南京市各功能区近地灰尘重金属污染及其潜在生态风险评价*

以南京市中东部不同功能区近地灰尘为研究对象,通过XRF光谱仪测定其重金属含量。分析结果表明:南京市不同功能区近地灰尘中Pb、Cu、Zn、Mn、Cr、Ni、As的平均含量均高于环境背景值,Pb、Cu、Zn的积累量大,Cr、Ni、As的累积量相对较小,Mn、Co与环境背景值接近。地累积指数评价结果显示,南京市不同功能区近地灰尘中Zn污染较重,为中度污染,商业功能区达到偏重污染,Pb、Cu为偏中污染,Cr、Ni、As为轻微污染,Mn、Co无污染。潜在生态风险指数评价结果表明,单个重金属元素的潜在生态风险风险情况为CuPbAsZnNiCoCrMn;多种重金属综合潜在生态风险指数除了在风景区处于轻微生态危害水平外,其他各功能区的潜在生态风险指数均达到了中等生态危害;造成不同功能区重金属含量和污染程度差异的主要原因是区域内的交通运输情况,同时也与功能区内自身的建设情况和功能区定位、以及与功能区内的绿化建设情况有关。

Heavy Metal Pollution and Ecological Risk Assessmentof Dust from Different Functional Areas of Nanjing City

In the study, we focuses on the near ground dust of various functional areas in Nanjing city, the heavy metal contents of dust are analyzed by X-Ray Fluorescence Spectroscope. The result showed that the average concentrations of Pb, Cu, Zn, Mn, Cr, Ni and As are higher than the background values of Nanjing-Zhenjiang-Yangzhou region soil, Cu, Pb and Zn values are highly enriched and accumulated; Cr, Ni and As values are slightly enriched and accumulated; Mn and Co values are close to the background values. The pollution assessment results of Geo-accumulation-index showed that Zn is moderate pollution, Pb and Cu are moderate to mild pollution, Cr, Ni and As are mild pollution, while Mn, Co are non-pollution. The assessment results of potential ecological risk of heavy metal pollution indicated that the pollution degree of single element showed the order of Cu>Pb>As>Zn>Ni>Co>Cr>Mn; The comprehensive potential ecological risk index of heavy metals reached moderate ecological hazards in the other functional areas except the scenic zone, and which reached mild ecological hazards in the scenic zone. The main reason for the difference of pollutant degree of heavy metal in various functional areas is the regional transportation conditions; construction activity and regional function are the minor reason; and greening condition also affect the heavy metal enrichment.