Distribution characteristics and potential ecological risk assessment of heavy metals in soil-vegetable system of Changchun suburb

With an aim to understand the concentration characteristics, potential ecological risk characteristics and accumulation ability in vegetables, we investigated five heavy metals including Pb, Cr, Cd, Hg and As in a soil-vegetable system in Changchun suburb.The results showed that the concentrations of heavy metals in surface vegetable soil were lower than those of China Soil Environmental Quality Standard level Ⅱ, which was suitable for planting vegetables and crops; while the concentrations were significantly higher than those of Changchun soil environmental background values, which was with an obvious accumulation phenomenon.The higher concentrations of heavy metals were mainly distributed in northeastern and southwestern regions of Changchun suburb.Generally, the vegetable soil was at a medium pollution level, with a medium potential ecological risk; while the heavy metals were with a stronger ecological risk in part of northern regions, and pollution sources were required to be controlled.The amounts of heavy metals in vegetables were not over the National Food Safety Limited Value except for several Pb samples from Chinese cabbage.The average Bio-concentration factor(BCF) of 6 kinds of vegetables for heavy metals was in an order of Hg>As>Cd>Pb> Cr.The root-tuber vegetables were with more concentration coefficient of As, while leaf vegetables were with more concentration coefficient of other heavy metals.The control of soil Hg and Cd should be strengthened for the guarantee of vegetable planting in Changchun suburb.