刘家峡水库表层沉积物微量元素地球化学特征

采用多元统计的方法对刘家峡水库表层沉积物中25种微量元素的含量、相关性、来源及控制因素进行了分析。结果显示:研究区表层沉积物中Sr、Zn、Zr和Ba的含量平均值超过了170 μg/g,Cd、Mo和Tl的含量平均值都在1 μg/g以下,其它元素含量平均值则在2.01~104.34 μg/g。元素Cu、V、Co、Cr、Ni、Rb、Li、Cd、Be、Pb、Sc、As、Ga、Nb、Sn、Cs、Tl、Th和Al₂O₃等存在较为明显的相关性,且它们分布规律基本相似。因子分析表明,水库中微量元素分为3个主要来源,第一组分的元素分布受控于矿物岩石的自然风化剥蚀,其贡献率为63.20%;第二组分的Zr和Ba主要受河流沉积物中元素的迁移和转化的影响,其贡献率为12.51%;第三组分的Sr则主要受控于生物成因,其贡献率为9.76%。另外,研究区重金属元素中,Zn和As含量远超过了全球页岩平均值,值得进一步的深入研究。

Trace element geochemistry of the surface sediments in the Liujiaxia Reservoir,Gansu

The concentration,correlation,spatial distribution,controlling factor and source of 25 trace elements in the surface sediments from the Liujiaxia Reservoir,Gansu are analyzed by using the multivariate statistical method. The mean contents of the elements Sr,Zn,Zr and Ba are higher than 170 μg/g,while the values of the elements Cd,Mo and Tl are lower than 1 μg/g in the surface sediments from the Liujiaxia Reservoir. The values of other analyzed elements lie within the range of 2.01-104.34 μg/g. Evident correlation and similar distribution exist among the elements Cu,V,Co,Cr,Ni,Rb,Li,Cd,Be,Pb,Sc,As,Ga,Nb,Sn,Cs,Tl,Th and Al2O3. Factor analysis shows that the trace elements in the Liujiaxia Reservoir are divided into three main sources in the following. The distribution of the first component elements is controlled by the weathering and erosion of the natural minerals and rocks,and their contribution rate is 63.20%. The Zr and Ba distribution of the second component elements are mainly affected by the migration and transformation of the elements in the fluvial sediments,and their contribution rate is 12.51%. The Sr distribution of the third component elements is mainly controlled by the biogenic origin,and their contribution rate is 9.76%. In addition,the contents of the elements Zn and As in the heavy metallic elements in the study area are much higher than the average values of the global shales,which is worth further study in the future.