Cd Accumulation and Risk Assessment for Arable Soils in the Karst Region of Northern Luodian, Guizhou

Abstract

Background levels of cadmium (Cd) in carbonate rock areas of Guizhou Province are high. In order to understand the characteristics of Cd in arable soils in these karst areas, the soils in the northern county of Luodian were selected as the study object. By comparing soils in non-karst areas, the distribution characteristics of soil Cd were studied by combining geostatistical analysis and GIS, and the potential ecological risk index and health risk were used to evaluate the potential level of risk to adults and children. The results show that the arable soil Cd content in this karst area is significantly higher than that in non-karst areas (P<0.05), with a geometric mean of 1.33mg·kg-1 and 0.27 mg·kg-1, respectively. In comparison, the geometric mean of soil Cd content in forested land in the same areas is 1.57mg·kg-1 and 0.22 mg·kg-1, respectively. Based on "soil pollution risk control standards", the Cd content of 90% and 22% of arable soil samples was higher than the risk screening value and the risk control value for karst and non-karst areas, respectively. The areas with medium and high Cd values were mainly distributed in the karst areas, presenting medium to strong ecological risks and extremely strong ecological risks, respectively. In contrast, the areas with the lowest Cd concentrations were distributed in the non-karst areas of Jiaoyan, presenting low potential ecological risk. The health risk assessment showed that the non-carcinogenic risk and carcinogenic risk of the three exposure pathways for adults and children in the karst areas are significantly higher than those in the non-karst areas, but the Cd content in the soil does not present non-carcinogenic and carcinogenic risks to local residents. Overall, the problem of Cd pollution in arable soils in the karst area of northern Luodian, Guizhou, is prominent. Therefore, the study of the risks posed by Cd pollution to the soil-plant-human system should be strengthened, and appropriate measures should be taken to prevent and control Cd pollution in the areas at risk.