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Occurrence and possible sources of polychlorinated biphenyls in surface sediments from the Wuhan reach of the Yangtze River, China
Chemosphere 74 (2009) 1522–1530
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Occurrence and possible sources of polychlorinated biphenyls in surface sediments from the Wuhan reach of the Yangtze River, China Zhifeng Yang *, Zhenyao Shen, Fan Gao, Zhenwu Tang, Junfeng Niu State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China
a r t i c l e
i n f o
Article history: Received 8 August 2008 Received in revised form 30 October 2008 Accepted 10 November 2008 Available online 23 December 2008 Keywords: PCBs Identification of sources Composition Sediment Toxicity
a b s t r a c t Twenty-seven surface sediment samples were collected from the mainstream and eight tributaries of the Wuhan reach of the Yangtze River, China, in 2005, in order to assess the distribution, possible sources, and potential risk of polychlorinated biphenyls (PCBs) in the environment. The total concentrations of PCBs (the sum of 39 congeners) ranged from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1. Sediment samples with the highest PCB concentrations came from the tributary sites, which are closer to PCB sources. Conversely, PCB concentrations in the sediment from the mainstream sites of Yangtze River were relatively low. The observed PCB levels were higher than those found in the sediments of other rivers in China, but lower than those in river sediments from other urban areas and harbors around the world. Low-chlorinated PCBs, dominated by tetra-PCBs and penta-PCBs, were identified as being prevalent in the surface sediments. Correlation analyses between the PCBs and the geochemistry and heavy metal content of the sediments suggest that the washing of these compounds from the land into the river by floods and heavy rains, or industrial wastewater and domestic sewage, may be the major sources of the PCBs. According to established sediment quality guidelines, the risk of adverse biological effects from the levels of PCBs recorded at most of the studied sites should be insignificant, although the higher concentrations at other sites could cause acute biological damage. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated biphenyls (PCBs), constituting a class of 209 chemical compounds, have been designated as typical persistent organic pollutants (POPs) by the Stockholm Convention of May 22, 2001 (Harrad et al., 1994; Ren et al., 2007). They are of great global concern due to their bioaccumulation, persistence, and impact on ecosystems. After the onset of commercial manufacturing of PCBs in 1929, they became used extensively as dielectric fluids, hydraulic fluids, organic diluents in electrical transformers and capacitors, and were used in a variety of consumer products (Jones and de Voogt, 1999). Although the production and usage of PCBs has been banned worldwide since the early 1970s, it is reported that the total global production of PCBs had already exceeded 1.3 million tons (Breivik et al., 2002). PCB pollution has been identified and reported all over the world, even in Antarctica and the Arctic Zone (Hartmann et al., 2004; Borgå et al., 2005; Xing et al., 2005; Negri et al., 2006; Ren et al., 2007). During the period from 1965, when China began producing PCBs, to the 1980s, when production was banned, China produced more than ten thousand tons of PCBs, nine thousand of which were
* Corresponding author. Tel./fax: +86 10 5880 7951. E-mail address: [email protected] (Z. Yang). 0045-6535/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2008.11.024
tri-PCB (mainly used in the insulation of electrical equipment) and one thousand of which were penta-PCB (a paint additive) (China SEPA, 2003). Since the ban, most equipment containing PCBs was retired from use and stored. Leakages from such equipment, however, have recently been reported. In recent years, pollution incidents involving PCBs have resulted in severe consequences in some regions of China (Wu et al., 1997; Zhang et al., 2004; Mai et al., 2005; Shen et al., 2006; Ren et al., 2007). PCBs enter the aquatic environment through a variety of sources that include direct deposition from the atmosphere, runoff from the land, and industrial and municipal wastewater discharge (Samara et al., 2006; Totten et al., 2006; Davis et al., 2007). Due to their low solubility in water and high octanol–water partition coefficients, PCBs quickly become associated with particulate matter once in aquatic environments, and ultimately accumulate in bottom sediments (Harrad et al., 1994). Remobilization of surficial sediment-associated PCBs can occur during natural events, such as high river flows and storms, or during human activities such as dredging, dredge disposal and fishing; both have implications for human health (Eggleton and Thomas (2004)). The Yangtze River, the largest river in China and the third largest in the world, flows 6300 km from its source in the Qinghai– Tibet Plateau to the East China Sea, and is characterized by the industrial and urban zones through which it flows. Wuhan is the largest city located in the middle reaches of the Yangtze River, with
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a population of around 8 million. Drinking water and a large amount of fishery products are taken from the Wuhan reach of the Yangtze River. The number of PCB related studies in the Chinese environment has increased recently thanks to a series of global initiatives on POPs and an increasing concern about the risks that these chemicals pose to human health and the environment. Most of the recent PCB investigations have focused on the lower reaches of the Yangtze River and its estuary (Jiang et al., 2000; Xu et al., 2000; Liu et al., 2003; Shen et al., 2006), while little information is available regarding PCB levels in its middle reaches. Therefore information relating to levels of PCBs in middle reaches of the Yangtze River is very important, both with respect to spatial distribution of the Yangtze River basin and to fill the information gap. The objective of the present study is to determine the spatial distributions of PCBs in sediments, to identify their possible sources, and to assess the ensuing environmental risks in the middle reaches of the Yangtze River.
2. Materials and methods 2.1. Sample collection Twenty-seven samples of surface sediments were collected from the mainstream and eight main tributaries of the Wuhan reach of the Yangtze River in December 2005. Details of the sampling sites are shown in Fig. 1. These sampling sites were recorded using a global positioning system (GPS). The sediments were collected using a Van Veen grab (Eijkelamp, the Netherlands). Approximately 2 cm of sediment were taken from the top of the river beds and placed in a precleaned aluminum box using a stainless-steel
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spoon. All of the sediment samples were freeze-dried, ground, homogenized, and stored at 20 °C prior to analysis. 2.2. Extraction and analysis The procedure for extracting PCBs from sediments was modified from a previously published method (Moret et al., 2001). All freeze-dried sediment samples were ground and homogenized. Sediment samples weighing 10 g were treated with 80 mL of hexane–dichloromethane (2:1, v/v, chromatographicgrade, Dima Co., USA) in an ultrasonic bath for 2.0 h. The samples were allowed to stand overnight (approximately 10 h), and were again sonicated for 30 min. The extracts were decanted and the remainder was then re-sonicated with 30 mL hexane for 30 min. The two extracts were then combined and treated with activated Cu to remove sulfates, and then concentrated to 5.0 mL by a rotary evaporator (RV 05 basic, IKA, Germany). The extract was subsequently removed using a separating funnel and 10 mL of concentrated sulfuric acid (98%, AR) were added 2–3 times to remove any impurities, such as lipoid and polycyclic aromatic hydrocarbons. The organic phase was washed in a 50 mL 5% NaCl solution and concentrated to about 1–2 mL. Further purification was carried out using a glass column (10 mm i.d.) loaded with 20 g of activated Florisil (100–200 mesh, Beijing Yizhong Chemical Regents Factory, China), which was activated in an oven at 650 °C for 8 h, and then deactivated with Milli-Q water at a ratio of 3%. PCBs were eluded with 100 mL of hexane. The hexane eluate was reduced under a gentle stream of nitrogen to 0.2 mL, and an internal standard (pentachloronitrobenzene, Sulpelco Co., USA) was added for GC/MS analysis. Quantification was undertaken by the internal standard method relative to a multilevel calibration for all compounds.
Fig. 1. Map of sampling sites in Wuhan reach of the Yangtze River. Y: the mainstream of the Yangtze River; B: the tributaries of the Yangtze River.
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PCBs were measured using a GC 2000/TRACETM MS with a DB-5 capillary column (30 m 0.25 mm 0.25 lm, J&W, USA). The GC/ MS conditions for sample analysis were as follows: the oven was set at a temperature of 150 °C for 2 min, which was then increased at a rate of 4 °C min1 to 290 °C, at which temperature it was held for 2 min; the injection was in splitless mode at 275 °C; the carrier gas was nitrogen, with a flow rate of 1.0 mL min1; the temperature of the transfer line was 200 °C; the full scan mode was used for qualitative analysis with a range of 35–500 m/z, and selected ion mode (SIM) was used for quantitative analysis, the electron energy was 70 eV, and the detector voltage was 500 V. The 32 chromatographic peaks representing 39 individual or coeluting congeners (designated as domains) were quantified by use of the standard mixture from Accustandard, Inc. (New Haven, CT), Catalog number C-QME-01, containing the following 41congeners: IUPAC Nos. 17, 18, 28, 31, 33, 44, 49, 52, 70, 74, 82, 87, 95, 99, 101, 105, 110, 118, 128, 132, 138, 149, 151, 153, 158, 169, 170, 171, 177, 180, 183, 187, 191, 194, 195, 199/201, 205, 206, 208 and 209. Congeners 17 and 18, 28 and 31, 74 and 95, 82 and 151, 118 and 149, 105 and 132, 138 and 153 were coeluted, but 169 and 199/201 was not determined. RPCB was defined as the sum of the concentrations of these congeners and domains. To calculate the contribution to the homologue groups from each congener in a domain, all congeners were considered equally abundant in the domain. 2.3. Quality assurance and control All data were subject to strict quality control procedures. For each set of 6 samples, a procedural blank and a matrix sample spiked with standards were used for monitoring interference and circumventing cross-contaminations, and all results were blank corrected. The quality assurance and control experiment was performed in duplicate (n = 3) and the relative standard deviations (RSD) were all below 13%. Spike recoveries were performed on the matrix sample (pre-extracted sediment). Ten grams of matrix sample spiked with a mixture of 41 PCBs was equilibrated for 24 h at 25 °C and then analyzed by the same procedure as for the samples. The spiked recovery for PCB congeners in the sediments ranged from 68.3% to 127.4%; the MDLs ranged from 0.05 to 0.3 ng g1; and the relative standard deviation (RSD) ranged from 6.8% to 20.9% (Table S1). All the results were corrected with the recovery ratios and reported in ng g1 dry wt. 2.4. Other analyses Samples were also used to determine the physicochemical properties of the sediments, such as pH values, total organic carbon (TOC), and grain size (Tang et al., 2007). Eight heavy metals of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were detected in order to investigate heavy metals contamination in this region. The full results will be reported elsewhere. This paper will focus on any relations that may exist between PCBs and heavy metals in the sediments. All samples were air dried at room temperature and sieved through a 2 mm nylon sieve to remove coarse debris. The sediments were then ground with a pestle and mortar until all particles passed a 200 mesh nylon sieve. About 0.25 g of sediment was digested with 5.0 mL HNO3, 2.0 mL HClO4 and 10 mL HF at a temperature of 90 ± 190 °C for 16 h. The residue was then dissolved in 5 mL of 4 M HCl, diluted to 25 mL with deionised water for Cr, Cu, Ni and Zn, and with 2% nitric acid solution for Cd and Pb. They were analysed by inductively coupled plasma mass spectrometer (ICP-MS, Thermo). Another small portion of each sample (0.5 g) was digested with HNO3/H2SO4 and total mercury, arsenic was
analyzed by cold vapor atomic spectrometry (CVAFS). Blank samples, standard samples and duplicated samples were simultaneously performed in the two analyses as quality control. 3. Results and discussion 3.1. PCB concentrations The concentrations of RPCBs (the sum of 39 congeners) in the surface sediments from the Wuhan reach of the Yangtze River ranged from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1 (Fig. 2). The highest concentration of RPCBs was found at site B14 (45.1 ng g1), and the second highest at site B15 (40.8 ng g1). Both of these sites lie in close proximity to the discharge points of wastewater treatment plants and of various chemical companies in the area, and both are in tributaries of the Yangtze River around Wuhan. It can be seen in Fig. 2 that PCB concentrations in the sediments of the tributaries were apparently higher than those in the Yangtze River itself, indicating the water flow and current velocity may play an important role in the PCB contamination of river sediments. In sediment samples, the most abundant PCB congeners were 49, 82/151, 99, 170 and 177, comprising up to 37.6 % of the total amount of PCBs. The mean concentrations of dioxin-like PCB congeners (DL-PCBs) were 0.22, 0.36 and 0.69 ng g1 dw for PCB 105, 118 and 156, respectively. The PCB concentrations in surface sediments from the Wuhan reach of the Yangtze River were found to be lower than those in the sediments of other rivers in China (Table 1), such as the Songhua, Qiantang, and the Pearl Rivers (Kang et al., 2000; Xing et al., 2005), and those reported in some urbanized and harbor areas around the world, such as Narragansett Bay, USA (Hartmann et al., 2004), Alexandria harbor, Egypt (Barakat et al., 2002), and Naples harbor, Italy (Sprovieri et al., 2007). However, the PCB levels around Wuhan were higher than those recently reported in the lower reaches of the Yangtze River (Shen et al., 2006) and the mid- and downstream reaches of the Yellow River (He et al., 2006). 3.2. PCB composition and source identification All 39 PCB congeners considered in this study were identified in the surface sediment samples. The proportion of the different PCBs in all sediment samples generally decreased in the following order: tetra-PCBs > penta-PCBs > hepta-PCBs > hexa-PCBs > octa-PCBs > tri-PCBs > deca-PCBs > nona-PCBs (Fig. 3). The compositions of PCBs were consistent with previous observations on PCB contaminations in freshwater sediments from the Guangzhou reach in the Pearl River, near Macao, the mid- and down-stream of the Yellow River, the Nanjing reach of the Yangtze River, and the Tonghui River, China (Kang et al., 2000; Zhang et al., 2004; He et al., 2006; Shen et al., 2006). Furthermore, such a PCB profile was also in accordance with those in previous research about urban soils in China (Ren et al., 2007). Approximately 10 000 tons of PCBs were produced in China from 1965 to 1974 (when production was banned), with 9000 tons as trichlorobiphenyl, known as #1 PCB, and 1000 tons as pentachlorobiphenyl, #2 PCB (Xing et al., 2005). Trichlorobiphenyl was used primarily in power capacitors, while pentachlorobiphenyl was used mainly as a paint additive (China SEPA, 2003). Number 1 PCB contained 42% chlorine, which was similar to Aroclor 1242, and #2 PCB contained 53% chlorine, similar to Aroclor 1254 (Jiang et al., 1997). Assuming that these two technical mixtures #1 PCB and #2 PCB were produced in the ratio of 9:1, the congeners production in China was estimated using congeners composition of Aroclor 1242 for #1 PCB and Aroclor 1254 for #2 PCB (Ren et al., 2007), As a result, the major congeners produced and used in China
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-1
Total PCBs concentrations (ng g )
50
40 TEL 30 ERL 20
10
0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10Y11 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B12B13B14B15B16
Sample sites Fig. 2. Concentrations of RPCB in sediments from Wuhan reach of the Yangtze River. Y: mainstream; B: tributaries. ERL: the effect range low value (Long et al., 1995); TEL: Canadian interim sediment quality guideline for PCBs in freshwater sediment, threshold effect level (CCME, 1999).
Table 1 Concentrations of RPCB (ng g1 dry weight) in surface sediments from various locations. Locations
RPCB
References
(ng g1) The Pearl River Estuary, South China Minjiang River, Southeast China Songhua River, Northeast China Narragansett Bay, USA Alexandria harbor, Egypt Naples harbour, Southern Italy The mid- and down-stream of the Yellow River, North China The lower reaches of the Yangtze River, East China Wuhan reach of the Yangtze River, Central China
11.5–485 15.1–58 0.62–337 20.8–1760 0.9–1210 10–899 nd–6.0
Kang et al. (2000) Xing et al. (2005) Xing et al. (2005) Hartmann et al. (2004) Barakat et al. (2002) Sprovieri et al. (2007) He et al. (2006)
0.92–9.7
Shen et al. (2006)
1.2–45.1
This work
was tri-PCB, followed by tetra-PCB. Although the major congener profile of the global PCB product is also tri-PCB followed by tetra-PCB (Breivik et al., 2002), the compositions of these two congeners are higher in Chinese product than in global product (40.4– 25.2% for tri-PCB, and 31.1–24.7% for tetra-PCB) (Ren et al., 2007). In this study, PCB congeners with the highest proportions consisted of the following: tetra-PCBs (36.6%), penta-PCBs (23.7%), hepta-PCBs (20.7%), octa-PCBs (3.0%) and tri-PCBs (2.5%) (Fig. 3). This indicated that the PCBs in sediments originated from sources other than power capacitors and paint additives. For example, the compounds may have come from industrial and domestic wastewater, or even been imported from other countries (e.g. Aroclor 1260) (Rushneck et al., 2004). Our sediment investigation revealed the general prevalence of lower molecular weight PCBs. The PCB congeners pattern was dominated by tetra-PCBs at sites B11 (70.8%), B10 (67.2%), B2 (67.1%), and Y10 (62.3%). Penta-PCBs also dominated the PCB congeners pattern at locations B3 (70.1%), and Y2 (61.6%). Upon assessment of Wuhan’s industry distribution, it was deduced that industrial activity related to steel manufacturing probably contributed to the lower chlorinated PCBs in these sediments. A number of previous studies have showed the production of PCBs during the
steel manufacturing processes (Alcock et al., 1999; Buekens et al., 2001). This is due to the presence of PCBs in fly ash generated from burning coal during the iron ore sintering process (Biterna and Voutsa, 2005). However, relatively higher percentage of the highchlorinated congeners, such as hepta-PCBs at sites Y9, B12 and B14 were found in this study (Fig. 3). These sites are close to the sources of untreated industrial and domestic wastewater of Wuhan city, which is indicative of the near-source emissions of PCBs from industrial wastewater and domestic sewage are the main contributors. The result is also consistent with that the heavier PCBs are deposited nearer the source while lower chlorinated PCBs are more easily biodegraded (Ashley and Baker, 1999; Zhang et al., 2004; de Mora et al., 2005; Hong et al., 2005). PCBs are an industrial product; there are no known natural sources. Atmospheric depositions, runoff from the land, and food chain transport (Morrison et al., 2002; Totten et al., 2006; Davis et al., 2007) have been regarded as the major sources of PCBs in aquatic environments. Urban runoff from local watersheds is a particularly significant pathway for PCB entry into the rivers. Also, stormwater in this region flows rapidly from urban soils and paved surfaces into storm drains and flood control channels that carry water and contaminants to the rivers. However, the diffuse and fleeting nature of urban runoff make it difficult to measure and quantify (Davis et al., 2007). Since PCBs are somewhat volatile and tend to enter the atmosphere, atmospheric transport and deposition can be important processes, such as exchange between the water and the atmosphere, and between the soil and the atmosphere. A fraction of the PCBs lost by this pathway may return to the water and land surface via deposition in the watershed and subsequent runoff. Besides, PCBs have been shown to bioconcentrate significantly in aquatic organisms (Morrison et al., 2002). Particle-associated PCBs in the Yangtze River of Wuhan watershed are slowly transported from their sites of origin through storm drains, creeks, and rivers toward the rivers in a recurring cycle of mobilization, deposition, and resuspension (Davis et al., 2007). The presence of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) was also tested in this investigation. Correlation analysis between the PCBs and heavy metals was conducted toward discerning any relations that may exist between PCBs and heavy met-
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als (Fig. 4). We found that five of the eight heavy metals (excluding As, Cd, and Ni) were positively related with PCB concentrations, which may suggest that there are some close relations between them. However, we also found the regression coefficient and their correlations, such as between PCBs and Zn, were dominated by a few higher concentration outliers. This result showed the correlations between PCBs and Zn probably depend on some others factors, such as exceptional sources or their sorption-desorption behaviors between water and sediment, etc. The transport and redistribution of PCBs in sediments are thought to be affected by the geochemical characteristics of the sediment (e.g. pH, TOC content, clay content, silt content). Fig. 5 shows the relations between PCB concentrations and the geochemical variables of the sediment. There are significant linear relation-
ships between all geochemical data and PCB concentrations, with the correlation coefficients decreasing in the following order: TOC, pH, clay, and silt. This result suggests that PCB distributions are influenced by the physicochemical properties of the sediments in which they occur, and is consistent with previous findings regarding the impact of different factors on the sorption and desorption processes of PCBs (Camacho-Ibar and McEvoy, 1996; Wu et al., 1997; Edgar et al., 2003). Fig. 5 clearly demonstrates that the correlation between TOC contents and PCB concentrations is more significant than those of other factors. This is consistent with the findings of previous studies reporting that the sorption of PCBs, as hydrophobic organic substances, is mainly influenced by TOC contents (Jeong et al., 2001; Lee et al., 2001; Edgar et al., 2003). The concentrations of PCBs
Tri-PCBs
Tetra-PCBs
Penta-PCBs
Hexa-PCBs
Hepta-PCBs
Octa-PCBs
Nano-PCBs
Deca-PCBs
B16 B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 Y 11 Y 10 Y9 Y8 Y7 Y6 Y5 Y4 Y3 Y2 Y1
0%
20%
40%
60%
80%
Fig. 3. Percentage compositions of PCBs in sediments from Wuhan reach of the Yangtze River.
100%
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40 30 20 10 0
10
15
20
25
50 R=0.262 p=0.187
-1
R=0.021 p=0.917
5
B14 and B15 would be higher than those at B10 and B7, contrary to their distribution without the normalization. The Yangtze River of Wuhan watershed is the recipient of about 2.5 108 m3 of industrial wastewater and 4.1 108 m3 of domestic sewage from Wuhan city every year (China SEPA, 2003). In addition, it receives contaminants from all upstream sources, nonpoint source land runoff via its tributaries, and direct atmospheric deposition. Consequently, the main inputs of PCBs into the Wuhan
PCBs concentration (ng g )
50
-1
PCBs concentration (ng g )
were therefore normalized with TOC contents in this study. The spatial distributions of TOC-normalized PCB concentrations, ranging between 97 and 2192 ng g1, are presented in Fig. 6. The highest levels of TOC-normalized PCB were found at site B10, with the next highest at sites B7 and B11. The marked contrast between Figs. 2 and 6 clearly demonstrates that TOC contents strongly influence the horizontal distribution of PCBs. If the effect of TOC contents were to be removed, the PCB concentrations at locations
30
35
40 30 20 10 0
0.0
-1
PCBs concentration (ng g )
p<0.001
40 30 20 10 0 -10
2.5
3.0
3.5
4.0
R=0.763
p<0.001
40 30 20 10 0
60
80
100 120
140 160 180
200 220
20
40
-1
60
80
100
120
140
-1
Cr concentration (mg kg )
Cu concentration (mg kg )
PCBs concentration (ng g )
50
50
-1
-1
PCBs concentration (ng g )
2.0
-10
40
40
R=0.799
p<0.01
30 20 10 0
0.0
.2
.4
.6
.8
1.0
1.2
1.4
40
R=0.323 p=0.123
30 20 10 0
1.6
20
-1
30 20 10 0 -10 20
40
60
80
100 -1
Pb concentration (mg kg )
35
40
45
50
55
60
50
-1
PCBs concentration (ng g )
-1
p<0.001
40
0
30
Ni concentration (mg kg )
50 R=0.641
25
-1
Hg concentration (mg kg )
PCBs concentration (ng g )
1.5
50
-1
-1
PCBs concentration (ng g )
1.0
Cd concentration (mg kg )
50 R=0.787
.5
-1
As concentration (mg kg )
120
R=0.668
p<0.001
40 30 20 10 0
0
200
400
600
800
1000
1200
-1
Zn concentration (mg kg )
Fig. 4. Relationships between PCB concentrations and the concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in surface sediments from Wuhan reach of the Yangtze River.
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reach of the Yangtze River may be a combination of runoff from the land during floods and heavy rains, water and contaminants from municipal and industrial sources, atmospheric deposition, and contaminants from all upstream sources (Morrison et al., 2002). It has generally been suggested that PCB contamination should occur indiscriminately in the mainstream sediments of the Yangtze
River due to its high flow volume and rapid current. However, only site Y7, near Wuhan Port, had relatively high TOC-normalized PCB, implying that shipping activity is a possible source of PCB emission at this site (Hong et al., 2005); as PCB-containing paints were frequently applied to ship hulls in the past (Kang et al., 2000; Edge et al., 2001; Hong et al., 2005).
50 -1
PCBs concentration (ng g )
-1
PCBs concentration (ng g )
50 R=0.784 p<0.001
40 30 20 10 0
R=0.460 p=0.016
40 30 20 10 0 -10
0
20
40
60
80
100
0
-1
20
30
40
50
60
50 -1
-1
PCBs concentration (ng g )
50
PCBs concentration (ng g )
10
Clay (%)
TOC concentration (mg kg )
R=0.469 p=0.014 40 30 20 10 0
R=0.563 p=0.002
40 30 20 10 0 -10
-10 10
20
30
40
50
60
70
6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4
pH
Silt (%)
Fig. 5. Relationships between PCB concentrations and geochemical data in surface sediments from Wuhan reach of the Yangtze River.
-1
TOC-normalized PCB concentrations (ng g )
2500
2000
1500
1000
500
0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10Y11 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B12B13B14B15B16
Sample sites Fig. 6. TOC-normalized PCB concentrations in sediments from Wuhan reach of the Yangtze River.
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3.3. Ecotoxicological concerns
Acknowledgments
Sediment-bound PCBs can affect benthic organisms. To evaluate the ecotoxicological aspect of sediment contamination, some published sediment quality guidelines and toxic equivalent (WHO-TEQ) of dioxin-like PCB congeners were applied in this study. Although the guidelines are limited in some cases, they provide useful indicators of the effects of PCB contamination in the absence of environmental assessment criteria for PCBs in China. The effect range low value (ERL, 22.7 ng g1 dry weight) suggests that PCBs can exert toxic biological effects on aquatic organisms, while the effect range median value (ERM, 180 ng g1 dry weight) indicates the high possibility of PCBs posing detrimental biological effects on aquatic organisms (Long et al., 1995). Based on Canadian quality guidelines for PCBs in freshwater sediment, PCB concentrations at the probable effect level (PEL, 277 ng g1 dry weight) frequently cause adverse effects on aquatic biota, whereas at concentrations corresponding to the threshold effect level (TEL, 34.1 ng g1 dry weight), the effects are negligible (CCME, 1999). The total PCB concentrations of the samples collected for this study do not exceed the ERM or PEL values, with the exception of sites B14 and B15, which show concentrations above the ERL and TEL values (Fig. 2). Thus, the sediments at sites B14 and B15 have a potential biological impact, but should cause no impairment. Although the TEF concept was originally developed to assess the toxicity of abiotic samples to humans, it has proven very useful in assessing the toxicity of a variety of environmental samples, including sediment ones. The WHO-TEQ is often used for legislation and risk assessment and management (van Bavel and Esteban, 2008). When the levels of DL-PCBs are reported, the actual congener concentrations in an environmental sample are multiplied with the respective TEF and the total toxic equivalent (TEQ) is calculated by the following equation:
The research was supported by the National Basic Research Program of PR China (973 Project, 2003CB415204). The authors wish to thank the Reviewers and the Editors for their painstaking work and constructive comments.
TEQ ¼
N X
C i TEF i
ð1Þ
i¼1
Three dioxin-like PCB congeners were PCB 105, 118 and 156 (WHO05-TEF, 0.00003) in mono-ortho DL-PCBs (Van den Berg et al., 2006). Mean WHO05-TEQ values calculated by WHO05-TEF were 0.01 (nd 0.05), 0.01 (nd 0.14), 0.02 (nd 0.15), and 0.03 (nd 0.20) pg g1 dw for PCB 105, 118, 156, and the sum of DLPCBs, respectively.
4. Conclusions Analyses of twenty-seven surface sediment samples from the Wuhan reach of the Yangtze River showed PCB levels ranging from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1. The levels of PCB concentrations ranged from relatively low to moderately high compared to other rivers and harbors worldwide. The highest PCB levels were found at tributary sites that are closer to PCB sources. Tetra-PCBs and penta-PCBs were predominant in the sediments of the Wuhan reach. Based on correlation analysis, PCBs in the sediment seem to have originated mostly from runoff from the land, probably associated with wastewater discharges and runoff from urbanized areas and metal mining and smelting activities. The PCBs levels in our sediment samples do not exceed ERM or PEL values, with the exception of two sites (B14 and B15) which show concentrations above the ERL and TEL values. Our results indicate that the adverse biological effects associated with the PCB levels at most of the studied sites should be insignificant, whereas those at the two higher-concentration sites could potentially cause acute biological impairment.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.chemosphere.2008.11.024. References Alcock, R.E., Gemmill, R., Jones, K.C., 1999. Improvements to the UK PCDD/F and PCB atmospheric emission inventory following an emissions measurement programme. Chemosphere 38, 759–770. Ashley, J.T.F., Baker, J.E., 1999. Hydrophobic organic contaminations in surficial sediments of Baltimore Harbor: inventories and sources. Environmental Toxicology and Chemistry 18, 838–849. Barakat, A.O., Kim, M., Qian, Y., Wade, T.L., 2002. Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt. Marine Pollution Bulletin 44, 1421–1434. Biterna, M., Voutsa, D., 2005. Polychlorinated biphenyls in ambient air of NW Greece and in particulate emissions. Environmental International 31, 671– 677. Borgå, K., Wolkers, H., Skaare, J.U., Hop, H., Muir, D.C.G., Gabrielsen, G.W., 2005. Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation. Environmental Pollution 134, 397–409. Breivik, K., Sweetman, A., Pacyna, J.M., Jones, K.C., 2002. Towards a global historical emission inventory for selected PCB congeners – a mass balance approach. 1. Global production and consumption. Science of the Total Environment 290, 181–198. Buekens, A., Stieglitz, L., Hell, K., Huang, H., Segers, P., 2001. Dioxins from thermal and metallurgical processes: recent studies for the iron and steel industry. Chemosphere 42, 729–735. Camacho-Ibar, V.F., McEvoy, J., 1996. Total PCBs in Liverpool Bay sediments. Marine Environmental Research 41 (3), 241–263. CCME (Canadian Council of Ministers of the Environment), 1999. Canadian Council of Ministers of the Environment Canadian sediment quality guidelines for the protection of aquatic life: polychlorinated biphenyls (PCBs). In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment: Winnipeg, Manitoba. China SEPA, 2003. Building the capacity of the People’s Republic of China to implement the Stockholm convention on POPs and develop a National implementation plan. GEF Project Brief (GF/CPR/02/010). Davis, J.A., Hetzel, F., Oram, J.J., McKeeet, L.J., 2007. Polychlorinated biphenyls (PCBs) in San Francisco Bay. Environmental Research 105, 67–86. de Mora, S., Fowler, S.W., Tolosa, I., Villeneuve, J.P., Cattini, C., 2005. Chlorinated hydrocarbons in marine biota and coastal sediments from the Gulf and Gulf of Oman. Marine Pollution Bulletin 50, 835–849. Edgar, P.J., Hursthouse, A.S., Matthews, J.E., Davies, I.M., 2003. An investigation of geochemical factors controlling the distribution of PCBs in intertidal sediments at a contamination hot spot, the Clyde Estuary, UK. Appl. Geochem. 18, 327– 338. Edge, M., Allen, N.S., Turner, D., Robinson, J., Seal, K., 2001. The enhanced performance of biocidal additives in paints and coatings. Progress Organic Coatings 43, 10–17. Eggleton, J., Thomas, K.V., 2004. A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events. Environment International 30, 973–980. Harrad, S.J., Sewart, A., Alcock, R., Boumphrey, R., Burnett, V., Duarte-Davison, R., Halsall, C., Sanders, G., Waterhouse, K., Wild, S., Jones, K.C., 1994. Polychlorinated biphenyls (PCBs) in the British environment: sinks, sources and temporal trends. Environmental Pollution 85, 131–146. Hartmann, P.C., Quinn, J.G., Cairns, R.W., King, J.W., 2004. Polychlorinated biphenyls in Narragansett Bay surface sediments. Chemosphere 57, 9–20. He, M.C., Sun, Y., Li, X.R., Yang, Z.W., 2006. Distribution patterns of nitrobenzenes and polychlorinated biphenyls in water, suspended particulate matter and sediment from mid- and down-stream of the Yellow River (China). Chemosphere 65, 365–374. Hong, S.H., Yim, U.H., Shim, W.J., Oh, J.R., 2005. Congener-specific survey for polychlorinated biphenlys in sediments of industrialized bays in Korea: regional characteristics and pollution sources. Environmental Science and Technology 39, 7380–7388. Jeong, G.H., Kim, H.J., Joo, Y.J., Kim, Y.B., So, H.Y., 2001. Distribution characteristics of PCBs in the sediments of the lower Nakdong River, Korea. Chemosphere 44, 1403–1411. Jiang, K., Li, L.J., Chen, Y.D., Jin, J., 1997. Determination of PCDD/Fs and dioxin-like PCBs in Chinese commercial PCBs and emissions from a testing PCB incinerator. Chemosphere 34, 941–950.
1530
Z. Yang et al. / Chemosphere 74 (2009) 1522–1530
Jiang, X., Martens, D., Schramm, K.W., Kettrup, A., Xu, S.F., Wang, L.S., 2000. Polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtze River. Chemosphere 41, 901–905. Jones, K.C., de Voogt, P., 1999. Persistent organic pollutants (POPs): State of the science. Environmental Pollution 100, 209–221. Kang, Y.H., Sheng, G.Y., Fu, J.M., Mai, B.X., Zhang, G., Lin, Z., Min, Y.S., 2000. Polychlorinated biphenyls in surface sediments from the Pearl River Delta and Macau. Marine Pollution Bulletin 40, 794–797. Lee, K.T., Tanabe, S., Koh, C.H., 2001. Contamination of polychlorinated biphenyls (PCBs) in sediments from Kyeonggi Bay and nearby areas, Korea. Marine Pollution Bulletin 42, 273–279. Liu, M., Yang, Y., Hou, L., Xu, S., Ou, D., Zhang, B., Liu, Q., 2003. Chlorinated organic contaminants in surface sediments from the Yangtze Estuary and nearby coastal areas, China. Marine Pollution Bulletin 46, 672–676. 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 estuary sediments. Environmental Management 19, 81–97. Mai, B.X., Zeng, E.Y., Luo, X.J., Yang, Q.S., Zhang, G., Li, X.D., Sheng, G.Y., Fu, J.M., 2005. Abundances, depositional fluxes, and homologue patterns of polychlorinated biphenyls in dated sediment cores from the Pearl River Delta, China. Environmental Science and Technology 39, 49–56. Moret, I., Piazza, R., Benedetti, M., Gambaro, A., Barbante, C., Cescon, P., 2001. Determination of polychlorobiphenyls in Venice Lagoon sediments. Chemosphere 43, 559–565. Morrison, H.A., Whittle, D.M., Haffner, G.D., 2002. A comparison of the transport and fate of polychlorinated biphenyl congeners in three Great Lakes food webs. Environmental Toxicology and Chemistry 21, 683–692. Negri, A., Burns, K., Boyle, S., Brinkman, D., Webster, N., 2006. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica. Environmental Pollution 143 (3), 456–467. Ren, N.Q., Que, M.X., Li, Y.F., Liu, Y., Wan, X.N., Xu, D.D., Sverko, E., Ma, J., 2007. Polychlorinated biphenyls in Chinese surface soils. Environmental Science and Technology 41, 3871–3876. Rushneck, D.R., Beliveau, A., Fowler, B., Hamilton, C., Hoover, D., Kaye, K., Berg, M., Smith, T., Telliard, W.A., Roman, H., Ruder, E., Ryan, L., 2004. Concentrations of dioxin-like PCB congeners in unweathered Aroclors by HRGC/HRMS using EPA Method 1668A. Chemosphere 54, 79–87.
Samara, F., Tsai, C.W., Aga, D.S., 2006. Determination of potential sources of PCBs and PBDEs in sediments of the Niagara River. Environmental Pollution 139, 489–497. Shen, M., Yu, Y.J., Zheng, G.J., Yu, H.X., Lam, P.K.S., Feng, J.F., Wei, Z.B., 2006. Polychlorinated biphenyls and polybrominated diphenyl ethers in surface sediments from the Yangtze River Delta. Marine Pollution Bulletin 52, 1299– 1304. Sprovieri, M., Feo, M.L., Prevedello, L., Manta, D.S., Sammartino, S., Tamburrino, S., Marsella, E., 2007. Heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface sediments of the Naples harbour (southern Italy). Chemosphere 67, 998–1009. Tang, Z.W., Yang, Z.F., Shen, Z.Y., Niu, J.F., Liao, R.F., 2007. Residue of organochlorine pesticides in sediments from typical catchment of Yangtze River, China. Archives of Environmental Contamination and Toxicology 53, 303–312. Totten, L.A., Panangadan, M., Eisenreich, S.J., Cavallo, G.J., Fikslin, T.J., 2006. Direct and indirect atmospheric deposition of PCBs to the Delaware River Watershed. Environmental Science Technology 40, 2171–2176. van Bavel, B., Esteban, A., 2008. Long-term worldwide QA/QC of dioxins and dioxinlike PCBs in environmental samples. Analytical Chemistry 80, 3956–3964. Van den Berg, M., Birnbaum, L.S., Denison, M., De Vito, M., Farland, W., Feeley, M., Fiedler, H., Hakansson, H., Hanberg, A., Haws, L., Rose, M., Safe, S., Schrenk, D., Tohyama, C., Tritscher, A., Tuomisto, J., Tysklind, M., Walker, N., Peterson, R.E., 2006. The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicological Science 93, 223–241. Wu, W.Z., Schramm, K.W., Henkelmann, B., Xu, Y., Yediler, A., Kettrup, A., 1997. PCDD/Fs, PCBs, HCHs, and HCB in sediments and soils of Ya–Er Lake area in China: results on residual levels and correlation to the organic carbon and the particle size. Chemosphere 34, 191–202. Xing, X., Lu, Y.L., Dawson, R.W., Shi, Y.J., Zhang, H., Wang, T.Y., Liu, W.B., Ren, H.C., 2005. A spatial temporal assessment of pollution from PCBs in China. Chemosphere 60, 731–739. Xu, S.F., Jiang, X., Dong, Y.Y., Sun, C., Feng, J.F., Wang, L.S., Martens, D., Gawlik, B.M., 2000. Polychlorinated organic compounds in Yangtze River sediments. Chemosphere 41, 1897–1903. Zhang, Z.L., Huang, J., Yu, G., Hong, H.S., 2004. Occurrence of PAHs, PCBs and organochlorine pesticides in the Tonghui River of Beijing, China. Environmental Pollution 130, 249–261.
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Occurrence and possible sources of polychlorinated biphenyls in surface sediments from the Wuhan reach of the Yangtze River, China Zhifeng Yang *, Zhenyao Shen, Fan Gao, Zhenwu Tang, Junfeng Niu State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China
a r t i c l e
i n f o
Article history: Received 8 August 2008 Received in revised form 30 October 2008 Accepted 10 November 2008 Available online 23 December 2008 Keywords: PCBs Identification of sources Composition Sediment Toxicity
a b s t r a c t Twenty-seven surface sediment samples were collected from the mainstream and eight tributaries of the Wuhan reach of the Yangtze River, China, in 2005, in order to assess the distribution, possible sources, and potential risk of polychlorinated biphenyls (PCBs) in the environment. The total concentrations of PCBs (the sum of 39 congeners) ranged from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1. Sediment samples with the highest PCB concentrations came from the tributary sites, which are closer to PCB sources. Conversely, PCB concentrations in the sediment from the mainstream sites of Yangtze River were relatively low. The observed PCB levels were higher than those found in the sediments of other rivers in China, but lower than those in river sediments from other urban areas and harbors around the world. Low-chlorinated PCBs, dominated by tetra-PCBs and penta-PCBs, were identified as being prevalent in the surface sediments. Correlation analyses between the PCBs and the geochemistry and heavy metal content of the sediments suggest that the washing of these compounds from the land into the river by floods and heavy rains, or industrial wastewater and domestic sewage, may be the major sources of the PCBs. According to established sediment quality guidelines, the risk of adverse biological effects from the levels of PCBs recorded at most of the studied sites should be insignificant, although the higher concentrations at other sites could cause acute biological damage. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated biphenyls (PCBs), constituting a class of 209 chemical compounds, have been designated as typical persistent organic pollutants (POPs) by the Stockholm Convention of May 22, 2001 (Harrad et al., 1994; Ren et al., 2007). They are of great global concern due to their bioaccumulation, persistence, and impact on ecosystems. After the onset of commercial manufacturing of PCBs in 1929, they became used extensively as dielectric fluids, hydraulic fluids, organic diluents in electrical transformers and capacitors, and were used in a variety of consumer products (Jones and de Voogt, 1999). Although the production and usage of PCBs has been banned worldwide since the early 1970s, it is reported that the total global production of PCBs had already exceeded 1.3 million tons (Breivik et al., 2002). PCB pollution has been identified and reported all over the world, even in Antarctica and the Arctic Zone (Hartmann et al., 2004; Borgå et al., 2005; Xing et al., 2005; Negri et al., 2006; Ren et al., 2007). During the period from 1965, when China began producing PCBs, to the 1980s, when production was banned, China produced more than ten thousand tons of PCBs, nine thousand of which were
* Corresponding author. Tel./fax: +86 10 5880 7951. E-mail address: [email protected] (Z. Yang). 0045-6535/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2008.11.024
tri-PCB (mainly used in the insulation of electrical equipment) and one thousand of which were penta-PCB (a paint additive) (China SEPA, 2003). Since the ban, most equipment containing PCBs was retired from use and stored. Leakages from such equipment, however, have recently been reported. In recent years, pollution incidents involving PCBs have resulted in severe consequences in some regions of China (Wu et al., 1997; Zhang et al., 2004; Mai et al., 2005; Shen et al., 2006; Ren et al., 2007). PCBs enter the aquatic environment through a variety of sources that include direct deposition from the atmosphere, runoff from the land, and industrial and municipal wastewater discharge (Samara et al., 2006; Totten et al., 2006; Davis et al., 2007). Due to their low solubility in water and high octanol–water partition coefficients, PCBs quickly become associated with particulate matter once in aquatic environments, and ultimately accumulate in bottom sediments (Harrad et al., 1994). Remobilization of surficial sediment-associated PCBs can occur during natural events, such as high river flows and storms, or during human activities such as dredging, dredge disposal and fishing; both have implications for human health (Eggleton and Thomas (2004)). The Yangtze River, the largest river in China and the third largest in the world, flows 6300 km from its source in the Qinghai– Tibet Plateau to the East China Sea, and is characterized by the industrial and urban zones through which it flows. Wuhan is the largest city located in the middle reaches of the Yangtze River, with
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a population of around 8 million. Drinking water and a large amount of fishery products are taken from the Wuhan reach of the Yangtze River. The number of PCB related studies in the Chinese environment has increased recently thanks to a series of global initiatives on POPs and an increasing concern about the risks that these chemicals pose to human health and the environment. Most of the recent PCB investigations have focused on the lower reaches of the Yangtze River and its estuary (Jiang et al., 2000; Xu et al., 2000; Liu et al., 2003; Shen et al., 2006), while little information is available regarding PCB levels in its middle reaches. Therefore information relating to levels of PCBs in middle reaches of the Yangtze River is very important, both with respect to spatial distribution of the Yangtze River basin and to fill the information gap. The objective of the present study is to determine the spatial distributions of PCBs in sediments, to identify their possible sources, and to assess the ensuing environmental risks in the middle reaches of the Yangtze River.
2. Materials and methods 2.1. Sample collection Twenty-seven samples of surface sediments were collected from the mainstream and eight main tributaries of the Wuhan reach of the Yangtze River in December 2005. Details of the sampling sites are shown in Fig. 1. These sampling sites were recorded using a global positioning system (GPS). The sediments were collected using a Van Veen grab (Eijkelamp, the Netherlands). Approximately 2 cm of sediment were taken from the top of the river beds and placed in a precleaned aluminum box using a stainless-steel
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spoon. All of the sediment samples were freeze-dried, ground, homogenized, and stored at 20 °C prior to analysis. 2.2. Extraction and analysis The procedure for extracting PCBs from sediments was modified from a previously published method (Moret et al., 2001). All freeze-dried sediment samples were ground and homogenized. Sediment samples weighing 10 g were treated with 80 mL of hexane–dichloromethane (2:1, v/v, chromatographicgrade, Dima Co., USA) in an ultrasonic bath for 2.0 h. The samples were allowed to stand overnight (approximately 10 h), and were again sonicated for 30 min. The extracts were decanted and the remainder was then re-sonicated with 30 mL hexane for 30 min. The two extracts were then combined and treated with activated Cu to remove sulfates, and then concentrated to 5.0 mL by a rotary evaporator (RV 05 basic, IKA, Germany). The extract was subsequently removed using a separating funnel and 10 mL of concentrated sulfuric acid (98%, AR) were added 2–3 times to remove any impurities, such as lipoid and polycyclic aromatic hydrocarbons. The organic phase was washed in a 50 mL 5% NaCl solution and concentrated to about 1–2 mL. Further purification was carried out using a glass column (10 mm i.d.) loaded with 20 g of activated Florisil (100–200 mesh, Beijing Yizhong Chemical Regents Factory, China), which was activated in an oven at 650 °C for 8 h, and then deactivated with Milli-Q water at a ratio of 3%. PCBs were eluded with 100 mL of hexane. The hexane eluate was reduced under a gentle stream of nitrogen to 0.2 mL, and an internal standard (pentachloronitrobenzene, Sulpelco Co., USA) was added for GC/MS analysis. Quantification was undertaken by the internal standard method relative to a multilevel calibration for all compounds.
Fig. 1. Map of sampling sites in Wuhan reach of the Yangtze River. Y: the mainstream of the Yangtze River; B: the tributaries of the Yangtze River.
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PCBs were measured using a GC 2000/TRACETM MS with a DB-5 capillary column (30 m 0.25 mm 0.25 lm, J&W, USA). The GC/ MS conditions for sample analysis were as follows: the oven was set at a temperature of 150 °C for 2 min, which was then increased at a rate of 4 °C min1 to 290 °C, at which temperature it was held for 2 min; the injection was in splitless mode at 275 °C; the carrier gas was nitrogen, with a flow rate of 1.0 mL min1; the temperature of the transfer line was 200 °C; the full scan mode was used for qualitative analysis with a range of 35–500 m/z, and selected ion mode (SIM) was used for quantitative analysis, the electron energy was 70 eV, and the detector voltage was 500 V. The 32 chromatographic peaks representing 39 individual or coeluting congeners (designated as domains) were quantified by use of the standard mixture from Accustandard, Inc. (New Haven, CT), Catalog number C-QME-01, containing the following 41congeners: IUPAC Nos. 17, 18, 28, 31, 33, 44, 49, 52, 70, 74, 82, 87, 95, 99, 101, 105, 110, 118, 128, 132, 138, 149, 151, 153, 158, 169, 170, 171, 177, 180, 183, 187, 191, 194, 195, 199/201, 205, 206, 208 and 209. Congeners 17 and 18, 28 and 31, 74 and 95, 82 and 151, 118 and 149, 105 and 132, 138 and 153 were coeluted, but 169 and 199/201 was not determined. RPCB was defined as the sum of the concentrations of these congeners and domains. To calculate the contribution to the homologue groups from each congener in a domain, all congeners were considered equally abundant in the domain. 2.3. Quality assurance and control All data were subject to strict quality control procedures. For each set of 6 samples, a procedural blank and a matrix sample spiked with standards were used for monitoring interference and circumventing cross-contaminations, and all results were blank corrected. The quality assurance and control experiment was performed in duplicate (n = 3) and the relative standard deviations (RSD) were all below 13%. Spike recoveries were performed on the matrix sample (pre-extracted sediment). Ten grams of matrix sample spiked with a mixture of 41 PCBs was equilibrated for 24 h at 25 °C and then analyzed by the same procedure as for the samples. The spiked recovery for PCB congeners in the sediments ranged from 68.3% to 127.4%; the MDLs ranged from 0.05 to 0.3 ng g1; and the relative standard deviation (RSD) ranged from 6.8% to 20.9% (Table S1). All the results were corrected with the recovery ratios and reported in ng g1 dry wt. 2.4. Other analyses Samples were also used to determine the physicochemical properties of the sediments, such as pH values, total organic carbon (TOC), and grain size (Tang et al., 2007). Eight heavy metals of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were detected in order to investigate heavy metals contamination in this region. The full results will be reported elsewhere. This paper will focus on any relations that may exist between PCBs and heavy metals in the sediments. All samples were air dried at room temperature and sieved through a 2 mm nylon sieve to remove coarse debris. The sediments were then ground with a pestle and mortar until all particles passed a 200 mesh nylon sieve. About 0.25 g of sediment was digested with 5.0 mL HNO3, 2.0 mL HClO4 and 10 mL HF at a temperature of 90 ± 190 °C for 16 h. The residue was then dissolved in 5 mL of 4 M HCl, diluted to 25 mL with deionised water for Cr, Cu, Ni and Zn, and with 2% nitric acid solution for Cd and Pb. They were analysed by inductively coupled plasma mass spectrometer (ICP-MS, Thermo). Another small portion of each sample (0.5 g) was digested with HNO3/H2SO4 and total mercury, arsenic was
analyzed by cold vapor atomic spectrometry (CVAFS). Blank samples, standard samples and duplicated samples were simultaneously performed in the two analyses as quality control. 3. Results and discussion 3.1. PCB concentrations The concentrations of RPCBs (the sum of 39 congeners) in the surface sediments from the Wuhan reach of the Yangtze River ranged from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1 (Fig. 2). The highest concentration of RPCBs was found at site B14 (45.1 ng g1), and the second highest at site B15 (40.8 ng g1). Both of these sites lie in close proximity to the discharge points of wastewater treatment plants and of various chemical companies in the area, and both are in tributaries of the Yangtze River around Wuhan. It can be seen in Fig. 2 that PCB concentrations in the sediments of the tributaries were apparently higher than those in the Yangtze River itself, indicating the water flow and current velocity may play an important role in the PCB contamination of river sediments. In sediment samples, the most abundant PCB congeners were 49, 82/151, 99, 170 and 177, comprising up to 37.6 % of the total amount of PCBs. The mean concentrations of dioxin-like PCB congeners (DL-PCBs) were 0.22, 0.36 and 0.69 ng g1 dw for PCB 105, 118 and 156, respectively. The PCB concentrations in surface sediments from the Wuhan reach of the Yangtze River were found to be lower than those in the sediments of other rivers in China (Table 1), such as the Songhua, Qiantang, and the Pearl Rivers (Kang et al., 2000; Xing et al., 2005), and those reported in some urbanized and harbor areas around the world, such as Narragansett Bay, USA (Hartmann et al., 2004), Alexandria harbor, Egypt (Barakat et al., 2002), and Naples harbor, Italy (Sprovieri et al., 2007). However, the PCB levels around Wuhan were higher than those recently reported in the lower reaches of the Yangtze River (Shen et al., 2006) and the mid- and downstream reaches of the Yellow River (He et al., 2006). 3.2. PCB composition and source identification All 39 PCB congeners considered in this study were identified in the surface sediment samples. The proportion of the different PCBs in all sediment samples generally decreased in the following order: tetra-PCBs > penta-PCBs > hepta-PCBs > hexa-PCBs > octa-PCBs > tri-PCBs > deca-PCBs > nona-PCBs (Fig. 3). The compositions of PCBs were consistent with previous observations on PCB contaminations in freshwater sediments from the Guangzhou reach in the Pearl River, near Macao, the mid- and down-stream of the Yellow River, the Nanjing reach of the Yangtze River, and the Tonghui River, China (Kang et al., 2000; Zhang et al., 2004; He et al., 2006; Shen et al., 2006). Furthermore, such a PCB profile was also in accordance with those in previous research about urban soils in China (Ren et al., 2007). Approximately 10 000 tons of PCBs were produced in China from 1965 to 1974 (when production was banned), with 9000 tons as trichlorobiphenyl, known as #1 PCB, and 1000 tons as pentachlorobiphenyl, #2 PCB (Xing et al., 2005). Trichlorobiphenyl was used primarily in power capacitors, while pentachlorobiphenyl was used mainly as a paint additive (China SEPA, 2003). Number 1 PCB contained 42% chlorine, which was similar to Aroclor 1242, and #2 PCB contained 53% chlorine, similar to Aroclor 1254 (Jiang et al., 1997). Assuming that these two technical mixtures #1 PCB and #2 PCB were produced in the ratio of 9:1, the congeners production in China was estimated using congeners composition of Aroclor 1242 for #1 PCB and Aroclor 1254 for #2 PCB (Ren et al., 2007), As a result, the major congeners produced and used in China
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-1
Total PCBs concentrations (ng g )
50
40 TEL 30 ERL 20
10
0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10Y11 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B12B13B14B15B16
Sample sites Fig. 2. Concentrations of RPCB in sediments from Wuhan reach of the Yangtze River. Y: mainstream; B: tributaries. ERL: the effect range low value (Long et al., 1995); TEL: Canadian interim sediment quality guideline for PCBs in freshwater sediment, threshold effect level (CCME, 1999).
Table 1 Concentrations of RPCB (ng g1 dry weight) in surface sediments from various locations. Locations
RPCB
References
(ng g1) The Pearl River Estuary, South China Minjiang River, Southeast China Songhua River, Northeast China Narragansett Bay, USA Alexandria harbor, Egypt Naples harbour, Southern Italy The mid- and down-stream of the Yellow River, North China The lower reaches of the Yangtze River, East China Wuhan reach of the Yangtze River, Central China
11.5–485 15.1–58 0.62–337 20.8–1760 0.9–1210 10–899 nd–6.0
Kang et al. (2000) Xing et al. (2005) Xing et al. (2005) Hartmann et al. (2004) Barakat et al. (2002) Sprovieri et al. (2007) He et al. (2006)
0.92–9.7
Shen et al. (2006)
1.2–45.1
This work
was tri-PCB, followed by tetra-PCB. Although the major congener profile of the global PCB product is also tri-PCB followed by tetra-PCB (Breivik et al., 2002), the compositions of these two congeners are higher in Chinese product than in global product (40.4– 25.2% for tri-PCB, and 31.1–24.7% for tetra-PCB) (Ren et al., 2007). In this study, PCB congeners with the highest proportions consisted of the following: tetra-PCBs (36.6%), penta-PCBs (23.7%), hepta-PCBs (20.7%), octa-PCBs (3.0%) and tri-PCBs (2.5%) (Fig. 3). This indicated that the PCBs in sediments originated from sources other than power capacitors and paint additives. For example, the compounds may have come from industrial and domestic wastewater, or even been imported from other countries (e.g. Aroclor 1260) (Rushneck et al., 2004). Our sediment investigation revealed the general prevalence of lower molecular weight PCBs. The PCB congeners pattern was dominated by tetra-PCBs at sites B11 (70.8%), B10 (67.2%), B2 (67.1%), and Y10 (62.3%). Penta-PCBs also dominated the PCB congeners pattern at locations B3 (70.1%), and Y2 (61.6%). Upon assessment of Wuhan’s industry distribution, it was deduced that industrial activity related to steel manufacturing probably contributed to the lower chlorinated PCBs in these sediments. A number of previous studies have showed the production of PCBs during the
steel manufacturing processes (Alcock et al., 1999; Buekens et al., 2001). This is due to the presence of PCBs in fly ash generated from burning coal during the iron ore sintering process (Biterna and Voutsa, 2005). However, relatively higher percentage of the highchlorinated congeners, such as hepta-PCBs at sites Y9, B12 and B14 were found in this study (Fig. 3). These sites are close to the sources of untreated industrial and domestic wastewater of Wuhan city, which is indicative of the near-source emissions of PCBs from industrial wastewater and domestic sewage are the main contributors. The result is also consistent with that the heavier PCBs are deposited nearer the source while lower chlorinated PCBs are more easily biodegraded (Ashley and Baker, 1999; Zhang et al., 2004; de Mora et al., 2005; Hong et al., 2005). PCBs are an industrial product; there are no known natural sources. Atmospheric depositions, runoff from the land, and food chain transport (Morrison et al., 2002; Totten et al., 2006; Davis et al., 2007) have been regarded as the major sources of PCBs in aquatic environments. Urban runoff from local watersheds is a particularly significant pathway for PCB entry into the rivers. Also, stormwater in this region flows rapidly from urban soils and paved surfaces into storm drains and flood control channels that carry water and contaminants to the rivers. However, the diffuse and fleeting nature of urban runoff make it difficult to measure and quantify (Davis et al., 2007). Since PCBs are somewhat volatile and tend to enter the atmosphere, atmospheric transport and deposition can be important processes, such as exchange between the water and the atmosphere, and between the soil and the atmosphere. A fraction of the PCBs lost by this pathway may return to the water and land surface via deposition in the watershed and subsequent runoff. Besides, PCBs have been shown to bioconcentrate significantly in aquatic organisms (Morrison et al., 2002). Particle-associated PCBs in the Yangtze River of Wuhan watershed are slowly transported from their sites of origin through storm drains, creeks, and rivers toward the rivers in a recurring cycle of mobilization, deposition, and resuspension (Davis et al., 2007). The presence of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) was also tested in this investigation. Correlation analysis between the PCBs and heavy metals was conducted toward discerning any relations that may exist between PCBs and heavy met-
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als (Fig. 4). We found that five of the eight heavy metals (excluding As, Cd, and Ni) were positively related with PCB concentrations, which may suggest that there are some close relations between them. However, we also found the regression coefficient and their correlations, such as between PCBs and Zn, were dominated by a few higher concentration outliers. This result showed the correlations between PCBs and Zn probably depend on some others factors, such as exceptional sources or their sorption-desorption behaviors between water and sediment, etc. The transport and redistribution of PCBs in sediments are thought to be affected by the geochemical characteristics of the sediment (e.g. pH, TOC content, clay content, silt content). Fig. 5 shows the relations between PCB concentrations and the geochemical variables of the sediment. There are significant linear relation-
ships between all geochemical data and PCB concentrations, with the correlation coefficients decreasing in the following order: TOC, pH, clay, and silt. This result suggests that PCB distributions are influenced by the physicochemical properties of the sediments in which they occur, and is consistent with previous findings regarding the impact of different factors on the sorption and desorption processes of PCBs (Camacho-Ibar and McEvoy, 1996; Wu et al., 1997; Edgar et al., 2003). Fig. 5 clearly demonstrates that the correlation between TOC contents and PCB concentrations is more significant than those of other factors. This is consistent with the findings of previous studies reporting that the sorption of PCBs, as hydrophobic organic substances, is mainly influenced by TOC contents (Jeong et al., 2001; Lee et al., 2001; Edgar et al., 2003). The concentrations of PCBs
Tri-PCBs
Tetra-PCBs
Penta-PCBs
Hexa-PCBs
Hepta-PCBs
Octa-PCBs
Nano-PCBs
Deca-PCBs
B16 B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 Y 11 Y 10 Y9 Y8 Y7 Y6 Y5 Y4 Y3 Y2 Y1
0%
20%
40%
60%
80%
Fig. 3. Percentage compositions of PCBs in sediments from Wuhan reach of the Yangtze River.
100%
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40 30 20 10 0
10
15
20
25
50 R=0.262 p=0.187
-1
R=0.021 p=0.917
5
B14 and B15 would be higher than those at B10 and B7, contrary to their distribution without the normalization. The Yangtze River of Wuhan watershed is the recipient of about 2.5 108 m3 of industrial wastewater and 4.1 108 m3 of domestic sewage from Wuhan city every year (China SEPA, 2003). In addition, it receives contaminants from all upstream sources, nonpoint source land runoff via its tributaries, and direct atmospheric deposition. Consequently, the main inputs of PCBs into the Wuhan
PCBs concentration (ng g )
50
-1
PCBs concentration (ng g )
were therefore normalized with TOC contents in this study. The spatial distributions of TOC-normalized PCB concentrations, ranging between 97 and 2192 ng g1, are presented in Fig. 6. The highest levels of TOC-normalized PCB were found at site B10, with the next highest at sites B7 and B11. The marked contrast between Figs. 2 and 6 clearly demonstrates that TOC contents strongly influence the horizontal distribution of PCBs. If the effect of TOC contents were to be removed, the PCB concentrations at locations
30
35
40 30 20 10 0
0.0
-1
PCBs concentration (ng g )
p<0.001
40 30 20 10 0 -10
2.5
3.0
3.5
4.0
R=0.763
p<0.001
40 30 20 10 0
60
80
100 120
140 160 180
200 220
20
40
-1
60
80
100
120
140
-1
Cr concentration (mg kg )
Cu concentration (mg kg )
PCBs concentration (ng g )
50
50
-1
-1
PCBs concentration (ng g )
2.0
-10
40
40
R=0.799
p<0.01
30 20 10 0
0.0
.2
.4
.6
.8
1.0
1.2
1.4
40
R=0.323 p=0.123
30 20 10 0
1.6
20
-1
30 20 10 0 -10 20
40
60
80
100 -1
Pb concentration (mg kg )
35
40
45
50
55
60
50
-1
PCBs concentration (ng g )
-1
p<0.001
40
0
30
Ni concentration (mg kg )
50 R=0.641
25
-1
Hg concentration (mg kg )
PCBs concentration (ng g )
1.5
50
-1
-1
PCBs concentration (ng g )
1.0
Cd concentration (mg kg )
50 R=0.787
.5
-1
As concentration (mg kg )
120
R=0.668
p<0.001
40 30 20 10 0
0
200
400
600
800
1000
1200
-1
Zn concentration (mg kg )
Fig. 4. Relationships between PCB concentrations and the concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in surface sediments from Wuhan reach of the Yangtze River.
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reach of the Yangtze River may be a combination of runoff from the land during floods and heavy rains, water and contaminants from municipal and industrial sources, atmospheric deposition, and contaminants from all upstream sources (Morrison et al., 2002). It has generally been suggested that PCB contamination should occur indiscriminately in the mainstream sediments of the Yangtze
River due to its high flow volume and rapid current. However, only site Y7, near Wuhan Port, had relatively high TOC-normalized PCB, implying that shipping activity is a possible source of PCB emission at this site (Hong et al., 2005); as PCB-containing paints were frequently applied to ship hulls in the past (Kang et al., 2000; Edge et al., 2001; Hong et al., 2005).
50 -1
PCBs concentration (ng g )
-1
PCBs concentration (ng g )
50 R=0.784 p<0.001
40 30 20 10 0
R=0.460 p=0.016
40 30 20 10 0 -10
0
20
40
60
80
100
0
-1
20
30
40
50
60
50 -1
-1
PCBs concentration (ng g )
50
PCBs concentration (ng g )
10
Clay (%)
TOC concentration (mg kg )
R=0.469 p=0.014 40 30 20 10 0
R=0.563 p=0.002
40 30 20 10 0 -10
-10 10
20
30
40
50
60
70
6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4
pH
Silt (%)
Fig. 5. Relationships between PCB concentrations and geochemical data in surface sediments from Wuhan reach of the Yangtze River.
-1
TOC-normalized PCB concentrations (ng g )
2500
2000
1500
1000
500
0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10Y11 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10B11B12B13B14B15B16
Sample sites Fig. 6. TOC-normalized PCB concentrations in sediments from Wuhan reach of the Yangtze River.
Z. Yang et al. / Chemosphere 74 (2009) 1522–1530
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3.3. Ecotoxicological concerns
Acknowledgments
Sediment-bound PCBs can affect benthic organisms. To evaluate the ecotoxicological aspect of sediment contamination, some published sediment quality guidelines and toxic equivalent (WHO-TEQ) of dioxin-like PCB congeners were applied in this study. Although the guidelines are limited in some cases, they provide useful indicators of the effects of PCB contamination in the absence of environmental assessment criteria for PCBs in China. The effect range low value (ERL, 22.7 ng g1 dry weight) suggests that PCBs can exert toxic biological effects on aquatic organisms, while the effect range median value (ERM, 180 ng g1 dry weight) indicates the high possibility of PCBs posing detrimental biological effects on aquatic organisms (Long et al., 1995). Based on Canadian quality guidelines for PCBs in freshwater sediment, PCB concentrations at the probable effect level (PEL, 277 ng g1 dry weight) frequently cause adverse effects on aquatic biota, whereas at concentrations corresponding to the threshold effect level (TEL, 34.1 ng g1 dry weight), the effects are negligible (CCME, 1999). The total PCB concentrations of the samples collected for this study do not exceed the ERM or PEL values, with the exception of sites B14 and B15, which show concentrations above the ERL and TEL values (Fig. 2). Thus, the sediments at sites B14 and B15 have a potential biological impact, but should cause no impairment. Although the TEF concept was originally developed to assess the toxicity of abiotic samples to humans, it has proven very useful in assessing the toxicity of a variety of environmental samples, including sediment ones. The WHO-TEQ is often used for legislation and risk assessment and management (van Bavel and Esteban, 2008). When the levels of DL-PCBs are reported, the actual congener concentrations in an environmental sample are multiplied with the respective TEF and the total toxic equivalent (TEQ) is calculated by the following equation:
The research was supported by the National Basic Research Program of PR China (973 Project, 2003CB415204). The authors wish to thank the Reviewers and the Editors for their painstaking work and constructive comments.
TEQ ¼
N X
C i TEF i
ð1Þ
i¼1
Three dioxin-like PCB congeners were PCB 105, 118 and 156 (WHO05-TEF, 0.00003) in mono-ortho DL-PCBs (Van den Berg et al., 2006). Mean WHO05-TEQ values calculated by WHO05-TEF were 0.01 (nd 0.05), 0.01 (nd 0.14), 0.02 (nd 0.15), and 0.03 (nd 0.20) pg g1 dw for PCB 105, 118, 156, and the sum of DLPCBs, respectively.
4. Conclusions Analyses of twenty-seven surface sediment samples from the Wuhan reach of the Yangtze River showed PCB levels ranging from 1.2 to 45.1 ng g1 dry weight, with a mean value of 9.2 ng g1. The levels of PCB concentrations ranged from relatively low to moderately high compared to other rivers and harbors worldwide. The highest PCB levels were found at tributary sites that are closer to PCB sources. Tetra-PCBs and penta-PCBs were predominant in the sediments of the Wuhan reach. Based on correlation analysis, PCBs in the sediment seem to have originated mostly from runoff from the land, probably associated with wastewater discharges and runoff from urbanized areas and metal mining and smelting activities. The PCBs levels in our sediment samples do not exceed ERM or PEL values, with the exception of two sites (B14 and B15) which show concentrations above the ERL and TEL values. Our results indicate that the adverse biological effects associated with the PCB levels at most of the studied sites should be insignificant, whereas those at the two higher-concentration sites could potentially cause acute biological impairment.
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.chemosphere.2008.11.024. References Alcock, R.E., Gemmill, R., Jones, K.C., 1999. Improvements to the UK PCDD/F and PCB atmospheric emission inventory following an emissions measurement programme. Chemosphere 38, 759–770. Ashley, J.T.F., Baker, J.E., 1999. Hydrophobic organic contaminations in surficial sediments of Baltimore Harbor: inventories and sources. Environmental Toxicology and Chemistry 18, 838–849. Barakat, A.O., Kim, M., Qian, Y., Wade, T.L., 2002. Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt. Marine Pollution Bulletin 44, 1421–1434. Biterna, M., Voutsa, D., 2005. Polychlorinated biphenyls in ambient air of NW Greece and in particulate emissions. Environmental International 31, 671– 677. Borgå, K., Wolkers, H., Skaare, J.U., Hop, H., Muir, D.C.G., Gabrielsen, G.W., 2005. Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation. Environmental Pollution 134, 397–409. Breivik, K., Sweetman, A., Pacyna, J.M., Jones, K.C., 2002. Towards a global historical emission inventory for selected PCB congeners – a mass balance approach. 1. Global production and consumption. Science of the Total Environment 290, 181–198. Buekens, A., Stieglitz, L., Hell, K., Huang, H., Segers, P., 2001. Dioxins from thermal and metallurgical processes: recent studies for the iron and steel industry. Chemosphere 42, 729–735. Camacho-Ibar, V.F., McEvoy, J., 1996. Total PCBs in Liverpool Bay sediments. Marine Environmental Research 41 (3), 241–263. CCME (Canadian Council of Ministers of the Environment), 1999. Canadian Council of Ministers of the Environment Canadian sediment quality guidelines for the protection of aquatic life: polychlorinated biphenyls (PCBs). In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment: Winnipeg, Manitoba. China SEPA, 2003. Building the capacity of the People’s Republic of China to implement the Stockholm convention on POPs and develop a National implementation plan. GEF Project Brief (GF/CPR/02/010). Davis, J.A., Hetzel, F., Oram, J.J., McKeeet, L.J., 2007. Polychlorinated biphenyls (PCBs) in San Francisco Bay. Environmental Research 105, 67–86. de Mora, S., Fowler, S.W., Tolosa, I., Villeneuve, J.P., Cattini, C., 2005. Chlorinated hydrocarbons in marine biota and coastal sediments from the Gulf and Gulf of Oman. Marine Pollution Bulletin 50, 835–849. Edgar, P.J., Hursthouse, A.S., Matthews, J.E., Davies, I.M., 2003. An investigation of geochemical factors controlling the distribution of PCBs in intertidal sediments at a contamination hot spot, the Clyde Estuary, UK. Appl. Geochem. 18, 327– 338. Edge, M., Allen, N.S., Turner, D., Robinson, J., Seal, K., 2001. The enhanced performance of biocidal additives in paints and coatings. Progress Organic Coatings 43, 10–17. Eggleton, J., Thomas, K.V., 2004. A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events. Environment International 30, 973–980. Harrad, S.J., Sewart, A., Alcock, R., Boumphrey, R., Burnett, V., Duarte-Davison, R., Halsall, C., Sanders, G., Waterhouse, K., Wild, S., Jones, K.C., 1994. Polychlorinated biphenyls (PCBs) in the British environment: sinks, sources and temporal trends. Environmental Pollution 85, 131–146. Hartmann, P.C., Quinn, J.G., Cairns, R.W., King, J.W., 2004. Polychlorinated biphenyls in Narragansett Bay surface sediments. Chemosphere 57, 9–20. He, M.C., Sun, Y., Li, X.R., Yang, Z.W., 2006. Distribution patterns of nitrobenzenes and polychlorinated biphenyls in water, suspended particulate matter and sediment from mid- and down-stream of the Yellow River (China). Chemosphere 65, 365–374. Hong, S.H., Yim, U.H., Shim, W.J., Oh, J.R., 2005. Congener-specific survey for polychlorinated biphenlys in sediments of industrialized bays in Korea: regional characteristics and pollution sources. Environmental Science and Technology 39, 7380–7388. Jeong, G.H., Kim, H.J., Joo, Y.J., Kim, Y.B., So, H.Y., 2001. Distribution characteristics of PCBs in the sediments of the lower Nakdong River, Korea. Chemosphere 44, 1403–1411. Jiang, K., Li, L.J., Chen, Y.D., Jin, J., 1997. Determination of PCDD/Fs and dioxin-like PCBs in Chinese commercial PCBs and emissions from a testing PCB incinerator. Chemosphere 34, 941–950.
1530
Z. Yang et al. / Chemosphere 74 (2009) 1522–1530
Jiang, X., Martens, D., Schramm, K.W., Kettrup, A., Xu, S.F., Wang, L.S., 2000. Polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtze River. Chemosphere 41, 901–905. Jones, K.C., de Voogt, P., 1999. Persistent organic pollutants (POPs): State of the science. Environmental Pollution 100, 209–221. Kang, Y.H., Sheng, G.Y., Fu, J.M., Mai, B.X., Zhang, G., Lin, Z., Min, Y.S., 2000. Polychlorinated biphenyls in surface sediments from the Pearl River Delta and Macau. Marine Pollution Bulletin 40, 794–797. Lee, K.T., Tanabe, S., Koh, C.H., 2001. Contamination of polychlorinated biphenyls (PCBs) in sediments from Kyeonggi Bay and nearby areas, Korea. Marine Pollution Bulletin 42, 273–279. Liu, M., Yang, Y., Hou, L., Xu, S., Ou, D., Zhang, B., Liu, Q., 2003. Chlorinated organic contaminants in surface sediments from the Yangtze Estuary and nearby coastal areas, China. Marine Pollution Bulletin 46, 672–676. 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 estuary sediments. Environmental Management 19, 81–97. Mai, B.X., Zeng, E.Y., Luo, X.J., Yang, Q.S., Zhang, G., Li, X.D., Sheng, G.Y., Fu, J.M., 2005. Abundances, depositional fluxes, and homologue patterns of polychlorinated biphenyls in dated sediment cores from the Pearl River Delta, China. Environmental Science and Technology 39, 49–56. Moret, I., Piazza, R., Benedetti, M., Gambaro, A., Barbante, C., Cescon, P., 2001. Determination of polychlorobiphenyls in Venice Lagoon sediments. Chemosphere 43, 559–565. Morrison, H.A., Whittle, D.M., Haffner, G.D., 2002. A comparison of the transport and fate of polychlorinated biphenyl congeners in three Great Lakes food webs. Environmental Toxicology and Chemistry 21, 683–692. Negri, A., Burns, K., Boyle, S., Brinkman, D., Webster, N., 2006. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica. Environmental Pollution 143 (3), 456–467. Ren, N.Q., Que, M.X., Li, Y.F., Liu, Y., Wan, X.N., Xu, D.D., Sverko, E., Ma, J., 2007. Polychlorinated biphenyls in Chinese surface soils. Environmental Science and Technology 41, 3871–3876. Rushneck, D.R., Beliveau, A., Fowler, B., Hamilton, C., Hoover, D., Kaye, K., Berg, M., Smith, T., Telliard, W.A., Roman, H., Ruder, E., Ryan, L., 2004. Concentrations of dioxin-like PCB congeners in unweathered Aroclors by HRGC/HRMS using EPA Method 1668A. Chemosphere 54, 79–87.
Samara, F., Tsai, C.W., Aga, D.S., 2006. Determination of potential sources of PCBs and PBDEs in sediments of the Niagara River. Environmental Pollution 139, 489–497. Shen, M., Yu, Y.J., Zheng, G.J., Yu, H.X., Lam, P.K.S., Feng, J.F., Wei, Z.B., 2006. Polychlorinated biphenyls and polybrominated diphenyl ethers in surface sediments from the Yangtze River Delta. Marine Pollution Bulletin 52, 1299– 1304. Sprovieri, M., Feo, M.L., Prevedello, L., Manta, D.S., Sammartino, S., Tamburrino, S., Marsella, E., 2007. Heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface sediments of the Naples harbour (southern Italy). Chemosphere 67, 998–1009. Tang, Z.W., Yang, Z.F., Shen, Z.Y., Niu, J.F., Liao, R.F., 2007. Residue of organochlorine pesticides in sediments from typical catchment of Yangtze River, China. Archives of Environmental Contamination and Toxicology 53, 303–312. Totten, L.A., Panangadan, M., Eisenreich, S.J., Cavallo, G.J., Fikslin, T.J., 2006. Direct and indirect atmospheric deposition of PCBs to the Delaware River Watershed. Environmental Science Technology 40, 2171–2176. van Bavel, B., Esteban, A., 2008. Long-term worldwide QA/QC of dioxins and dioxinlike PCBs in environmental samples. Analytical Chemistry 80, 3956–3964. Van den Berg, M., Birnbaum, L.S., Denison, M., De Vito, M., Farland, W., Feeley, M., Fiedler, H., Hakansson, H., Hanberg, A., Haws, L., Rose, M., Safe, S., Schrenk, D., Tohyama, C., Tritscher, A., Tuomisto, J., Tysklind, M., Walker, N., Peterson, R.E., 2006. The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicological Science 93, 223–241. Wu, W.Z., Schramm, K.W., Henkelmann, B., Xu, Y., Yediler, A., Kettrup, A., 1997. PCDD/Fs, PCBs, HCHs, and HCB in sediments and soils of Ya–Er Lake area in China: results on residual levels and correlation to the organic carbon and the particle size. Chemosphere 34, 191–202. Xing, X., Lu, Y.L., Dawson, R.W., Shi, Y.J., Zhang, H., Wang, T.Y., Liu, W.B., Ren, H.C., 2005. A spatial temporal assessment of pollution from PCBs in China. Chemosphere 60, 731–739. Xu, S.F., Jiang, X., Dong, Y.Y., Sun, C., Feng, J.F., Wang, L.S., Martens, D., Gawlik, B.M., 2000. Polychlorinated organic compounds in Yangtze River sediments. Chemosphere 41, 1897–1903. Zhang, Z.L., Huang, J., Yu, G., Hong, H.S., 2004. Occurrence of PAHs, PCBs and organochlorine pesticides in the Tonghui River of Beijing, China. Environmental Pollution 130, 249–261.