关键词: 重金属, 景观地球化学, 亚热带

Abstract: In this paper, an attempt has been made to study the relationship between some heavy metals and soil separates as well as the composition of minerals in the soils of the Zhang Jia Jie-Suo Xi Yu protected area, Western Hunan Province.The total content of heavy metals in the soils of geochemical landscapes is influenced by the parent rock and the biocycle as well as the geocycle in the soil-forming processes. The studies show that the contents of heavy metals for various particle-size groups increase from the largest particle sizes downward and the heavy metals have a tendency to concentrate in clay (< 0.001 mm). From the data obtained in this study, the total content of heavy metals in soil is atributed to the integrated influences of heavy metal enrichment in clay and the content of clay itself in soil.The various particle-size groups have been made by X-ray diffration, Mineralogical analysis indicates that there is a gradual transition from the soil minerals that mainly consist of Chlorite, Kalinite and Illite to those that mainly consist of Quartz with increasing particle size. This kind of transition could result in the distribution of heavy metal in different particle-size groups, which conforms to the principle of chemical crystallography and the characteristic of colloids. The higher heavy metal concentrations at smaller particle sizes in soil has been suggested.

Key words: Heavy metal, Landscape geochemical, Sub-tropical belt