快速城市化区域不同用地类型土壤重金属含量分布特征及生态风险

Content and Ecological Risks of Heavy Metals in Soil with Different Land Uses in a Rapidly Urbanizing Area

以上海市闵行区典型快速城市化区域为例,基于36个地块595个点位土壤样品数据,分析5种不同土地利用类型中8项土壤重金属的含量分布特征,通过内梅罗综合指数法和潜在生态风险指数法进行生态风险评价.结果表明,重金属锌和镉含量的变异系数较高,受人为活动影响特征明显.涉重工业用地、非涉重工业用地的重金属赋存相对较高,住宅用地和耕地重金属含量总体不高但具有其特异性组成特征,公共管理与公共服务用地相对最低.重金属锌和镉的内梅罗综合污染指数较高,分别处于重度和中度污染水平,其余重金属均为警戒或轻度污染水平.不同土地利用类型的土壤重金属潜在生态风险水平为:涉重工业用地>非涉重工业用地≈住宅用地>耕地≈公共管理与公共服务用地,工业用地由于行业类别多、历史生产复杂和管理水平差异大等原因,具有较大的土壤重金属污染风险,住宅用地和耕地等其他用地类型也呈现出一定的重金属累积趋势.不同土地利用的土壤重金属污染源头防控和地块再开发利用的安全性及风险管控,是快速城市化区域土壤污染防治的重点和难点.

Taking the Minhang District of Shanghai as a typical rapidly urbanizing area,and based on 595 soil samples from 36 plots,the content of eight heavy metals in soils from five different land uses were analyzed.The ecological risk was evaluated using the Nemerow composite index and the potential ecological risk index.The results showed that the variation coefficients of the heavy metals Zn and Cd were highest,and were notably affected by human activities.The content of heavy metals in industrial land soil was relatively high compared to residential land and cultivated land soils,and heavy metal content was lowest in public management and service land soil.The Nemerow composite index of Zn and Cd was high,corresponding to severe and moderate levels of pollution,respectively.The other heavy metals were found at warning or light levels of pollution.The potential ecological risks posed by heavy metals in the soils from different land uses,in descending order,were heavy-metal-related industry land>non-heavy-metalrelated industry land≈residential land>cultivated land≈public management and service land.Industrial land had a greater risk of heavy metal pollution due to industrial operations,complex historical production,and widely variable levels of management.Heavy metal accumulation also tended to occur in residential land and cultivated land soils.Therefore,the prevention of soil heavy metal pollution in association with different land uses,and the control of associated risks during redevelopment,are key challenges in rapidly urbanizing area.