Distribution and Evaluation on Potential Ecological Risk of Heavy Metals in Soils of Huzhou

The potential ecological risk of heavy metals in soil was evaluated according to relevant standard and method based on the investigation of heavy metal pollution status in soil of Huzhou. The results showed that the single-factor pollution index of Pb was the lowest while the single-factor pollution index of Cd was the highest. Pb content in soil complied with the standard but the contents of other heavy metals in some soils exceeded the standard. 68.9% of soils were at the level of security, 21.6% of soils were at the alert limit, 8.1% of soils were at the level of light pollution, 1.4% of soils were polluted seriously. 68.9% of soils were at the low risk level, 27.0% of soils were at the middle risk level, 2.7% of soils were at the strong risk level, 1.4% of soils were at the very strong level. The ranges of heavy metal contents in woodland were generally higher than those of paddy land. The degree of soils pollution of paddy fields was lower than that of woodland. The contribution to pollution of heavy metals in soil was in an order of CdNiCrHgZnCuAsPb.