Assessment and Source Analysis of Heavy Metal Pollution in Farmland Soils in Southern Youyang County, Chongqing

Abstract

To investigate the impact of mining activities and geological background on the soil environment, 156 soil samples were collected from an agricultural land in southern Youyang County, Chongqing. The content and pH of heavy metals in the soil were analyzed, and the Nemerow index method was used to evaluate the pollution status of soil heavy metals. The source of soil heavy metals was discussed using the principal component analysis/absolute principal component score (PCA/APCS) receptor model. The results showed that the soil Cd pollution was distributed in a planar shape, while soil Hg mainly appeared as point pollution. The medium-severe soil pollution was mainly distributed at the junction of Tushi Town, Mawang Town, and Longtan Town, where the soil was predominantly acidic and there was a higher risk of crop contamination; the indicator Kriging evaluation results showed that there was a higher probability of soil contamination at the junction of the three towns and the northern part of Tushi Township. The results of the PCA/APCS receptor model analysis showed that the sources of soil As, Cd, Cr, and Ni were mainly controlled by geological background; soil Hg, Pb, and Zn were mainly controlled by mining activities; further, soil Cu was affected by both geological background and mining activities. In addition, the agricultural activities were also one of the sources of soil As, Cd, Pb, Cu, and Zn. The medium-heavy pollution of the soil in the study area was mainly caused by mining activities, while the heavy metal pollution of the soil caused by geological background was mainly light pollution. This study can provide a theoretical basis for the safe use of land and the prevention and control of soil pollution in typical regions.