| 2015年北京城区大气PM2.5中NH4+、NO3-、SO42-及前体气体的污染特征 |
| 摘要点击 3273 全文点击 1209 投稿时间：2016-07-01 修订日期：2016-10-25 |
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| 中文关键词 北京城区 PM2.5 SNA 前体气体 相关性 |
| 英文关键词 urban area of Beijing PM2.5 SNA precursor gases correlation |
| 作者 | 单位 | E-mail | | 丁萌萌 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | dingmeng2010@126.com | | 周健楠 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 刘保献 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | liubaoxian28@163.com | | 王焱 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 张博韬 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 石爱军 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 杨懂艳 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | | | 常淼 | 北京市环境保护监测中心, 大气颗粒物监测技术北京市重点实验室, 北京 100048 | |
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| 中文摘要 |
| 2015年1~12月对北京市城区开展PM2.5中主要水溶性离子NH4+、NO3-和SO42-（统称SNA）及其前体气体NH3、NO、NO2和SO2的监测，共获得样本325组.用特氟龙滤膜采集PM2.5中SNA，用在线仪器实时监测各前体气体.分析各前体气体和SNA的污染特征并同时对其相关性进行研究.观测期间NH3、NO、NO2、SO2、NH4+、NO3-和SO42-的年平均浓度分别为21.5、17.7、54.3、14.2、8.1、13.5和12.7 μg·m-3，SNA质量浓度占PM2.5的43.4%.NO、NO2和SO2冬季最高，夏季最低；NH3为夏季最高，秋冬较低；NH4+浓度和体积分数四季波动不大；NO3-浓度和体积分数均夏季最低；SO42-浓度为冬季最高，百分含量为夏季最大.全年（[NO3-]+2[SO42-]）与NH4+的比值为0.97，表明阴离子主要以NO3-和SO42-的形式存在.随着污染程度的增加，各化合物浓度均有明显上升，NO3-是重污染过程累积效应比较明显且贡献率最大的离子.SO42-则在污染级别较低时，贡献率较大.NO3-与NO2，NO、NH4+与NH3，SO42-与SO2在置信度为0.01水平上均显著相关；SO42-和SO2变化规律呈负相关，NO2和NO3-基本呈正相关，相比NH3，NH4+浓度的高低受酸性气体NO2、SO2影响更大. |
| 英文摘要 |
| Simultaneous measurements of precursor gases NH3,NO,NO2,SO2 and the main water-soluble ions in PM2.5 such as sulphate (SO42-),nitrate (NO3-) and ammonium (NH4+) (collectively called SNA)were carried out in the urban area of Beijing during 2015-01 to 2015-12,which obtained 325 groups of samples. PTFE membrane filters were used to collect particulate NH4+, NO3- and SO42-, followed by the online instruments to collect precursor gases. The pollution characteristics of the precursor gases and SNA were analyzed and their correlation was studied. The mean concentrations of NH3, NO, NO2, SO2, NH4+,NO3- and SO42- were 21.5, 17.7, 54.3, 14.2, 8.1, 13.5 and 12.7 μg·m-3 respectively during the period of monitoring, and SNA accounted for 43.4% of PM2.5. The concentrations of SO2,NOx and SNA declined compared to 2014. The concentrations of NO,NO2 and SO2 were highest in winter and lowest in summer. The concentration of NH3 was higher in summer and lower in autumn; The concentration and the percentage of NH4+ were stable during the four seasons,both the concentrations and the percentage of NO3- were lowest in summer. The concentrations of SO42- was highest in winter and the percentage was lowest in summer. The ratio of ([NO3-]+2[SO42-]) and NH4+ was 0.97 during the whole year, showing that anions mainly existed in the form of NO3- and SO42-. In summer, the ratio of[NO3-]+2[SO42-] and[NH4+] was slightly higher than 1.0, which was the reason why NO3- was bound to Ca2+, Mg2+ and Na+besides NH4+. With the increase of pollution, the mass concentration of precursor gases and SNA increased dramatically, among which NOx increased most rapidly, and SO2 decreased from severe pollution to serious pollution. The contribution rate of NH4+ was maintained at a relatively stable level. SO42- had a higher contribution when the pollution level was lower, whereas the concentration of NO3- was higher than others and contributed most to PM2.5 in heavy pollution. Heterogeneous transformation on the surface of particulate matter played a more important role in the formation of SO42- and NO3-. The correlations between NO3-, NO2 and NO,NH4+ and NH3,SO42- and SO2 were significant at the confidence level of 0.01. SO42- had negative correlation with SO2, and NO3- had positive correlation with NO2. Compared with NH3, the NH4+ concentration was more obviously affected by acid gases NO2, SO2. |
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