上海嘉定区表土磁性强度的空间分异及环境指示意义

在上海嘉定区,按土地利用方式的多样性和空间分布的均匀性,采集31个表土(0～5 cm)样品,分析表土磁化率(χlf)和重金属元素(Cu、Zn、Pb、Cd、Cr、Mn)含量。结果表明:表土χlf普遍增强,且空间分异很大,变幅在35.1×10-8～1 676.9×10-8m3kg-1,平均值为177.9×10-8m3kg-1。表土磁化率随土地利用方式的不同呈现出显著差异,总体看:工业土壤>马路绿地>农耕土壤>林地土壤。表土磁性的增强与重金属元素的累积有密切联系:表土χlf与Zn、Cr、Cd的含量呈极显著正相关(p<0.01);表土χlf与重金属综合污染指数呈显著正相关(p<0.05)。嘉定表土磁性特征的研究进一步表明,磁学方法可作为监测和评估上海土壤重金属污染的有效手段。

Spatial variation of magnetic intensity of toposils in Jiading district, Shanghai and its environmental implication

31 topsoil samples(0~5 cm) were collected in Jiading District,Shanghai in light of diversity of landuse patterns and uniformity of spatial distribution.Magnetic susceptibility(χlf) and heavy metal contents(Cu,Zn,Pb,Cd,Cr and Mn) of the samples were determined.Results show that the topsoils in Jiading District are generally enhanced in magnetic intensity,which varies much spatially within a range from 35.1×10-8 m3 kg-1~1 676.9×10-8 m3 kg-1,and is averaged to be 177.9×10-8 m3 kg-1.Moreover,the topsoil χlf also varies with the landuse pattern,and generally follows a decreasing order of industral soils>roadside soils>cultivated soils>forest soils.A close relationship between the enhancement of χlf and accumulation of heavy metals in the topsoils was also observed: Topsoil χlf values are in significant positive correlation with contents of Zn,Cr and Cd(p<0.01),and with the integrated pollution indexes(p<0.05) as well.The findings further suggest that the magnetic method can be used as an effective tool in monitoring and evaluating heavy metal pollution of the soils in Shanghai.