Abstract:

In this paper, the typical soil profiles of carbonate rock and terrigenous clastic rock in Wuming County of Guangxi were chosen as our investigative objects. The vertical migration and influencing factors of the selenium chemical speciation in soil formation process were studied. The results showed that the soil selenium content was inherited from the parent materials, with average values of 0.55 mg/kg and 1.43 mg/kg respectively; and the selenium content of the carbonate rock was enriched significantly in the surface soil, but relatively stable in the terrigenous clastic rock. The total water soluble selenium content of the carbonate rock was higher than that in the terrigenous clastic rock, with arithmetic average values of 3.48 μg/kg and 1.81 μg/kg respectively, and they were both given priority to with selenate, followed by selenite and humic acid combined with selenium. The results showed that the contents and chemical speciations of selenium in soil profiles originated from the carbo-nate rock were mainly dominated by the total organic carbon (TOC) contents and pH values, while of which originated from the terrigenous clastic rock were controlled by the pH values, the contents of TOC, aluminum oxide (Al₂O₃), iron oxide (Fe₂O₃) and soil texture.

Key words: parent material, soil profile, selenium content, selenium speciation, influencing factor, Wu-ming, Guangxi