| From the beginning of the nineteenth century, world population tended to congregating in city. By the mid-eighteenth century urban population only accounted for 3% of the total population, while by the mid-nineteenth century this value increased to 29%. At present, urban population accounts for 55% of the total population, and this proportion is constantly growing. With such a rapid increase in population density, urban environmental pollution has drawn more and more attention. The environmental pollution caused by rapid growth of municipal solid waste is one of the most serious problems. Jiang Cungou landfill has taken responsibility for 90% of solid waste generated in Xi'an since 1993.The aim of this thesis is to (1) evaluate soil pollution in the Jiang Cungou landfill in Xi'an. (2) study dust pollution, including deposition rate and physical characteristics of the dusts collected from a highrise building on the Shaanxi Normal University campus in the city of Xi'an.This thesis includes four chapters. The first chapter is introduction, in which the definition, development and environmental impacts of landfill are described, and especially includes current waste disposal situation and pollution prevention methods at home and abroad are reviewed. Chapter 2 to 4 is devoted to the research report.The second chapter is the research of soil pollution status around the Jiang Cungou landfill in Xi'an. A totle of 57 soil samples and 8 water samples were collected to examine soil contamination degrees. Water content, pH, and organic content were determined following the standards methods promulgated by State Environmental Protection Administration. Mercury content in the soil was determined by Cold Vapor Atomic Fluorescence. Thirtynine (39) elements (Ba, Bi, Ce, Co, Cr, Cs, Cu, Ga, Hf, La, Nb, Ni, Pb, Rb, Sb, Sr, Th, U, Y, Zn, Zr, Fe, Mn, Sc, Ti, V, Ca, K, Mg, Na, Al, As, Br, Cl, P, S, Si, N, CO32-) in the soil samples were determined by X-ray fluorescence. The results showed that the water content and organic content in the soil samples collected in the landfill area were higher than those in the samples collected in the area around the landfill. The Chemical Oxygen Demand (COD) of water samples from the landfill area ranged form 32.1 mg/L to 7808.4 mg/L, with 353.5 mg/L for treated waste water which is much higher than 40 mg/L of the standard COD for agricultural water in China. Mrcury content in soil samples ranged form 251.2 to 1760.1 ng/g, with an average of 567.9±272.6 ng/g. On the basis of the enrichment factor for each element, the contamination level of elements in the soil samples were: slight enriched elements:Rb, Th, Ga, Ce, Y, U, Zn, Ba, Pb, Co, Sr, Cu, Cr, Ti, Br, V, As, K, Mn, Sc and Ni, moderate enriched elements:Na, Fe, Al and Mg, and highly enriched elements Bi and Ca. Integrated pollution index was cited to investigate soil pollution at the sampling sites. Average individual pollution index between 1.6 and 2.5, together with soil pollution index between 7.6 and 10.5 showed that farmland around Jiang Cungou landfill had already been polluted. In the soil sample 57#, which was seriously affected by discharged leachate, Uranium was strongly decayed since its enrichment factor dropped to 0.04, while Cs, Sb, Sr, Bi, Mn, Ca, Mg, Cl, P and S were concentrated since their enrichment factors were higher than 2. An average individual pollution index of 2.5 and soil pollution index of 15.7 indicated that soil sampling at site 57 has been serious polluted.In the third chapter, dust deposition rates and size distribution at High Building No.1, Shaanxi Normal University, Xi'an were investigated. The deposition rate of deposited dust ranged form 0.13 to 0.18 g m-2 day-1, with an average of 0.14 g m-2 day-1, and 0.035 g m-2 day-1 within the machine room in the top. The particle size distribution (v/v) in the samples was calculated from the continued size distribution spectra as:10.44% having size< 2μm (clay),57.15% having size 2-20μm (fine silt),24.50% having size 20-50μm (coarse silt),5.07% having size 50-125μm (fine sand), and 2.46% having size> 125μm (coarse silt). This suggests that the settled dusts consist of mainly silt. Fine particle (<10μm) content in deposited dusts in height distribution showed two peaks: one was at the lowest floor close to surface while the other one was between floors 10 and 13. And coarse particle (>10μm) content in deposited dusts presented a U-shaped height distribution, with the lowest content between floors 10 and 13.The results of soil pollution assessment in Jiang Cungou landfill and the deposition rate, size distribution of dusts in High Building No.1, Shaanxi Normal University in this work provided effencient information which benefits to take environmental protection process. |
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