Study On The Influence Of Shenyang Urban Greenland Communities And Their Allocation Methods On Particulate Matter Concentration

Air pollution had become a major environmental problem in our country and even in the world,and it has seriously endangered people's production and life health.Among them,one of the main ways to prevent and control haze is through the stagnation effect of urban green space and individual plants on particulate pollution.This article selected Shenyang Agricultural University Botanical Garden,Wanliutang Park,Shenyang Agricultural University campus,etc.as the research objects.Adopted fixed-point observation method and particle resuspension method.Mainly study two different types of urban green space?park green space,campus green space?in Shenyang city to study the daily,monthly,and seasonal changes of four particulate matter concentrations of TSP,PM₁₀,PM_2.5,PM₁and their relationship with meteorological factors,and conduct structural survey and analysis of the plant communities in the park green space.The campus green space combined the functions of different tree species on campus to trap air particles,and explored the influence mechanisms of different types of urban green spaces and their plant communities on the concentration of particles,in order to provide reference for the planting and management of urban green spaces in Shenyang.The main conclusions were as followed:?1?The type of urban green space could influence the concentration of particulate matter.In autumn and spring,park green space was larger than campus green space.In winter and summer,the opposite is true.Campus green space was larger than park green space.The average concentration of PM₁₀in parks and green spaces was winter>autumn>summer>spring,while the average concentration of PM₁₀in campus green spaces shows the highest concentration in autumn and the lowest concentration in spring.The two types of green spaces had PM_2.5and PM₁.The seasonal average concentration was winter>summer>autumn>spring.?2?The correlation between the three meteorological factors and the four particulate matter was different.Relative air humidity was the most important factor affecting the concentration of particulate matter,showing a significant positive correlation;secondly,there was a significant negative correlation between wind speed and the monthly average particulate concentration of parks green spaces,and the northerly wind had a dilution and diffusion effect on particulate matter.The temperature had a positive correlation with the daily and monthly average concentrations of particulate matter and showed a certain negative correlation with the seasonal average concentrations.Meteorological factors played a greater role in the microenvironment of park green space than campus green space.?3?The arrangement of plants could influence the concentration of particulate matter in the green space to diffferent degrees.In soft wind or light wind,the concentration of particulate matter in the shrub and grass communities was higher than that in arbor-grass and arbor-shrub-grass communities;the concentration of arbor-shrub and grass communities was higher than the coniferous trees and grass communities.The concentration of particulate matter in a plant community was not only affected by the community type and vertical structure of the community,but also by the number density of the community and the canopy closure will inhibit plant growth,reduced air circulation in the plant community,accelerated the growth and reproduction of bacteria,greatly reduced the diffusion and dilution of particulate matter,and leaded to an increase in the concentration of particulate matter in the community.Among them,the community structure characteristics had a greater correlation with PM_2.5.In autumn there was a significant negative correlation between the average concentration of PM_2.5and the average plant height,and a significant positive correlation with the average crown width.?4?The concentration of particulate matter in various places of campus green space was affected by human activities and the distance of pollution sources.The concentration of green space on campus was also discrepant in different functional zones.The concentration of particulate matter in the student living area was the highest in autumn,the concentration of particulate matter in the green space of the student living area was the highest in spring,and the concentration of green space in the student living area and student activity area was the highest in summer.Combined with the analysis of plant community structure,it could be found that trees,shrubs and grass are greatly affected by the external environment,and the concentration of trees and grass community changes steadily.When human activities were less,the concentration of particles in the trees,shrubs and grass communities is lower.When there were a large number of coniferous trees in the plant community,the plant's dust removal ability and plant landscape effect will be relatively good,and the concentration change will be relatively stable.Different tree species in campus green space had different characteristics in terms of retention and adsorption of particulate matter,and their abilities in different places were also different.The results showed that the leaf absorption capacity of coniferous trees in the same life tree species was stronger than the broad-leaved trees,while the absorption capacity of individual shrub species was stronger than the arbor species,such as flowering plum.The pines of conifers were slightly better than the cypresses.