广州市郊区农业土壤重金属污染评价分析

采用单项污染指数、单项平均污染指数、算术均数、加权均数、内梅罗污染指数法、聚类分析评价法和主成分分析法对广州市郊区土壤重金属Cu,Pb,Zn,Cr,Ni,Cd,As,Hg污染进行评价.从单项污染指数频率分布可以看出,8种重金属中Hg的污染频率最大,即轻污染、中污染和重污染的出现频率都较大,分别为25.4%,9.3%和16.1%;其次是Cd和Zn,也出现了较高频率的轻污染、中污染和重污染.聚类分析法将8种重金属共分为4组,第1组包括Pb,Ni,As,Cr和Cu,第2组、第3组和第4组分别是Zn,Cd和Hg,这4组的污染指数逐渐增大,并以Hg的污染指数最大.主成分分析中的前2个主成分就已经能解释信息的67.81%,尤其是第一主成分,它能解释接近50%的信息量.第一主成分主要反映重金属Cu,Pb,Zn,Ni,Cd,As和Hg的富集程度,第二主成分主要反映了重金属Cr和Ni的富集信息量以及Hg的释放信息. 

Evaluation on the Pollution of Agricultural Soil Heavy Metal in Guangzhou City

The methods of single pollution index, single average pollution index, arithmetic mean, weighted average, the Nemerow pollution index, cluster analysis and principal component analysis were adopted to evaluate the pollution of soil heavy metals, such as Cu, Pb, Zn, Cr, Ni, Cd, As and Hg, in suburb area of Guangzhou City. From aspect of frequency distribution of single pollution index, Hg has the most pollution frequency among the eight heavy metals, which means that the frequencies are all great of slight pollution, middle degree pollution and heaviest pollution of Hg, being 25.4%, 9.3% and 16.1% respectively. Next to it are Cd and Zn, both having high frequencies of slight pollution, middle degree pollution and heaviest pollution. The eight heavy metals are classified into 4 groups by the cluster analysis, and the first group includes Pb, Ni, As, Cr, and Cu, the second group is Zn, the third group and the fourth group are Cd and Hg, respectively. The pollution indexes of the first group are the lowest, while the fourth is the highest. In principal component analysis, the first two principal components can explain 67.81% of the information, and the first one can explain nearly 50% of the information in particular. The first principal component mainly reflects the enrichment degree of Cu, Pb, Zn, Ni, Cd, As and Hg, while the second principal component reflects the enrichment information of Cr and Ni and the release information of Hg.