Spatial And Temporal Variation Of Atmospheric Particulate Matters And The Capture Ability Of Plants To Particles In Chongqing City

Particulate matters pollution has become a serious problem in China as it has impact on human health, environmental pollution, and atmospheric visibility. Recently researches of particulate matters are mostly focused on source analysis, composition analysis, harm evaluation, and dynamic characteristics.This study was taken on daily variation characteristics of pollutant concentration and its relationship between meteorological factors within the downtown areas of Chongqing city. PM10 and PM2.5 concentration were separately collected in different land use types, and distribution regulation and reason of it were studied as well. Seasonal difference and spatial distribution of PM2.5 were predicted by using ArcGIS. Distribution of PM2.5 both in summer and winter were detected in 4 typical types of forest (Phyllostachys heterocycla forest, broad-leaved forest, coniferous forest, and Pleioblastus amarus forest). Moreover, influence of typical weather on particulate matters in different size (TSP, PM10, PM2.5, and PM1) was studied at the same time. Block and absorption capacity of leaves on dominant species of Chongqing city to PM2.5 was quantified by using scanning electron microscope and self-made gas chamber, and the reason of particles block capacity among different leaves or different physiological structures in the same leaf were compared analysis combined with plant physiology. The main results are as follows:(1)Concentration of PM2.5 PM10 in main district of Chongqing show the tendency of curves with two peaks and two valleys. The seasonal and spatial distribution that predicted by ArcGIS shows the highest concentration of PM2.5 occured in winter, the chief reasons are the variation of meteorological condition and reduction of vegetation physiological activity. In space, concentration of PM2.5 decreased from city centre to the surrounding area. In other words, PM2.5 pollution was more serious in those areas with more human acticities, larger building density, and heavier traffic status; however, it turned lighter in those areas that far from the city and went green well by vegetation, have larger public green area per capita, and located close to water.(2) PM2.5 is the chief pollutant particle in downtown areas of Chongqing, business zone was polluted most seriously, while green land and control point were lightly polluted. Vegetation and waters are helpful in reducing PM2.5 pollution considering the spatial distribution characteristics of PM2.5 and different land use types.(3) Atmospheric particles concentration among seasons was highest in winter, then in spring, and was least in summer. Coniferous forest has strong block capacity of PM2.5. Concentration of particles in the forest is obvious decreased in rainy days, and it raise fast again in the cloudy after precipitation.(4) Conclusions obtained through the self-made gas chamber are:coniferous species has better capacity in dust retention than broad-leaved species. However, the particles retention among different broad-leaved species is also quite different.(5) Foliages has it advantage in particulate matters retention due to the physiological structure and roughness of the leaf surface. It is also related to the difference of retention capacity of particulate matters in different sizes.