| Since the reform and opening up, the speed of economic and social development of our country has being on a high level, which get great achievements in the world. However, there are so much danger hide behind this remarkable economic achievements. Governments at all levels blindly pursuing economic benefits, even at the expense of the environment, causing environmental pollution problems have become increasingly prominent today. Air quality evaluation system and no previous detection for PM2.5, there are many loopholes. But with more frequent haze events continue to people’s production and life has brought a serious impact, people began to understand even familiar with PM2.5. It is in this context, the state will PM2.5content into the air quality testing and the existing evaluation system to real-time information released to the public. This paper first introduces the definition of PM2.5, the related characteristics, sources and hazards, in Xi’an city as an example, in Xi’an City air pollution more serious areas set up monitoring points, the indicators and environmental acquisition on PM2.5data, and the data analysis, providing a data base for the city of Xi’an air purification.The monitoring period (2009November to2012December) the data collected in the display, the content of PM2.5within three years, Xi’an city average values were73.470±55.357μg/m3、107.208±75.626μg/m3、110.010±77.449μg/m3, and the provisions of the state standard of class two (35g/m3) compared with PM2.5are serious, three years exceed the standard. As the source of all seasons PM2.5are not the same, so the statistical data related to the author on the seasonal interval, three years of PM2.5content in the four seasons within24hours of the average value of more than two standard limits the proportion of order from big to small is the winter (64.09%)> autumn> spring (62.40%)(50.05%)"Summer (38%). Compared to the same data display, each season PM2.5content of three years average upward trend. Winter Xi’an people was high for heating requirements, and provide heating industry mostly takes coal as fuel, the combustion of coal is one of the main reasons causing increased PM2.5content. Monitoring data show, three year heating period in24hours of PM2.5Han mean values of two times followed by the1108.605±75.893μg/m3、112.217±84.354μg/m3,146.160±94.550μg/m3, This shows that the environmental pollution situation is still deteriorating Xi’an city.In addition to human factors lead to the increase of PM2.5content in Xi’an City, one of the special geographical and climatic conditions is also an important cause of Xi’an city. Xi’an city at lower elevations, the near ground air mobility is poor, the vertical flow and turbulence activities are relatively weak. The atmosphere stability is very high, the mixed layer from the ground very close, so the atmospheric diffusion ability is very weak, so the PM2.5particles floating in the air would be as the air spread, long-term accumulation in the near ground atmosphere in Xi’an City, the formation of haze weather. So first of all we have to accumulate enough knowledge through the scientific method of Xi’an city PM2.5, then adopt targeted policies and measures to reduce the content of PM2.5in Xi’an air, to create a good production and living environment of air. |
PDF Full Text Request