城市化进程中蔬菜基地土壤重金属污染评价与成因分析———以深圳市为例

通过对深圳市蔬菜生产基地土壤的抽样分析,土壤重金属总体超标率为23.3%。污染物主要是N i、Cu、Cd、As和Zn,超标率分别为13.0%、10.0%、6.7%、6.7%和6.7%,其中N i超标0.07～1.66倍,Cu超标0.10～0.88倍,Cd超标0.33～0.53倍,As超标0.28～0.74倍,Zn超标0.11～0.50倍,而Hg、Pb和Cr均无超标。按照土壤综合污染指数(内梅罗污染指数)进行评价,有50%的菜场土壤重金属污染程度仍处于安全水平,其余属警戒限至中污染水平,以警戒限占大多数,只有个别菜场达到中污染。As、Zn污染较为典型,超标率高于珠三角其它城市。在城市化进程中土壤污染状况有日趋严重的态势。土壤重金属污染的主要成因可能与生产环境恶化和肥料的不合理施用有关。

Investigation on the pollution statns and sources of heavy metals in vegetable base soils in the process of urbanization——A case study of Shenzhen city

This paper investigated the contents of heavy metals in soils of vegetable production bases of Shenzhen,the pollution status and the sources were also analyzed in the present study.The results indicated that the percentage of contents of heavy metals that exceed the provided standards was 23.3%.The main pollutant include Ni,Cu,Cd,As and Zn,with exceeding the standards by 13%(0.07～1.66 times of standard)for Ni,10%(0.10～0.88 times of standard)for Cu,6.7%(0.33～0.53 times of standard)for Cd,6.7%(0.28～0.74 times of standard)for As and 6.7%(0.11～0.50 times of standard)for Zn,respectively.The contents of Hg,Pb,Cr in soils were below the thresholds of the soils quality standards.Half of the vegetable production bases were safe in Shenzhen,and only individual farms reached a moderately polluted.The concentrations of As and Zn in soils were much higher than the corresponding in Pearl-River-Delta region.Soil heavy mental pollution has become increasingly serious in process of urbanization.The reason of the heavy mental pollution of soil may be environment deteriorate and unreasonable fertilization.