Abstract:An unusual precipitation occurred in a sand-dust storm process was sampled in Beijing area on April 5, 2010. Nine inorganic ions of the sample were analyzed using an ion chromatography approach. pH of the precipitation sample was valued 7.33, the conductivity 24.50 mS/m, the total concentration of 9 inorganic ions 3080μeq/L, the ratio of SO42-/NO3- (in equivalent concentration) 1.27, and Ca2+/NH4+ 1.25. To further understand the impact of the sandstorm on chemical compositions of the precipitation, 39 cases of precipitation were examined of the Aprils in 2005-2010 at three ground monitoring sites in Beijing. The chemical analysis of the 39 cases showed that the average pH was valued 6.84, the average conductivity 9.20 mS/m, SO42-/NO3- 2.37, and Ca2+/NH4+ 1.87. Comparison between the 5-4-2010 case and the 39 April-cases indicated that a great increment was observed in concentration of NO3- in the sandstorm precipitation process. Compared to the annual averaged levels, however, the April-cases had lower SO42-/NO3- and higher Ca2+/NH4+, implying a relatively large increase in Ca2+ and NO3- concentration in precipitation processes during the sand-dust season in Beijing. The mass concentrations of the precursors of SO42- and NO3- , namely the gaseous pollutants SO2 and NO2 monitored at the same site on 5 April 2010 were further examined, and the result proved that the concentration of NO2 remained low and the concentration of SO2 obviously dropped down during the precipitation, indicating that atmospheric humidity could constrain the gas-particle conversion of SO2.
李金香, 李峰. 北京市一次沙尘过程中降水化学组分的监测分析[J]. 中国环境科学, 2012, 32(12): 2149-2154.
LI Jin-Xiang, LI Feng. Characterization of chemical compounds of rainfall samples collected in a sand-storm process in Beijing. CHINA ENVIRONMENTAL SCIENCECE, 2012, 32(12): 2149-2154.