ASSESSMENT OF HEAVY METAL POLLUTION IN AGRICULTURAL SOILS FROM SUBURBAN VEGETABLE FIELDS UNDER DIFFERENT PLANTING TIME

摘要

Due to rapid industrialization and urbanization, lands under suburban agriculture are the worst affected by the contamination of heavy metals. The objective of this study was to assess the extent and severity of metal contamination in suburban vegetable fields under different planting time. Forty-four top soil samples were collected from suburban vegetable plots under five levels of planting time in Songyuan, China. The study results showed that heavy metal concentrations of Pb, Cr, Cu, Ni, Zn and Cd in soils varied from 13.5 to 40.9, 26.8 to 47.9, 7.7 to 40.2, 13.0 to 27.7, 63.8 to 189.6, and 0.06 to 0.32 mg kg1, respectively. The contents of Pb, Cu and Zn in suburban vegetable soils had obvious trend of escalation with the increase of planting time. The assessment results of PI indicated that there was obvious pollution of Zn and Cd in some fields, which were classified as High PI. Besides that, the comprehensive assessment results of IPI further showed that the IPI values in study area were greater than 1 in the long-term cultivation fields (above 20 years), indicating the soil quality has clearly been impacted, particularly those areas cultivated for several decades.