长春市城郊蔬菜—土壤系统重金属分布特征及生态风险评价
Distribution characteristics and potential ecological risk assessment of heavy metals in soil-vegetable system of Changchun suburb
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摘要: 以长春市城郊蔬菜地为研究对象,研究了蔬菜-土壤系统中Pb、Cr、Cd、Hg和As 5种重金属的含量特征、潜在生态风险及蔬菜的累积富集能力。结果表明,蔬菜地表层土壤中Pb、Cr、Cd、Hg和As含量均低于国家土壤环境质量二级标准,适宜种植蔬菜及农作物;但其含量明显高于长春市土壤环境背景值,具有较明显的累积现象,高含量区主要分布在长春市城郊东北与西南部。蔬菜农田土壤呈现中度污染水平,达到中等潜在生态风险等级,北部局部地区达到较强生态风险等级,应控制其污染来源。除白菜中Pb含量超标外,其余蔬菜中的重金属均未超过国家食品安全限量值。6种蔬菜对重金属的平均富集系数表现为:Hg>As>Cd>Pb>Cr。根茎类对As的富集能力强,而叶菜类对其他重金属富集明显。该区应加强土壤Hg、Cd的防治,以保障城郊区域蔬菜种植安全。Abstract: 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.