Abstract:

Selenium is an essential element for mammals. In order to study the distribution characteristics, the important influencing factors of selenium distribution in soils and to classify selenium-rich soil resources, this study systematically collected and analyzed 199 top-soil samples and 60 crop samples in Shadi township of Enshi City. The correlation of the geochemical parameters, such as the selenium concentrations of corn seeds and top soils, was analyzed, and as a result an absorption model of selenium in corn seeds was established. Results of the analysis show that concentrations of total selenium in the top-soils ranged from 0.19 mg·kg^-1 to 15.57 mg·kg^-1, and averaged 1.88 mg·kg^-1, which is clearly higher than the average concentrations in Hubei Pro-vince and China as a whole. The area with selenium-sufficient soil and selenium-rich soil accounts for 84.43% of the study area. The distribution of selenium is mainly influenced by geology. There is a significant difference in selenium content distribution in top-soils formed in proximity to different geologies. The selenium content in the outcropping area of Permian Maokou Formation is higher than that of other stratigraphic regions. The results also indicate that soil TOC and altitude were important influencing factors on selenium content. The selenium concentrations in crops had a large range. Se-enriched crops have the largest proportions, accounting for 43.22%. The selenium-rich land and potentially selenium-rich land accounted for 65.33% and 23.12% of the study area, respectively.

Key words: selenium, influencing factor, model, selenium-rich soil, Enshi, Hubei