Selenium Uptake Characteristics of Reclaimed Soil-Crop from Mining Wasteland and Its Antagonistic Effects on Heavy Metals

Abstract

To fully exploit selenium-rich land resources and ensure crop safety, the phenomenon of "double high" of Se and heavy metals in reclaimed soil of mining wasteland was studied. Soil and maize samples collected from "point-to-point" were weighted by the inverse distance weighted (IDW) method; multiple linear regression (MLR), partial least squares regression (PLSR), random forest regression (RFR), and other methods were used to predict selenium uptake by maize in a sulfur mine reclamation area in southwest China. Meanwhile, the antagonistic effects of selenium (Se) on heavy metals (Hg, As, Cd, and Cr) were analyzed. The results showed that the soil in the study area was rich in selenium resources. The average Se content in the soil reached 0.83 mg·kg-1, which was 2.87 times that of the average Se content in Chinese soil. The Se content in maize grains ranged from 0.02 mg·kg-1 to 0.16 mg·kg-1. According to correlation analysis and model prediction, the main influencing factors of selenium content in maize grains in the study area were soil selenium, pH value, organic matter, and heavy metal As. Multivariate linear regression (MLR) was the most effective method for predicting selenium content in maize grains, and the determinant coefficient R2 was 0.52. By comparing the enrichment characteristics of maize to heavy metals (Hg, As, Cd, and Cr) under different concentration gradients of Se in the soil of the study area, the results showed that Se had antagonistic effects on Hg, As, Cd, and Cr. The results can provide a basis for the development of selenium-rich agriculture in similar mining wasteland reclamation in the future.