轻稀土矿区土壤和植物中铀和钍核素的分布特征

Distribution Characteristics of Uranium and Thorium Nuclides in Soil and Plants of Light Rare Earth Mining Area

研究轻稀土矿区土壤和植物中放射性核素含量,采用内梅罗综合分析法对土壤中污染物分布进行分析,用富集系数、转移系数分析植物体内核素的分布特征。设置11个采样点,用γ能谱仪法测定土壤和5种优势植物。结果显示:矿区土壤中放射性核素含量未高于中国或世界背景值,但高于包头市对照组背景值,土壤中放射性核素含量西北侧最高,东南侧最低,该区域属于轻度污染;5种植物的铀核素富集、转运和根滞留系数范围分别为0.01~0.05、0.10~0.45、0.55~0.90;钍核素富集、转运和根滞留系数范围分别为0.01~0.09、0.26~0.84、0.16~0.74。5种植物富集、转运系数均小于1,且钍核素>铀核素,当地植物的耐受性有利于生态修复土壤中的铀和钍核素。

Radionuclides contents in soil and plants of light rare earth mining area were studied.Distribution of pollutants in soil was analyzed by Nemero comprehensive analysis method,and distribution characteristics of radionuclides in plants were analyzed by enrichment coefficient and transfer coefficient.Together 11 sampling points were set up,and the soil and 5 dominant plants were determined byγ-ray spectrometer.The results show that radionuclides content in soil of mining area is not higher than background value of China or the world,but higher than background value of Baotou City control group.Radionuclides content in soil is the highest in northwest and the lowest in southeast,which causes light pollution.Enrichment,transport and root retention coefficients of five plants are 0.01-0.05,0.10-0.45,0.55-0.90,respectively.Enrichment,transport and retention coefficients of thorium nuclides range from 0.01 to 0.09,0.26 to 0.84,and 0.16 to 0.74,respectively.Enrichment and transport coefficients of 5 dominant plants are all less than 1,and thorium radionuclides is higher than uranium radionuclides.Tolerance of local plants is conducive to ecological restoration of uranium and thorium in soil.