Impacts of Industrial Zone in Arid Area in Ningxia Province on the Accumulation of Heavy Metals in Agricultural Soils

Abstract

With the transferring of the industry from the east coastal regions of China to the mid and west regions, those places once called "Clean Earth" in the arid north-west region are facing the contamination risks by industrial emission. In order to study the impacts of the industrial zone on the accumulation of heavy metals Zn, Cr, Ni, Mn, Co, Cu, Cd, Pb in agricultural soils, we collected the agricultural soil samples in a county in Ningxia province using GIS technology. Samples were collected in a belt way along the yellow river and expanding from the industrial zone as the center according to the main local wind direction. It was suggested that the accumulation of heavy metals in studied agricultural soils was slight. High accumulation of Zn and Cd only occurred in several sites. However, the accumulation of heavy metals in industrial zone was more apparent. Except for Ni, the rest 7 elements had obvious accumulation. One third of the sites had Cd concentration at contamination level. The spatial analysis revealed that the distributions of Cd, Zn, Cu, Mn, and Pb were closely related to the location of industrial zone. Industrial zone had not caused the contamination of heavy metals in agricultural soils yet. Due to the high pH value (average pH value of 8.54), no soil contamination issue was found at present. However, the impacts of industrial zone on the accumulation of heavy metals in agricultural soils were apparent. The input pathway of heavy metals into agricultural soils was mainly dust deposition. The industrial zone also increased the heavy metal concentrations in irrigation water to some extent.