title: [Characteristics of chemical compositions of precipitation in Beijing].
abstract: Characteristics of chemical compositions of precipitation in Beijing were analyzed. The average value of pH was 5.19 from 2005 to 2009, showing stable characteristics of acidification with precipitation. The lowest annual average pH was 4. 87 in 2008 with the highest acidification frequency of 42% and 23% in Chegongzhuang and Daxing districts respectively. The inorganic ion concentrations declined in 5a, indicating an increasing improvement of air quality in Beijing. The concentrations of NH4+ and NO3- were found to increase and contributed to the high nitrogen amount in precipitation. Different seasons have influence on composition concentrations. Generally speaking, the ion concentrations in winter were higher that that in summer. SO4(2-) was the main factor responsible for the acidification of snow in winter, SO4(2-) and NO3- had similar contributions to the acidification of precipitation in summer. It was also found that the local pollutants of SO2, NO(x) and NH3 were major contributors to the acidification of precipitation in Beijing area, local geological conditions and long-distance transfers have important effects on the neutralization of the precipitation.
authors.affiliation: Beijing Municipal Environmental Monitoring Center, Beijing 100048, China. ydongyan@163.com
authors.forename: Dong-Yan
authors.initials: DY
authors.lastname: Yang
authors.forename: Xiu-Jinz
authors.initials: XJ
authors.lastname: Li
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Chen
authors.forename: Ben-Dong
authors.initials: BD
authors.lastname: Zou
authors.forename: An-Guo
authors.initials: AG
authors.lastname: Lin
mesh_terms: D015258:Acid Rain / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D011891:Rain / Q000737:chemistry*; D012621:Seasons; D012914:Snow / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000032:analysis*; D014872:Water Movements
chemical_list: D015258:Acid Rain; D000393:Air Pollutants; D000644:Quaternary Ammonium Compounds; D013458:Sulfur Dioxide