南京城郊蔬菜基地土壤有效态铅、锌、铜和镉的空间分异及其驱动因子研究

利用地统计学和地理信息系统相结合的方法,从小尺度区域角度上研究了南京城郊土壤中铅(Pb)、锌(Zn)、铜(Cu)和镉(Cd)4 种重金属有效态含量的空间分布特征及其主要的影响因子。结果表明:(1) 研究区土壤中有效 Zn 变异程度相对较大,有效 Pb 的变异程度相对较小,而有效 Cu 和 Cd 为中等程度变异。(2) 研究区有效 Pb、Zn 含量空间分布具有中等程度的空间自相关性,而 Cu、Cd 空间分布具有强烈的空间自相关性;有效 Zn、Cd 的空间自相关尺度相对较大,而有效 Cu、Pb 相对较小。(3) 研究区土壤中有效 Pb 的空间分布主要受交通影响,交通量越大的道路附近土壤中有效 Pb 含量越高;有效 Zn 主要受城市生活废水的影响,城市生活污水灌溉和城市地表径流是土壤中有效 Zn 积累的主要原因;有效 Cu 主要与蔬菜种植过程中有机肥(主要是牛粪)施用关系密切,有机肥施用量越大,土壤中有效 Cu 含量越高;有效 Cd 受地形影响较大,地形低洼处土壤中有效 Cd 含量相对较高。

CHARACTERISTICS OF SPATIAL VARIABILITY OF SOIL AVAILABLE LEAD, ZINC, COPPER AND CADMIUM IN A VEGETABLE BASE IN THE SUBURBS OF NANJING

The spatial variability and its dominating factors of soil available lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd) in a small-scaled region in the suburbs of Nanjing City was studied through the method of geostatistics coupled with Geographic Information System (GIS). The results showed: (1)in terms of spatial variation soil available Zn was higher, soil available Pb relatively lower and soil available Cu and Cd medium; (2)soil available Pb and Zn were auto-correlated to a moderate degree while the soil available Cu and Cd were done to a high degree. The spatial scale of auto-correlation of Zn and Cd was relatively large, 2088m and 1077m, respectively, while that of Cu and Pb was relatively small, 375m and 800m, respectively. The dominating factors of the accumulation of Pb, Zn, Cu and Cd included traffic, irrigation with sewage, application of cow manure, landform, etc.