Study on the Distribution of Selenium-rich Soil and the Regularity of Selenium Enrichment-Migration in Shitai Area, Anhui, China

Shitai County in the southern Anhui Province is a potential Selenium (Se)-rich area. Investigating the distribution characteristics of Se-rich soil and studying the regularity of Se enrichment-migration are of great significance for the development of Se-rich agricultural products in this area. In this study, the distribution characteristics of Se-rich soil and the regularity of selenium enrichment and migration in the Shitai area were studied using elemental analysis techniques. Our results show that the average Se contents in the surface soils of the Shitai area are 0.56 mg/kg, which are significantly higher than the threshold value (0.4 mg/kg) of Se enrichment in soil. The distribution of Se contents in the Shitai area is not uniform, and the average soil Se contents of five towns in Shita have reached the standard Se-enrichment, i.e., Xianyu town, Dayan township, Xiaohe town, Dingxiang town, and Renli town. High-Se areas in Shitai are mainly concentrated in the areas where the Cambrian Hetang and Huangboling formation strata, especially the stone coal stratum are exposed. This indicates that these strata are the main sources of Se in the soil of the Shitai area. There are good correlations between soil selenium contents and pH values, and the contents of carbon, sulfur, and organic matter, indicating that the composition and property of soil play an important role in the migration and distribution of Se. Local Se-rich strata (especially the Cambrian Huangboling formation) in the Shitai area are also rich in heavy metals such as Cd and Hg, resulting in both selenium enrichment and heavy-metal pollution in surrounding soils. These areas with high heavy metal contents should be avoided when developing Se-rich agriculture in the Shitai area.