Yang Dong-Yan, Li Xiu-Jinz, Chen Yuan-Yuan, Zou Ben-Dong, Lin An-Guo
Beijing Municipal Environmental Monitoring Center, Beijing 100048, China.
Huan Jing Ke Xue. 2011 Jul;32(7):1867-73.
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.
分析了北京降水化学成分特征。2005年至2009年pH平均值为5.19，降水酸化特征呈稳定状态。2008年年均pH最低值为4.87，车公庄和大兴区酸化频率最高，分别为42%和23%。5年间无机离子浓度下降，表明北京空气质量在不断改善。发现NH4+和NO3-浓度增加，导致降水中氮含量较高。不同季节对成分浓度有影响。一般来说，冬季离子浓度高于夏季。SO4(2-)是冬季降雪酸化的主要因素，SO4(2-)和NO3-对夏季降水酸化贡献相似。还发现，北京地区SO2、NO(x)和NH3等本地污染物是降水酸化的主要贡献者，本地地质条件和长距离传输对降水的中和作用有重要影响。
