Levels, distributions and profiles of polychlorinated biphenyls in surface soils of Dalian, China De-Gao Wang a , Meng Yang a , Hong-Liang Jia a , Lei Zhou a , Yi-Fan Li a,b, * a International Joint Research Center for Persistent Toxic Substances, Dalian Maritime University, 1 Linghai Road, Dalian, Liaoning 116026, China b Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4, Canada article info Article history: Received 15 November 2007 Received in revised form 20 May 2008 Accepted 22 May 2008 Available online 7 July 2008 Keywords: POPs PCBs Surface soil Urban fractionation effect China abstract Surface soil (0–5 cm) samples from 14 sampling sites including rural and urban areas of Dalian, a coastal city in Liaoning Province, China, were collected and analyzed for 84 polychlorinated biphenyls (PCBs). Total 57 PCB congeners were identified and mean concentration of total PCBs among all the sites was 2.8 lg kg 1 dry weight (dw) with a range of 1.3 (rural site) to 4.8 lg kg 1 dw (urban site). For the urban sites, total PCB concentrations in the soil samples collected in industrial area are highest, followed by those from business/residential sites and the garden sites, but the differences are not significant. Higher percentage of lighter weighted molecular PCBs were found in the rural site than urban sites in Dalian, possibly indicating the ‘‘urban fractionation effect”. Total seven dioxin-like PCBs (CB-77, 81, 105, 114, 118, 123, and 126) have been found in Dalian soils and the mean concentration (in lg kg 1 dw) among all the sites of CB-105 (0.17) is higher than any other dioxin-like PCBs, followed by that for CB-81 (0.14) and for 118 (0.06). No significant correlation relationship between the concentrations of dioxin- like PCBs and those of total PCBs was found. The toxic equivalency (TEQ) concentrations (in ng kg 1 dw) of these seven dioxin-like PCBs in 14 soil samples range from 0.006 7 to 4.885 7 (with a mean 1.372 7 ) for humans and mammals, from 0.001 7 to 0.37 7 (with a mean 0.14 7 ) for fish, and from 0.01 7 to 31.47 7 (with a mean 17.23 7 ) for birds. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Polychlorinated biphenyls (PCBs) are highly persistent, toxic, bioaccumulative and widespread environmental contaminants, which are typical persistent organic pollutants (POPs) in the envi- ronment (Halsall et al., 1995). PCBs had been widely used for industrial purposes such as dielectric fluids in electrical transform- ers, capacitors, hydraulic and heat transfer fluids, and plasticizers. PCBs can be released from commercial PCB products, which are the potential primary source of PCBs in the environment (Herrick et al., 2007). Due to their toxic effects in both humans and wildlife (Cogliano, 1998; Giesy and Kannan, 1998), the levels and distribu- tions of PCBs have aroused great concerns on environmental health. Soils are natural sinks and environmental reservoirs for POPs in the terrestrial environment and thus understand of the fate of PCBs deposited to the surface soils is important. Being lipophilic com- pounds, PCBs adsorb to the organic carbon of the soil, and due to the high persistence and low mobility, PCBs can accumulate and remain in the soil for very long periods of time. Atmospheric trans- port from major urban areas can lead to significant PCBs loading to surrounding terrestrial and aquatic ecosystems (Harner et al., 1995, 2004; Ockenden et al., 1998). Even today, many years after restrictions of PCBs manufacture and use were introduced in many countries, urban areas continue to act as major sources of atmo- spheric PCBs to surrounding regions (Halsall et al., 1995). It has been generally observed that PCB concentrations were higher in urban soils than in other soils (Wilcke et al., 2006; Jamshidi et al., 2007). Therefore, the soil of urban areas is an important contamination source of PCBs. A number of studies have been conducted on the pollution of PCBs in environmental media such as atmosphere (Bi et al., 2002; Lammel et al., 2007), sediments (Zhou et al., 2001; Mai et al., 2005; Fu and Wu, 2006), and water (He et al., 2006) in China. However, few of the studies surveyed PCBs contamination in the soil, and when undertaken, the focus was on already heavily polluted areas (Xing et al., 2005). Recently, Ren et al. (2007) have for the first time investigated levels and distributions of PCBs in Chinese surface soil on a national scale. They found the average concentration of total PCBs among 52 sites (4 background, 39 rural, and 9 urban) across China in 2005 was 515 ng kg 1 dry weight (dw), approximately one-tenth of that in global background soil in 1998 (Meijer et al., 2003). The major PCB homologue group in 0045-6535/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2008.05.055 * Corresponding author. Address: Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4, Canada. Tel.: +1 416 739 4892; fax: +1 416 739 4288. E-mail address: yi-fan.li@ec.gc.ca (Y.-F. Li). Chemosphere 73 (2008) 38–42 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere