Study On Relationship Between Atmospheric Particles And Acid Precipitation

To study the effect of atmospheric particles in acid precipitation, Lots of scholars measured its acidity and Chemical Composition. Water-Soluble Components in atmospheric particles can easy dissolve in the rainwater, being direct source of Chemical Composition in rainwater. It migrates into the environment organism and will have an impact on human health and ecological environment, so studying its variation characteristics is very important to the study on acid rain.In this study, the acid rain data from 2005 to 2007 and atmospheric particles (TSP and PM₁₀) from December 2007 to June 2008 were collected. From March to June during the of 2008, precipitation samples in the Campus at Qianhu school district of Nanchang University were collected, and Laboratory analysis was done at this time. Some new and valuable results obtained as follow:(1) In Nanchang, the acid rain pollution is very serious, monthly acid rain frequency almost reached 100%. Urban acidity is greater than the suburb, acid rain frequency is also greater than the suburb.Acid rain in our city is sulfate type, precipitation acidity is mainly provided by sulfate ion.(2) Atmospheric particle pollution is also very serious, The over standard rate of TSP and PM₁₀ were 38.46% and 50.55%, superstandard multiple were 0.948 and 1.068, pollution degree is TSP＞PM₁₀. Mass concentration about TSP and PM₁₀ in the atmosphere changes relatively greatly, but they have a similar variation tendency,with very good correlation. Pollution degree at five sampling points is Luojia＞Qianhu＞Beiqu＞Xialuo.(3) Water-soluble inorganic ions in the atmospheric particles(TSP and PM₁₀) of Nanchang City,neither in TSP or PM₁₀, mass concentration of anion is SO₄^2-＞NO₃^-＞Cl^-＞F^- and mass concentration of cation is Ca²⁺＞K⁺＞Na⁺＞Mg²⁺. Detection level of NO₃^- and SO₄² at each sampling point is high, these two ions a very important part of the water-soluble inorganic ions in the atmospheric particles of Nanchang City, which is obviously related to the local coal-burning pollution and natural sources. Mass percentages of water-soluble inorganic ions in the atmospheric particle were not the same, but in general it is higher in PM₁₀ than in TSP. There was no obvious correlation between most ions,but significantly correlation coefficient exists in some ions.This was was affected by the sources of ions. Chemical composition in precipitation is similar to the pollution characteristics of the water-soluble inorganic ions in the atmospheric particles.They were the same pollution type, which shew that ion concentration in precipitation is greatly influenced by paniculate matter.(4) Acidity of airborne particulate matter at five sampling points have some difference, but initial acidity at Luojia was smaller. The reason maybe Luojia was grestly affected by ammonia plant and Nanchang steel plant. Acidification buffer ability of airborne particulate matter in Nanchang is very poor, which is beneficial to acidification of rainfall. This reflects the pollution characteristics of the aerosols in southern area of China. Acidity and acidification buffer ability of particles decreased with the decrease of particle size.(5) At different stages in one precipitation process, rainwater had different removal effect on atmospheric particles. EC and chemical composition of rain water decreased great ly at the beginning of the rain. Rainwater had significantly removal effect on atmospheric particles. As the precipitation process last, EC and chemical composition of rain water had fluctuation at different degree.Rainwater had great removal effect on different chemical composition of atmospheric particles.Ecxept unconspicuous removal effect on Na⁺ and Mg²⁺, rainwater can effectively remove the secondary aerosol such as NO₃^-, SO₄^2-, NH₄⁺ as well as K⁺ , Ca²⁺.