广西武鸣县典型土壤剖面Se的地球化学特征及其影响因素研究

Study of Geochemical Characteristics and Influencing Factors of Soil Selenium in the Typical Soil Profiles in Wuming County of Guangxi

以广西武鸣县典型的碳酸盐岩成土剖面和陆源碎屑岩成土剖面为研究对象,研究了不同成土母质在成土过程中Se元素与其形态在垂向上的迁移变化规律及其影响因素。结果表明:碳酸盐岩和陆源碎屑岩在成土过程中,土壤Se含量均继承了成土母质的特点,且前者在表层明显富集,而后者相对较稳定,算术平均值分别为0.55 mg/kg和1.43 mg/kg。前者的水溶性总硒含量高于后者,平均含量分别为3.48μg/kg和1.81μg/kg,但均以硒酸态硒为主,其次是亚硒酸态硒和腐殖酸结合态硒。成土剖面上,土壤Se含量及其形态影响因素研究表明,碳酸盐岩成土剖面上,Se的含量与形态主要受土壤TOC含量和p H值影响;陆源碎屑岩成土剖面上,影响Se的含量及其形态的因素较多,土壤p H值、TOC、Al2O3和Fe2O3含量以及土壤质地等均对其有不同程度的影响。

In this paper,the typical soil profiles of carbonate rock and terrigenous clastic rock in Wuming Coun-ty of Guangxi were chosen as our investigative objects.The vertical migration and influencing factors of the sele-nium chemical speciation in soil formation process were studied.The results showed that the soil selenium con-tent 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 car-bo-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 (Al2 O3 ),iron oxide (Fe2 O3 )and soil texture.