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Environ Monit Assess (2007) 133:447–458 DOI 10.1007/s10661-006-9599-5

Distribution and sources of polycyclic aromatic hydrocarbons in Wuhan section of the Yangtze River, China Chenglian Feng & Xinghui Xia & Zhenyao Shen & Zhui Zhou

Received: 7 October 2006 / Accepted: 12 December 2006 / Published online: 1 February 2007 # Springer Science + Business Media B.V. 2007

Abstract Polycyclic aromatic hydrocarbons (PAHs) are important organic contaminants with great significance for China, where coal burning is the main source of energy. In this study, concentrations, distribution between different phases, possible sources and eco-toxicological effect of PAHs of the Yangtze River were assessed. PAHs in water, suspended particulate matters (SPM) and sediment samples at seven main river sites, 23 tributary and lake sites of the Yangtze River at the Wuhan section were analyzed. The total concentrations of PAHs in the studied area ranged from 0.242 to 6.235 μg/l in waters and from 31 to 4,812 μg/kg in sediment. The average concentration of PAHs in SPM was 4,677 μg/kg, higher than that in sediment. Benzo(a)pyrene was detected only at two stations, but the concentrations were above drinking water standard. The PAHs level of the Yangtze River was similar to that of some other rivers in China but higher than some rivers in foreign countries. There existed a positive relationship between PAHs concentrations and the TOC contents in sediment. The ratio of specific PAHs indicated that PAHs mainly came from combustion process, such as C. Feng : X. Xia (*) : Z. Shen : Z. Zhou State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, People’s Republic of China e-mail: [email protected] C. Feng e-mail: [email protected]

coal and wood burning. PAHs may cause potential toxic effect but will not cause acute biological effects in sedimentary environment of the Wuhan section of the Yangtze River. Keywords Benzo[a]pyrene (BaP) . Polycyclic aromatic hydrocarbons (PAHs) . Sediment . Sources . Suspended particulate matters (SPM) . Yangtze River

Introduction Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in different compartments of environment. Due to their toxic, mutagenic and carcinogenic characteristics, PAHs are considered to be hazardous to the biota and environment. These compounds are generally produced by natural and anthropogenic processes and can be introduced into the environment through various routes. Anthropogenic input from incomplete combustion, oil spills, domestic and industrial wastewater discharges, as well as atmospheric fallout of vehicle exhaust and industrial stack emission have caused significant accumulation of PAHs in aquatic environment. It is believed that the environmental fate and behavior of PAHs are ultimately determined by their physicochemical properties and sediment characteristics, such as organic content, size distribution and partition coefficient. For example, a positive linear relationship has been demonstrated between PAH

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concentrations and the total organic carbon (TOC) in sediment (Simpson, Mosi, Cullen, & Reimer, 1996). Because of their low water solubility and high partition coefficients, these compounds are strongly sorbed to the particles associated with the organic compounds of solid phase matrix and can be deposited to the underlying sediments. In order to minimize or prevent the adverse effects of persistent organic pollutants (POPs), many studies illustrated the fate of PAHs in natural environments. PAHs occurrence in some European river waters were extensively investigated (Manoli & Samara, 1999; Notar, Leskovsek, & Faganeli, 2001; Soclo, Garrigues, & Ewald, 2000). In China, the major investigation focused on PAHs concentrations of offshore water and sediments (Mai et al., 2001; Zhou & Maskaoui, 2003). In addition, PAH distribution of inland rivers in some big cities such as Hangzhou and Tianjin were also investigated (Shi et al., 2005; Zhu, Chen, & Wang, 2004). The Yangtze River is the longest river in China and the third longest river in the world. It is one of the most important rivers for water supply and irrigation in southern China. Wuhan is the capital city of Hubei province and a very important city along the mainstream of the Yangtze River. The population of Wuhan is about 7.86 million with a density of 919 persons/km2. The gross domestic product (GDP) of Wuhan city accounted for about 31% of the whole GDP of Hubei province in 2004. Wuhan section of the Yangtze River provides about 764,660,000 m3 water per year for domestic, industrial and agricultural uses of Wuhan city (Hubei Statistical Bureau, 2005). Wuhan city has five basic industries including electronic information, automobiles, steel, bioengineering and pharmaceutics. Its industry is becoming stronger and stronger (Xiong, Gan, & Luo, 2004). In the past few decades, with the industrial and economic development, water pollution has become more and more serious, especially for the organic pollution. A few researchers have studied the pollution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) of some sections of the Yangtze River (Jiang, Xu, Martens, & Wang, 2000; H. L. Liu, M. Liu, Cheng, & Ou, 2005). As for PAHs pollution, although a few investigations have been carried out in some sections of the Yangtze River, most of them focused on only one or two phases (Liu et al., 2001; Xu, Jiang, Wang, Quan, & Martens, 2000). PAH

Environ Monit Assess (2007) 133:447–458

distribution in the three phases of surface water, sediments and SPM has not been particularly reported in Wuhan section of the Yangtze River. The purpose of the present research was to determine the concentration, distribution and sources of PAHs in water, sediment and SPM phases of the Wuhan section of the Yangtze River. Samples at seven main river sites and 23 tributary and lake sites of the section were collected in both high-water and low-water seasons in 2005. PAH concentrations in the three phases were analyzed. Also, molecular-ratio method was applied to identify possible sources of PAHs. Finally, the potential toxic effects of PAHs in the Yangtze River were assessed.

Materials and methods Study area Wuhan section is in the middle reach of the Yangtze River. There are many tributaries and lakes converging to the main river in the Wuhan section. Among them the longest tributary is the Han River, which stores almost 10,000,000 kw water energy and extends as long as 1,577 km with the average water flow of 1,640 m3/s. A total of 30 sampling stations in the mainstream and its tributaries of the Wuhan section were selected (Fig. 1). Seven stations were located in the main river, and 23 stations were located in the tributaries. The Jinkou sampling station (Station 2) represents the inflow to the Wuhan section of the Yangtze River. The Wuhanguan (Station 18) and Yujiatou (Station 19) stations reflect the PAHs contamination level after the main tributaries (such as Han River) merge into the main river. The Yangluo sampling station (Station 29) represents contamination level after the Yangtze River flow out of the Wuhan section. Sample collection and pre-treatment Samples were collected in July 27–30, 2005 (high water season) and December 6–10, 2005 (low water season). Surface sediment samples were collected using a pre-cleaned grab sampler and water samples were collected using 3 l pre-cleaned aluminum jars with on-site extraction. Suspended particle samples were taken with a press filter (0.8 μm, glass fiber


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Fig. 1 Map of sampling sites in Wuhan section of the Yangtze River (1. Jinshui, 2. Jinkou, 3. Dongjing River, 4. Zhuankou, 5. Dongfengzha, 6. Baishazhou, 7. Tangxun River, 8. Houguan Lake, 9. Longyang Lake, 10. Moshui Lake, 11. Xunsi River, 12. Dong Lake, 13. Yanxi Lake, 14. Changfengqiao, 15. Qinduan River, 16. Guocikou, 17. Jijiazui, 18. Wuhanguan, 19. Yujiatou, 20. Luojiadun, 21. Lijiadun, 22. Fu River, 23. Zhujia River, 24. Xiao Bay, 25. Hou Lake, 26. Tianxingzhou, 27. Qingshangang, 28. Wuhu, 29. Yangluo, 30. Daoshui River)

filter membrane). All sediment, suspended particle and water extracts were quickly carried back to the laboratory where they were stored at 4°C before further analysis. Water samples were extracted using a solid-phase extraction (SPE) system (Supelco). The SPE cartridges were first conditioned with 10 ml methanol followed by 10 ml de-ionized water. Two liters of water samples were filtered by 0.45 μm membrane and then water samples passed through the cartridges at a flow rate of 6 ml/min under vacuum. Following extraction, the cartridges were eluted with 10 ml dichloromethane. The volume of the extracts was reduced by N2 blow-down in a water bath and was adjusted to 0.5 ml volume with methanol for analysis. After the sediment and SPM were freezing dried, they were grounded and sieved (100 mesh). Ten grams of sediment was extracted three times based on the modified procedure of International Organization for Standardization (1998); the detailed procedure for the pretreatment of sediment and SPM samples has been described in the previous research (Li, Xia, & Yang, 2006).

Chemicals Standard PAHs in a mixture were obtained from state standard center (Dr. Ehrenstorfer GmbH PAH-Mix9), these compounds are as follows: naphthalene (Nap), acenaphthylene (Acy), acenaphthene (Ace), fluorine (Fle), phenanthrene (Phe), anthracene (An), fluoranthene (Flu), pyrene (Pyr), benzo(a)anthracene (BaA), chrysene (Chr), benzo(b)fluoranthene (BbF), benzo (k)fluofanthene (BkF), benzo(a)pyrene (BaP), dibenzo(a,h)anthracene (DahA), benzo(ghi)perylene (BghiP), indeno(1,2,3-cd)pyrene (InD). All solvents used for sample processing and analysis (dichloromethane, acetone, hexane petroleum ether, cyclohexane, methanol) were HPLC grade. Anhydrous sodium sulfate was of analytical grade and was activated at 450°C to remove impurities before using. Analytical method The physicochemical properties of sediment were detected at the Analytical and Testing center. Particle size was measured using Laser Particle Size Ana-

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lyzer (Mastersizer 2000, UK). TOC was measured using Total Organic Carbon Analyzer (Elementar, Germany). The PAHs extracts of the water, sediment and SPM samples were analyzed by high-performance liquid chromatography (HPLC) using a Varian PAH special column (Varian ChromSper 5 PAHs 250×4.6 mm) installed in a liquid chromatogram (Waters1525, USA) with fluorescence detector (Waters 474). Excitation wavelengths were automatically set by a time program. The mobile phases were HPLC-grade methanol and de-ionized water in a linear gradient program. The temperature of the column oven was kept under the room temperature (around 25°C). Detailed instrumental conditions were as follows: eluent A, methanol (HPLC grade.); eluent B, deionized water plus methanol (1:1,v/v); methanol gradients were 75 to 100%; flow rate, 1 ml/min. Gradients were 50 to 100% A using curve 6 in 35 min, hold 10 min using curve 3, then back to initial conditions. Before sample analysis, relevant standards were analyzed to check column performance. Peak height and resolution and the limit of detection, with each set of samples to be analyzed, a solvent blank, a standard mixture and procedural blank were run in sequence to check for contamination peak identification and quantification. Identity and retention time of PAHs were confirmed by the mixture and reference materials of Phe, Flu, Chr, BaP, BghiP, acquired from the National Research Center for Certified Reference Materials of China. The 16 PAHs were identified mainly by their retention time.

Quality control A strict regime of quality control was operated in the experiment. Quantification was performed by the external standard method using a 16 PAHs reference material mixture (16 PAHs, Dr.Ehrenstorfer GmbH PAH-Mix9), with correlation coefficients for calibration curves all higher than 0.993. Recoveries of 16 PAHs ranged from 87.2 to 92.8% with Nap relatively low (64.4%) in water phase, and from 70.4 to 94.8% in sediment. PAH concentrations were recoverycorrected. Field and analytical duplicates were analyzed on 20% of the samples taken.

Results and discussion PAHs contents in water phase We only analyzed PAHs concentrations in the water phase in high water season. As shown in Table 1, concentrations of PAHs in water samples ranged from 0.322 to 6.235 μg/l with a mean value of 2.095 μg/ l in the main river, and ranged from 0.242 to 1.379 μg/l with a mean value of 0.681 μg/l in the tributaries. PAH concentrations in the mainstream were higher than those in the tributaries probably because of the re-suspension of sediment. In the mainstream, the water flow rate is higher than the tributaries and lakes, so sorbed PAHs could be released from the suspended particles, which increased the water phase concentration. Meanwhile,

Table 1 PAHs concentrations in water samples of the Yangtze River (μg/l) Location

Nap

Acy

Ace

Fle

Phe

An

Flu

Pyr

BaA

Chr

B(a)P Σ11 PAHs

Main stream Zhuankou Baishazhou Left Wuhanguan Right Wuhanguan Left Yujiatou Right Yujiatou Tributaries Dongfengzha Jijiazui Moshui Lake Dong Lake Yanxi Lake

nd 0.065 0.109 0.109 nd 0.322 0.470 0.046 nd 0.080 0.053

0.297 nd 0.263 0.262 nd nd nd 0.104 nd nd 0.195

nd nd 1.696 0.696 nd nd nd nd nd nd nd

0.603 nd 0.492 nd nd nd nd 0.201 nd nd nd

0.122 0.399 0.193 0.193 0.122 nd nd 0.104 0.397 0.116 0.115

0.159 0.194 nd nd nd nd nd nd nd nd 0.108

0.354 nd nd 2.611 0.248 nd nd 0.162 nd nd 0.215

0.023 nd nd 1.029 nd nd nd nd 0.703 0.046 nd

0.125 nd 0.214 0.215 nd nd nd 0.012 nd nd nd

nd nd 0.120 0.120 nd nd nd nd nd nd nd

nd 0.214 nd nd nd nd nd nd 0.279 nd nd

nd-not detected

1.684 0.874 3.087 6.235 0.370 0.322 0.470 0.629 1.379 0.242 0.686


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PAHs species detected in the tributary stations were fewer than those in the mainstream mainly because of the different origins of PAHs. Of all the water sampling sites, the PAHs detected in water phase were mainly two to four rings. The detection frequencies of the predominant PAHs were as follows: Phe 81.8%, Nap 72.7%, Flu 45.5%. Phe was the most frequently detected PAHs in water samples. Although the detection frequency of Nap was very high, its concentration was relatively low probably because of its high vaporization properties. Fewer high-weight PAHs were detected mainly because of their low solubility and high partition coefficient. For example, five-ring PAHs was rarely detected, and Benzo(a)pyrene was detected only at Baishazhou of the mainstream and Moshui Lake of the tributaries, with the concentration exceeding the Environmental Quality Standard for Surface Water (2.8 ng/l, GB3838-2002) (SEPA, 2002a, 2002b). For the six specified PAHs (Flu, BbF, BkF, BaP, BghiP, InD), their concentration in the water phase of the main stream at Zhuankou, Wuhanguan, Baishazhou and Yujiatou were above the standard (0.2 μg/l) (State standard of China (GB13198-91)); while in the tributaries, only the concentrations in the Moshui Lake and Yanxi Lake were above the standard.

Compared with other rivers in China, the total PAHs concentrations in water samples of the Yangtze River are higher than the levels found in the Yellow River (Li et al., 2006), the Tonghui River in Beijing (Zhang, Huang, Yu, & Hong, 2004), the Gaoping River in Taiwan (Doong & Lin, 2004), but lower than the Jiulong River in Hong Kong (Maskaoui, Zhoub, Hong, & Zhang, 2002) (Table 2). Compared with the rivers in some foreign countries, the PAH concentrations of the Yangtze River are higher than those of the Seine River in France (Fernandes, Sicre, Boireau, & Tronszynski, 1997) and the Mississippi River in the US (Mitra & Bianchi, 2003). PAHs contents in sediment As shown in Table 3, the PAH concentrations in sediment at different sampling stations showed wide variations. In high water season, the PAH concentrations ranged from 303 to 3,995 μg/kg with a mean value of 2,032 μg/kg in the mainstream, and ranged from 4,121 to 4,262 μg/kg with a mean value of 2,229 μg/kg in the tributaries. In low water season, the PAH concentrations ranged from 72 to 1,206 μg/ kg with a mean value of 497 μg/kg in the mainstream, and ranged from 31 to 4,813 μg/kg with a mean value

Table 2 Total PAHs concentration in water and sediment from various sites in the world Phase

Locations

ΣPAHs range (ng/L, μg/kg)

Mean(ng/L, μg/kg) ±SD

References

Water

Seine River, France Mississippi River, US Yellow River, China Tonghui River, China Gaoping River, China Jiulong River Estuary, China Wuhan section of Yangtze Chesapeake Bay, US Kitimat Harbour, Canada Todos Santos Bay, Mexico Malaysia Victoria Harbour, HongKong Yellow River, China Pearl River Delta, China Yangtze Estuary, China Jiulong River Estuary, China Tonghui River, Beijing, China Nanjing section of Yangtze Wuhan section of Yangtze

4∼36 5.6∼68.9 179∼369 192.9∼2651 10∼940 6960∼26920 321.8∼6234.9 0.56∼180 310∼528000 7.6∼813 4∼924 700∼26100 31∼133 156∼10811 263∼6372 59∼1177 127.1∼927.7 213.8∼550.3 72.4∼3995.2

20±13 40.8±32.9 248±78 762.3±777.4 430 17050±5280 2095.2±2276.2 52 66700±140000 96 187 5277±7904 76.7±42.3 2057±3063 1661±1915 334±337 540.4±291.8 – 1334.5±1215.1

Fernandes et al. (1997) Mitra and Bianchi (2003) Li et al. (2006) Zhang et al. (2004) Doong and Lin (2004) Maskaoui et al. (2002) This study Forster and Wright (1988) Simpson et al. (1996) Macias-Zamora et al. (2002) Zakaria et al. (2002) Hong et al. (1995) Li et al. (2006) Mai et al. (2002) Liu et al. (2001) Maskaoui et al. (2002) Zhang et al. (2004) Xu et al. (2000) This study

Sediment

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Table 3 The concentration ranges and mean values of PAH in sediment of the mainstream and tributaries from the Yangtze River PAH

Range in the main river(μg/kg)

Mean ± standard deviation (μg/kg)

Range in the tributaries (μg/kg)

Mean ± standard deviation (μg/kg)

Nap Acy Ace Fle Phe An Flu Pyr BaA Chr BbF BkF BaP DahA BghiP InD Total PAHs

nd 9.4∼595.3 3.0∼567.6 18.1∼671.8 42.2∼146.3 15.6∼506.6 17.0∼1852.8 18.9∼185.1 5.4∼132.3 8.2∼66.7 7.0∼1115.1 46.7∼62.0 0.7∼95.4 31.2∼316.8 7.2∼369.3 4.9∼328.1 72.4∼3995.2

nd 146.5±222.7 173.6±228.3 360.8±317.8 103.0±42.8 302.4±185.4 828.0±695.3 136.4±79.0 39.2±42.6 45.6±24.4 259.1±479.9 52.5±8.3 49.5±44.1 146.2±115.4 102.2±150.8 104.1±124.4 1334.5±1215.1

16.9∼113.7 31.2∼336.6 0.5∼728.7 16.8∼217.7 0.4∼130.0 41.6∼434.7 3.5∼1242.9 4.1∼189.7 5.7∼409.5 19.5∼247.5 8.8∼748.7 5.9∼231.2 1.8∼559.6 24.4∼2796.9 0.9∼1934.6 7.4∼991.4 31.1∼4812.6

43.6±61.3 133.0±117.5 108.4±222.0 59.8±53.8 62.4±59.0 205.1±178.8 289.4±451.6 69.5±71.6 108.3±126.2 125.7±112.0 207.0±226.7 60.6±78.4 93.8±160.6 655.8±965.7 319.0±661.2 164.2±266.7 1294.6±1543.1

of 1,119 μg/kg in the tributaries. Therefore, the PAH concentrations in the tributaries were higher than those in the mainstream. The PAHs contamination in sediment was mainly dominated by three-, four- and five- ring PAHs. In high water season, there was a high detection frequency for InD and BghiP (66.7%), and Phe and Flu (55.6%). In low water season, the predominant PAH were BaA, Fle, InD with the detection frequencies of 90.9, 81.8 and 77.3%, respectively. This was due to the fact that high-molecular-weight PAHs tend to be associated with sediment. According to the above mentioned data, the mean concentration of PAHs in high water season was higher than that in low water season. This was probably due to the differences of total organic carbon (TOC) content in these two seasons. As shown in Table 4, TOC content was higher in the high-water season than in the low-water season. Since TOC content in sediment is a major factor controlling the fate of PAHs, and a higher TOC content will lead to a higher partition coefficient of PAHs between sediment and water, the relatively higher concentration occurred in the sediment samples of the high-water season. As shown in Table 2, the total PAHs concentration in sediment of the Wuhan section of the Yangtze

River are higher than the levels found in some other Chinese sites such as the Yellow River (Li et al., 2006), the Tonghui River (Zhang et al., 2004), the Jiulong River (Maskaoui et al., 2002) and the Nanjing section of the Yangtze River (Xu et al., 2000), but lower than the Victoria Harbour (Hong et al., 1995) of Hong Kong, the Pearl River Delta (Mai et al., 2002) and the Yangtze estuary (Liu et al., 2001). Compared with the rivers of some foreign countries, the PAHs concentrations of the study area are higher than the Chesapeake Bay, US (Forster & Wrighrt, 1988), the Todos Santos Bay, Mexico (Macias-Zamora, MendozaVega, & Villaescusa-Celaya, 2002), but lower than the Kitimat Harbour, Canada (Simpson et al., 1996). PAHs contents in SPM PAH concentration in SPM samples from three sampling stations in high water season and six sampling stations in low water season were analyzed (Table 5). In high water season, the concentration of PAHs in SPM ranged from 4,287 to 5,001 μg/kg with a mean value of 4,532 μg/kg. The predominant PAHs were Ace and Flu and they accounted for 37.95 and 35.11% of the total PAHs content, respectively. In low water season, the total PAH


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Table 4 Physicochemical properties of sediments in the mainstream and tributaries of the Yangtze River Time

High water season

Sampling sites

Mainstream

Tributaries Low water season

Mainstream

Tributaries

pH

Zhuankou Left Wuhanguan Right Wuhanguan Baishazhou Left Yujiatou Right Yujiatou Longyang Lake Dongjing River Jinkou Zhuankou Wuhanguan Wuhu Yangluo Jinshui Qinduan River Qingshangang Daoshui River Tangxun Lake Hou Lake Xunsi River Xiao Bay Fu River Lijiadun Luojiadun Zhujia River Dong Lake Jijiazui Dongjing River Changfengqiao Guocikou

7.99 7.84 7.88 7.91 8.02 7.65 7.03 7.62 7.89 7.73 8.10 7.93 7.86 7.51 7.32 7.70 6.49 6.25 6.40 7.12 7.08 7.08 7.10 6.94 7.46 7.23 7.91 7.42 8.21 8.05

concentration ranged from 952 to 15,347 μg/kg with the average concentration of 4,822 μg/kg. The predominant compounds were Ace, Fle and BaA. Compared with sediment phase, more kinds of PAHs were detected and relatively higher concentrations of PAHs were found in SPM from the sampling sites (Fig. 2). This indicated that SPM is the most active factor in water bodies, which plays an important role in the whole transportation process of PAHs. On the one hand, SPM can absorb organic pollutants from water phase, and carry them into sediment; on the other hand, sediment can re-suspend and become SPM and release organic pollutants into water phase.

TOC/%

2.09 1.82 2.02 1.27 0.66 1.16 8.47 1.03 1.06 1.90 0.16 0.47 0.49 8.98 1.04 1.41 1.77 1.09 1.83 7.83 0.97 6.03 1.63 8.38 1.49 2.56 0.32 1.84 0.21 0.22

Grain size analysis /% 250 μm

33.4 34.9 38.8 46.7 14.1 46.1 48.5 43.3 44.8 30.7 7.3 9.4 25.0 44.3 49.5 53.0 59.7 50.3 63.0 61.8 73.4 63.5 57.7 57.4 49.1 39.3 11.7 59.2 4.7 5.1

32.3 34.7 35.6 35.3 19.2 35.9 41.1 29.3 37.8 33.2 14.1 19.1 25.2 40.6 40.6 44.1 32.0 43.6 34.7 33.8 25.3 35.1 40.4 38.7 40.2 46.2 25.5 31.1 18.8 18.1

34.3 30.4 25.6 18.0 66.4 18.0 10.4 27.4 17.4 36.1 72.6 71.2 49.5 15.1 9.9 2.9 8.2 6.2 2.4 4.3 1.3 1.4 2.0 3.9 10.6 14.6 59.3 9.7 70.9 68.9

0.01 0.01 0 0 0.35 0 0 0.03 0 0.02 5.97 0.34 0.29 0.00 0 0 0 0 0 0 0 0 0 0 0 0 3.48 0 5.58 7.88

Relationship between PAHs concentration and physicochemical properties of sediment TOC and particle size (Table 4) analysis of the sediments demonstrated some differences among the characteristics of samples. TOC content of the tributary sediments ranged from 0.22 to 8.98% with a mean value of 2.92%. TOC of the mainstream sediment ranged from 0.16 to 2.09% with a mean value of 1.18%. It is obvious that the TOC content of the tributaries was higher than that of the mainstream. Besides, the content of particles with size less than 50 μm was higher in the tributaries than in the mainstream. The relationship between total PAHs concen-

12.3 nd 1648.7 476.2 178.0 192.7 1178.5 288.2 nd nd nd 311.9 1.0 4287.7

149.5 nd 2048.7 515.3 168.4 300.2 1365.7 305.2 nd nd nd 140.3 7.7 5001.5

nd nd 1482.6 nd 127.2 169.3 2175.6 259.4 nd nd nd 89.9 2.1 4306.5

13.8 613.1 196.8 179.8 nd nd nd nd 55.8 25.3 nd nd nd 1084.6

nd nd 14.7 80.6 nd nd nd nd nd nd nd nd nd 95.3

Wuhanguan

Zhuankou

Yujiatou

Zhuankou

Wuhanguan

Low water season

High water season

nd-not detected

Nap Acy Ace Fle Phe An Flu Pyr B(a)A Chr BbF BaP BghiP Total

PAHs

nd 3161.5 109.9 837.1 nd nd 198.4 114.7 367.4 nd 1735.6 nd 454.1 6978.7

Zhujia River

Table 5 Distribution of PAHs concentrations in suspended particulate matters (μg/kg)

124.9 nd 536.1 nd nd nd nd nd 24.3 nd 69.5 nd nd 754.7

Jijiazui nd 2284.9 2723.7 727.9 nd nd nd nd 699.5 nd 2362.1 nd nd 8798.1

Xunsi River nd 192.5 42.6 86.7 nd 278.9 nd nd 12.7 31.9 52.1 nd nd 697.3

Changfengqiao 12.3∼149.5 192.5∼3161.5 14.7∼2723.7 80.6∼837.1 127.3∼178.0 169.4∼300.2 198.4∼2175.6 114.7∼305.2 12.7∼699.5 25.3∼31.9 52.1∼2362.1 89.9∼311.9 1.0∼454.1 95.3∼8798.1

Concentration range

75.1±72.4 1563.0±1397.2 978.2±1016.2 363.0±319.7 157.9±27.0 235.3±64.0 1229.6±812.3 241.9±86.9 231.9±299.7 28.6±4.6 1054.8±1176.0 180.8±116.4 116.2±225.3 3556.1±3092.0

Mean ± SD

454 Environ Monit Assess (2007) 133:447–458


455

Fig. 2 Distribution of PAHs concentration in different phases of the Yangtze River

trations and TOC content was not obvious while some individual PAHs concentration correlated well with TOC content. The correlation coefficients were DahA (R=0.9828), BghiP (R=0.8783) and BaA (R=0.9318) in high water season, and Fle(R=0.8792), InD (R= 0.9001), BbF(R=0.9154), BaP(R=0.8960) and Acy (R=0.9256) in low water season. It demonstrated that the sorbed PAHs had a positive relationship with TOC content in the sediments. This was expected as it is well documented that hydrophobic organic substances will be mainly sorbed into particles through partition, which is in correlation with content of organic carbon (Chiou, Porter, & Schmeddling, 1983). When we conducted correlation analyses between the PAHs concentration and sediment particle size, we didn’t find significant relationship between them. Only InD concentration was positively correlated with the particle content with the size less than 10 μm (R= 0.6148) and Fle concentration with the particle content with the size from 10 to 50 μm (R=0.6123). Therefore, it was concluded that particle size was not a major influence factor for PAHs concentration in sediment. Source of PAHs in the Yangtze River Parent PAHs has both natural (plant debris, forest and prairie fires) and anthropogenic sources (fossil fuels combustion, etc.). Incomplete combustion of fossil fuels is always treated as a major production process

for PAHs. The ratios of individual PAHs could be used to assess the possible origins of PAHs. In an attempt to identify sources for the PAHs detected in this study, a source analysis was undertaken. Concentration ratios of PAHs with the same molecular weight including An/ (An+Phe) and Flu/(Flu+Pyr) were used to distinguish between combustion and petroleum sources of PAHs (Yunker et al., 2002). PAHs ratios in sediment with An/(An+Phe)0.1 indicates a typical of fuel combustion source. Another molecular ratio used to differentiate the sources of PAHs is Flu/(Flu+Pyr), with 0.4 being defined as the petroleum/combustion transition point. A ratio of Flu/ (Flu+Pyr)>0.5 is characteristic of grass, wood and coal combustion, while PAHs ratio of 0.4