中文摘要：

本次工作利用X射线荧光（XRF）和电感耦合等离子质谱（ICP-MS）分析技术，对湘江人湖河段沉积物进行主元素和重金属元素分析。结果表明，湘江人湖沉积物中主元素含量变化相对稳定，沉积物具有明显亏CaO、Na20，而富MnO、A1203的化学组成特征。其化学组成和风化蚀变特征（蚀变指数CIA值大于78）指示流域上游花岗岩为沉积物提供了主要的物源。主元素揭示的沉积物矿物组成主要包括Al2O3表征的细粒黏土矿物类和SiO2、Na2O表征的粗粒碎屑矿物类两部分。沉积物中重金属元素含量变化大，重金属综合富集指数EI值白湾河WH（EI=4．7、14．2）向湘阴XY（6．6、5．6）再向屈原农场QN沉积柱（18．4）趋于增大，重金属污染程度自上游向下游趋于增强。重金属污染程度主要与以AhO，为代表的I类元素呈正相关关系。预示重金属污染主要与黏土矿物、铁锰氧化物、有机质、及磷灰石等副矿物相关。其中Bj、Pb、Mn、T1等重金属污染更趋于在黏土矿物、锰氧化物、有机质等矿物相中增强，Cd污染可能主要与铁锰氧化物、有机质等有关，U污染则主要与铁氧化物矿物有关，而Cu、Sb污染主要与有机质关系密切。不同的矿物相可能引起不同种类的重金属污染。

英文摘要：

Concentrations of major elements and heavy metals in sediments from the lowermost Xiangjiang River in Hunan Province （China） were analyzed using the XI and ICP-MS techniques. The purpose of the study is to unearth the geochemical relation of chemical composition to heavy metal contamination of the sediments. The results show that concentrations of major elements in the sediments are relatively less variable, i.e. the chemical composition of the sediments was characterized by significant depletion of CaO and Na20, and by relative enrichment of MnO and A1203. Such chemical composition was resulted from chemical alteration indicated by the chemical index alteration （CIA vaine 〉 78）, and implies that granite rocks distributed in upper river areas of the watershed may be the major material source for the sediments deposited in the river. The principal component analysis taken on the major elements suggests that the sediments are composed of two major types of minerals： the final grain-sized clay minerals ilinstmted by chemical Al2O3, and the coarser grain-sized detrial minerals by chemicals SiO2 and Na2O. Concentrations of heavy metals in the sediments are more variable, with complex enrichment index （El） values in average increased from 4.7 and 14.2, to 6.6 and 5.6, and then to 18.4, in sediments from the WH, to the XY, and then to the QN core, suggesting contamination degree increased from upper to down river sediments. The degree of heavy metal contamination developed in the sediments is positively correlated with the contents of fine grain-sized clay minerals, Fe-Mn oxides, organic matters, and accessory mineral such as apatite. The contamination by metals Bi, Pb, Mn and TI is more closely related to clay minerals, Mn-oxides and organic matters, those by metal Cd to Fe-Mn oxides and organic matters, those by U to clay minerals and Fe-oxides, and those by Sb and Cu to clay minerals and organic matters. Different mineral phases may cause different types （metal assemblage） of heavy metal contamina