Variation characteristics of air pollutant concentrations in Urumqi

In this paper,the daily and seasonal variations of air pollutant concentrations were analyzed based on the average daily data of air pollutant concentrations in Urumqi during the period of March 1,2014 to February 28,2014. Also,based on the corresponding meteorological data,PM2.5concentration prediction models based on gaseous pollutants were built. Moreover,the main factors affecting the variations of air pollutant concentrations were discussed. The results obtained were as follow:( 1) Annual average concentrations of PM2.5,PM10,SO2,NO2 and O3were 67. 9,159.3,24. 9,56. 1 and 31. 5 μg·m-3,respectively,with the concentration of CO found to be1.4 mg·m-3.( 2) Frequency distribution of each pollutant concentration varied during theobservation. SO2 concentrations all fell below standard rate,indicating the significant role that the adjustment of energy structure coal to gas had played in reducing SO2 concentrations. NO2 exceeded standard with 15. 3% rate which can be attributed to the increase in vehicle ownership.Thus,automobile emissions of NO2 exceeded the coal-fired plants.( 3) Strong correlation between PM2.5and PM10,SO2,CO,NO2,O3 was observed,with more significant correlation between PM2.5and SO2,CO,NO2. This shows that the vehicle exhaust and the burning of fossil fuels are important sources of PM2.5in Urumqi City. In addition,a PM2.5concentration prediction model based on gaseous pollutants was built,that is CPM 2.5= 0.21376CPM10+0.42422CSO2+41.66384CCO-0.24325CNO2+0.12466CO3-24.15316.( 4) PM2.5,SO2 and CO correlated negatively to temperature and water vapor pressure,but positive correlation occurred in the case of O3. The correlation coefficient of the relative humidity and the concentration of O3was-0.62. It was discovered that the wind speed had little effect on the air pollution whilst the solar radiation influenced the air pollution.