Temporal And Spatial Variation Of Sulfur Dioxide Concentration And Pollution Control In Guodu Town, Xi'an

With the rapid development, the atmospheric pollution continues to increase in the southern suburbs of Xi’an. Although SO2 pollution has been reduced in recent years, it taking serious threat to people’s daily life and industrial and agricultural production. Therefore, it is not only to reveals the change law of the local SO2, but also has the important practical significance to control SO2 pollution and improvement the local atmospheric environmental quality by researching the concentration of SO2 variation in Guodu Town in the southern suburbs of Xi’an.In April and May 2014, the concentration of SO2 and four main meteorological factors in a range of 52 m in the southern suburbs of Xi’an were observed in six days and nights. Using correlation analysis to study the change rule of SO2 concentration and the correlation relationship between meteorological factors and SO2 concentration, and reverse tracing SO2 remote source in observation area, find the effect of remote transmission source to the concentration of SO2, and predict the variation trends of SO2 concentration. To the SO2 pollution in Guodu Town of Xi’an at present, the relevant pollution control technologies and countermeasures are put forward. The main conclusions are as follows:(1) In April and May 2014, the concentration of SO2 showed unimodal variation characteristics in the southern suburbs of Xi’an in day and night, overall SO2 concentration in April was higher than May. The diurnal variation range of SO2 concentration is larger in April, the highest appeared at 18:00, the lowest appeared at 10:00. The peak of SO2 concentration appeared at 12:00, the lowest appeared at 10:00 in May.(2) The concentration of SO2 at different heights showed three stages of variation characteristics in the Guodu Town of Xi’an in April and May. In April, The first stage appeared at 8:00～16:00; The second stage appeared at 18:00～20:00; The third stage appeared at 22:00～06:00. In May, The first stage appeared at 8:00～10:00; The second stage appeared at 12:00～18:00; The third stage 20:00～06:00.(3) With the increase of altitude, the vertical variation of SO2 concentration showed 4 types of distribution characteristics in Guodu Town in the southern suburbs of Xi’an in April. The first type was characterized by SO2 concentration increasing with the increase of altitude and appeared unimodal. The second type was characterized by SO2 concentration decreasing firstly and increasing later, and appeared unimodal. The third type was characterized by SO2 concentration decreasing with the increase of altitude. The fourth type concentration of SO2 was unchanged. The vertical variation of SO2 concentration showed 3 types of distribution characteristics in May. The first type was characterized by SO2 concentration decreasing with the increase of altitude, at 12:00, SO2 concentration was higher than other time in a day. The second type was characterized by SO2 concentration was unchanged basically. The third type was characterized by SO2 concentration decreasing firstly and increasing later with altitude increasing.(4) In April and May in the Guodu Town of Xi’an, one part of SO2 source remote came from the developed Yangtze River delta and the Sichuan basin, the other came from Gansu and Inner Mongolia, where reserve coal and mineral resources.(5) SO2 concentration near the ground showed negative correlation with temperature, wind speed, relative humidity in the Guodu Town of Xi’an in the Spring, and the correlation coefficient were -0.49,-0.59 and -0.51 respectively. Positively correlated with air pressure, the correlation coefficient was 0.39.(6) The average concentration daily of SO2 was 15.6μg/m3 in the Guodu Town of Xi’an, far below the national《environmental air quality standard》, the average level of standard is 5Oμg/m3, and it also lower than the average SO2 concentration in Xi’an at the same period in 2013 (26μg/m3).(7) Based on the characteristics of SO2 emission in Xi’an, we put forward SO2 pollution control should be taken to wet calcium method (limestone-gypsum method), spraying calcium inside the furnace desulfurization technology. The corresponding policies and measures is the total emission control, the implementation of the regional environmental access and elimination system; promoting the use of clean energy, optimizing energy structure of the region; adjusting the industrial structure, speeding up urban greening.