The Geochemical Characteristic And The Sources Analysis Of Atmospheric Dust Fall And TSP

The particles in atmospheric dust fall were analyzed in terms of morphology, chemical and mineralogical composition by Environmental Scanning Electron Microscopy coupled with energy dispersive X-ray detector (ESEM-EDX) and X-ray diffraction (XRD). The results indicated that the particles were mainly composed of spherule, plate, irregularly shaped and agglomerate, which contains variable size and amount of particles, and the size of particle was between 4μm to 200μm. The particles could be categorized into five groups based on their chemical characteristic tested by EDS: Al-, Si-, Ca-, C-rich particles and aggregate, these particles and aggregate are directly related with the people’s polluting activities, such as, building construction, traffic emission, coal combustion, biological dust and the particles originated from atmospheric secondary reaction.The results of element analysis of atmospheric dust fall showed that the main component of particles was C, O, Si, Ca, Al, S, Mg, Fe and K, and their content was 56.91%, 27.82%, 5.58%, 4.28%, 1.82%, 1.34%, 0.33%, 0.38% and 0.45% respectively. The mineral identify of atmospheric dust showed that gypsum, quartz and calcite were the primary minerals in all fractions, and mica, halloysite, montmorillonite, hematite, brushite, zeolite, sepiolite, feldspar, alite, dickitewere also identified in lower content. Illite, clinochlore, zircn, , , Zn and S were possible component.AAS was used to exam five heavy metals: Cr, Cu, Zn, Cd and Pb, the content of them was 403.5 , 126 , 1541.5 , 2.5 and 348 The concentration of Cr, Cu, Zn, Cd and Pb was more higher compared with background value of soil choosen, this indicated that the heavy metal (Cr, Cu, Zn, Cd and Pb) in the atmospheric dust mainly contributed to human activities. HRTEM/EDS and ESEM/EDS were used to test the particles in TSP collected by automatic sampler. The fine particles (50nm-2μm) in the TSP were analyzed by HRTEM/EDS, the results showed that the particles were in shapes of plate, irregular shape and agglomerate. Based on EDS results, these fine particulate matter was primarily composed of Fe- rich particle( ), Ca- rich particle( )and Si-rich particle . The sources analysis indicated that the fine particles in TSP mainly originated from coal combustion, traffic emission, vehicles exhaust, fugitive soil and cement particulate matter. The coarse particles (4μm-50μm) were detected by ESEM/EDS, most of them exhibit obvious crystalline structure. Based on results tested by EDS, the coarse particles were categoried into five groups:C-rich -rich , -rich Si-rich and aggregate , and four kinds of particles mainly derived from vehicles exhaust emission, coal combustion, soil and biomass burning, while the aggregates were indicative of atmospheric reaction progress.