Sources, transport pathways and ecological risks of heavy metals present in roadside soil environment in urban areas

Abstract

The study investigated sources and transport pathways of heavy metals in roadside soils in urban areas of a typical nodal city, alongside the associated eco-risks. Soil, leaf and bark samples were collected along the routes and analysed for metal concentration using standard methods. The data were analysed using ANOVA, principal component analysis and factor analysis. The results showed that Pb, Cu and Ni in the roadside soil were found to be mainly from traffic emissions, whereas Cd in the soil was primarily through municipal waste incineration. Pb, Cd and Ni in leaf samples were absorbed from the soil via foliar uptake, while root uptake was the primary pathway for Cu in the leaves. Potential ecological risk indicated a moderate eco-risk for 5 routes with Cd being the primary contributor to the risk. Therefore, it is important to control the source of Cd to reduce the eco-risks associated with metal pollution.