| This study selects the green belt of the Hetan Expressway(Guanghui Bridge-Zhujiang Bridge)section with heavy traffic in Urumqi and the teaching area of the Xinjiang University Headquarters with less pollution sources as the research area,and selects 20 kinds of landscape plants commonly used in the green belt.The surface soil is the research object.The distribution of heavy metal organs and the correlation between heavy metal elements in plants are analyzed.The bio concentration coefficient is used to systematically cluster the enrichment ability of different plant heavy metal elements,and the superior enrichment is selected plant.According to the heavy metal concentration and biomass equation,the heavy metal enrichment of plant communities in the greening pattern of arbor,shrub,and herb are estimated,and the amount of heavy metal in the greening area of different greening modes is compared.Eventually,the heavy metal enrichment efficiency of different greening patterns was evaluated on the community scale research shows:1)The ability of green plants to absorb heavy metals varies according to organs,life forms and types of elements.The distribution of Cr,Pb and Zn elements in trees and shrubs is similar in leaves,branches and trees.The content in the skin is arbor plants > shrub plants.The content of Cu and Mn in each organ is shrub plant > arbor plant,Ni element is in addition to shrub plant > arbor plant in leaves,and the distribution in other branches and bark is arbor plant > shrub plant.The enrichment ability of each life-type plant was evaluated by bio concentration factor.Among them,the ability of arbor plants to enrich heavy metals was: Crataegus pinnatifida >Populus alba var.pyramidalis > Syringa oblata > Picea asperata > Fraxinus rhynchophylla > Ulmus pumila > Malus spectabilis > Amygdalus davidiana 。 The ability of shrub plants to enrich heavy metals is Cornus alba>Ligustrum lucidum>Amygdalus triloba > Forsythia suspensa > Prunus × cistena > Ulmus pumila >Robinia pseudoacacia>Euonymus maackii>Ligustrum obtusifoliumb.and absorption capacity of herbaceous plants is Parthenocissus tricuspidata > Trifolium repens >Hemerocallis fulva.Urban greening,planting process should give priority to the treespecies with strong ability to enrich heavy metals,hawthorn,red arbor,and brocade.2)Pearson correlation analysis found that there were significant correlations among individual heavy metal elements in trees,shrubs and herbaceous plants.The ammonium nitrogen in soil was significantly correlated with Pb elements(p<0.05),and the correlation coefficient was 0.648,respectively.There was a significant correlation with the Cu element in the soil(p<0.01),and the correlation coefficient reached 0.830.The ammonium nitrogen was significantly negatively correlated with the Mn element in the soil(p<0.05),and the correlation coefficient reached 0.578.There is no correlation between nitrate nitrogen in soil and seven heavy metal elements.In general,except for Ni,the other six heavy metal elements in the soil were significantly correlated with ammonium nitrogen and pH.3)Using the single pollution assessment method to evaluate the soil heavy metal pollution in the green belt of Hetan Road and the teaching area of Xinjiang University.The pollution levels of each single factor are as follows: the road green belt shows Cu>Pb>Zn>Ni>Cr>Mn,the clean area is: Cu>Zn>Pb>Ni>Cr>Mn,the Pi of Pb,Zn and Cu is all greater than 2.It indicates that the pollution level is also serious;the heavy metal elements in the control area,Pi is less than 2,indicating slight pollution.Correlation analysis of heavy metal elements in soil showed that Pb was significantly correlated with Cu(P<0.01),and the correlation coefficient was 0.699,indicating that the two heavy metals have the same pollution source.4)The total storage of heavy metals in the greening pattern composed of living plants has a certain correlation with the biomass.The biomass per unit area of the shrub-type greening model is higher than that of the arborvitae typ e,but for the heavy metal storage,the total storage capacity of the arbor-type configuration pattern is higher than that of the shrub type,indicating that the b iomass does not determine the greening pattern.The only factor in the storage of heavy metals is that the plant types of different greening patterns are diffe rent.The ability of plants to accumulate heavy metals varies from species to s pecies.The concentration of heavy metal elements affects the total storage of h eavy metals in the greening mode.In general,the order of total heavy metal storage in each greening mode is: arbor+shrub+herb > arbor+herb > shrub+herb type.The amount of metal enrichment in the greening of different greening m odes is in order of order:arbor+shrub+herb > shrub+herb > arbor+herb.In the f uture greening work,planting landscape plants without scientific basis should b e avoided,and green plants should be properly screened.And cultivate a green ing model with a large amount of heavy metal enrichment per unit area,there by improving the ecological benefits of road greening land. |
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