Characteristics, Source Apportionment And Influence On Visual Range Of PM_2.5 In Jinan

To investigate the characteristics of the fine particle matter in Jinan,PM_2.5samples were collected by two/four channel and MOUDI sampler from February 2007 to September 2005.The samples were analyzed by IC,C/H/O,XRF and so on.The chemical characteristics of the fine particle matter and source appointments were studied in detail.Furthermore,the impact of meteorological conditions on PM_2.5level and the influence of PM_2.5on visibility were also carefully investigated.The results were obtained as follows:1.PM_2.5pollution in Jinan is serious and PM_2.5pollution of urban is more serious than suburban.The daily PM_2.5concentrations of Shandong University and Miaopu station exceed US EPA daily average standard(35μg/m³)of 2.98 and 1.79 times. Water-soluble ions in Jinan account for the largest proportion in PM_2.5components. While,SO₄^2-,NO₃⁺ and NH₄⁺ are the most important water-soluble ions.The form of above three ions are(NH₄)₂SO₄ and NH₄NO₃.Carbonaceous components(OC + EC) are the second largest proportion.The organic compounds and secondary pollution in the atmosphere are very serious,showing compound pollution characteristics.2.Winter is affected by Mongolia hypertension in Shandong.While,other season is due to the impact of the North China terrain trough in the vicinity.There is a Northeast - Southwest Composite Strip in longitude 115°,the return to movement of Composite Strip in Shandong could hinder the diffusion of pollutants.When fild-flow is the Northwest,convergent flow of air and anti-cyclone type,it favorite high concentrations of PM_2.5pollution.3.Using multiple linear regression models to simulate the PM_2.5concentrations, the results of simulations is relatively lower than experimental data.When the concentration of PM_2.5is more than 200μg/m³,simulation results is good,and when PM_2.5concentration is less than 200μg/m³,the simulation method does not work well. From the concentrations of Log,the results of simulations are better than directly from the concentration.4.The visual range in Jinan showed a general decreasing trend from 1961 to 2005. Meteorological conditions and particulate matter made comparable contributions to the decrease of visual range in Jinan.In every season,the visual range accorded well with the concentrations of PM₂.5)and PM₁₀in an exponential relationship and showed a higher correlation with PM_2.5than PM₁₀.Sulfate is the largest contributor to visual range degradation The results demonstrate that secondary particulate matter((NH₄)₂SO₄, NH₄NO₃,POM)contributed much more to the decrease of visual range in Jinan than primary particles(BC).Long-range transport of air masses from the north(including northwest and northeast)of Jinan and from the ocean,carrying high concentrations of secondary aerosol(SO₄^2-,NH₄⁺,NO₃^-)combined with weather conditions of high relative and low wind speed can make contributions to the formation of hazy days in winter and summer respectively.5.The main source of PM_2.5and annual contribution is no obviously different between Jinan City and the suburban.Their sources were:road dust and vehicle exhaust (15.0-16.0%),industrial sources of emissions(15.1-17.5%),coal(13.6 -18.7%),soil dust(19.0-22.8%),secondary sources(19.5-20.0%),biomass burning(17.7%).