关中盆地表土重金属空间分布特征

Spatial Distribution Patterns of Heavy Metals of Topsoil in Guanzhong Basin

以关中盆地表土重金属为研究对象,结合样品实测数据,通过ArcGIS普通克里金空间插值及数理统计分析,研究关中盆地表土重金属(Cu、Zn、Pb、Cr、As、Ni)空间分布特征及其与土地利用、城市化进程和地貌之间的关系。研究结果表明:(1)关中盆地表土的Cu、Zn、Pb、Cr、As、Ni平均含量分别为29.85,82.40,30.90,65.29,11.78,30.16mg/kg。(2)由南向北,南部地区重金属含量总体高于北部,但As含量南部低于北部。Cu和Zn、Cr和Ni空间分布特征具有较强的相关性。(3)在不同地貌部位,秦岭北麓山谷重金属含量最高,丘陵最低,平原、黄土塬沟谷居中。(4)从城乡分布看,城市化进程明显影响土壤重金属的空间分布特征,城市城区为重金属空间分布的高值区,由此向周边辐射(例如:宝鸡、咸阳、西安、铜川,但渭南市除外),Cu、Zn、Pb、As均表现出由城区经城乡结合带向乡村衰减的过程,Cr城乡结合部>乡村>城区,Ni乡村>城乡结合部>城区。(5)从土地利用类型看,在城市,Cu、Zn、Pb、Ni含量,庭院绿地>道路绿化带>广场绿地,Cr道路绿化带>庭院绿地>广场绿地,As庭院绿地>广场绿地>道路绿化带;在乡村,Cu、Zn、Cr在菜地含量最高,Pb在林地最高,As、Ni在农田最高;Cu、Pb、Cr在果园含量最低,Zn在农田最低,As、Ni在菜地最低。

The objective of study was to investigate spatial distribution patterns of heavy metals（Cu,Zn,Pb, Cr, As, Ni） in topsoil and the relationships between heavy metal content and land use types, urbanization and topography in the Guanzhong Basin. Statistical analysis and GIS interpolation techniques were employed based on laboratory analysis. Results showed that： Firstly, the average content of Cu,Zn,Pb,Cr,As and Ni in topsoil in the Guanzhong Basin was 29.85,82.40,30.90,65.29,11.78,30. 16 mg/kg, respectively. Sec- ondly, the heavy metal content in the southern region was higher than that in the north, except for the As content. Obvious spatial correlations existed among Cu and Zn,Cr and Ni content. From the landform types, the maximum of heavy metal content was in the valley of the northern piedmont of the Qinling mountains, the minimum was in the hills, and the medium values were in the valley in Loess Plateau and the Guanzhong plain. The values of the Cu,Zn,Pb,As content decreased from urban to rural, except the Weinan city. The content of Cr was highest in the urban fringe, moderate in the rural areas, and lowest in the urban areas. The content of Ni was highest in the rural areas, moderate in the urban fringe areas and lowest in the urban areas. As for land use types, in the city, the content of Cu,Zn,Pb and Ni content： Courtyard road〉green belt〉square;Cr： Green belt〉courtyard〉square; As： Courtyard〉square〉green belt. In the countryside, Cu,Zn,Cr content in the vegetable garden was the highest, Pb in woodland was the highest, As and Ni in farmland was the highest. Cu, Pb and Cr in orchard was the highest, Zn in farmland was the lowest, As, Ni in the vegetable field was the lowest.