Quantitative analysis of factors influencing soil Pb content in the high eco-nomic development region of South Jiangsu Province: a case study in Kun-shan City

One hundred and twenty-six soil samples were collected from paddy field, traditional vegetable and protected vegetable fields in Kunshan City, a typical area of the high economic development region of South Jiangsu Province. Multi-statistics regression analysis was used to quantify the factors influencing soil Pb forms in the studied area. The results showed 1.04~12.04 mg·kg^-1 of soil available Pb, with an average value of 3.75 mg·kg^-1. While the average content of soil total Pb was 27.42 mg·kg^-1, the available rate of soil Pb was 15.64%. The order of contents of different forms of soil Pb was as follows: soil residue Pb (15.35 mg·kg^-1) > soil organic-matter bonded Pb (6.68 mg·kg^-1) > soil iron/manganese-oxide bonded Pb (4.27 mg·kg^-1) > soil carbonate bonded Pb (0.76 mg·kg^-1) > soil exchangeable Pb (0.36 mg·kg^-1). Soil residue Pb content was significantly higher (49.79%) than the contents of the other forms of soil Pb. pH was the most important factor affecting soil exchangeable Pb and iron/manganese-oxide bonded Pb contents, it was significantly negatively correlated with contents of the two forms of soil Pb. Soil total Pb content was the most important factor for soil carbonate bonded Pb and residue Pb contents, both of which had significant positive correlation. Soil organic-matter content was the most important for soil organic-matter bonded Pb content, and both had significant positive correlation. pH was also an important factor for soil organic-matter bonded Pb content.