区域土壤重金属空间差异及对蔬菜品质安全影响的分析——以南京八卦洲、江心洲为例

Regionally Spatial Variation of Soil Heavy Metals and Their Influences on Vegetable Quality:A Case Study of Baguazhou and Jiangxinzhou,Nanjing,China

以南京城郊典型蔬菜生产基地八卦洲和江心洲为研究对象,通过设置不同调查小区,采样分析剖面土壤、表层土壤及其对应蔬菜中重金属含量,探讨区域土壤重金属空间差异和土壤重金属污染对蔬菜品质安全的影响。结果表明:南京八卦洲土壤重金属呈现表聚性特点,这与周边存在化工园区、境内贯穿长江二桥公路和靠近长江航道等外源因素有关;深层土壤重金属含量与成土母质中的含量均相近,八卦洲与江心洲两处成土母质均为长江冲积物,具有同源性特点。同步采集表层土壤样品和对应的蔬菜样品能较好地评估土壤污染的危害,与全量指标相比,土壤重金属有效态含量与蔬菜中重金属含量之间具有更好的相关性。

Understanding spatial variation of soil heavy metals is critical to ensuring vegetable quality.Two typical suburban vegetable pro-duction bases in Nanjing(Baguazhou and Jiangxinzhou) were selected for this study.Topsoils and corresponding vegetable samples were collected and content of heavy metals in the samples were measured to evaluate the effect of spatial variation of soil heavy metals on vegetable quality.Results showed that the accumulation of heavy metals occurred in the topsoils of Baguazhou,which was resulted from the surrounding chemical industries,the 2nd Nanjing Yangtze River Bridge Highway and the Yangtze River channel.The content of heavy metals in subsoils was similar to that of soil parent materials.Both Baguazhou and Jiangxinzhou had the same soil parent materials:Yangtze River alluvial materials.The simultaneous topsoil and vegetable sampling could improve the risk assessment of soil heavy metal pollution.Available metals in soils showed better correlations with metals in vegetables than total metals did.