Risk Assessment of Heavy Metal(loid)S Contamination in Agricultural Soil-Crop Systems in a Black Shale High Geologic Background Area

Heavy metal(loid)s accumulation in soil-crop systems is associated with lithologies weathering (black shales) a high geological background. To explore the heavy metal(loid)s pollution in areas with high geological background of black shale, pollution of As, Cd, Cr, Se, Hg and Pb in the soil-crop system in areas of typical black shale was investigated. The results showed that the soil-crop system was heavily contaminated with Se and Cd, with Se concentrations exceeding the environmental standard limit by a factor of 5.2. The bioaccumulation coefficients (BCFs) indicated that the crops had a high uptake capacity for Se and Cd. The BCF of cabbage for Se reached 14.7, followed by elemental Cd at 2.57, and that of maize for Cd was 2.95.The results of health risk showed that cabbage and rice were the main crops constituting the health risk in the study area, and the HI values of rice for elements other than Pb were greater than 10, which meets the criteria for toxicity, and elemental As was the high contributor to the HI value of rice, which reached 36.6. This study is crucial for understanding heavy metals (loids) in soil crop systems in black shale areas under high geological backgrounds.