岷江下游五通桥区土壤的铅污染分布格局

Spatial Heterogeneity and Distribution of Lead in Topsoil of Lower Reaches of Minjiang River,Wutongqiao

在岷江下游五通桥区境内采集了93个土壤样品,分析检测其重金属Pb的含量水平.在ARCGIS等地理信息系统软件的支持下,以地统计学原理等空间分析方法,分析数据的空间自相关特征以及变异函数特征,以讨论流域范围内的Pb污染分布格局.结果表明:研究区的土壤Pb含量水平较背景值增加了14.88%,具有大范围低强度的Pb污染特征;城乡结合部和沿岷江两岸是Pb污染的主要发生区;土壤Pb的分布具有一定的空间异质性,其空间自相关性和分布格局与岷江的地理走向关系密切,初步认为Pb元素有沿岷江向下游迁移的趋势;区域范围内的Pb污染来源较为隐蔽且不确定,具有一定的面源污染特征.

The application of spatial heterogeneity analysis based on geographical information system （GIS） to environmental geochemistry was studied. Spatial analysis methods, including geostatistics and spatial autocorrelation, were used for lead content in 93 topsoil samples from Wutongqiao county at the lower reaches of Minjiang River, for analyzing the lead spatial heterogeneity in topsoil and its pollution characteristic. The results of geostatistics showed that the lead content had good spatial structure and its semi-variogram can be fitted by exponential model. The distribution characteristics of Pb in soil was shown obviously anisotropy and had significant spatial autocorrelation at the Minjiang River＇s azimuth, deduced the lead in soil had a migration tendency along the Minjing River. The map of classification of soil Pb con- tent by Kriging method showed the bank and urban-rural marginal area were the mainly contaminative area, preliminary result indicated there had Non point source pollution of lead at these areas.