Abstract:
To investigate the geochemical characteristics, sources and correlations with heavy metals of selenium (Se) in the soil of the Guobu area in southern Jiangxi Province, this study carried out 1:50,000 scale surface soil areal sampling and soil vertical profile sampling in the area, as well as elemental testing and analysis, scanning electron microscopy observation and electron probe analysis. The results show that: ①The Se content of the surface soil in the study area generally shows a pattern of more distribution in the west and less in the east, with an average value of 0.44 mg/kg. Vertically, the soil Se content overall presents a feature of being higher in the middle and lower at the top and bottom, that is, the Se content in the middle accumulation layer is high, while that in the top leaching layer and the bottom parent material layer is low. ②The area of selenium-rich soil in the entire district is 66.66 km
2, accounting for 59.31% of the total soil area, which indicates a promising prospect for the development of selenium-rich soil. ③The Se content in the surface soil and the vertical soil profile is positively correlated with the contents of heavy metals such as Cr and As to various extent. This indicates that Se, Cr and As are prone to accumulate in the soil, suggesting that Se-rich soils have pollution risks from Cr and As. ④ The main metallic mineral in the soil is hematite, with an average Se content of 0.134%; in the bedrock, the main metallic mineral is pyrite, with an average Se content of 0.235%. Therefore, it is speculated that the Se in the soil may partly come from the weathering and oxidation of pyrite. The selenium content in the study area's soil is mainly influenced by the parent material and organic matter. In addition, factors such as soil type, genesis, land use type, and fault structure also have certain effects on the selenium content in the soil.