利用对数正态分布图解析徐州城市土壤中重金属元素来源和确定地球化学背景值

Application of lognormal distribution plot to interpreting sources and determining geochemical background levels of heavy metals in Xuzhou urban soils,Jiangsu Province

城市土壤指示了城市环境中重金属污染的状况。为了更好地评价人为因素对城市土壤的影响强度,确定城市土壤重金属元素的地球化学背景值是十分必要的。以徐州城市表层土壤中Pb、Cu、Zn、V、Se和Ti等重金属为例,利用对数正态分布图区分了不同元素的来源,其中Ti和V主要来自土壤母质的分化,而Pb、Cu、Zn和Se等的来源则比较复杂,表现为受人为因素作用强烈。这些结果与利用多元统计方法(如聚类分析和主成分分析)获得的结果一致。利用对数正态分布图获得了Pb、Cu、Zn、V、Se和Ti等元素的地球化学背景值。

Urban soils are valuable indicators of heavy metal contamination in urban environment. In order to assess the extent to which urban soils have been altered by anthropogenic influences, it is important to establish the geochemical background levels by which their changes may be evaluated. In this study, concentrations of Pb, Cu, Zn, V, Se and Ti in Xuzhou urban soils were determined. Lognormal distribution plots are applied to discriminate heavy metals Ti and V, which are inherited from parent minerals, from Pb, Cu, Zn and Se, which are a significant influence of sources related to anthropogenic activities. This result is in agreement with those obtained from multivariate statistical analysis （i. e. cluster analysis and principal component analysis）. The geochemical background levels are obtained by applying lognormal distribution plots to Pb, Cu, Zn, V, Se and Ti.