Vertical Distribution Of Atmospheric Particles In The Ground Layer In Kaifeng

Atmospheric particles can affect urban visibility and threat human health and ecological environment. Especially the particles in ground layer of atmosphere damage human health strongly. In this thesis, sampling of atmospheric particles at diferent height were did to declose the vertical distributive characters of atmospheric particles, that can provide a new comprehensive scientific basis for the multi-scale urban air planning and the comprehensive pollution control, and benefit for the further study of the basic distribution, sources, transmission and transformation characteristics and the climatic micro-changes of atmospheric aerosols in Kaifeng City.Sampling were carried out during October 27-November 6, November16-20 2009 and January 8-16, 2010. Two spots that Yuxiang Hotel in the center of Kaifeng and National Electric Net Ltd Building in the District Jinming were selected as the observation platform, they which represent residents-commercial-transportation mixed district and administrative-education district separetely. PM10, PM2.5 and drop dust samples in different height were collected. Analyses of concentration, metal elements and grain size were carried with the samples to disclose the spatial and temporal distribution of .particles The major results are showed as follows:(1) The concentration of PM10 and PM2.5 vary significantly in different season, and are higher in winter. There are more particles in residents-commercial-transportation mixed district than in the administrative-education district. The concentration of PM10 decrease with increasing altitude, and the decreasing rate in fall is higher than in winter. and the rate in Yuxiang hotel is higher than National Electric Net Ltd Building. The concentration of PM2.5 doesn't vary regularly with increasing altitude, in winter the concentrations of PM2.5 is highest at 70m above the ground, which is 356.56μg/m3, in autumn it's highest at 2m above the ground, which is 255.66μg/m3. The vavule of PM2.5/PM10 is 59.6% ~ 78.7%, and rise with increasing altitude, which is 65.5%~71.6% in the ground and 70.1%~78.7% in the highest level of division. It is speculated that particles mainly come from transport and ground dust.(2) The content of metal elements in particles are higher in residents-commercial -transportation mixed district than that in administrative-education district, and are higher in winter than in fall. The content of Ca, Fe, Mg, Cr, Ni near ground are higher than those in high altitude. The content of Pb, Zn and Cu don't vary significantly with increasing altitude, and the content of Mn is equidistribution within a certain height. Ca, Mg, Fe, Mn are the common elements in the earth, they come from soil dust and other natural sources, and enriched near ground. The heavy metals such as Pb, Zn, Cr, Cu,and Ni have high enrichment factor more than 10, they are typical polluting elements that closely related to human activities and less affected by soil dust. The enrichment factor of metal elements in partles in the residents-commercial- transportation mixed district than are higher which in administrative-education district, and the enrichment factor in PM10 is bigger than which in PM2.5. Enrichment factor of most elements decreased significantly with height increasing in PM10 in fall , but the enrichment factor in PM2.5 decreased much more significant with height increasing in winter.(3) Heavy fog is conducive to the formation of fine particulate matter, and is not conducive to the horizontal and vertical diffusion of particles.The contents of natural-source elements such as Ca, Mg, Fe and Mn increased but the artificial-source heavy metals such as Pb, Zn, Cr, Cu and Ni reduced in fog. The particles accumulated rapidly in the windy weather, and the concentration of coarse particle decreased with increasing altitude. The content of metals in PM10 and PM2.5 increased significantly. Enrichment factor of most elements in PM10 are higher in ground level than that in high altitude, but the enrichment factor in the PM2.5 is lower in ground level than that in high altitude. (4) The diameter of drop dust vary mainly in 10 ~ 30μm, and the particles <30μm is 67.1% ~ 99.6%. The contents of fine particles increased evidently with increasing altitude. The contents of heavy metal in drop dust do not vary significantly with increasing altitude. The enrichment factors of the heavy metals in drop dust indoor are greater than that outdoor. The contribution of smoking activities to the heavy metals can not be ignored.