Ding Meng-Meng, Zhou Jian-Nan, Liu Bao-Xian, Wang Yan, Zhang Bo-Tao, Shi Ai-Jun, Yang Dong-Yan, Chang Miao
Beijing Key Laboratory of Airborne Particulate Matter Monitoring Technology, Beijing Municipal Environmental Monitoring Center, Beijing 100048, China.
Huan Jing Ke Xue. 2017 Apr 8;38(4):1307-1316. doi: 10.13227/j.hjkx.201607005.
Simultaneous measurements of precursor gases NH,NO,NO,SO and the main water-soluble ions in PM such as sulphate (SO),nitrate (NO) and ammonium (NH) (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 NH, NO and SO, 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 NH, NO, NO, SO, NH,NO and SO were 21.5, 17.7, 54.3, 14.2, 8.1, 13.5 and 12.7 μg·m respectively during the period of monitoring, and SNA accounted for 43.4% of PM. The concentrations of SO,NO and SNA declined compared to 2014. The concentrations of NO,NO and SO were highest in winter and lowest in summer. The concentration of NH was higher in summer and lower in autumn; The concentration and the percentage of NH were stable during the four seasons,both the concentrations and the percentage of NO were lowest in summer. The concentrations of SO was highest in winter and the percentage was lowest in summer. The ratio of ([NO]+2[SO]) and NH was 0.97 during the whole year, showing that anions mainly existed in the form of NO and SO. In summer, the ratio of[NO]+2[SO] and[NH] was slightly higher than 1.0, which was the reason why NO was bound to Ca, Mg and Nabesides NH. With the increase of pollution, the mass concentration of precursor gases and SNA increased dramatically, among which NO increased most rapidly, and SO decreased from severe pollution to serious pollution. The contribution rate of NH was maintained at a relatively stable level. SO had a higher contribution when the pollution level was lower, whereas the concentration of NO was higher than others and contributed most to PM in heavy pollution. Heterogeneous transformation on the surface of particulate matter played a more important role in the formation of SO and NO. The correlations between NO, NO and NO,NH and NH,SO and SO were significant at the confidence level of 0.01. SO had negative correlation with SO, and NO had positive correlation with NO. Compared with NH, the NH concentration was more obviously affected by acid gases NO, SO.
2015年1月至2015年12月期间，在北京城区同步测量了前驱体气体NH、NO、NO、SO以及颗粒物中主要水溶性离子，如硫酸盐（SO）、硝酸盐（NO）和铵盐（NH）（统称为SNA），共获得325组样本。使用聚四氟乙烯（PTFE）膜滤膜采集颗粒物NH、NO和SO，同时利用在线仪器采集前驱体气体。分析了前驱体气体和SNA的污染特征并研究了它们之间的相关性。监测期间，NH、NO、NO、SO、NH、NO和SO的平均浓度分别为21.5、17.7、54.3、14.2、8.1、13.5和12.7 μg·m，SNA占颗粒物的43.4%。与2014年相比，SO、NO和SNA的浓度有所下降。NO、NO和SO的浓度冬季最高，夏季最低。NH的浓度夏季较高，秋季较低；NH的浓度和占比在四季较为稳定，NO的浓度和占比夏季最低。SO的浓度冬季最高，占比夏季最低。全年([NO]+2[SO])与NH的比值为0.97，表明阴离子主要以NO和SO的形式存在。夏季，[NO]+2[SO]与[NH]的比值略高于1.0，这是NO除了与NH结合外还与Ca、Mg和Na结合的原因。随着污染加重，前驱体气体和SNA的质量浓度急剧增加，其中NO增加最为迅速，SO从重度污染到严重污染阶段浓度下降。NH的贡献率保持在相对稳定的水平。污染水平较低时，SO的贡献率较高，而在重度污染时，NO的浓度高于其他物质，对颗粒物的贡献最大。颗粒物表面的非均相转化在SO和NO的形成中起更重要的作用。在置信水平为0.01时，NO、NO与NO、NH与NH、SO与SO之间的相关性显著。SO与SO呈负相关，NO与NO呈正相关。与NH相比，NH的浓度受酸性气体NO、SO的影响更明显。
