中文摘要：

以湘中发育于下寒武统黑色页岩之上的土壤为研究对象，选择安化东坪、烟溪，桃江，宁乡等地的典型土壤及相应成土母岩，利用等离子质谱（ICP—MS）、X射线荧光光谱（XRF）等分析技术，对土壤、成土母岩（黑色页岩）的主量元素和微量元素（包括重金属元素、稀土元素等）进行了较系统的分析测定。结果表明，湘中下寒武统黑色页岩土壤风化作用强烈，风化指数CIA均在73以上。强烈的风化使得土壤具有明显贫CaO、Na2O，而富Al2O3、Fe2O3的化学组成特征。土壤因继承成土母岩（黑色页岩）的特征而富集Mo、Cd、Sn、Sb、U、V、Cr,Co、Ni、Cu、Zn、T1、Pb、Th等多种重金属元素，其综合富集指数（EI值）平均在3以上，最高达17。地质累计指数（Igeo）评价结果显示，土壤重金属的富集已达到污染程度，土壤存在Cd、Mo、Sb、U、Sn、V、Cu、Tl、Ba等重金属的污染，并以Cd、Mo、Sb等重金属污染最强，达中度至极强污染程度。重金属与主量元素的相关性分析显示，土壤中的重金属主要赋存于黏土矿物和铁氧化物（针铁矿）等矿物相中，其中Ba、Sn、Th、Cu、Sc等主要赋存黏土矿物中；Zn、Ni、Mn、Co、Cd、T1、Pb等则主要赋存于铁氧化物矿物（针铁矿）中；而Cr、V、Mo、Xb、U等则不受黏土矿物和铁氧化物矿物的控制。此外，不同地区土壤的Zr／Hf、Ta／Nb、Nd／Sm等元素比值相对稳定，依次为36．20、0．085、5．30（n=73），并与相应的成土母岩（黑色页岩）相应值基本一致。土壤与成土母岩具有相同的稀土配分型式，且成土过程中稀土元素不发生明显的分异。微量元素比值和稀土元素特征指示土壤中的重金属来自成土母岩（黑色页岩）本身，为自然污染源。

英文摘要：

The geochemistry of major and trace elements of soils derived from the Lower-Cambrian black shales （the black-shale soils） were studied by samples of typical soils and corresponding parent rocks from Dongping, Yanxi, Taojiang and Ningxiang in central Hunan province （China） , using ICP-MS and XRF techniques. Results show that the black-shale soils were strongly weathered, with chemical weathering index （CIA） values of higher than 73. Due to the higher intensity of chemical weathering, the chemical compositions of the soils are characterized by distinct depletion of CaO and Na2O, and by significant enrichment of Al2O3 and Fe2O3. The soils were also enriched with heavy metals including Mo, Cd, Sn, Sb, U, V, Cr, Co, Ni, Cu, Zn, TI, Pb and Th, when compared to the China average soils, and the complex enrichment indexes （EI） are higher than 3 in average with the highest up to 17.0. This heavy metal enrichment of the soils probably reflected the chemical components of the parent rocks. Assessment using the geoaccumulation index （Igeo） shows that the soils are contaminated by heavy metals Mo, Cd, Sb, Sn, U, V, Cu, Tl and Ba, for which the contamination of metals Mo, Cd and Sb is the most heavy, reaching moderate to extreme pollution degrees. Significant correlations of heavy metals to major elements indicate that heavy metals in the soils are hosted mostly in clay minerals and Fe-oxides （goethite）, among which metals Ba, Sn, Th and Sc are hosted in clay minerals, metals Zn, Ni, Mn, Co, Cd, Tl and Pb in Fe-oxides, and metals Cr, V, Mo, Sb and U neither in clay minerals nor in Fe-oxides （goethite）. Elemental ratios of Zr/Hf, Ta/Nb and Nd/Sm of the soils are similar to each other with values of 36.20, 0.085 and 5.30, respectively, and these ratios are also consistent to those of their corresponding parent rocks. In addition, the REE distribution patterns of the soils from different area are similar, and similar to that of their corresponding parent rocks. The rare earth elements were not differen