| Urumqi city located in the northwest arid areas,belong to the typical "valley model city",the winter long,and no wind inversion,high frequency,atmospheric stability type for medium and more stable class,meteorological conditions hardly conducive to atmospheric pollutants diffusion,cause serious atmospheric pollution of the environment.In 2011 the world health organization in 1100 cities of the world's environmental quality,Urumqi city was located in 1052.Especially in the winter,the haze weather is becoming more and more like a black hat cover in the sky.As a result,caused the attention of people,Especially,as a "way" of strategic important node in the city,the environment quality is particularly important,in order to objective analysis of the whole city environmental pollution problems,and to take effective control measures.This article researched mainly from the following several aspects.First,In order to understand the spatial and temporal variations of Urumqi pollutants,this paper used date from 2013 to 2014 in downtown Urumqi 22 automatic air quality monitoring station of research analyzed,discussed the space-time characteristics of PM2.5 concentrations.The results showed that the annual concentration is 92?g/m3 in 2014,that higher than in 2011 and 2013,the concentrations of PM2.5 in season from high to low in turn is winter?181.16?g/m3?,spring?82.10?g/m3?,autumn?76.10?g/m3?and Summer?47.21?g/m3?.PM2.5concentration distribution is U shaped,The highest average concentration in January,reached up to 212.96?g/m3.PM2.5 concentrations present in the spatial distribution of the southwest to northeast gradually is increasing,this change level is extremely obvious in summer,autumn and winter.Second,in order to explore the reasons that caused serious pollution,the main reason is that the emissions,meteorological conditions have effected importantly on the dilution and diffusion of pollution also,therefore,and then selected the data of PM2.5 concentrations and five kinds of meteorological factors of the same period,Pearson correlation analyzed.The results showed that there are correlation between meteorological factors and PM2.5 concentration,wind speed,relative humidity,temperature,vapor pressure and the correlation between PM2.5 concentrations significantly in heating period,relative humidity and PM2.5 concentrations significantly related in the non-heating period.Heating period small wind speed inhibits pollutants spread in the levels,made the pollutant accumulation,and with theloss of the temperature,the power consumption of energy increased,pollutant emissions increased,coupled with inversion enhanced,restrained the pollutants spread in the vertical direction,high relative humidity and contribute to the formation of the fog weather,in the end,resulted that PM2.5.concentration is higher in the heating period.Third,Natural precipitation could clear pollutions well.This paper selected five kinds of pollutants concentration data of SO2,NO2,CO,PM10,PM2.5 and precipitation data for analyzed in Urumqi,The results showed that the precipitation clear effect is stronger,the snow clear effect is better than rainfall;The precipitation time was longer,greater and stronger the removal effect of the pollutant was better;Different levels of rainfall on the pollutant removal effect showed that moderate rain >heavy rain > light rain > small rain,the relationship between different levels of snow showed moderate snow >heavy snow > light snow > micro snow;there were difference that pollutants recovered and rebound time after precipitation,because which was effeced by initial concentration,rainfall duration,and other meteorological conditions.In the end,the prediction model of PM2.5 concentration in the whole year,heating period and non-heating period was established based on the multiple linear.Verification results show that the annual model has better reliability,the heating period was best,non-heating period was general. |
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