工业园道路两侧土壤及行道树的叶片Cr富集与污染评价

Chromium( Cr ) enrichment and pollution assessment in soil and leaves of street-by trees on both sides of industrial park roads

为了探讨重金属铬的富集情况,选取益阳市龙岭工业园内道路两侧9种行道树叶片及其土壤作为研究对象,采用二苯碳酰二肼分光光度法对Cr的质量比分别进行测定,引入单项污染指数法、地质累积指数法和潜在生态危害指数法,利用土壤Cr含量和湖南土壤环境背景值对土壤环境的重金属铬进行污染评价,并进一步分析了土壤中重金属铬在3个采样点中的分布特征。结果表明:1)行道树叶片的Cr生物富集系数由大到小依次为广玉兰、紫叶李、金边黄杨、红叶石楠、樟树、含笑、桂花树、雪松、青果树;2)单因子污染指数法和潜在生态危害指数法的评价结果基本一致,樟树、含笑和桂花树的土壤存在轻微Cr污染和中等生态危害;地质累积指数法的评价结果表明9种行道树土壤均无Cr污染;3种评价方法的评价结果中无严重Cr污染状况出现;3) 1号和3号采样点的土壤Cr质量比随距离水平分布呈先下降后上升的趋势,2号采样点的土壤Cr质量比整体呈逐渐减小的趋势。

In this paper,the mass ratio of Cr( short for the heavy metal chromium) has to be determined by the diphenylcarbazide spectrophotometry. In order to investigate the enrichment of Cr,9 kinds of street border tree leaves and soil on the both sides of the road along the Longling industrial park of Yiyang City( Hunan) has been chosen as the research target. And,in the paper,we have also introduced the single pollution index method,the geological accumulation index method and the potential ecological hazard pollution index method to the readers. And,in the paper,we have also analyzed and evaluated the pollution situation of the heavy metal Cr in the soil environment by the mass ratio of the soil and the background value of soil environment with the distribution features of Cr in the soil. The results of our investigation show that:( 1) The mass ratios of Cr in the leaves of 9 kinds of street-border trees can be shown as follows: magnolia grandiflora > camphor tree > michelia figo > purple-leaf plum > osmanthus fragrans > olivia > phnom penh > photinia fraseri > deodar. The Cr bioaccumulation factors of the leaves of the street border trees can also be demonstrated as fallows: magnolia grandiflora > purple-leaf plum > phnom penh > photinia fraseri > camphor tree > michelia figo > osmanthus fragrans >deodar > olivia.( 2) The analysis results by using the single factor pollution index method and the potential ecological hazard index method prove basically to be the same. The soils of camphor tree,michelia figo and osmanthus fragrans prove to have been polluted by Cr a bit slight and moderate in the ecological hazards. The results of the geological accumulation index method show that there does not exist Cr pollution in the soil of 9 kinds of the border trees. Neither dose there exist serious Cr contamination in the evaluation results of the 3 evaluation methods.( 3)The mass ratio of soil Cr at the sampling sites of No. 1 and No. 3 indicates a trend of decreasing first and then increasing with the horizontal distribution of the distance. Therefore,the mass ratio of soil Cr at the sampling site of No. 2 should be gradually turning to be reduced and even deceased.