Research On Soil Quality Of Urnan Green Areas In Xi'an

Urban green space soil is not only the material and nutrient basis of urban ecosystem,but also carries various wastes and pollutants generated by urban human activities.The sustainable development of the city is closely related to the quality of urban soil.In view of significant changes of urban soil environment caused by urbanization,this research studied the different functional area green space in Xi'an city based on the field investigation and sampling and laboratory analysis,to explore the characteristics of Xi 'an urban road green space soil enzyme activity and soil physical and chemical properties,as well as the influence factors of soil enzyme activity,the pollution level of main soil heavy metal elements are discussed.Based on the result,we could comprehensively understand the quality of the urban road green space in the study area soil condition.This research could provide theoretical basis for urban soil quality evaluation and management of urban green space in Xi 'an.The main conclusions were as follows:(1)The variation range of soil moisture content of urban green space in Xi 'an District is 2.1-19.2%,The soil moisture content of educational area and park area is significantly higher than the other areas.The soil is weakly alkaline,the value of pH were basically higher than 8.0,the value of pH in 0-15 cm layer same as the 15-30 cm layer.The pH value in the industrial zone and the busy traffic area are higher than the residential cultural and educational area,the northern part of the city has a higher than the southern part of the city.The content of organic matter in the urban green space is low overall.The variation of 0-15 cm soil layer is 0.72-3.65 g.kg-1,and 15-30 cm soil layer is 0.83-2.68 g.kg-1.The south and north part of the city showed the content of organic matter in the park area the highest,and the lowest values of the two areas appeared in the industrial area and the busy traffic area,respectively,indicating that human interference and management methods had great influence on the organic matter content.(2)There were significant differences in the enzyme activities of green soil in different functional areas of Xi'an,with 0-15 cm soil layer higher than 15-30 cm soil layer.Land use mode greatly impacted the enzyme activities of soil,and changed with different soil enzyme.The spatial distribution of soil phosphatase showed homogeneous,while urease,sucrase and catalase were vice versa did not showed this tendency.There are different correlation between the physical and chemical properties and soil enzyme activity,and different soil enzymes activity.Metal elements exerted different effect to the soil enzyme activity.Cr and Cu activated urease,sucrase and catalase,but contrary to phosphatase.Pb and Zn could stimulate catalase but not showed inhibitory effects to other enzymes.(3)The contents of different heavy metals in urban soil of different functional areas of Xi'an showed that,the content of Cu,Ni,Pb,Zn were the highest in the industrial area.Major heavy metal pollution assessment shows that Cu,Ni,Pb belong to slightly-polluted,the most serious pollution in functional areas is industrial areas,followed by traffic busy areas,and the park environment is the best,which needs to be controlled and managed from the source of pollution.(4)Factor characteristics classification and regression analysis showed that 0-15 cm soil enzyme activity was affected by multiple and complex factors than 15-30 cm layer.Soil phosphatase activity is directly related to urease and indirectly affected by soil water content and organic matter.Soil phosphatase activity and the content of Zn,Pb,Cu,soil water content could also represent soil enzyme activity intensity and soil pollution quality status.