Distribution Characteristics and Ecological Risk Assessment of Soil Heavy Metals in the Eastern Mountainous Area of the Nanyang Basin

Abstract

The spatial distribution, pollution degree, and ecological risk of heavy metals in the soil were studied by analyzing the contents of As, Hg, Cd, Cr, Pb, Zn, Ni, and Cu and pH values in surface soil samples of the eastern mountainous area of the Nanyang basin. The results showed that the contents of Cd, Cu, Cr, Ni, Pb, Zn, and As in the soil exceeded the screening value of soil pollution risk. The spatial distribution of soil heavy metals displayed regional-and island-shaped. The highest concentration of heavy metals was found in the south of the study area, where a mining area is located. Most of the samples had no pollution levels except some samples with high contents of Cd. For As, Cr, Pb, Zn, Ni, and Cu, the potential ecological risk of most samples were low, while Cd and Hg posed medium risk in most areas. The areas with high and relatively high ecological risk index accounted for 58.93% and 37.66%, respectively. Soil Hg, Cd, and Pb contents were related to anthropogenic activities such mineral mining. As derives from geological processes, while Zn, Ni, Cr, and Cu are both controlled by anthropogenic activities and geological processes. The mining of mineral resources is the main driving factor of soil heavy metal pollution and ecological risk in the study area.