PCBs Residues Characteristics and Ecological Risk Assessment in a Chinese Paddy Fields

14 kinds of PCBs were determined in water and soil of a paddy field in Dragon Bridge, Nanjing, P. R. China, which is a typical small watershed irrigated area. The results showed that: 14 congeners of PCBs were detected at different residue levels, the dominant components of PCBs were tri-, tetra-, and penta-chlorinated PCB congeners, accounting for 82.37% ~ 95.45% of total PCBs. The concentration range of PCBs in the water of paddy field was 34.0 ~ 148.6 ng/L, their mean content in surface water was 144.01ng/L and that in groundwater was 53.77 ng/L, the trend of vertical migration in the paddy field is very obvious. The concentration range of PCBs in paddy soil was 288.6 ~ 473.7 ng/g, and their mean value was 357.5ng/g. The ΣTEQ range was 0.75 ~ 1.89 pg/g, the ecological risk of research area was a bit high than other region in China. The residual content of PCBs in the paddy field is mainly affected by the using of fertilization and pesticides.