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

Abstract

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-metal-related 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.