Pollution Characteristics Of Trace Elements In Atmospheric Cloud And Deposition At Mount Lushan

We chose Mount Lushan which is a typical background and regional transportation site as the sampling site to research the background concentrations of trace elements in the atmosphere in southern China, to explore the relationship between trace elements in different phase and the sources of different trace elements. In this study, we collected and analyzed the trace elements in cloud, rain and 17total suspended particulate (TSP) during March 17,2012 to May 20,2012. Totally 79 cloud samples,41 rain samples and 42 TSP samples were collected. The inductive coupling plasma mass spectrometer (ICP-MS) was chosen to analyze trace elements (Al、V、 Cr、Mn、Ni、Cu、Zn、As、Se、Mo、Cd、Sb、Ba、Pb) in the samples.The result showed that the concentrations of trace elements in the atmosphere at Mt. Lushan were close to the elemental concentrations of domestic background sites, but higher than the elemental concentrations of background sites abroad. Zn and Al were the two highest concentration trace elements, accounting for about 61%,60%, 74% and 80% in cloud, rain, total TSP and soluble TSP respectively. Toxic metals such as Pb, As, Cd presented higher concentration levels than the level of domestic background sites.The concentration of trace elements in the atmosphere at Mt. Lushan represented the background level of southern China and influenced by anthropogenic pollution to some degree. Different elements showed different characteristics in different phase, revealing different pollution levels. The proportion of Al showed total TSP> soluble TSP> rain> cloud. While the proportion of Zn showed soluble TSP> cloud> rain> total TSP. The concentrations of trace elements in the process of a cloud event presented higher in the beginning, and maintain lower in the mid-time, and higher in the end. This phenomenon mainly explained by the dissolution of particulate and the role of rain. The ratios of elements Al and Zn showed opposite trend because of different remove efficiency of particulate. Rainfall is easier to remove coarse mode aerosols. But due to the complexity of reactions, different elements showed different characteristics. There were significant difference of trace elements between cloud and total TSP. But the characteristics of trace element in soluble TSP were more similar with cloud elements. The transfer efficiency of Al and Mn from particulate to cloud in cloud event were low. While Pb, As and Cd showed higher transfer efficiency. In general, anthropogenic trace elements were more easily transport into cloud. The wet deposition flux of analyzed trace element was 44.78mg/m2*period,195.6 mg/m2*year. Element Al and Zn contributed about 60% of deposition flux. The wet deposition of trace element of Mt. Lushan area is about 59.lt/year. The dry deposition flux of analyzed trace element was 204 mg/m2*period,1.77 kg/m2*year. Element Al contributed about 92% of dry deposition flux. Wet deposition fluxes of typical anthropogenic sources elements of Cu, Zn, As, Se, Cd, Pb were much higher than dry deposition fluxes. The deposition fluxes of anthropogenic sources elements through long-range transport to Mt. Lu and then fall to the ground through wet deposition is much higher dry deposition of local elements, which caused more serious damage.Factor analysis showed that the main contribution of trace element were slightly different among cloud, rain and particulate. The trace element in cloud of Mount Lushan was mainly affected by soil and coal, accounted for 53.1%, followed by metallurgical industry, contributed 19.3%. Soil and coal contributed about 39.7% in rain, motor vehicle exhaust emission contributed about 18.9%, metallurgical industry contributed about 12.5%. The mainly source of trace element in TSP was soil, contributing about 39.8%, followed by steel, mining, construction, waste incineration, contributing about 27.8%. Metallurgical industry contributed about 12.8%. Consequently, soil and coal were the main sources of trace element at Mount Lushan. We analyzed the influence of long-range transport through HYPLIT model. Results showed that the frequences of air masses from Henan province and Yangzi River Delta and Jiangsu province is high, cpntributed about 64% of cloud air masses. The concentration of trace elements of cloud from Pearl River Delta and Yangzi River Delta is high, which pollution id serious.