Accumulation characteristics and environmental risk assessment of heavy metals in typical karst soils

• Main Authors: LIU Nanting, LIU Hongyan, WU Pan, LUO Guangfei, LI Xuexian
• Format: Article
• Language: zho
• Published: Agro-Environmental Protection Institute, Ministry of Agriculture 2021-09-01
• Series: Journal of Agricultural Resources and Environment
• Subjects: soil heavy metals; accumulation; ecological risk; health risk; risk assessment; karst area
• Online Access: http://www.aed.org.cn/nyzyyhjxb/html/2021/5/20210510.htm

In this study, 225 topsoil samples were collected from different areas(natural background, agricultural planting, and mining areas) in Guizhou Province to systematically investigate the concentrations, distribution, and accumulation characteristics of heavy metals As, Cd, Cr, Cu, Hg, Pb, and Zn. Based on this, the potential ecological risk index(RI) and human health risk assessment were used to assess the ecological risk level and human health risk of heavy metal exposure in different areas. Results indicated that the concentrations of heavy metals in the topsoil of different regions in Guizhou Province were significantly different. Compared with the corresponding background value of soil in Guizhou Province, the accumulations of Hg, Zn, Cd, and As in agricultural planting area soil were significant. The mean concentrations of Hg, Zn, Cd, Pb, and As in the soil of mining areas were 52.55, 23.22, 16.32, 14.48, and 4.85 times of the soil background values of Guizhou Province, respectively. The geoaccumulation index(<i>I</i>_geo) values showed that the heavy metals in the soil of the natural background areas were uncontaminated, while the pollution from heavy metals in the agricultural planting areas were at uncontaminated or uncontaminated to moderately contaminated levels. The heavy metals contaminated levels were more prominent in the mining area, and the pollution of Hg, Zn, Cd and Pb reached moderately contaminated levels. especially in the mineral resources distribution areas, such as northwest Guizhou and Tongren areas. The RI results showed that the ecological risk levels of heavy metals in the soil of the mining area were considerably higher than those in agricultural planting areas and natural background areas. The ecological risks of heavy metals in the soil of mineral-resource concentrated-distribution areas were relatively high, with some samples were in high ecological risk levels. The potential ecological risk assessment of single heavy metal revealed that Hg, Cd, Pb, and As were the main risk factors in the soil of agricultural planting and mining areas, while Cr and Cu were in low risk levels. The health risk assessment results indicated that the non-carcinogenic risks existing in soils of agricultural planting and mining areas to adults were acceptable, but the carcinogenic risk could not be neglected. The non-carcinogenic and carcinogenic risks to children were evident. The overall human health risks in mining areas were higher than those in agricultural planting areas, and the human health risks for children were higher than those for adults.