. Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in Singapore’s coastal marine sediments. Chemosphere 58 (7), 925–933. Yang, Y., Liu, M., Hou, L.J., 2002. Distribution of polychlorinated organic compounds in Yangtze estuary and its correlation with TOC and particle size. Shanghai Environ. Sci. 21, 530–532. Ye, R.K., 2007. A study on the features and causes of the vulnerability in the coastal environment of Guangxi. Territory Nat. Resour. Study 2, 56–57 (in Chinese). Yu, Y., Mu, Y., 2006. The new institutional arrangements for fisheries management in Beibu Gulf. Mar. Policy 30, 249–260.

J. Zhang et al. / Marine Pollution Bulletin 80 (2014) 338–343 Zhang, G., Li, J., Cheng, H., Li, X., Xu, W., Jones, K.C., 2007a. Distribution of organochlorine pesticides in the northern South China Sea: implications for land outflow and air-sea exchange. Environ. Sci. Technol. 41, 3884–3890. Zhang, J.Y., Qiu, L.M., He, J., Liao, Y., Luo, Y.M., 2007b. Occurrence and congeners specific of polychlorinated biphenyls in agricultural soils from Southern Jiangsu, China. J. Environ. Sci. (China) 19 (3), 338–342.

343

Zhou, J.L., Maskaoui, K., Qiu, Y.W., Hong, H.S., Wang, Z.D., 2001. Polychlorinated biphenyl congeners and organochlorine insecticides in the water column and sediments of Daya Bay, China. Environ. Pollut. 113 (3), 373–384.