气象因素对大气降水中有机酸浓度的影响

低分子有机酸是对流层大气的重要组成成分,采用离子色谱法测定了贵阳市大气降水中的有机酸浓度.结果表明,气象因素是影响贵阳市大气降水中有机酸浓度的重要因素.其中,降雨系统对雨水中有机酸浓度的影响显著.大气有机酸主要是在降雨初期进入降水并被清除的,降雨初期对大气有机酸的清除量占总清除量的50%-70%.随着降雨的进行,雨水中的有机酸浓度逐渐降低,降雨后期略有升高,大降雨量对雨水中有机酸浓度起稀释的作用.雷雨和台风雨中有机酸浓度明显偏低,降雪中有机酸浓度也远远低于雨水中有机酸浓度,暗示贵阳市雨水中有机酸主要是在云下过程进入降水的.天气因素是通过影响大气中有机酸浓度进而影响雨水中有机酸浓度的,如气温对雨水中有机酸浓度的影响远没有降雨量明显.不同来源气团雨水中有机酸浓度明显不同,其中以北面方向气团降水中有机酸浓度最高,与我国内陆大气污染较重有关,而源于海洋方向的东南气团雨水中有机酸浓度最低.

Impact of meteorological parameters on the concentrations of organic acids in precipitation

Organic acids are important and ubiquitous constituent in atmosphere.The levels of organic acids in precipitation in Guiyang city were determined with ICS-90 Ion Chromatography.The results show that meteorological parameters have important impacts on the concentration levels of organic acids in precipitation.During the wet precipitation events,the rain fluxes of organic acids generally decreased as a function of time and the scavenging of atmospheric organic acids by wet precipitation mostly take place during the early stage of the precipitation.Thunderstorm and typhoon rain were determined with lower organic acids concentrations,and the concentration levels of organic acids in snow were much lower than those in precipitation which indicate atmosphere organic acids were mainly incorporated into the precipitation during the below-cloud process.Weather parameters such as temperature have little effect on the organic acid concentrations compared to rainfall amount.The air-mass back-trajectory analysis indicated that precipitation with inland back-trajectory coming from the north had the highest concentrations of organic acids while the marine back-trajectory coming from the southeast had the lowest concentrations.