Analysis and Risk Assessment of Heavy Metal Pollution Sources in Cultivated Soil at Small Regional Scale around Ningbo Industrial Zone
In this study,the small regional scale cultivated land around a typical industrial agglomeration in a certain area of Ningbo City was taken as an example.Classical descriptive statistics,single factor pollution index and geological accumulation index analysis were used to study the characteristics of regional soil heavy metal pollution.Meanwhile,pollution source monitoring and principal component analysis(PCA)were combined to analyze the sources of heavy metal pollution in cultivated soil.The potential ecological risk index method was used to evaluate the existing risks in the study area.The results showed that Hg,Zn and Cd had local mild or moderate pollution in the statistical evaluation of single pollution index of heavy metals,and the pollution rates were 12.5%,8.3%and 8.3%,respectively.In the analysis of geological accumulation index,Hg and Ni geological accumulation index are relatively high,and the proportion of soil points with no to moderate accumulation is 58.3%and 75.0%,respectively.Three major heavy metal pollution sources were analyzed by principal component analysis.Combined with the monitoring results of pollution sources,it was concluded that the main sources of Zn,Cr,Ni,Cu and Cd in factor I were industrial activities.The main sources of Hg,Pb and Cd in factor Ⅱ are atmospheric deposition such as petroleum and coal combustion and agricultural activities.The main source of As and Cr in factor Ⅲ was soil parent material.According to the analysis results of potential ecological risk index method,only 12.5%of Hg and 4.2%of Cd were in the medium ecological hazard.From the perspective of soil potential ecological hazard index(RI),all the sites were slight ecological hazards,and the ecological risk in the study area was low on the whole.
万方数据
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