南宁市土壤硒分布特征及其影响因素探讨

DISTRIBUTION OF SELENIUM IN SOILS OF NANNING CITY AND ITS INFLUENCING FACTORS

以南宁市土壤为对象,系统采集了2 767个表层土壤(0～20 cm)和711个母质样(150～200 cm)。用AFS原子荧光光谱法进行了样品全硒含量质量分数分析;研究了南宁市土壤全硒含量的分布特征及其与成土母质、土壤类型和土壤理化性质的关系。结果表明,南宁市土壤全硒含量变幅为0.09～1.34 mg kg-1,算术平均值为0.57 mg kg-1。土壤类型中,新积土全硒含量最高,平均为0.89 mg kg-1;紫色土全硒含量最低,平均为0.37 mg kg-1。成土母质中,全硒含量以二叠系碳酸盐岩母质发育土壤为最高,平均为0.79 mg kg-1;以下白垩系紫红色碎屑岩母质发育土壤为最低,平均为0.39 mg kg-1。影响南宁市土壤硒含量的主要因素是成土母质,土壤pH、有机碳及铁和铝的含量对土壤全硒含量的富集与分布也有一定影响。

The main objective of this paper is to study characteristics of selenium distribution in soils and their rela- tionships to genesis and physio-chemical properties of the soils in Nanning City. A total of 2 767 samples of surface soils （0 -20 cm） and 711 of parent materials were collected for analysis of total soil selenium with atomic fluorescence spec- trometry and soil properties with various methods. Results of the analysis show that concentration of total selenium in the surface soils ranged from 0.09 mg kg^-1 to 1.34 mg kg^-1 and averaged 0.57 mg kg^-1. Among the different types of parentmaterials, the lowest and highest concentrations were recorded in Permian carbonate was the highest in total Se content, averaging 0.79 mg kg^-1 and Cretaceous purplish clastic rocks the lowest, averaging 0.39 mg kg^-1, while among the dif- ferent types of soils, Alluvial soil was the highest, averaging 0. 89 mg kg^-1 and purple soil the lowest averaging 0.37 mg kg^-1. Obviously soil parent material is the major factor that influences selenium concentration and distribution in the soils in Nanning, whereas soil pH, and contents of organic matter, iron and aluminum are also factors of certain signif- lcance