Spatial distribution and source identification of indicator polychlorinated biphenyls in soil collected from the coastal multi-industrial city of Ulsan, South Korea for three consecutive years

The concentrations, profiles, and source-receptor relationships of seven indicator polychlorinated biphenyls (PCBs) (#28, 52, 101, 118, 138, 153, and 180) found in soil at 25 rural, urban, and industrial sites in Ulsan, South Korea were investigated. For this study, 75 soil samples were collected, 25 each in January of 2011, 2012, and 2013. Principal component analysis was used to evaluate the influence of the emission sources on the soil samples. The concentrations of total seven PCBs (Σ7 PCBs) ranged between 0.034 ng/g and 143 ng/g (mean: 5.10 ng/g, median: 0.440 ng/g), which indicated slight or moderate contamination levels, respectively, compared to those in the other countries or other cities in Korea. The concentrations of Σ7 PCBs at the industrial and urban sites were significantly higher than those at the rural sites, due to the direct influence of emission sources related to industrial activities rather than urban emission sources. Generally, the profiles of PCBs were dominated by penta- and hexa-chlorinated biphenyls at all the study sites, suggesting common sources of PCBs in Ulsan. PCB source identification indicated that leakage from transformer oils in the major industrial complexes and PCB-containing paints used in the automobile and shipbuilding industrial complexes were possibly the main sources of indicator PCBs in the study areas.