上海市不同工业类型土壤重金属含量差异性分析

为揭示不同工业类型土壤重金属含量的差异性,研究以上海市为例,选取机械制造、化工、印染三种污染较为严重的工业类型,进行实地采样分析.结果表明,上海工业土壤重金属元素As、Cr、Cu、Pb、Zn没有超过国家土壤环境质量二级标准,但Ni的平均值达到75.23 mg·kg~(-1),是国家土壤环境质量二级标准的1.5倍;以上海市土壤背景值为评价标准,除As外,各元素单因子污染指数均大于1,由高到低依次为:Ni,Zn、Pb,Cu,Cr,As;印染企业、机械制造、化工企业综合污染指数均大于2,属于中度污染,污染程度由高到低依次为:印染企业,化工企业,机械制造,表现出明显的累积趋势.相关分析和因子分析表明,元素Pb、Cu和Zn有相似来源,Cr和Ni有相似来源,As为另一来源;前两类元素含量远高于对应元素背景值,超标率均在90%以上,来源主要受人为活动影响;As元素含量与背景值相当,来源主要与成土母质有关.通过对比分析发现,Cr、Ni来源主要与机械制造和化工等企业污染排放有关;印染企业生产过程中污染物的排放可能是Pb、Cu、Zn的主要来源;各类型企业土壤均存在多个元素累积,呈现出复合污染的趋势.

Analysis on differences of heavy metal concentrations in different types of industrial soil in Shanghai

To reveal differences of heavy metal Concentrations in different types of industrial soil, taking Shanghai as an example, the study selected three industrial types of machine building, chemical industry, printing and dyeing which are more serious pollution, samples of soil was taken and analyzed. The results showed that heavy metals of As, Cr, Cu, Pb, Zn did not exceed the national envi-ronmental quality standards in Shanghai industrial soil, but the average of Ni reached 75.23 mg·kg~(-1), it is 1.5 times of national soil environmental quality standards. Taking Shanghai soil background value as an evaluation standard, except for As, each single-factor pollution index of element is greater than 1, Pollution levels were presented as: Ni>Zn、Pb> Cu>Cr>As; The integrated pollution index of printing and dyeing, machine building and chemical industry is greater than 2, which belong to moderate pollution. Pollution levels were as follows: printing and dyeing >chemical industry>machine building, which show dramatic cumulative trend. Correla-tion analysis and factor analysis were taken, the results showed that sources of Pb, Cu and Zn are similar, sources of Cr and Ni are similar, source of As is not similar with others. The contents of the first two ranges of elements are much higher than the background values, all of the over-limit rates were more than 90%, mainly affected by human activities. The content of As is consistent with the context value, and the main source is relevant with soil parent material. Through comparing analysis, Cr, Ni are mainly related with the discharge of pollutants, such as chemical and mechanical manufacturing enterprises. Pollutants in the production process of printing and dyeing enterprises may be the main sources of Pb, Cu, Zn. There are a number of elements accumulating in various types of industrial soil, showing a trend of combined pollution.