喀斯特山区不同母质（岩）发育的土壤主要重金属含量差异性研究

在贵州喀斯特山区采集了白云岩、石灰岩、钙质紫色砂页岩等9种母质(岩)上发育的土壤样品763个,测定了土壤主要重金属元素含量和土壤理化性质.对比分析表明,不同母质(岩)发育的土壤重金属含量具有很大的差异:钙质紫色砂页岩、石灰岩、河流冲积物等发育的土壤中镉、铬、汞的含量较高,而红色粘土、河流冲积物和石灰岩等发育的土壤中铅和砷的含量较高,砂岩发育的土壤中5种重金属元素的含量均为最低,其余母质(岩)发育的土壤中5种重金属元素的含量均介于上述之间.相关性分析结果表明,研究区域内土壤重金属镉、铬、汞、铅、砷的含量差异主要是由于成土母质(岩)的"遗传"差异性所致,土壤理化性质的变化是影响土壤重金属含量的次要因素.

Differences of Heavy Metal Contents in Soils Derived from Different Parent Materials/Rocks in Karst Mountain Area

763 soil samples were collected from Wudang county of Guiyang city in Guizhou province, where the karst feature was well developed and the soils were developed from 9 types of parent material/rock, i.e. dolomite, limestone, calcareous purple sandy shale, shale, sandstone, red clay, old mantlerock, fluvial sediment and sandy shale, and the physical-chemical properties and heavy metal contents of these soils were analyzed. Significant differences between each of the soils were found through comparing the soils developed from different types of parent material/rock. The contents of cadmium, chromium and hydrargyrum were higher in the soils developed from calcareous purple sandy shale, limestone and fluvial sediment; the contents of plumbum and arsenic were higher in the soils developed from red clay, fluvial sediment and limestone; the contents of the 5 types of heavy metal elements were the lowest in the soil developed from sandstone; the contents of the 5 types of heavy metals in the soils developed from the rest parent material/rock were between the above mentioned quantity. The results of correlation analyses indicated the differences in cadmium, chromium, hydrargyrum, plumbum and arsenic contents were mainly resulted from the difference of soil-forming parent material/rock in the study area. The type of parent material/rock was the principal factor that affected the heavy metal contents in the soils, and the changes of physical-chemical properties of soil were the minor factors.