南昌市秋季大气PM_(2.5)浓度及化学组分特征分析

Content and chemical composition characteristics of PM_(2.5) in autumn in Nanchang

2013年秋季在南昌市6个空气自动站点连续采集了10d的大气PM2.5样品,对采集的样品进行无机元素、有机碳、元素碳和水溶性离子等组分的分析。结果表明,监测期间南昌市PM2.5均值都低于《环境空气质量标准》(GB 3095—2012)二级标准限值(75μg/m3)。南昌市大气PM2.5主要组成元素为S、Si、Ca、Al、Fe、Na和Mg,说明城市扬尘、建筑水泥尘和燃煤尘等源类贡献率高;SO2-4、NO-3和NH+4是最主要的水溶性离子,NO-3与SO2-4浓度比为0.63,说明相比于固定源,以机动车排放为代表的流动源对南昌市大气PM2.5浓度影响更大;有机碳/元素碳(质量比)为2.9,说明南昌市有显著的二次有机碳生成。

During autumn in 2013,PM2.5samples were collected for 10 days in six ambient air auto-monitoring stations in Nanchang.The PM2.5content,elements,water soluble ions and organic carbon（OC）,elementaly carbon（EC）in PM2.5were analyzed.It was shown that the average content of PM2.5during autumn in Nanchang was under the＂Ambient air quality standards＂（GB 3095-2012）,which daily average limit of secondary standard was 75μg/m3.Sample analysis results showed that the elemental compositions（mass concentration〉1%）were dominated by S,Si,Ca,Al,Fe,Na and Mg,indicating that re-suspended dust,cement dust and coal combust fly ash had high contribution rate.SO2-4,NO-3and NH＋4were the most abundant water soluble ions.The concentration ratio of NO-3/SO2-4was0.63,indicating that the mobile emission sources with the vehicle emission as the representative contributes more than stationary source emissions.The ratio of OC/EC was 2.9,indicating that the existence of secondary OC in Nanchang.