开封市不同功能区叶面尘重金属含量及潜在生态风险

以开封市5个功能区(文教区、旅游区、居民区、闹市区、工业区)叶面尘为研究对象,获得冬青(Ilex chinensis Sims.)及石楠(Photinia Lindl.)叶面尘样品22个.采用电感耦合等离子体发射光谱仪(ICP-AES)测定叶面尘Cd、Cr、Cu、Pb、Zn和Ni含量,用相关性分析对叶面尘重金属来源进行解析,同时应用地积累指数及潜在生态风险评价法分析不同功能区叶面尘重金属污染及潜在生态风险.结果表明:叶面尘Cd、Pb、Zn、Cu和Cr含量均显著高于开封市周边灰尘背景值.叶面尘Pb、Zn、Cd属于人为源重金属,Cr、Cu、Ni属于混合源重金属.叶面尘不同重金属地积累指数的大小顺序为CdPbZnCuCrNi,Cd为重污染,Pb和Zn为中污染,Cu和Cr为偏中污染,Ni无污染.7种重金属的单项潜在生态风险指数(Er)的顺序依次为CdPbCuZnCrNi,Cd达到极高生态风险,Pb达到中等生态风险,其余重金属为低生态风险.不同功能区潜在生态风险(RI)的顺序为工业区闹市区居民区文教区旅游区.所有功能区的RI均属于极高生态风险,Cd是最主要的致险因子.

Content and potential ecological risk of heavy metals in foliar dust of different functional of Kaifeng City

Foliar dust is a good indicator of airborne pollution in a certain area for a time period. In this study, twenty-two foliar dusts were collected in cultural and educational districts (CED), tourist districts (TD), residential districts (RD), downtown districts (DD), and industrial districts (ID) in Kaifeng city, China in 2019. The concentrations of heavy metals (Cd, Cr, Ni, Cu, Pb, and Zn) were measured in collected samples by inductively coupled plasma emission spectrometry (ICP-AES). The sources of heavy metals were identified by correlation analysis (CA). The foliar dust pollution and the ecological risk were assessed through Geo-accumulation Index (I_geo) and Risk Index (RI), respectively. Our results show that the average contents of Cd, Cr, Cu, Pb, and Zn in foliar dusts were much higher than those in control values in Kaifeng. The results of CA show that the elements Pb, Zn, and Cd came mainly from anthropogenic activities, while Cr, Cu, and Ni were influenced by industrial and natural sources. The I_geo values varied widely across different metals, with the mean values showing a decreasing trend in the order:Cd, Pb, Zn, Cu, Cr and Ni. The most of the I_geo values for Cd, Pb, Zn, Cu, and Cr in foliar dusts were higher than 0, indicating the foliar dusts were contaminated with heavy metals. The single potential ecological risk index (Er) decreased in the order of Cd > Pb > Cu > Zn > Cr > Ni. The Er_Cd in foliar dust was higher than 240, suggesting that the most of sampling sites were at very high ecological risk district, while the Er_Pb was between 30 and 60, suggesting moderate ecological risk,and the Ers of the other heavy metals were lower than 30, showing low ecological risk. The potential ecological total risk (RI) of heavy metals in foliar dust in each functional district was above the high ecological risk, and the order of RI was ID > DD > RD > CED > TD. The average ecological total risk contribution rate of Cd reached 87.43%, which was the most important risk factor in foliar dust of Kaifeng city.