A Study Of Heavy Metal Contamination Characteristics Of Soil And Plant Under Flyovers Of Core Metropolitan Function Area In Chongqing

This paper took heavy metal of soil and plant under flyovers in Chongqing Core Metropolitan Function Area as the research object. According to the Chongqing main city traffic distribution map, 48 flyovers were choosed as sampling points. Number of total soil samples were 48, and plant samples 45. We also collected the corresponding plant of Jinyun mountainin Beibei district as the control group. Analyzed the concentration of As, Cd, Cr, Cu, Pb and Znin the soil and plant samples by an experiment. Pollution status, pollution sources, the influence factors and spatial distribution of soil and plant were analyzed. The main contents and results can be summarized as follows:1) Based on the single factor pollution index, the Nemerow comprehensive pollution index and potential ecological risk index assessment method, heavy metal pollution characteristics of soil under flyovers in Chongqing Core Metropolitan Function Areawas analyzed.Heavy metal pollution of soil was caused by the As in common, suffered light pollution and above from the Nemerow comprehensive pollution index, accounted for 70.83%. It showed that heavy metal pollution of flyovers in Chongqing Core Metropolitan Function Area was wide. With high heavy mental pollution levels of the administrative region was Jiulongpo district, then in turn Shapingba district, Yuzhong district, Jiangbei district, Nanan distract, Dadukou district. Average potential ecological risk index of overpasses soil in Chongqing Core Metropolitan Function Area was 66.72, risk degree was light. Although the potential risk level is low, but the potential risk of single potential ecological risk index was in strong ecological risk grades in individual points. Single factor pollution index and the Nemerow comprehensive pollution index also were used to assess heavy metal contamination of plant.It’s found that Cr and Cu pollution are common, 95.56% of flyovers were in light pollution and above. 2)Based on the statistical analysis technologyof SPSS software, using correlation analysis and cluster analysis to explore the possible sources of heavy metal pollutionand influencing factors of soil and plants. The results showed that: significant correlation was found between each element in soil, but there were differences. Common source of 6 kinds heavy mental of soil probably was traffic pollution, because all the position of samples were under the road. The sources of the heavy metals Cd were associated with industrial pollution, and As may beassociated with passenger transport, more flow of passenger transport, more contamination of As. The rest of the four elements concentration were associated with density of road net and human activities, more intensive of road net and human activities, contamination of rest four kinds of heavy metal elements content were increased accordingly. Correlation analysis of heavy metals in soil and plants can be concluded that heavy metal content in soil and plants didn’t have significant correlation. But combinedthe soil and plant heavy metal index evaluationwith correlation analysis and cluster analysis of plant, plant heavy metalssources and soil heavy metal content had certain relevance. The 6 kinds of heavy metal elements concentration in soil can affect the content of the corresponding element in plant, but could not fully explain the heavy metal content in plants. Heavy metals concentration in plant had other sources.Themore sources still need further study.3)Based on the ArcGIS software, Kriging interpolation technique were used to visualize 6 kinds heavy metal of soil and plant in order to analysis spatial distribution characteristics. Results showed that: spatial distribution of As, Cr, Cu, Pb in soil were similar, highconcentration values appeared in west and northeast of Core Metropolitan Function Area, and lowconcentration value was located in the southeast.Cd pollution serious areas was Jiulongpo district in the west, high valueconcentration of As was found in Jiangbei district. The content of As, Cr, Pb, and Zn in plant had common features, western concentration were high in spatial distribution map. Inaddition, content of As and Cr were also high in the northeast;Pb and Zn in the northeast and southwest were high. The distribution of Cu and Cd have big difference with other elements. Most seriouspollution of Cu was in Niujiaotuo overpassofYuzhong district, higheconcentration values of Cd wasin Nanan district.