Evaluation Of Urban Forest Ecosystem Service Value As A Purification Of Urban Atmospheric Environment

Urban air pollution is caused by many factors,such as vehicle exhaust emissions,construction of urban works,environmental pollution caused by industrial gases,etc.The treatment of urban air pollution includes various aspects,Whereas the role of urban forests in cleaning urban air cannot be disregarded.whereas,on the basis of the assessment of the service value of urban forests in air cleaning,this paper aims to:improve the role of urban forests in air purification through quantitative analyses.Based on the research of related scientists,this paper designs and implements the corresponding monitoring scheme according to the geographical location,topography,vegetation distribution and other actual conditions of Yamalike Mountain Forest Park in Urumqi City.By sorting and analyzing the measured data,the main characteristics of forest dust accumulation,gas pollutant absorption and negative ion supply in the target area are first discussed;The economic evaluation method of the system service function estimates the functional value of the purification of the atmospheric environment of the Yamalike Mountain Forest Park.the analytical hierarchy is used to build the value model of Yamalike Mountain Forest Park,to calculate the weight of each index and finally to obtain the comprehensive value of cleaning the atmospheric environment ecosystem service function of Yamalike Mountain Forest Park.The main conclusions of this study are as follows:（1）If the environmental conditions are constant,the dust binding of plant leaves is in direct proportion to the time.Over time,the storage of TSP,PM₁₀ and PM_2.5 in the leaves of plants at different heights gradually increased,and the retention gradually approached the limit value on the 24th day after rain.（2）If the environmental conditions are not changed,the dust storage capacity of the plant leaves and the height are approximately V-shaped;and the retention capacity of the plant leaves at different heights to particles of different sizes in the atmosphere is significantly different.The maximum and minimum retention of TSP by plant leaves was at 844m and 890m above sea level;the maximum and minimum retention of PM₁₀by plant leaves reached at 960m above sea level and the minimum height of 910m above sea level;the maximum and minimum retention of PM_2.5 by plant leaves at 960m and 869m above sea level.（3）The sulphur content in plant leaves is directly proportional to the growth period of the plants and it is V-shaped with the height or trend of decreasing decrease.With the development of the leaves,the sulphur content in mature leaves is higher than in new leaves.new leaves of the plant first descended and then rose.The minimum value was at 869m height and the maximum value was at 960m height.The sulphur content in mature leaves decreased,increased and decreased with the increase in height.The maximum and minimum sulphur content in the leaves was at 869m and 910m respectively.At an altitude of 930m,the intensity of sulfur absorption by the blade is the largest.（4）The nitrogen content of plant leaves is closely related to the seasons and is slightly dependent on the height.As the seasons change,the nitrogen content of the plant leaves is lower in spring,summer and autumn,but there is no significant change with the height.（5）The negative ion concentration in the air shows a clear seasonal and daily variation,With the change of seasons the concentrations of aerial anion are from high to low:summer>autumn>spring.The daily trend of negative ion concentration in the air of the monitoring points shows a double peak（m）type change,below which the highest value for approx.11:00 and 18:00 appears at the height of 844m,930m and 960m and the lowest value for approx.14:00.The highest value appeared at approx.11:00 and18:30 at the height of 869m and 910m,and the lowest value was at about 14:30.The concentration of the air anions first increased and then decreased with the increase of the height,reached a peak value of 1445/cm³ in 910m height and the lowest in 844m height,1076/cm³.（6）The overall value of the air purification function of the yamalike mountain park is 2.51×10⁹ yuan·a^-1.The maximum single-factor service value was 2.07×10⁹ yuan?a^-1for the service value of PM_2.5,and the maximum weight of single factor is 0.466 for stranded TSP service value.