Accumulation and Health Risk Assessment of Heavy Metal(loid)s in Soil-Crop Systems from Central Guizhou, Southwest China

Heavy metal(loid)s (HMs) contamination in agricultural soil and crops is related to the quality and safety of agricultural products and public health and has attracted worldwide attention. This study systematically investigated the bioaccumulation of HMs including Cd, Pb, Cr, Hg, As and Se in soil and associated crops (Tea, Plum and Corn) in Guizhou Province, China, and assessed the health risks of the edible part of the crops using the bioconcentration factor ( BCF ), geoaccumulation index ( I geo ), and target hazard quotient (THQ). The results indicate that the mean concentrations of Pb (39.54 ± 16.56 mg/kg), Cr (122.50 ± 33.36 mg/kg), Hg (0.26 ± 0.33 mg/kg), As (25.40 ± 21.34 mg/kg), and Se (0.90 ± 0.46 mg/kg) in cultivated soil exceed the background values of Guizhou Province by 1.12, 1.28, 2.36, 1.27, and 2.4 times, respectively. However, the average concentration of Cd is 0.49 ± 0.49 mg/kg, which is lower than the corresponding background value. The average I geo values of Pb, Cd, Cr, and As in the soil samples were lower than 1, indicating a relatively low degree of enrichment, whereas the enrichment of Hg was relatively obvious, as approximately 32.9% of the samples were at moderate and above enrichment levels. The contents of HMs in samples of corn, plum, and tea were lower than the corresponding pollutant limit. The BCF values of Cd, Hg, and Se in the three crops were relatively high, indicating a strong migration ability, and the average BCF values of tea in the soil-crop system were higher than those of corn and plum. Correlation analysis showed that the soil pH and concentrations of K 2 O, Fe 2 O 3 , and Al 2 O 3 were negatively correlated with the BCF of Pb, Cr, and Hg in the soil-crop system, indicating that they were affected by macro-oxidation in the soil, whereas Cd and As were basically not affected. The human health risk assessment of THQ values demonstrated that the health risks to local residents from eating corn and drinking tea were low.