江苏省典型工业开发区土壤重金属污染及其潜在生态风险评价

Sources and ecological risks of heavy metals in the soils of the typical industry-based development zones in Jiangsu

测定了江苏省5个典型工业开发区30个土壤样品的Hg、Cr、Cd、Cu、As和Zn质量比,采用地累积指数法和潜在生态危害指数法从不同角度进行了重金属污染评价。结果表明:对照全国土壤环境二级质量标准,5个开发区的6类重金属均不超标,但对照江苏省土壤环境背景值,各类重金属产生了不同程度的累积效应,各种重金属污染程度从大到小依次为Hg、Cu、Zn、Cd、Cr和As;重金属的潜在生态危害指数从大到小依次为Hg、Cd、Cu、As、Cr和Zn,其中,Hg的影响占绝对主导地位;重金属潜在生态风险最严重的是吴中经济技术开发区,潜在生态危害指数RI达到276.6,为中等风险,其次是江宁经济技术开发区、江阴市经济技术开发区、镇江经济技术开发区和常州滨江经济技术开发区,RI分别为222.4、185.0、130.5和112.6,表明开发区产业结构和能源结构与土壤中重金属含量和生态危害程度密切相关。因此,控制好开发区电镀、含电镀工序的重金属污染源及调整能源结构、减少燃煤使用量是改善土壤环境质量的关键。

In this paper,we would like to report our investigation findings and analysis of the current heavy metal pollution status insitu in the soils of the industry-based development zones in Jiangsu.For the research purpose,we have collected thirty samples from the soils of the five typical such zones in the province from July,2012 to March,2013,and determined the content rates of Zn,Cu and Cr,as well as those of Cd,Hg and As,in the soils by using the flame atomic absorption spectrophotometry,the graphite furnace atomic absorption spectrophotometer,the cold-vapor atomic absorption and the silver diethyldithiocarbamate photometric method,respectively. We have used the above methods to analyze the content rates or indexes of Hg,Cr,Cd,Cu,As and Zn in the samples,too. And,then,we have done an evaluation of such heavy metals pollution rates by the index of the geoaccumulation and the potential ecological risk indexes from other different points of view,too. The results of our investigation and analysis indicate that the heavy metal contaminants of the aforementioned six kinds of heavy metals turn to be lower than the national soil environmental quality classification standards. In spite of this,according to the soil＇s background indexes of the province,heavy metal contamination rates of the above six heavy metals still exceed the standard indexes. The pollution rates of the various heavy metals can be illustrated in a descending order as shown below： Hg Cu Zn Cd Cr As,whereas the potential ecological hazard coefficients of the various heavy metals can be also listed in a descending order as： Hg Cd Cu As Cr Zn,with Hg being the predominant one among them. What is more,the most serious area suffering from the potential ecological risk of heavy metals is the Economic and Technological Development Zone of Wuzhong,whose indexes can be found as high as 276. 6 for the medium risk. And,then,they are followed by the Economic and Technological Development Zone of Jiangning,the Economic and Technological Development Zone of Jiangyin,the Economic and Technological Development Zone of Zhenjiang and Economic and the Riverside Technological Development Zone of Changzhou,with their respective indexes being222. 4,185,130. 5 and 112. 6. Thus,the above investigation and analysis results demonstrate that the content rates of the detrimental heavy metals and the ecological hazards they brought about to the soils are closely related to the industrial structure and energy consumption structure in the development zones. It can thus be concluded that it is imperative to take effective measures to improve the quality of the soil environment and control the electroplating pollution sources in the those zones so as to adjust the constitution of the energy resources by reducing the rate of coal use.