The Study Of The Seasonal Variation Characteristic Of The Atmospheric Aerosol And Its Chemical Composition In Guiyang City

The variation of the concentration of atmospheric aerosol particles, will cause the weather, the climate and the human survival environment change directly, extremely receive the attention. By studying the water-soluble components of Total suspended particles(TSP),collected from an urbanized area (Guiyang, China) in 2003 and in 2005, the paper analyze the seasonal variations of their water-soluble components, as well as the reasons.In Guiyang, the annual mean mass concentration of the TSP in 2003 was 153.55±64.16μgm-3, yet in 2005, the annual variation scope was 106.60±47.00 ugm-3. The reduction indicated that the comprehensive clean energy project implemented by the local government made certain progress to improve the air quality. And the relative humidity (RH) is a key factor influencing the mass concentration of the TSP. The molar concentrations of the water-soluble inorganic ions in the Guiyang aerosol are decreased in order of SO42> NH4+>Ca2+>NO3->K+>Na+>Cl->Mg2+ >F-, and SO42- and NH4+are the most main ions. The massive uses of high-sulfur coal cause the high SO42- content in Guiyang. And SO42-, Ca2+, NH4+are the highest concentrations ions in TSP. The close relation between SO42-, Ca2+, NH4+ and the concentration ratio of(NH4+×2+Ca2+)/SO42- show that these ions are mainly existed in form of (NH4) 2SO4 and CaSO4 in TSP.In 2003, the concentration of Guiyang aerosol soluble ions was relevant with the rain. The concentration variation rules of almost all soluble inorganic ions in rainy days (lower value) and non-rainy days (high value) are similar. But the percentages of SO42-, NH4+, Ca2+, Mg2+in rainy days are higher than those in non-rainy days. The study manifest that SO42-, NH4+, Ca2+, Mg2+ incline to be existed in form of fine particles, which can exist longer in atmosphere than coarse particles.All soluble components In TSP show the obvious seasonal variation rule. The NH4+, NO3-, SO42- concentration and percentage in winter are higher than in summer, while the Ca2+ and Mg2+ concentration and percentage in winter are lower than in summer. This is because their formation is different, the first three kinds of ions are formed by man-made, namely the burning coal in Guiyang; while the latter are the typical Earth crust ingredients, with the closer relevance with meteorological parameters such as temperature and rainfall.The Guiyang aerosol's sulfate composition in 2003 and 2005 occupy separately 53.3% and 66% of the total ions, which indicate the increasing rise of the sulfate content in the aerosol of Guiyang; yet the mean of the nitrate content in the two years are separately 3.03±2.48μg m-3 and 2.24±2.58μg m-3, which manifest the reduction of the nitrate content in the aerosol of Guiyang; meanwhile, the mean concentrations of the ammonium salt are separately 3.81±1.64μg m-3 and 3.05±2.23μg m-3, which show the reduction of the ammonium content in the aerosol of Guiyang, and reflect that the management of wastewater discharge has improved.Besides SO42-, water-soluble organic carbon (WSOC) is the main soluble ingredient in TSP, with 3.7% in TSP. The WSOC concentration and percentage in rainy days (in summer), are lower than in non-rainy days (in winter), due to the lack of WSOC caused by moisture absorption in rainy days. When the pH is smaller than 8, WSOC/TSP and the temperature (y=-0.14x+5.88, r=0.72) or the TSP pH (y=-1.79x+14.74, R=0.70) has the close relation, which manifest that the WSOC percentage is extremely dependent upon the temperature and the TSP pH.