The status of soil contamination by semivolatile organic chemicals (SVOCs) in China: A review

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a v a i l a b l e a t w w w. s c i e n c e d i r e c t . c o m

w w w. e l s e v i e r. c o m / l o c a t e / s c i t o t e n v

Review

The status of soil contamination by semivolatile organic chemicals (SVOCs) in China: A review Quan-Ying Cai a , Ce-Hui Mo b,⁎, Qi-Tang Wu a , Athanasios Katsoyiannis c,1 , Qiao-Yun Zeng a a

College of Resources and Environment, South China Agricultural University, Guangzhou 510642, China Department of Environmental Engineering, Jinan University, Guangzhou 510632, China c European Commission, Joint Research Centre, Institute for Health and Consumer Protection (IHCP), Physical and Chemical Exposure Unit, Ispra (VA), TP-281, Via E. Fermi 1, I-21020, Italy b

AR TIC LE I N FO

ABS TR ACT

Article history:

This paper summarizes the published scientific data on the soil contamination by

Received 13 June 2007

semivolatile organic chemicals (SVOCs) in China. Data has been found for more than 150

Received in revised form

organic compounds which were grouped into six classes, namely, polychlorinated dibenzo-

14 August 2007

p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), organochlorine

Accepted 17 August 2007

pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl

Available online 22 October 2007

ethers (PBDEs) and phthalic acid esters (PAEs). An overview of data collected from the literature is presented in this paper. The Chinese regulation and/or other maximum

Keywords:

acceptable values for SVOCs were used for the characterization of soils. In general, the

Semivolatile organic chemicals

compounds that are mostly studied in Chinese soils are OCPs, PAHs and PCBs. According to

Persistent organic pollutants

the studies reviewed here, the most abundant compounds were PAEs and PAHs (up to 46 and

Soil

28 mg kg− 1 dry weight, respectively); PCBs and OCPs occurred generally at concentrations

Contamination

lower than 100 μg kg− 1 dry weight. Nevertheless, quite high concentrations of PCDD/Fs, PCBs and PBDEs were observed in contaminated sites (e.g., the sites affected by electronic waste activities). The average concentrations of PAHs and OCPs in soils of North China were higher than those in South China. The principal component analysis demonstrated different distribution patterns for PAH, PCB and PCDD/F congeners and for the various sites/regions examined. The isomer ratios of DDTs and hexachlorocyclohexanes (HCHs) indicated different sources and residue levels in soils. Finally, this review has highlighted several areas where further research is considered necessary. © 2007 Elsevier B.V. All rights reserved.

Contents 1. 2. 3.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Materials studied and area descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Occurrence and distribution of SVOCs in the soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

210 210 211

3.1. 3.2.

211 214

Polycyclic aromatic hydrocarbons (PAHs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Polychlorinated biphenyls (PCBs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

⁎ Corresponding author. Tel./fax: +86 20 85226615. E-mail addresses: [email protected] (Q.-Y. Cai), [email protected] (C.-H. Mo), [email protected] (A. Katsoyiannis). 1 Currently at EC-JRC. 0048-9697/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2007.08.026

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3.3. Organochlorine pesticides (OCPs). . . . . . . . . . . . 3.4. Polychlorinated dibenzo-p-dioxins and dibenzofurans 3.5. Polybrominated diphenyl ethers (PBDEs) . . . . . . . 3.6. Phthalic acid esters (PAEs) . . . . . . . . . . . . . . . 4. Conclusion and future perspectives . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.

Introduction

The last decades are characterized by the increased usage of complex hydrophobic organic chemicals for various purposes such as organochlorine pesticides (OCPs) in agriculture; polychlorinated biphenyls (PCBs) in transformers, capacitors, paints; polybrominated diphenyl ethers (PBDEs) as flame retardants, etc. Furthermore, phthalic acid esters (PAEs) can nowadays be found everywhere as a result of the usage of plastics. Polycyclic aromatic hydrocarbons (PAHs) have also been detected in all kinds of environmental compartments because of the usage of fossil fuels and of the various combustion processes. In addition, municipal solid waste incineration or uncontrolled burning (e.g., plastics, crop residues), the common practices for waste elimination, has resulted in emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. All these are semivolatile organic chemicals (SVOCs); they are highly toxic, recalcitrant to degradation processes and have a potential for long-range transport (Katsoyiannis and Samara, 2004). Their global occurrence and the various health effects that are associated with them have caused the increased concern of public, scientific and governmental organizations. Among these SVOCs, PCDD/Fs, PCBs, and some of OCPs have been internationally classified as the “persistent organic pollutants (POPs)”; the Stockholm convention of 2001 banned the production and use of POPs worldwide (Katsoyiannis and Samara, 2007). Chemicals that have some of the POPs characteristics, like PAHs or PBDEs, are usually characterized as “potential POPs”, or POP-like chemicals. In China, the rapidly developing industrial and agricultural activities, municipal development and increased usage of chemicals have severely deteriorated the environmental

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215 217 220 220 221 221 222

quality (Fu et al., 2003). Subsequently, during the last few decades, the scientific interest about the occurrence of SVOCs in various environmental compartments of China is continuously increasing, something that can be mirrored by the number of relevant publications (Fig. 1). The soil quality has always been important for soil microbial, plant and animal life, including humans. Soil pollutants can pass to vegetation and enter food chains. Furthermore, the soil has high affinity for hydrophobic organic pollutants and can act as a natural sink. It is said that the halflife of SVOCs in soils can be very long (months to several years), highlighting the importance of soil pollution monitoring and characterization. To date, a limited number of studies have focused on the occurrence of SVOCs in Chinese soils and thus the present work aimed at gathering (to our knowledge for the first time) all the existing data published after 1995. The literature data is presented, discussed, statistically treated to glean further information, gaps are highlighted and recommendations for further studies are given.

2.

Materials studied and area descriptions

In China, the studies about soil SVOCs have focused on various classes of priority organic pollutants listed by the US environmental protection agency (USEPA), including PAHs, PCBs, PCDD/Fs, PBDEs, PAEs, OCPs, organic phosphorous pesticide, etc. In this work, the aforementioned six classes of SVOCs are reviewed and discussed. The main cities and regions that have been studied are North China (e.g., Beijing, Shengyang, Tianjin, Dalian), East China (e.g., Qingdao, Nanjing, Shanghai, Hangzhou, Xiamen, Taiwan) and South China

Fig. 1 – Number of publications about PCBs/PAHs/pesticides per year in China (source: ELSEVIER — SCOPUS™; searching for China and PCBs or PAHs or Pesticides in article's “title, abstract or keywords”).

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211

Fig. 2 – The main areas examined for the SVOCs in the soil of China.

(e.g., Guangzhou, Shantou, Hong Kong), particularly in the Yangtze River Delta (including Shanghai, part of Zhejiang Province and Jiangsu Province) and the Pearl River Delta (including Guangzhou, Foshan, Dongguan, Shenzhen, Hong Kong, Macao, etc.) (Fig. 2). It should be noted that all comparisons attempted between the SVOC levels of regions or cities are based on the reported results and is assumed that no big differences exist between the results produced by all reporting scientists/laboratories. The authors are aware of the fact that differences between laboratories are common in trace chemical analysis, but when dealing with published results, the latter cannot but be considered as correct. Moreover, when only descriptive statistical data of individual compounds are available in the literature, only the average values of chemicals were applied for statistics and the corresponding area examined was taken as one sample in the present work. Statistical analysis including the analysis of variance (ANOVA) and principal component analysis (PCA) was performed using SPSS 10.0 for Windows software packages.

3. Occurrence and distribution of SVOCs in the soil 3.1.

Polycyclic aromatic hydrocarbons (PAHs)

More than 600 soil samples collected from different cities and regions have been analyzed for the occurrence of PAHs in nearly 30 studies. The target compounds were mainly the 16 USEPA PAHs, namely, naphthalene (Nap), acenaphthylene (Acy), acenaphthene (Ace), fluorene (Fl), phenanthrene (Phe),

anthracene (Ant), fluoranthene (Fla), pyrene (Pyr), benzo[a] anthracene⁎ (BaA), chrysene⁎ (Chr), benzo[b]fluoranthene⁎ (BbF), benzo[k]fluoranthene⁎ (BkF), benzo[a]pyrene⁎ (BaP), dibenzo[a,h]anthracene⁎ (DahA), indeno[1,2,3-cd]pyrene⁎ (InP) and benzo[ghi]perylene (BghiP) (The compounds with asteroid are carcinogenic PAHs). An overview of the results presented in the various studies is given in Table 1 (all results are expressed on a dry weight basis). Great variations were observed among different cities/regions, even within the same city (e.g., Beijing). The sum concentrations of PAHs (∑PAHs) ranged from not detectable (ND) (Hong Kong) to 27.8 mg kg− 1 (Beijing) (except the one obtained near a small-scale smelting industry, where the ∑PAHs was up to 183 mg kg− 1; Lin et al., 2005), with a mean value of 1.2 (±1.1) mg kg− 1 (mean±S.D.). The sum concentrations of seven carcinogenic PAHs (∑PAHscarc) varied from ND to 2.63 mg kg− 1, with a mean value of 0.45 (± 0.47) mg kg− 1. These values were comparable with the ones reported for Orleans, USA (Mielke et al., 2004), France (Motelay-Massei et al., 2004), Germany and other regions (Wilcke, 2007). The occurrence of PAHs in soils is not yet regulated in China, and, even worldwide, there are only a few recommendations or guidelines. Maliszewska-Kordybach (1996) proposed a classification of soil contamination based on the ∑PAHs as follows: non-contaminated soil (b200 μg kg− 1), weakly contaminated soil (200–600 μg kg− 1), contaminated soil (600– 1000 μg kg− 1) and heavily contaminated soil (N1000 μg kg− 1). According to this classification, 32% of samples are characterized as heavily contaminated, 12% as contaminated, 34% as weakly contaminated and only 22% as not contaminated. Another classification by the Canadian Council of Ministers of Environment was proposed and included three main

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Table 1 – Concentrations of polycyclic aromatic hydrocarbons (PAHs) in the soil, China Location

Na

Soil type

Total concentrations of PAHs (mg kg− 1) Min

Max

Mean

References

Median

North China Shenyang Dalian Tianjin Beijing Beijing Beijing Beijing Beijing

30 17 – 9 47 8 31 20

Agriculture b Surface Surface Farmland b Rural and suburban Greenhouse Urban Roadside

950 190 301 5 16 1920 112 147

2790 8595 6248 297 3884 7840 27,800 6610

2133 1964 3275 87 1347 3510 6400 1818

– 1104 – 58 – – 1601 –

Song et al. (2006) Wang et al. (2007a) Tao et al. (2004) Duan et al. (2005) Chen et al. (2005b) Ma et al. (2005) Ma et al. (2003) Tang et al. (2006) Chu et al. (2003)

East China Hangzhou Zhejiang Province Xiamen Minjiang River Estuary Yangtze River Delta Eastern China Ya-Er Lake area Southeast China

3 21 2 – 30 – – 65

Surface Surface Agricultural Rural Rural and suburban Paddy c Surface Surface d

60 85 502 128 8.6 108,000 – 0

616 676 945 465 3881 183,000 – 530

298 350 724 313 397 152,000 58 33

220 – – – 219 – –

Chen et al. (2004) Zhu et al. (2007) Maskaoui et al. (2006) Zhang et al. (2004) Ping et al. (2006) Lin et al. (2005) Chen et al. (1997) Xing et al. (2006)

Southwest China Guiyang Lhasa

13 –

Urban and suburban Wetland

61 ND

1560 195

567 82

511 –

Hu et al. (2006) Liu et al. (2003)

South China Guangzhou Shantou Shantou Guiyu (Shantou) Guiyu (Shantou) Hong Kong Hong Kong Pearl River Delta Pearl River Delta

43 – – 18 49 138 53 50 260

Vegetable filed Surface Urban and suburban Surface d Surface d Surface Rural and urban Vegetable field Agricultural

42 45 22 94 45 ND 7.0 160 3.3

3077 3206 1256 593 3206 19,500 410 3700 4.79

422

285

317 372 582 443 55 1480 244

– 428 389 – – 1327 139

Chen et al. (2005a) Yu et al. (2006) Hao et al. (2004) Leung et al. (2006) Yu et al. (2006) Chung et al. (2007) Zhang et al. (2006b) Cai et al. (2007) Yang et al. (2007)

Other countries Orleans Orleans France

19 19 37

Inner-city Suburban Surface

906 527 450

7285 3753 5650

– – 2510

2927 731 –

Mielke et al. (2004) Mielke et al. (2004) Motelay-Massei et al. (2004)

a b c d

Number of samples or sampling sites. Soil was irrigated by effluents from biological treatment plants. Adjacent to a small-scale metal smelting industry. Affected by electronic waste activities.

categories, namely, class A, or clean soil when the concentration of BaP is less than 100 μg kg− 1; class B, or slightly polluted soil (and further investigation is required) when the concentration of BaP is less than 1000 μg kg− 1; and class C, or seriously polluted soil (immediate remediation is required) when the concentration of BaP is up to 10,000 μg kg− 1 (CCME, 1991). Following this classification, only 19% of samples were slightly polluted by BaP, mainly the ones from North China. Totally, the average ∑PAHs and ∑PAHscarc in the soils of North China were significantly higher (P b 0.01) than in the other regions (Fig. 3). This is in good agreement with the fact that PAH concentrations in tropical/subtropical soils are lower than in temperate soils under similar land use (Wilcke, 2000). The higher PAH concentrations in soils of North China than in South China is potentially the result of more frequent burning for

space heating in the north. Furthermore, PAHs in soils may be removed through the process of volatilization, which is expected to occur in higher rate in South China, as temperatures are generally higher. When comparing within the same region or city, the ∑PAHs in soils decreased along industrial ≈ roadside N urban N residential N suburban N agricultural (Table 2). Several studies in other countries also demonstrate that the ∑PAHs in industrial and urban soils are generally higher than in suburban and agricultural ones (Wilcke, 2000; Mielke et al., 2004; MotelayMassei et al., 2004). All 16 individual PAHs were detected in various frequencies of occurrence. The average concentrations of individual PAHs in the soils throughout China ranged from 31 to 136 μg kg− 1, and the ones in North China were also higher than the respective ones of other regions (except of acenaphthylene

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213

Fig. 3 – The average concentrations of SVOCs in the soils of different regions (a) ∑PAHs and ∑PAHscarc; (b) ∑PCBs, ∑DDTs and ∑HCHs; (c) individual PAHs.

and indeno[1,2,3-cd]pyrene) (Fig. 3c). Concerning the ratio of sum low molecular weight PAHs (≤3 rings) concentrations to high molecular weight PAHs (≥4 rings) concentrations (R≤ 3/≥ 4), it is less than 1.0 in 87% of samples, but up to 14 was observed in agricultural soils used for growing vegetables (vegetable soils) in the Pearl River Delta (Cai et al., 2007), indicating again that large variations exist throughout the country. The average ratios of R≤ 3/≥ 4 were 0.54, 0.30, 0.75, 0.17 and 0.45 in North, East, South, Southwest China and throughout China, respectively, suggesting the predominance of high molecular weight PAHs in soils. Principal component analysis (PCA) is a multivariate statistical method that is frequently employed in environmental science to reduce the dimensionality of a data set. In the present work, PCA was applied to evaluate the similarities and differences of distribution patterns for various samples or chemicals. Each sampling site and each chemical were assigned a score after PCA analysis, allowing the summarized data to be further plotted and analyzed. It is important to note that the concentrations of chemicals were subjected to PCA and no transformation of the data is performed during the statistical analysis. Principal components (PCs) derived from the correlation matrix. The plot of loading factors for the first and second principal components (PC1 and PC2) is shown in Fig. 4. As seen in Fig. 4a, the PC1 and PC2 represent 47% and

16% of the total variance, respectively. There are two groups discriminated on the factor loading plot. One clusters samples from Hangzhou, Xiamen, the Mining River Estuary, Southeast China and the Pearl River Delta which was dominated by fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k] fluoranthene, benzo[a]pyrene; the other group was dominated by phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo [a]pyrene. Regarding the 16 PAHs, the majority of the variance (74%) of the scaled data was explained by two eigenvectors– principal components and the 16 PAHs can also be clustered in two groups (Fig. 4b). There exists strongly significant positive correlation (P b 0.01) between some individual PAHs, e.g., phenanthrene and anthracene (R2 = 0.94), phenanthrene and pyrene (R2 = 0.95), pyrene and chrysene (R2 = 0.97), anthracene and dibenzo[a,h]anthracene (R2 = 0.90). No significant correlation was observed between the ∑PAHs and individual PAHs (R2 b 0.20, P N 0.05; except from acenaphthylene and fluorene), demonstrating the different distribution profiles of the 16 PAHs found in various cities or regions. Several factors may have an impact on the PAH load of an area, such as industrialization, house heating, automotive traffic, atmospheric deposition, type of land use, soil physico-chemical properties (Wilcke, 2000; Mielke et al., 2004; Chen et al., 2005a; Zhang et al., 2006b). The use of large quantities of fertilizers might also have an impact

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Table 2 – Concentrations (μg kg− 1) of SVOCs in the soils of various types of land use Location

Industrial Range

Urban

Mean

Range

Roadside

Mean

PAHs Dalian

–a

–

–

Beijing

–

–

220–28,000 –

–

3952 ± 2832 1500– 15,000 –

Mean

Range

(2702) b 820 ± 363

Suburban

Mean Range

Range Mean

(356)b

219 ± 28 –

–

366–5284

(796) b 360 ± 89 – –

–

–

–

–

–

22–133 52–888

92 202 (127) c 2180

–

620–2090 –

–

Shantou Hong Kong France

372–1256 578 ND–2790 590 (213) c – 4520

202–363 280 23–19,500 d 458 d

– – ND–4810 (707) c

– –

– –

–

–

–

–

–

India (Agra)

13,720 ± 11,900 b

–

12,980 ± 13,870 b

–

9370 ± 10,460 b

PCBs Beijing

–

–

0.78–9.1 d

5.5 d

1.3–13

6.5

Qingdao France

– –

– 100

– –

– 1.5

–

9.6 –

– –

–

Romania

23 ± 17 b

57 ± 41 b

–

–

–

–

–

DDTs Nanjing

12–62

31

–

–

–

Qingdao Romania

– 72 ± 36 b

–

– 131 ± 152 b

– –

– –

3.6 –

– –

– –

–

–

HCHs Nanjing

14–26

20

–

–

–

–

–

–

–

–

Qingdao Romania

– 6.5 ± 1.6 b

– –

– 29 ± 27 b

– –

– –

1.5 –

– –

– –

– –

–

b c d

2780

Agricultural

Mean

Xiamen

a

–

Range

Residential

(221) b Wang et al. (2007a) –

500– – 950 – – 21–554 153 (89) c 695 6730 ± 7120 b

0.39

–

– –

– 11

0.49– 1.5 – –

Tang et al. (2004) Maskaoui et al. (2006) Hao et al. (2004) Chung et al. (2007) Motelay-Massei et al. (2004) Masih and Taneja (2006)

1.0

Liu et al. (2006)

7.0 5.4

Geng et al. (2006) Motelay-Massei et al. (2004) Covaci et al. (2001)

6.3– 1051 – 227 ± 157 b

64

An et al. (2005)

32

Geng et al. (2006) Covaci et al. (2001)

2.7– 131 – 28 ± 34 b

14

An et al. (2005)

4.6

Geng et al. (2006) Covaci et al. (2001)

4.0 ± 2.5 b

–

References

No data. Mean ± S.D. (median). Number in parentheses is median value. Park soil.

on the PAH concentrations of soils, as fertilizers have been shown to contain different levels of PAHs (Mo et al., 2007).

3.2.

Polychlorinated biphenyls (PCBs)

Compared to the studies about PAHs, the studies that have dealt with PCBs in soils are fewer (Fig. 1). More than 50 PCB congeners have been detected in Chinese soils, e.g., in Beijing (Bi et al., 2002) and across China (Ren et al., 2007a). The current total PCB concentrations (∑PCBs) ranged from 0.01 to 1840 μg kg− 1 (Table 3), with a mean of 21 (±330) μg kg− 1, being consistent with the values observed in soils from Germany (Manz et al., 2001), France (Motelay-Massei et al., 2004), Romania (Covaci et al., 2001) and Switzerland (Schmid et al., 2005). It can be seen that the ∑PCBs in the soils from the Wentai Area of Beijing decreased substantially from 1100 (in 1993) to 744 μg kg− 1 (in 1997), then down to 4.7 μg kg− 1 (in 1999) (Bi et al.,

2002). Bi et al. (2002) attributed this decrease to volatilization, leaching and biodegradation. To our knowledge, no remediation was going on in this region. Only the ∑PCBs in soils from sites affected by electronic waste activities (Leung et al., 2006; Zhao et al., 2006b) exceeded the maximum acceptable soil PCB concentration (100 μg kg− 1) proposed by NYSDEC (2003). The ∑PCBs in urban, roadside and residential soils were higher than in suburban and agricultural soils (Liu et al., 2006; Geng et al., 2006), being in accordance with a PCB distribution reported from Romania (Table 2). Concerning the different regions, the highest and lowest ∑PCBs were observed in Southwest and North China (Fig. 3b), being different from those of PAHs. This can be attributed primarily to their different sources and is suggesting that for the overall assessment of the contamination status of a region, it is not enough to investigate only a class of chemicals, but rather, as many pollutants as possible. The ∑PCBs were

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28) strongly associated with PC1, representing 92% of the total variance, while the least chlorinated PCB congener, PCB-28, loaded significantly on PC2 which represented only 5% of the total variance. This finding is similar to the PCA results for PCBs from various countries (Škrbić and Đurišić-Mladenović, 2007), where the more volatile ones represented by PCB-28 and PCB-52 were closely associated with PC2 and those less volatile like PCB-138, PCB-153 and PCB-180 were strongly associated with PC1. Regarding the different cities or regions, the majority of the variance (92%) was explained by three principal components (60% for PC1, 23% for PC2 and 9% for PC3). The soils from Beijing (Wentai; Bi et al., 2002), the disassembly of transformer site (Zhao et al., 2006a), the Ya-Er Lake area (Wu et al., 1997) and Guiyu (Leung et al., 2006) were strongly associated with PC1 (Fig. 5b). These soils were dominated by PCB-28, PCB-101, PCB-153 and PCB-138. On the contrary, the soil samples from Qingdao (Geng et al., 2006), the Yangtze River Delta (An et al., 2006) and across China (Ren et al., 2007b) were less strongly associated with each other (R2 b 0.50, P N 0.05), and in these samples the average concentrations of each congener contributed 5–30% to the ∑7PCB.

3.3. Fig. 4 – PCA showing the pattern of PAHs in the soil. (a) 16 Individual PAHs; (b) different sites. The locations in (b) are as follows: 1 = Beijing (Ma et al., 2005), 2 = Shenyang (Song et al., 2007), 3 = Tianjin (Tao et al., 2004), 4 = Dalian (Wang et al., 2007b), 5 = Hubei (Chen et al., 1997), 6 = the Yangtze River Delta (Ping et al., 2007), 7 = the Minjiang River Estuary (Zhang et al., 2004), 8 = Southeast China (Xing et al., 2006), 9 = Xiamen (Maskaoui et al., 2006), 10 = Hangzhou (Chen et al., 2004), 11 = Guiyang (Hu et al., 2006), 12 = Guangzhou (Chen et al., 2005a,b), 13 = Hong Kong (Zhang et al., 2006b), 14 = Hong Kong (Chung et al., 2007), 15 = the Pearl River Delta (Cai et al., 2007), 16 = Orleans Inner-city (Mielke et al., 2004), 17 = Orleans suburban (Mielke et al., 2004).

quite high in the soils of Guiyu (Leung et al., 2006), South China (Zhao et al., 2006b), a large site used for the disassembly of obsolete transformers and other electronic or electric waste (Zhao et al., 2006a). The ∑PCBs reached as high as 4545 μg kg− 1 in the directly polluted soils of some sealed storage locations (China SEPA, 2003). In China, the total production of PCBs was approximately 10,000 tonnes from 1965 to 1974 (Xing et al., 2005). Most of the PCB-containing equipments were stored at special sites after they were withdrawn. Due to inefficient management and storage conditions, it is hypothesized that PCBs are released to surrounding areas, ending mainly at the soils. Furthermore, along China's southeast coast there has been illegal trading or dismantling of PCB-containing equipments, something that may also explain the elevated PCB concentrations (China SEPA, 2003; Zhao et al., 2006b). In the literature, the seven indicative PCB congeners (PCB28, PCB-52, PCB-101, PCB-118, PCB-153, PCB-138 and PCB-180; Katsoyiannis, 2006) have been frequently detected in the soils. When PCA was applied for the distribution profiles of these PCB congeners, two principal components explained 97% of the total variance (Fig. 5a). The six PCB congeners (except PCB-

Organochlorine pesticides (OCPs)

The concentrations of OCPs have been determined in a large number of soil samples in more than 30 studies (Table 4). The total concentrations of DDTs (including p,p′-DDT, p,p′-DDE, p, p′-DDD, o,p′-DDT) and HCHs (including α, β, γ, δ-isomers) varied from ND to 2910 μg kg− 1 (with a mean value of 60 (± 83) μg kg− 1) and from ND to 131 μg kg− 1 (with a mean value of 8.7 (±7.2) μg kg− 1), respectively, being similar to those reported from Germany (Manz et al., 2001) and Romania (Covaci et al., 2001). In most soil samples, the concentrations of DDTs were higher than those of HCHs. To date, the China's environmental quality standard for soils containing organic chemicals concerns only DDTs and HCHs (GB 15618-1995). According to this standard (the limits for both DDTs and HCHs in the soils are 50, 500 and 1000 μg kg− 1, corresponding to Class I, II and III, respectively), the average concentrations of DDTs exceeded the limit of Class I in soils of Tianjin (Gong et al., 2004), Beijing (Ma et al., 2003; Shi et al., 2005; Zhu et al., 2005; Li et al., 2006b; Zhang et al., 2006d), Nanjing (agricultural soils) (An et al., 2005), South of Jiangsu (An et al., 2004) and Guangzhou (Chen et al., 2005a). The total concentrations of HCHs in all samples were within the limit of Class I. Hexachlorobenzene (HCB) was not determined in all studies (Table 4), but elevated concentrations (35.4–37.7 mg kg− 1) were recorded in soils of the Ya-Er Lake area (Wu et al., 1997). This might be due to the direct discharge of effluents from a large chemical factory situated on the bank of this lake during 1962–1987 (Wu et al., 1997). Concerning the various regions, the average concentration of DDTs in the soils of East China was greater by 14- and 5-fold than those of South and Southwest China (Fig. 3b). In contrast, the ones of HCHs in South and Southwest China were higher by 4-fold and 2-fold than those in North China. These distribution patterns are different from those reported in 1988 (Wang et al., 2005a), suggesting the different recent usages and residue levels of DDTs and HCHs in the various regions. The total concentrations of DDTs in soils from Nanjing decreased in the order of open vegetable land N

216

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Table 3 – Concentrations of polychlorinated biphenyls (PCBs) in the soil, China Location

Na

Total concentrations of PCBs (mg kg− 1)

Soil type

Min

References

Max

Mean

Median

15 20 – 920 7.3 – 13

– – 1100 744 4.7 0.18 3.1

– – – – – – 1.3

Jing et al. (1992) Song et al. (2006) Bi et al. (2002)

North China Shenyang Shenyang Beijing (Wentai)

– 5 17

Agriculture Paddy b Paddy

Beijing Beijing

– 16

Agriculture Surface

6.4 4.4 In 1993: In 1997: 568 In 1999: 2.0 – 0.39

East China Qingdao Ya-Er Lake area Zhejiang Shanghai-Hangzhou A large site c Yangtze River Delta

60 2 54 7 5 34

Surface Surface Surface Agriculture Paddy Agriculture

3.1 7.1 0.008 0.41 – 0.55

15 8.2 0.26 0.62 – 3.6

8.0 7.7 0.045 0.51 42 ± 30 1.1

– – – – – 0.92

Geng et al. (2006) Wu et al. (1997) Gao et al. (2006) Nakata et al. (2005) Zhao et al. (2006a) An et al. (2006)

Southwest China Guizhou

4

Paddy

8.9

56

30

–

Wei et al. (2007)

South China Guiyu (Shantou) Hong Kong South China d Taiwan Taiwan Across China

12 66 1 – 12 52

Surface c Surface Surface Surface Agriculture Surface

23 0.07 – – 44 0.14

102 9.9 – – 650 1.84

62 2.5 739 d 95 168 0.52

– 0.53 – – 128 –

Leung et al. (2006) Zhang et al. (2007a) Zhao et al. (2006b) Thao et al. (1993) Jou et al. (2007) Ren et al. (2007a)

Other countries France Germany Romania Swiss

37 11 46 25

Surface Agriculture Surface Surface

0.09 0.95 ND 0.86

150 3.8 134 12

40 1.7 25 3.6

– 1.9 – –

Motelay-Massei et al. (2004) Manz et al. (2001) Covaci et al. (2001) Schmid et al. (2005)

a b c d

Chu et al. (1995) Liu et al. (2006)

Number of samples or sampling sites. Soils was irrigated by effluents from biological treatment plants. Near a large site used for the disassembly of obsolete transformers and other electronic or electric waste. Effected by electronic waste activities.

greenhouse vegetable land N wasteland N dry land N industry land N paddy field N woodland (An et al., 2005), being similar to the distribution reported from Romania (Covaci et al., 2001). Furthermore, the residual concentration in vegetable fields was higher than that in crop fields (Wang et al., 2006a). The concentrations of HCHs and DDTs in the deeper layers of outskirt soils of Beijing were approximately an order of magnitude lower than those in shallow subsurface soils (Zhu et al., 2005), whereas their values in the layer of 10–20 cm of Guizhou soils were higher than those of 0–10 cm (Wei et al., 2007). Additionally, DDTs were detected in soils collected from Mt. Qomolangma (Everest) area (at the elevation range of 4700 to 5620 m, with a concentration range of 0.39–6.1 μg kg− 1) (Wang et al., 2007b). All these results indicate that the soils of China were widely contaminated by DDTs and HCHs. Being a large agricultural country, China has been a major producer and consumer of OCPs. The total production of DDTs surpassed 400,000 tonnes since the 1950s, until 1983 when its production was banned and accounted for 20% of the global production (Hua and Shan, 1996). Additionally, the release of

DDTs to the environment continues, because of its usage as an anti-malaria agent or as an impurity in other pesticides, such as dicofol (Wong et al., 2005). Similar to PCBs, the concentrations of DDTs and HCHs in the Chinese soils decreased significantly (Wang et al., 2005a) after the ban of usage in agricultural soils. In general, technical DDT has about 70–80% p,p′-DDT and 20% o,p′-DDT (Wong et al., 2005). DDT is dechlorinated to p,p′DDE under aerobic conditions and reductively dechlorinated to p,p′-DDD under anaerobic conditions (Katsoyiannis and Samara, 2005). The ratio of p,p′-DDE/p,p′-DDT, or its reciprocal value, has been used to determine recent inputs of DDT and resident time of p,p′-DDT in the environment. Elliott et al. (1994) estimated that the ratio of DDE/DDT should exceed 20:1, if the usage of DDT has been restricted for 15–20 years. In the present work, the p,p′-DDE/p,p′-DDT ratios calculated using the literature data ranged from 0.05 (Guangzhou) to 87 (Hong Kong) (Table 4), with a mean value of 4.0 (±12) (1.6 if soils of Hong Kong are excluded). However, a closer look at the ratios reveals that they were b5.0 in 88% of samples and b1.0 in 50%

S CIE N CE OF T H E TOT AL E N V I RO N ME N T 3 8 9 ( 2 00 8 ) 2 0 9–2 24

Fig. 5 – PCA showing the pattern of PCBs in the soil. (a) PCB congeners; (b) different sites. The locations in (b) are as follows: 1 = Beijing (Wentai; Bi et al., 2002), 2 = Qingdao (Geng et al., 2006), 3 = the Yangtze River Delta (An et al., 2006), 4 = a large site (Zhao et al., 2006a), 5 = the Ya-Er Lake (Wu et al., 1997), 6 = Guizhou (Wei et al., 2007), 7 = Guiyu (Leung et al., 2006), 8 = Hong Kong (Zhang et al., 2007a), 9 = South China (Zhao et al., 2006b), 10 = across China (Ren et al., 2007a), 11 = Swiss (Schmid et al., 2005), 12 = Germany (Manz et al., 2001).

of samples. These low ratios suggest that there are new inputs of DDT. Concerning HCHs, two types of HCH products have been manufactured throughout the world: technical HCH (containing about 60–70% α-HCH, 5–14% β-HCH, 10–15% γ-HCH and minor proportions of minor isomers) and lindane (γ-HCH N 99%) (UNEP, 1995). In China, the production and application of technical HCH was restricted in 1983, while lindane is currently used for pest control. Based on the composition of the two main HCH isomers, a high ratio of α-HCH to γ-HCH in the soil indicates the input of technical HCH and a low ratio indicates the use of lindane. In the soils investigated, the ratios of α-HCH to γ-HCH ranged from 0.28 (Guizhou) to 11 (Urumqi Shuimohe) (Table 4), with an average value of 2.7 (± 2.4), being higher than that for soils in Germany (Manz et al., 2001). In total, the ratios in 68% of samples were between 1.0 and 5.0, and only in 12% of samples N 5.0. Most ratios were lower than that of the technical HCH, indicating that HCHs in soils analyzed are a mixture of past technical HCH and current lindane application.

3.4. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) Soils are among the most important environmental sinks for PCDD/Fs. In China, studies have investigated the occurrence of PCDD/Fs in more than 200 soil samples or sampling sites,

217

mainly focusing on polluted areas (Table 5) and on the 17 most toxic (2,3,7,8-substituted) PCDD/F congeners. The total concentrations of tetra- to octa-CDD/Fs (∑PCDD/Fs) ranged from 17 ng kg− 1 (the Ya-Er Lake Region) to 606,000 ng kg− 1 (Taiwan) (from 0.11 to 1400 ng I-TEQ kg− 1). The ∑PCDD/Fs were b100 ng kg− 1 in 26% of samples and N1000 ng kg− 1 in 30% of samples. The ∑PCDD/Fs in urban soils of Guangzhou (Ren et al., 2007b) and Taiwan (Wang et al., 2006c), and in agricultural and nonpolluted soils of Beijing (Zhou et al., 2006), the Ya-Er Lake Area (Wu et al., 1997, 2001, 2002), the Yangtze River Delta (Luo et al., 2006), Foshan (Han et al., 2006) and Taiwan (Jou et al., 2007) were comparable with those reported in the contemporary surface soils from around the world (Green et al., 2004), and most of them were within the acceptable limit (600 ng kg− 1) proposed by NYSDEC (2003) for soils. In total, the ∑PCDD/Fs decreased in order of contaminated site N urban soils N agricultural soils (Wang et al., 2006c; Jou et al., 2007). The ∑PCDD/Fs were quite high and exceeded the Taiwan soil regulation (1000 ng I-TEQ kg− 1) in the soils of a landfill site (Wang et al., 2006c) and from a sea reservoir surrounding the pentachlorophenol plant (Lee et al., 2006). Interestingly, the ∑PCDD/Fs in the soils adjacent to a municipal solid waste incinerator in Hsinchu, Taiwan (Cheng et al., 2003) were comparable with those in agricultural sites and natural preserve areas of Taiwan (Jou et al., 2007). In the former, the results of PCA and hierarchical cluster analysis did not provide sufficient evidence that soil PCDD/F contamination was caused by emissions from the municipal solid waste incinerator. On the other hand, the soil-specific homologue profile of PCDD/Fs in Guangzhou was similar to that in atmospheric deposition (Ren et al., 2007b), suggesting that atmospheric deposition was one of the most important PCDD/F sources in the soils. Concerning the homologue profile, the sum concentrations of polychlorinated dibenzo-p-dioxins (∑PCDDs) in 83% of samples were higher than those of polychlorinated dibenzofurans (∑PCDFs), producing ratios of ∑PCDDs to ∑PCDFs between 0.09 and 511 (except of the samples from Foshan, where the PCDFs were below the detection limits in 4 out of 5 samples). Wagrowski and Hites (2000) suggested that, when PCDFs are predominant, the profile is classified as “source”, whilst “sink” profiles are dominated by PCDDs. This corresponds to profiles observed in China soils. The concentrations of individual PCDD/F congeners varied from ND to 437 μg kg− 1 (Taiwan; Lee et al., 2006). Octachlorodibenzo-p-dioxin (OCDD) was predominant in the soils of Guangzhou (Ren et al., 2007b), the Ya-Er Lake area (Wu et al., 2002) and Taiwan (Wang et al., 2006c; Jou et al., 2007), being similar to PCDD/F homologue patterns reported for Australia, Thailand and Poland (Green et al., 2004); while 2,3,7,8-tetrachlorodibenzo-p-dioxin/dibenzofuran (TCDD/F) and pentachlorodibenzo-p-dioxins/dibenzofurans (PeCDD/Fs) accounted for 77% of the ∑PCDD/Fs in contaminated soils from South China (Zhao et al., 2006b). As the results of PCA for the 17 most toxic PCDD/F congeners show (Fig. 6a), Group A clusters 9 congeners including OCDD/F, and these congeners are strongly associated with PC1 which represents 77% of the total variance, indicating they are the dominant congeners. Fig. 6b shows that almost all sites analyzed fall in one group, confirming again the similar abundant congeners. One exception (the site of South China; Zhao et al., 2006b)

218

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Table 4 – Concentrations of organochlorine pesticides (OCPs) in the soil, China Location

Soil type

p,p′-DDE/ DDT

DDTs (mg kg− 1)

α-/γ-HCH

HCHs (mg kg− 1)

HCB (mg kg− 1)

OCPs (mg kg− 1) a

References

Range Mean Range Mean Range Mean Range Mean Range Mean Range Mean North China Tianjin

56

–

0.68

–

64

–

2.91

12–30

6.6

–

110

–

0.88

77

–

2.6

141

–

0.89

Beijing

0.77– 2179 1.4– 5910 Outskirts (47) 0.77– 2179 Topsoil (30) 0–76

9.5

Beijing

Agricultural

Huang-HuaiHai Plain

Surface (129)

7.2– 2910 ND– 126

Surface (60)

3.9–80

Paddy

–

Surface

ND– 5.3 12–989

Surface

–

–

Agricultural

164

Beijing Beijing Beijing Beijing Beijing

East China Qingdao Taihu Lake Region Taihu Lake Region Ya-Er Lake Region Nanjing

Surface

0.7– 972 18–101

Greenhouse (8 b) Farmland c (9) 2.4–20 Urban and outskirts (63) Surface (131)

Nanjing

Industrial

63– 1051 11–62

South of Jiangsu ShanghaiHangzhou Hubei

Agricultural (77) Surface

17– 1115 11–115

Tea growing area (9)

10–100

Southwest China Mt. Qomolangma Surface (24) area Urumqi Surface c Shuimohe Guizhou Paddy (4)

South China Guangzhou Dongguan Hong Kong Hong Kong Pearl River Delta Pearl River Delta

0.39– 6.1 0.52– 10 4.7–43

Vegetable (43) 7.60– 831 Surface (64) 0.05– 36 Surface 0.13– 1.9 Surface (46) ND– 5.7 Surface (74) 0.52– 414 Surface (30) 0.16– 33

–

–

16

–

–

0.76– 6.9 1.4–49

3.0

–

5.5–23

8.8

–

0.45

–

0.64– 33 1.4–57

1.5

–

1.3

–

10

–

0.52

–

–

0–7.3

0.69

–

–

381

–

32

–

–

11

–

2.0– 760 0.53– 14

4.0

–

27

–

0.41– 9.7 ND– 3.4 –

4.0

–

5.1–88

–

–

–

–

9.0

1.3–1.6

14

–

31

0.06– 5.1 0.4–0.7

0.53– 1.3 2.7– 131 14–26

20

163

1.2

5.6–23

11

0.64– 3.3 –

0.2–3.1

2.5–3.5

10–80

–

–

ND

–

3.1

–

3.4 14

90 3.5 0.52 0.52 35 4.1

0.45– 0.65 0.32– 3.1

0.56

–

1.6

1.4

10– 1060 26–88

2.1

13– 1167 –

3.0

ND

–

2.7

–

1.8

0.36– 11 –

1.6

–

5.7–7.6

6.2

5.0–7.0

5.7

2.5–11

6.2

6.0

ND–24

3.2

1.2–2.3

5.6

0.05– 5.9 –

1.5

7.6–42

4.5

6.5

ND–16

0.94– 87 14

28

0.59– 6.5 0.72

2.7

–

–

51 174

–

0.81

1.2

0.45– 11 0.28– 1.4

78

–

–

4.4

33

35,400– 37,700

4.8

0.19– 7.0 3.4–8.3

9.6

0.007– 0.31

1.6

– –

Geng et al. (2006) Feng et al. (2003) Shen et al. (2005) Wu et al. (1997) An et al. (2005) An et al. (2005) An et al. (2004) Nakata et al. (2005) Hu and Ai (2006)

Wang et al. (2007b) Lv et al. (2006) Wei et al. (2007)

– 3.0–13

Gong et al. (2004) Ma et al. (2003) Chen et al. (2005b) Li et al. (2006b) Zhang et al. (2006a) Zhu et al. (2005) Wang et al. (2006b) Shi et al. (2005) Zhao et al. (2005)

6.7

Chen et al. (2005a) Zhang et al. (2005) Zhang et al. (2006c) Zhang et al. (2006d) Li et al. (2006a) Zhang et al. (2006e)

219

S CIE N CE OF T H E TOT AL E N V I RO N ME N T 3 8 9 ( 2 00 8 ) 2 0 9–2 24

Table 4 (continued ) Location

Soil type

DDTs (mg kg− 1)

p,p′-DDE/ DDT

α-/γ-HCH

HCHs (mg kg− 1)

HCB (mg kg− 1)

OCPs (mg kg− 1) a

References

Range Mean Range Mean Range Mean Range Mean Range Mean Range Mean Taiwan

Surface

20

–

14

–

Other countries Romania

Surface (46)

3.5– 537 1542 24–173 72

–

0.7–90 16

–

4.6–12 7.5

0–1.0

Germany

a b c

Agricultural (11)

0.01– 0.28

0.11

–

0.18

ND–67

18

0.57– 3.8

1.6

Thao et al. (1993)

Covaci et al. (2001) Manz et al. (2001)

Sum concentration of DDT isomers and HCH isomers. Number of samples or sampling sites. Soils was irrigated by effluents from biological treatment plants.

might be attributed to the fact that the concentrations of only 10 congeners are detectable in which TCDD/Fs and PeCDD/Fs dominated. The concentrations of 2,3,7,8-TCDD, the most toxic dioxin congener, were generally less than 1.0 ng kg− 1 in urban and agricultural soils (Wu et al., 1997, 2001, 2002; Wang

et al., 2006c; Zhao et al., 2006b) and within the maximum permissible value for soils (0.6 ng kg− 1) proposed by NYSDEC (2003). Regarding the vertical distribution pattern, the maximum concentrations of PCDD/Fs in the soils of Ya-Er Lake area were in the layer of 20–30 cm or 0–10 cm (Wu et al., 2002).

Table 5 – Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs) in the soil, China Location

Na

Soil type

ng I-TEQ kg− 1

Total concentrations (ng kg− 1) Min

Max

Mean Median Min

Max

References

Mean Median

PCDD/Fs Beijing Ya-Er Lake area b Ya-Er Lake area b Ya-Er Lake area b Yangtze River Delta Yangtze River Delta Hangzhou Guiyu (Shantou) Guiyu (Shantou) Guangzhou Foshan Hong Kong

16 2 – 10 2 3 33 15 10 7 5 3

Surface Surface Surface Agricultural Agricultural Agricultural Agricultural Surface c Surface Urban Surface Surface

– 18 – 6.4 2552 425 54 228 466 – 855 2493

– 34 – 121 2726 655 285 39,300 96,7500 – 7652 8651

– 26 143 40 2639 556 105 10,081 – – 4113 6136

– – – 27 – 588 86 – – – 3107

0.23 0.11 – 0.08 20.8 15 0.39 0.39 0.57 0.7 0.90 –

7.3 0.16 – 2.2 21.3 29 5.0 1100 13,900 4.5 7.9 –

2.4 0.14 31 0.54 21 20 1.2 122 – – 4.4 –

0.98 – – 0.33 – 17 0.84 – – – 3.8 –

South China Taiwan Taiwan Taiwan Taiwan

1 108 8 9 9

Surface Agricultural Surface d Surface e Surface f

– 23 – 151

– 2061 – 23,400 –

278 398 – 10,944 606 ± 807 f

– 405 – – –

– 0.10 0.52 2.7

– 15 5.0 2810 –

2.6 3.2 2.1 67 1400 ± 1740 f

– 3.3 – –

2 3 15 6

Surface c Surface c Surface c Surface

1109 g 1140 g 2.0 g 858 g

1137 g 1169 g 4250 g 991 g

1123 g 1155 g 1092 g 941 g

– – – 972 g

– – – –

Wang et al. (2005b) Leung et al. (2006) Leung et al. (2007) Cai and Jiang (2006)

54

Surface

0.03 g

840 g

–

–

–

Hassanin et al. (2004)

PBDEs Guiyu (Shantou) Guiyu (Shantou) Guiyu (Shantou) An electronic waste disposal site Europe a b c d e f g

Zhou et al. (2006) Wu et al. (1997) Wu et al. (2001b) Wu et al. (2002) Luo et al. (2005) Luo et al. (2006) Yan et al. (2007) Leung et al. (2007) Wong et al. (2007) Ren et al. (2007b) Han et al. (2006) Wagrowski and Hites (2000) Zhao et al. (2006b) Jou et al. (2007) Cheng et al. (2003) Wang et al. (2006c) Lee et al. (2006)

Number of samples or sampling sites. The lake was seriously polluted by industrial effluents containing HCH and HCB from a large chemical plant from 1962 to 1978. Effected by electronic waste activities. Near or in a municipal solid waste incinerator (MSWI) in Hsinchu, Taiwan. Including urban soil, the soil of landfill site and inner soil. The soil samples collected from the sea reservoir surrounding the PCP plant. Unit is μg kg− 1. The unit of PBDE concentrations is μg kg− 1.

220

SC IE N CE OF T H E TOT AL E N V I RO N ME N T 3 8 9 ( 2 00 8 ) 2 0 9–2 24

retained in land after wet and dry deposition and subsequently result in elevated levels of PCDD/Fs in the soils of China.

3.5.

Fig. 6 – PCA showing the pattern of PCDD/Fs in the soil. (a) 17 PCDD/F congeners; (b) different sites. The corresponding congeners in (a): 1 = 2,3,7,8-TCDD; 2 = 1,2,3,7,8-PeCDD; 3 = 1,2,3,4,7,8-HxCDD; 4 = 1,2,3,6,7,8-HxCDD; 5 = 1,2,3,7,8,9HxCDD; 6 = 1,2,3,4,6,7,8-HpCDD; 7= OCDD; 8 = 2,3,7,8-TCDF; 9 = 1,2,3,7,8-PeCDF; 10 = 2,3,4,7,8-PeCDF; 11 = 1,2,3,4,7,8HxCDF; 12 = 1,2,3,6,7,8-HxCDF; 13 = 1,2,3,7,8,9-HxCDF; 14 = 2,3,4,6,7,8-HxCDF; 15 = 1,2,3,4,6,7,8-HpCDF; 16 = 1,2,3,4,7,8HpCDF; 17 = OCDF. The corresponding sites in (b): 1 = the Yangtze River Delta (Luo et al., 2005), 2 = the Yangtze River Delta (Luo et al., 2006), 3 = the Ya-Er lake area (Wu et al., 1997), 4 = the Ya-Er lake area (Wu et al., 2002), 5 = South China (Zhao et al., 2006b), 6 = Guiyu (Leung et al., 2007), 7 = Taiwan (Lee et al., 2006), 8 = Taiwan (urban soil; Wang et al., 2006c), 9 = Taiwan (landfill site; Wand et al., 2006c), 10 = Taiwan (Jou et al., 2007).

PCDD/Fs are not produced intentionally but are released into the environment from various combustion processes (e.g., municipal solid waste incineration, domestic and open burning, traffic source) and as unwanted byproducts from the production of various chlorinated chemicals. In China, Jun et al. (2004) estimated that the total emissions of PCDD/Fs from potential emission sources (not including uncontrolled combustion activities) ranged from about 7144 to 13,575 g ITEQ yr− 1 (for mainland). Zhang et al. (2007a,in press) estimated that annual emissions of PCDD/Fs from open burning of crop residues in each province of China mainland between 1997 and 2004 varied from 1380 to 1520 g I-TEQ yr− 1 (with a mean of 1500 g I-TEQ yr− 1), which accounted for approximately 10–20% of the total emissions of PCDD/Fs in China and were higher than those in the developed countries. The use of chemicals (e.g., pentachlorophenol/phenate) and the manufacture of pesticides are also large contributors of PCDD/Fs. According to the inventory of PCDD/F emissions in the mainland of China, 572 g I-TEQ yr− 1 of PCDD/Fs were released to soils and water through the usage of pentachlorophenol/phenate (Jun et al., 2004). The PCDD/Fs released to the environment might be

Polybrominated diphenyl ethers (PBDEs)

As flame retardants, PBDEs have been increasingly added to industrial products, and subsequently resulted in more and more extensive environmental pollution. Recent studies indicate that the levels of PBDEs seem to be increasing and that this increase is rapid (de Wit, 2002), although the production of penta- and octa-BDEs is ceased in North America and Europe (Streets et al., 2006). Thus, the occurrence of PBDEs in the soils is of great concern. However, as PBDEs are a class of chemicals that started to be studied mainly during the last decade, only limited data about PBDEs in Chinese soils is available in the literature, except of the investigation performed in or near the dumping sites of electronic waste (Table 5). Wang et al. (2005b) and Leung et al. (2006, 2007) studied the occurrence of 43 mono- to hepta-brominated congeners in the soils and sediments adjacent to the dumping sites of electronic waste in Guiyu town, Shantou city (Guangdong Province). The concentrations of individual PBDEs ranged from ND to 1270 μg kg− 1, and the total PBDE concentrations in the soils were between 2.0 and 4250 μg kg− 1 (Table 5). Moreover, total PBDE concentrations increased in order of reservoir area b rice field b area near an open-burning site b printer roller dumping site b open-burning site or acid leaching (Leung et al., 2007; Wong et al., 2007). The levels of total PBDEs in soil samples of reservoir area and rice field were comparable with the values recorded in European surface soils (Hassanin et al., 2004), but the levels in the other sites were higher, suggesting that these soils were contaminated by PBDEs. With respect to the different congeners, the major PBDE congeners detected in soils were BDE-71,-47,-66,-99,-100,-154,153,-139,-138, and -183. Tetra-(BDE-47), penta-(BDE-99) and hexa-BDE (BDE-139, BDE-153, BDE-154) were the predominant congeners in the studies of Wang et al. (2005b) and Cai and Jiang (2006), whereas deca-BDE (BDE-209) was the predominant congener (accounting for 35–82% of total concentrations) in the study of Leung et al. (2007), showing the prevalence of commercial deca-DBE.

3.6.

Phthalic acid esters (PAEs)

Six PAE compounds, namely, dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), di-n-octyl phthalate (DOP) and di(2ethylhexyl) phthalate (DEHP), have been classified as priority organic pollutants by USEPA. Only five studies have focused on the occurrence of PAEs in the soils although the survey area covered the whole country. Six PAEs were frequently identified in the soils from different regions of China (Meng et al., 1996; Hu et al., 2003; Cai et al., 2005; Li et al., 2006c). The total concentrations of six PAEs (∑PAEs) ranged from 0.89 to 46 mg kg− 1 (Table 6), with a mean value of 5.5 (±6.8) mg kg− 1. These values were considerably higher than those reported in soils from the Netherlands (Peijnenburg and Struijs, 2006) and Denmark (Vikelsøe et al., 2002). The highest ∑PAEs value was observed in vegetable soils within the Pearl River Delta (Cai et al., 2005). This might be due to the wide usage of polyvinyl

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Table 6 – Concentration (mg kg− 1) of phthalic acid esters (PAEs) in the soil, China Location

Beijing Beijing Jinan Northeast China North China East China Northwest China South China Southwest China Pearl River Delta

Soil type

b c d e

Di(2-ethylhexyl) phthalate (DEHP)

References

Min Max Mean Median

Urban (30 a) Greenhouse (8) Surface (16) Surface (3)

0.28 0.34

3.8 1.7

0.79 1.1

0.46 –

0.17 0.22

6.5 0.74

1.9 0.47

1.4 –

0.51 b 1.3 c

8.0 b 3.2 c

2.8 b 2.2 c

2.2 –

Li et al. (2006c) Ma et al. (2003)

1.2 0.16

4.6 1.6

2.7 –

– –

1.6 3.3

5.2 7.1

3.3 –

– –

7.3 d 4.4 e

10 d 10 e

6.2 d 6.7 e

– 2.7

Meng et al. (1996) Hu et al. (2003)

Surface (4)

0.27

0.98

–

–

0.51

2.2

–

–

1.8 e

3.8 e

2.8 e

2.4

Hu et al. (2003)

Surface (7) Surface (2)

0.21 0.38

1.4 0.39

– –

– –

0.20 1.7

6.0 2.2

– –

– –

1.3 e 2.2 e

7.1 e 2.8 e

4.0 e 2.5 e

2.6 –

Hu et al. (2003) Hu et al. (2003)

Surface (4)

ND

0.26

–

–

0.54

3.4

–

–

0.89

1.7

Hu et al. (2003)

Surface (3)

0.51

0.64

–

–

1.9–

3.0

–

–

1.9 e

30 e

2.2 e

1.9

Hu et al. (2003)

18

9.5

9.2

6.2

16

11

9.3

3.0 b

46 b

21 b

21

Cai et al. (2005)

0.11

3.6

0.012 1.9

0.39

38

0.014

2.5

0.53

–

Vikelsøe et al. (2002)

Vegetable (50) 3.8

0.0005 0.45

e

3.2

e

1.9

e

Number of samples or sampling sites. Sum concentration of DMP, DEP, DBP, BBP, DOP and DEHP. Sum concentration of DMP, DEP, DBP, di-iso-butyl phthalate, DOP and DEHP. Sum concentration of DEP, DBP and DEHP. Sum concentration of DMP, DEP, DBP and DEHP.

chloride plastics films containing PAEs in vegetable fields. Furthermore, some wide-used fertilizers in China were found to contain PAEs (Mo et al., 2007). In all examined soils, di-nbutyl phthalate and di(2-ethylhexyl) phthalate were the most abundant (Table 6) and accounted for 24–95% of the ∑PAEs, while dimethyl phthalate, diethyl phthalate, butylbenzyl phthalate always occurred in lower concentrations (Meng et al., 1996; Hu et al., 2003; Cai et al., 2005).

4.

Total concentrations of PAEs

Min Max Mean Median Min Max Mean Median

Other country Denmark Agricultural (7) a

Di-n-butyl phthalate (DBP)

Conclusion and future perspectives

An increasing number of papers on the occurrence of SVOCs in the Chinese soils are being produced. Nevertheless, as described and cited above, the data available are mainly for North, East and South China, whereas very few data are available for the Northwest, Southwest and Central China. Moreover, investigations on PCBs, PCDD/Fs and PBDEs were conducted mainly in contaminated areas or special sites and not throughout the whole country. This does not provide scientists with a clear perspective of SVOCs pollution throughout the country. There is a gap in the literature concerning new and emerging pollutants, such as perfluorinated compounds, pharmaceuticals and personal care products, or polychlorinated naphthalenes, and further research is considered necessary. Furthermore, as a major signatory, China has paid more and more attention to the pollution of POPs and initiated a series of activities to control POPs. For instance, on 27th

December, 2006, the State Environmental Protection Administration of China issued a notice to investigate the POPs pollution and their sources between 2006 and 2015 (China SEPA, 2006), although that is focused mainly on some industrial areas and some polluted sites, etc. The latter encourages researchers to survey the occurrence of SVOCs in soils, in order to understand the occurrence of SVOCs in the archived soils, pollution sources, future pollution trends and to build SVOC database for soils. In total, the concentrations of PCBs and OCPs in the examined soils were generally below the maximum acceptable values, but the ones of PAHs and PCDD/Fs in some cases exceeded the allowable values proposed by other countries. On the other hand, in China, only limited guidelines exist for the levels of SVOCs in the soils (mainly for DDTs and HCHs). More effective and imperative activities are needed for the setting of standards on the other SVOCs as well. Remediation strategies of the soils contaminated by SVOCs are also needed in specific areas.

Acknowledgements This work was supported by the Natural Science Foundation of China (no. 39870435, 30471007), Key Scientific Research Project of Ministry of Education of China (no. 02112), the Natural Science Foundation of Guangdong Province (no. 021011, 036716, 043005970) and Project of Department of Science and Technology of Guangdong (no. 01C21202, 03A20504, 03C34505), and the

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Research Foundation of State Key Laboratory of Organic Geochemistry, Chinese Academy of Sciences.

REFERENCES An Q, Dong YH, Wang H, Wang X, Wang MN, Guo ZX. Organochlorine pesticide residues in cultivated soils in the south of Jiangsu, China. Acta Pedol Sin 2004;41:414–9 [in Chinese]. An Q, Dong YH, Wang J, Ge CJ. Residues and distribution character of organochlorine pesticides in soils in Nanjing area. Acta Sci Circumst 2005;25:470–4 [in Chinese]. An Q, Dong YH, Wang H, Chen F, Zhang JQ. Residues of PCBs in agricultural fields in the Yangtze Delta, China. Environ Sci 2006;27:528–32 [in Chinese]. Bi XH, Chu SG, Meng QY, Xu XB. Movement and retention of polychlorinated biphenyls in a paddy field of WenTai area in China. Agr Ecosyst Environ 2002;89:241–52. Cai QY, Mo CH, Li YH, Zeng QY, Wang BG, Xiao KE, et al. Preliminary study of PAEs in soils from typical vegetable fields in areas of Guangzhou and Shenzhen, South China. Acta Ecol Sin 2005;25:283–8 [in Chinese]. Cai QY, Mo CH, Li YH, Zeng QY, Katsoyiannis A, Wu QT, et al. Occurrence and assessment of polycyclic aromatic hydrocarbons in soils from vegetable fields of the Pearl River Delta, South China. Chemosphere 2007;68:159–68. Cai Z, Jiang G. Determination of polybrominated diphenyl ethers in soil from e-waste recycling site. Talanta 2006;70:88–90. CCME (Canadian Council of Ministers of the Environment). Interim Canadian environmental quality criteria for contaminated sites. Report CCME EPC-CS34, 1–20. Canada: Manitoba; 1991. Chen GS, Schramm KW, Klimm C, Xu Y, Zhang YY, Kettrup A. Polycyclic aromatic hydrocarbons in Ya-Er Lake (Hubei, China): sources and distribution. Fresenius J Anal Chem 1997;359:280–4. Chen B, Xuan X, Zhu L, Wang J, Gao Y, Yang K, et al. Distributions of polycyclic aromatic hydrocarbons in surface waters, sediments and soils of Hangzhou City, China. Water Res 2004;38:3558–68. Chen L, Ran Y, Xing B, Mai B, He J, Wei X, et al. Contents and sources of polycyclic aromatic hydrocarbons and organochlorine pesticides in vegetable soils of Guangzhou, China. Chemosphere 2005a;60:879–90. Chen Y, Wang C, Wang Z. Residues and source identification of persistent organic pollutants in farmland soils irrigated by effluents from biological treatment plants. Environ Int 2005b;31:778–83. Cheng PS, Hsu MS, Ma E, Chou U, Ling YC. Levels of PCDD/FS in ambient air and soil in the vicinity of a municipal solid waste incinerator in Hsinchu. Chemosphere 2003;52:1389–96. China SEPA. 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); 2003 [in Chinese]. China SEPA (State Environmental Protection Administration). The notice about investigation of persistent organic pollutants (POPs) throughout China. HF (2006), 207; 2006. http://www.zhb.gov.cn/ info/gw/huangfa/200612/t20061230_99148.htm [in Chinese]. Chu SG, Liu H, Ma LL, Xu XB. Polycyclic aromatic hydrocarbons in soil adjacent to highways in Beijing, People's Republic of China. Bull Environ Contam Toxicol 2003;70:972–7. Chu SG, Yang C, Xu XB, Liu XX. Polychlorinated biphenyl congener residues in sediment and soil from pollution area, China. Environ Sci 1995;15:199–203 [in Chinese]. Chung MK, Hu R, Cheung KC, Wong MH. Pollutants in Hong Kong soils: polycyclic aromatic hydrocarbons. Chemosphere 2007;67:464–73.

Covaci A, Hura C, Schepens P. Selected persistent organochlorine pollutants in Romania. Sci Total Environ 2001;280:143–52. de Wit CA. An overview of brominated flame retardants in the environment. Chemosphere 2002;46:583–624. Duan YH, Tao S, Wang XJ, Li BG, Xu FL, Liu WX, et al. Spatial distribution and sources of PAHs in Tianjin's topsoil. Acta Pedol Sin 2005;42:942–7 [in Chinese]. Elliott JE, Martin PA, Arnold TW, Sinclair PH. Organochlorines and reproductive success of birds in orchard and non-orchard areas of central British Columbia, Canada, 1990–91. Arch Environ Contam Toxicol 1994;26:435–43. Feng K, Yu BY, Ge DM, Wong MH, Wang XC, Cao ZH. Organochlorine pesticide (DDT and HCH) residues in the Taihu Lake Region and its movement in soil-water system I. Field survey of DDT and HCH residues in ecosystem of the region. Chemosphere 2003;50:683–7. Fu JM, Mai BX, Sheng GY, Zhang G, Wang XM, Peng PA. Persistent organic pollutants in environment of the Pearl River Delta, China: an overview. Chemosphere 2003;52:1411–22. Gao J, Luo Y, Li Q, Zhang H, Wu L, Song J, et al. Distribution patterns of polychlorinated biphenyls in soils collected from Zhejiang province, east China. Environ Geochem Health 2006;28:79–87. Geng CZ, Li ML, Yang YL, Zhang LF, Nie LM. Study and analysis of pollution levels of OCPs and PCBs in soils in Qingdao Area. J Qingdao Univ Eng Technol 2006;21:42–8 [in Chinese]. Gong ZM, Tao S, Xu FL, Dawson R, Liu WX, Cui YH, et al. Level and distribution of DDT in surface soils from Tianjin, China. Chemosphere 2004;54:1247–53. Green NJL, Hassanin A, Johnston AE, Jones KC. Observations on historical, contemporary, and natural PCDD/Fs. Environ Sci Technol 2004;38:715–23. Han JL, Ren MZ, Xu ZC, Peng XC, Zhang SK. Levels of PCDD/Fs in clivose natural soils of Pear River Delta. China Environ Sci 2006;26:328–32 [in Chinese]. Hao R, Peng S, Song Y, Yang G, Wan H. Distribution of priority polycyclic aromatic hydrocarbons in soils in Shantou Specific Economic Zone. Ecol Environ 2004;13:323–6 [in Chinese]. Hassanin A, Breivik K, Meijer SN, Steinnes E, Thomas GO, Jones KC. PBDEs in European background soils: levels and factors controlling their distribution. Environ Sci Technol 2004;38:738–45. Hua XM, Shan ZJ. The production and application of pesticides and factor analysis of their pollution in environment in China. Adv Environ Sci 1996;4:33–45. Hu J, Zhang G, Liu CQ. Pilot study of polycyclic aromatic hydrocarbons in surface soils of Guiyang city, People's Republic of China. Bull Environ Contam Toxicol 2006;76:80–9. Hu XY, Wen B, Shan XQ. Survey of phthalate pollution in arable soils in China. J Environ Monit 2003;5:649–53. Hu XY, Ai TC. Pesticide Residues in Tea and Soils in East (Northeast) Hubei. J Agric Environ Sci 2006;25:61–4 [in Chinese]. Jing ZY, Li YH, Feng XB, Wang FQ, Zhang YX. The study of polychlorinated biphenyls for their loss, contamination and protection strategy in Shenyang City. Congkan Environ Sci 1992;13:1-28 [in Chinese]. Jou J, Lin KL, Chung JC, Liaw SL. Soil dioxins levels at agriculture sites and natural preserve areas of Taiwan. J Hazard Mater 2007;147(1-2):1–7. Jun J, Hao P, Tang XY. An inventory of potential PCDD and PCDF emission sources in the mainland of China. Organohalog Compd 2004;66:852–8. Katsoyiannis A. Occurrence of polychlorinated biphenyls (PCBs) in the Soulou stream in the power generation area of Eordea, northwestern Greece. Chemosphere 2006;65:1551–61. Katsoyiannis A, Samara C. Persistent organic pollutants (POPs) in the sewage treatment plant of Thessaloniki, northern Greece: Occurrence and removal. Water Res. 2004;38:2685–98. Katsoyiannis A, Samara C. Persistent organic pollutants (POPs) in the conventional activated sludge treatment process: fate and mass balance. Environ Res 2005;97:245–57.

S CIE N CE OF T H E TOT AL E N V I RO N ME N T 3 8 9 ( 2 00 8 ) 2 0 9–2 24

Katsoyiannis A, Samara C. Comparison of active and passive sampling for the determination of persistent organic pollutants (POPs) in sewage treatment plants. Chemosphere 2007;67:1375–82. Lee CC, Guo YL, Kuei CH, Chang HY, Hsu JF, Wang ST, et al. Human PCDD/PCDF levels near a pentachlorophenol contamination site in Tainan, Taiwan. Chemosphere 2006;65:436–48. Leung A, Cai ZW, Wong MH. Environmental contamination from electronic waste recycling at Guiyu, southeast China. J Mater Cycl Waste Manag 2006;8:21–33. Leung AOW, Luksemburg WJ, Wong AS, Wong MH. Spatial distribution of polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in soil and combusted residue at Guiyu, an electronic waste recycling site in Southeast China. Environ Sci Technol 2007;41:2730–7. Li J, Zhang G, Qi S, Li X, Peng X. Concentrations, enantiomeric compositions, and sources of HCH, DDT and chlordane in soils from the Pearl River Delta, South China. Sci Total Environ 2006a;372:215–24. Li X, Zhu Y, Liu X, Fu S, Xu X, Cheng H. Distribution of HCHs and DDTs in soils from Beijing City, China. Arch Environ Contam Toxicol 2006b;51:329–36. Li XH, Ma LL, Liu XF, Fu S, Cheng HX, Xu XB. Phthalate ester pollution in urban soil of Beijing, People's Republic of China. Bull Environ Contam Toxicol 2006c;77:252–9. Lin DH, Zhu LZ, Wang J. Assessment on the contamination and risk of PAHs in a metal smelting area. Acta Ecol Sin 2005;25:261–7 [in Chinese]. Liu J, Qi S, Zhang G, Zhang W. Polycyclic aromatic hydrocarbons in Lalu wetland of Lhasa city and their sources. Geohys Geochem Explor 2003;27:490–2. Liu GY, Chen ZS, Shi YH, Wang GY, Li W, Li CQ. The levels and compositions of PCBs in Beijing soil. Acta Sci Circumst 2006;26:2013–7 [in Chinese]. Luo Y, Teng Y, Li Q, Wu L, Li ZY, Zhang Q. Soil environmental quality and remediation in Yangtze River Delta region. I. Composition and pollution of polychlorinated dibenzo-p-dioxins and dibenzpfurans (PCDD/Fs) in a typical farmland. Acta Pedol Sin 2005;42:570–6 [in Chinese]. Luo Y, Teng Y, Li Z, Wu Y, Bu Y, Fang L, et al. Soil environmental quality and remediation in Yangtze River Delta region. II. Bioaccumulation and potential health risk of polychlorinated dibenzp-p-dioxins and dibenzpfurans PCDD/Fs in farmland and ecological system in a typical polluted area. Acta Pedol Sin 2006;43:563–70 [in Chinese]. Lv AH, Yang RQ, Jiang GB, Yang XG, Xiong JH. The distribution of organochlorine pesticides in sediments and sewage irrigated area soils collected from Urumqi Shuimohe valley. Environ Chem 2006;24:508–10 [in Chinese]. Ma LL, Chu SG, Xu XB. Organic contamination in the greenhouse soils from Beijing suburbs, China. J Environ Monit 2003;5:786–90. Ma LL, Chu SG, Wang XT, Cheng HX, Liu XF, Xu XB. Polycyclic aromatic hydrocarbons in the surface soils from outskirts of Beijing, China. Chemosphere 2005;58:1355–63. Maliszewska-Kordybach B. Polycyclic aromatic hydrocarbons in agricultural soils in Poland: preliminary proposals for criteria to evaluate the level of soil contamination. Appl Geochem 1996;11:121–7. Manz M, Wenzel KD, Dietze U, Schüürmann G. Persistent organic pollutants in agricultural soils of central Germany. Sci Total Environ 2001;277:187–98. Masih A, Taneja A. Polycyclic aromatic hydrocarbons (PAHs) concentrations and related carcinogenic potencies in soil at a semi-arid region of India. Chemosphere 2006;65:449–56. Maskaoui K, Hu Z, Zhou JL, Han YL. Levels of polycyclic aromatic hydrocarbons in some agricultural, industrial and urban areas along Xiamen coastal waters, China. J Environ Sci 2006;18:318–22. Meng P, Wang X, Xu G, Wang X, Li H. Determination and distribution of phthalate alkyl esters in soil of Jinan. Environ Chem 1996;15:427–32 [in Chinese].

223

Mielke HW, Wang GD, Gonzales CR, Powell ET, Le B, Quach VN. Distributions of polycyclic aromatic hydrocarbons in surface PAHs and metals in the soils of inner-city and suburban New Orleans, Louisiana, USA. Environ Toxicol Pharmacol 2004;18:243–7. Mo CH, Cai QY, Li YH, Zeng QY. Occurrence of priority organic pollutants in the fertilizers, China. J Hazard Mater 2007. doi:10.1016/j.jhazmat.2007.07.105. Motelay-Massei A, Ollivon D, Garban B, Teil MJ, Blanchard M, Chevreuil M. Distribution and spatial trends of PAHs and PCBs in soils in the Seine River basin, France. Chemosphere 2004;55:555–65. Nakata H, Hirakawa Y, Kawazoe M, Nakabo T, Arizono K, Abe SI, et al. Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China. Environ Pollut 2005;133:415–29. NYSDEC (New York State Department of Environmental Conservation). SVOCs soil cleanup objectives. Appendix A of TAGM #4046. 2003-04-04, 2003. http://www.dec.state.ny.us/ website/der/tagms/prtg4046c.html. Peijnenburg WJGM, Struijs J. Occurrence of phthalate esters in the environment of the Netherlands. Ecotoxicol Environ Saf 2006;63:204–15. Ping LF, Luo YM, Zhang HB, Li QB, Wu LH. Distribution of polycyclic aromatic hydrocarbons in thirty typical soil profiles in the Yangtze River Delta region, east China. Environ Pollut 2006;147:358–65. Ren NQ, Que MX, Li YF, Liu YF, Wan XN, Xu DD, et al. Polychlorinated Biphenyls in Chinese Surface Soils. Environ Sci Technol 2007a;41:3871–6. Ren M, Peng P, Zhang S, Yu L, Zhang G, Mai B, et al. Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Guangzhou, China. Atmos Environ 2007b;41:592–605. Shen G, Lu Y, Wang M, Sun Y. Status and fuzzy comprehensive assessment of combined heavy metal and organo-chlorine pesticide pollution in the Taihu Lake region of China. J Environ Manag 2005;76:355–62 [in Chinese]. Schmid P, Gujer E, Zennegg M, Bucheli TD, Desaules A. Correlation of PCDD/F and PCB concentrations in soil samples from the Swiss soil monitoring network (NABO) to specific parameters of the observation sites. Chemosphere 2005;58:227–34. Shi Y, Meng F, Guo F, Lu Y, Wang T, Zhang H. Residues of organic chlorinated pesticides in agricultural soils of Beijing, China. Arch Environ Contam Toxicol 2005;49:37–44. Škrbić B, Đurišić-Mladenović N. Principal component analysis for soil contamination with organochlorine compounds. Chemosphere 2007;68:2144–52. Song YF, Wilke BM, Song XY, Gong P, Zhou QX, Yang GF. Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals (HMs) as well as their genotoxicity in soil after long-term wastewater irrigation. Chemosphere 2006;65:1859–68. Streets SS, Henderson SS, Stoner AD, Carlson DL, Simcik MF, Swackhamer DL. Partitioning and bioaccumulation of PBDEs and PCBs in lake Michigan. Environ Sci Technol 2006;40:7263–9. Tang L, Tang X, Zhu Y, Miao Q. Distribution of polycyclic aromatic hydrocarbons in soil of Beijing. J PLA Univ Sci Technol 2004;5:95–9 [in Chinese]. Tang XY, Tang L, Zhu Y, Xing B, Duan J, Zheng M. Assessment of the bioaccessibility of polycyclic aromatic hydrocarbons in soils from Beijing using an in vitro test. Environ Pollut 2006;140:279–85. Tao S, Cui YH, Xu FL, Li BG, Cao J, Liu WX, et al. Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin. Sci Total Environ 2004;320:11–24. Thao VD, Kawano M, Tatsukawa R. Persistent organochlorine residues in soils from tropical and sub-tropical asian countries. Environ Pollut 1993;81:61–71.

224

SC IE N CE OF T H E TOT AL E N V I RO N ME N T 3 8 9 ( 2 00 8 ) 2 0 9–2 24

UNEP (Union Nation Environmental Program). Towards global action. Presented at International experts meeting on persistent organic pollutants. Vancouver: UNEP; 1995. Vikelsøe J, Thomsen M, Carlsen L. Phthalates and nonylphenols in profiles of differently dressed soils. Sci Total Environ 2002;296:105–16. Wagrowski DM, Hites RA. Insights into the global distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans. Environ Sci Technol 2000;34:2952–8. Wang T, Lu Y, Zhang H, Shi Y. Contamination of persistent organic pollutants (SVOCs) and relevant management in China. Environ Int 2005a;31:813–21. Wang DL, Cai ZW, Jiang GB, Leung A, Wong MH, Wong WK. Determination of polybrominated diphenyl ethers in soil and sediment from an electronic waste recycling facility. Chemosphere 2005b;60:810–6. Wang F, Bian YR, Jiang X, Gao HJ, Yu GF, Deng JC. Residual characteristics of organochlorine pesticides in lou soils with different fertilization modes. Pedosphere 2006a;16:161–8. Wang TY, Lu YL, Dawson RW, Shi YJ, Zhang H, Xing Y. Effects of environmental factors on organochlorine pesticide residues in soils of the Guanting Reservoir Area, China. J Environ Sci Health Part B 2006b;41:309–21. Wang MS, Wang LC, Chang-Chien GP. Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans in the landfill site for solidified monoliths of fly ash. J Hazard Mater 2006c;133:177–82. Wang Z, Chen J, Yang P, Qiao X, Tian F. Polycyclic aromatic hydrocarbons in Dalian soils: Distribution and toxicity assessment. J Environ Monit 2007a;9:199–204. Wang XP, Yao TD, Cong ZY, Yan XL, Kang SC, Zhang Y. Distribution of persistent organic pollutants in soil and grasses around Mt. Qomolangma, China. Arch Environ Contam Toxicol 2007b;52:153–62. Wei ZQ, Liu ZQ, Liang XB, Wang FS, Wang SF. Residue of PCBs and OCPs in the paddy soil from Hongfeng Reservoir Area, Guizhou, China. Environ Sci 2007;28:255–60 [in Chinese]. Wilcke W. Polycyclic aromatic hydrocarbons (PAHs) in soil — a review. J Soil Sci Plant Nutr 2000;163:229–48. Wilcke W. Global patterns of polycyclic aromatic hydrocarbons (PAHs) in soil. Geoderma 2007;141:157–66. Wong MH, Leung AOW, Chan JKY, Choi MPK. A review on the usage of POP pesticides in China, with emphasis on DDT loadings in human milk. Chemosphere 2005;60:740–52. Wong MH, Wu SC, Deng WJ, Yu XZ, Luo Q, Leung AOW, et al. Export of toxic chemicals — a review of the case of uncontrolled electronic-waste recycling. Environ Pollut 2007;149:131–40. Wu WZ, Schramm KW, Henkelmann B, Xu Y, Yediler A, Kettrup A. 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 1997;34:191–202. Wu WZ, Xu Y, Schramm KW, Kettrup A. Persistence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in Ya-Er Lake area, China. Environ Int 2001;26:323–6. Wu WZ, Schramm KW, Xu Y, Kettrup A. Contamination and distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in agriculture fields in Ya-Er Lake area, China. Ecotoxicol Environ Saf 2002;53:141–7. Xing Y, Lu Y, Dawson RW, Shi Y, Zhang H, Wang T, et al. A spatial temporal assessment of pollution from PCBs in China. Chemosphere 2005;60:731–9. Xing W, Luo Y, Wu L, Song J, Qian W, Christie P. Spatial distribution of PAHs in a contaminated valley in Southeast China. Environ Geochem Health 2006;28:89–96.

Yan JH, Xu MX, Lu SY, Li XD, Chen T, Ni MJ, et al. PCDD/F concentrations of agricultural soil in the vicinity of fluidized bed incinerators of co-firing MSW with coal in Hangzhou, China. J Hazard Mater 2007. doi:10.1016/j.jhazmat.2007.06.018. Yang G, Zhang T, Guo Z, Wan H, Luo W, Gao Y. The source and distribution characteristics of polycycclic aromatic hydrocarbons in agricultural soils in the Pearl River Delta. Environ Sci 2007;28:60–7. Yu XZ, Gao Y, Wu SC, Zhang HB, Cheung KC, Wong MH. Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies. Chemosphere 2006;65:1500–9. Zhang ZL, Hong HS, Zhou JL, Yu G. Phase association of polycyclic aromatic hydrocarbons in the Minjiang River Estuary, China. Sci Total Environ 2004;323:71–86. Zhang TB, Rao Y, Wan HF, Yang GY, Xia YS. Content and compositions of organochlorinated pesticides in soil of Dongguan City. China Environ Sci 2005;25:89–93 [in Chinese]. Zhang H, Gao R, Jiang S, Huang Y. Spatial Variability of organochlorine pesticides (DDTs and HCHs) in surface soils of farmland in Beijing, China. Sci Agric Sin 2006a;39:1403–10. Zhang HB, Luo YM, Wong MH, Zhao QG, Zhang GL. Distributions and concentrations of PAHs in Hong Kong soils. Environ Pollut 2006b;141:107–14. Zhang HB, Luo YM, Zhao QG, Wong MH, Zhang GL. Residues of organochlorine pesticides in Hong Kong soils. Chemosphere 2006c;63:633–41. Zhang HB, Luo YM, Zhao QG, Zhang GL, Wong MH. Hong Kong soil researches IV. Contents and compositions of organochlorines in soil. Acta Pedol Sin 2006d;43:220–5 [in Chinese]. Zhang HB, Luo YM, Teng Y, Zhao QG, Wang HF. DDT residual in the typical soil types of Pearl River Delta Region and its potential risk. Soil 2006e;38:547–51 [in Chinese]. Zhang HB, Luo YM, Wong MH, Zhao QG, Zhang GL. Concentrations and possible sources of polychlorinated biphenyls in the soils of Hong Kong. Geoderma 2007a;138:244–51. Zhang Q., Huang J., Yu G. Polychlorinated dibenzo-p-dioxins and dibenzofurans emissions from open burning of crop residues in China between 1997 and 2004. Environ Pollut; in press. doi: 10.1016/j.envpol.2007.03.011. Zhao BZ, Zhang JB, Zhou LY, Zhu AN, Xia M, Lu X. Residues of HCH and DDT in typical agricultural soils of Huang-Huai-Hai Plain, China. I. Residues in surface soils and their isomeric composition. Acta Pedol Sin 2005;42:761–8 [in Chinese]. Zhao G, Xu Y, Han G, Ling B. Biotransfer of persistent organic pollutants from a large site in China used for the disassembly of electronic and electrical waste. Environ Geochem Health 2006a;28:341–51. Zhao X, Zheng M, Zhang B, Zhang Q, Liu W. Evidence for the transfer of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans from soil into biota. Sci Total Environ 2006b;368:744–52. Zhou Z, Tian H, Li N, Ren Y, Liu A, Du B, Li L. Preliminary study on level and pattern of PCDD/PCDFs in soil in part of Beijing city. Res Environ Sci 2006;19:54–8 [in Chinese]. Zhu L, Chen Y, Zhou R. Distribution of polycyclic aromatic hydrocarbons in water, sediment and soil in drinking water resource of Zhejiang Province, China. J Hazard Mater 2007. doi:10.1016/j.jhazmat.2007.04.102. Zhu Y, Liu H, Xi Z, Cheng H, Xu X. Organochlorine pesticides (DDTs and HCHs) in soils from the outskirts of Beijing, China. Chemosphere 2005;60:770–8.