YANG Xiaoxiao^1,2, ZENG Daoming^2,3, LUO Xianrong¹, SUN Bingbing^2,3, WU Chao^2,3, HUANG Wenbin¹, YANG Chunli¹

（1. College of Earth Sciences, Guilin University of Technology , Guilin 541004, Guangxi, China；
2. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 06500, China；
3. Key Laboratory of Geochemical Exploration, Ministry of Land and Resources, Langfang 06500, China）

Abstract: Taking soils of Sanjiang, Muzhou and Gujing towns in the Xinhui area of the Pearl River Delta as the main research objects, the physical and chemical parameters, including contents of total nitrogen (N), organic carbon (OC), pH, silicon dioxide (SiO2), aluminum trioxide (Al2O3), selenium (Se), fluorine (F), iodine (I) and selenium (Se), of 1567 surface soil samples and Se contents in 60 rice samples were determined. The contents, distributions and key control factors of Se, I and F in this area were discussed. The results showed that average contents of Se, F and I in the study area were 0.50 mg/kg, 617.39 mg/kg and 3.57 mg/kg, respectively, and average contents of Se and F were higher than their national soil background values, the average content of I was lower than the national soil background value. Contents of Se, F and I correlated consistently with Al2O3, OC and pH, meanwhile contents of F showed no significant correlation with contents of Se, but contents of F showed a negatively correlation with contents of I. The geochemical characteristics, such as, content distributions of Se, F and I, were obviously controlled by strata of different parent materials, for example, contents of Se and I were higher in bedrock and granite areas and contents of F in quaternary sedimentary areas were higher, indicating that Se and I mainly derived from Yanshanian volcanic activities and F mainly derived from the delta deposition. In summary, soils of the study area could be characterized by abundant selenium, adequate amount of iodine, and excess fluorine. The enrichment of selenium in rice samples suggested the prospect of developing natural selenium-rich agricultural products.

Key words: Selenium; Iodine; Fluorine; Geochemistry; Xinhui area

EARTH AND ENVIRONMENT Vol.48, No.2, Tot No.334, 2020, Page 181-189