Variation Characteristics And Influencing Factors Of Atmospheric Particulate Matter Concentration In The Fish & Flower Harbor Park,Hangzhou

City park is not only the major carrier of citizen activities,but also plays a significant role in the balance of the urban ecological environment.With Fish&Flower Harbor Park in West Lake scenic spot,Hangzhou chosen as the object of study,this research analyzes the change rule of PM(PM_2.5 and PM₁₀)concentration in city park from the macro,meso and micro perspective.A comprehensive analysis was also conducted between meteorological factors,types of plant arrangement,tourist volume and the PM concentration so as to probe into the leading influence factors of the concentration and provide scientific reference and basis for the construction and management of city parks.Here are the findings:From the macro and the meso perspective,there was significant difference between the PM concentration in weekdays and weekends.Specifically,there was a weekend effect and a holiday effect in Hangzhou while there was an anti weekend effect and a holiday effect in Fish&Flower Harbor Park.There is a holiday effect in both downtown Hangzhou and the park,and a synchronization of the variation of PM concentration can be observed in holidays in both areas.The air quality index in the park was pretty good,reaching the national second level 75%of the time in a year.The ranking of the average concentration of PM_2.5 and PM₁₀ in different seasons was:winter>spring>autumn>summer.And the daily concentration of them showed high value in the morning and low value in the afternoon.During the decline period,PM_2.5 revealed hysteresis,which explains that the smaller the particle size is,the more difficult the deposition is.From the micro perspective,the variation of PM concentration was analyzed from three aspects,meteorological factors,types of plant arrangement and tourist volume.The result indicates that meteorological factors are the major external influence factor of the variation of PM concentration.And the concentration is significantly negatively correlated with temperature and wind speed while is notably positively correlated to relative humidity.There are two types of the correlation,the linear type and the nolinear type.Temperature and relative humidity are the major factors causing the variation of PM concentration in the park.The type of plant arrangement can influence the distribution and aggregation of particulates in the park and is closely related to the degree of porosity and the canopy density of the arrangement,while tourist volume is the leading factor of the concentration variation in weekdays and weekends.