Characteristics Of Air Pollution And Chemical Composition Of PM_2.5 In Handan City In Winter

As one of Chinese three big haze pollution serious areas, Beijing-Tianjin-Hebeiregion has been one of the haziest in China, especially in the middle and south part ofHebei province. Many of the previous studies focused on the municipal cities of Beijingand Tianjin, but very few studies aimed at quantitatively understanding the air pollutioncharacteristics and chemical composition of PM2.5, and this information are necessary inthe policy making of a long-term control strategy of regional haze pollution in the southof Hebei province.This study observed the concentrations of PM10and PM2.5, sulfur dioxide (SO2),nitrogen oxide (NOX), ozone (O3) and other gaseous pollutants, and relatedmeteorological factors using air quality monitoring system and a high volume PM2.5airsampler during December2012to January2013. This paper mainly discusses thevariation characteristics of air pollutants and chemical composition of PM2.5,quantitative relationship among pollution factors, meteorological factors and visibilityduring winter. This paper explores air pollution characteristics and provides somescientific basis to control and treatment of air pollution. The main conclusions of thisstudy are as follows:(1) The pollution of PM10and PM2.5during winter in Handan were very serious,and the daily average concentrationa reached299.5μg·m-3and184.0μg·m-3, respectively.According to second grade standard, the rate of PM10and PM2.5exceeding the standardreached90.3%and88.7%, respectively. And hourly concentrations of NO2and O3werewithin the limits of the standard, the rate of reaching the standard of SO2and CO were98.2%and95.2%, respectively. The daily average concentrations of NO2, SO2and COwere out of the limits of the standard, and their rate of exceeding the standard reached58.1%,32.3%and56.5%during the period of winter observation in Handan city.(2) The analysis result of water soluble inorganic ions in PM2.5indicated that SO42-,NO3-, Cl-and NH4+were important water soluble components in PM2.5in Handan. Thecontent of those species showed large variations in total water soluble ion (TWSI) indifferent times and different weather conditions, SO42-and NH4+mainly exists in theform of (NH4)2SO4in the atmosphere. Secondary pollutants were converted by sulfateand nitrate and the formation rate of NO2converting to NO3-was relatively higher in the atmosphere.(3) This paper applied TOR method to analyze the daily concentrations of organiccarbon (OC) and elemental carbon (EC) in PM2.5and studied correlation between OCand EC, variation characteristics of OC/EC and estimate the pollution of secondaryorganic carbon in Handan by the method of OC/EC minimum The results showed thatdaily concentrations of OC and EC were27.6μg·m-3and16.2μg·m-3, respectively. OCand K+, NH4+, EC and Cl-may come from the same pollution source. Carbonaceousspecies were very important and SOC existed in a certain extent during January, and thedaily average concentration of SOC was17.1μg·m-3, which slightly higher than primaryorganic carbon.(4) This paper applied ICP-MS technology to analyze the daily averageconcentrations of13kinds of trace metal elements (Ti, V, Cr, Mn, Ni, Cu and zinc, As,Se, Sr, Cd, Ba, Pb) in PM2.5, and the variation characteristics, relationships andenrichment of metal elements were studied. The results showed that the peakconcentration in13kinds of metal elements were Zn and Pb, and the daily averageconcentrations reached317.6ng·m-3and287.8ng·m-3. The main contribution of V, Sr,Ba were from natural source and the natural source contribution of As, Se, Cd, Pb wassmall, these elements mainly comes from anthropogenic.(5) Organic matter, sulfate, ammonium, nitrate were the main compositions inPM2.5during winter observation in Handan, which accounted for21.1%,13.2%,10.9%,13.2%, respectively.(6) The study on the visibility indicated that it emerged low visibility duringoverall observation, and frequency of occurrence of visibility of less than2km wasreached58.1%, followed by the visibility between3km to5km, of which thefrequency of occurrence was about16.1%. However, frequency of occurrence of greaterthan10km was only about3.2%. The visibility was common influenced by relativehumidity (RH), the concentration of particulate matter and CO, NH4+, SO42-, NO3-andOC in PM2.5.