Characteristics of Mass Distributions of Aerosol Particle and Its Inorganic Water-Soluble Ions in Summer over a Suburb Farmland in Beijing
北京郊区农田夏季大气颗粒物质量和离子成分谱分布特征

Agricultural activity is one of the important sources of aerosol particle. To understand the mass distribution and sources of aerosol particle and its inorganic water-soluble ions in the suburb farmland of Beijing, particle samples were collected with a MOUDI cascade impactor in the summer of 2004 in a suburb vegetable field. The mass distributions of the particle and its inorganic water-soluble ions in the diameter range of 0.18 to approximately 18 microm were measured. The dominant ions in the fine particle were SO4(2-), NOS3(-) and NH4+. The association of day to day variation of the concentration of these ions with temperature, humidity and solar radiation suggests that they are formed by the reaction of NH3 released from the vegetable field with the acid species produced from photochemical reactions. K+ in the fine particle is likely from the vegetation emission and biomass burning. Ca2+, Mg2+, NO3(-) and SO4(2-) in the coarse particle are suggested to come from the mechanical process by which the soil particle entered the atmosphere, and from the reactions of the acid species at the surface of the soil particle. The results show that fertilizer and soil are possibly important factors determining the aerosol particle over the agricultural fields, and the vegetable fields in suburb Beijing could contribute significantly to the aerosol particle.