西安冬季非灰霾天与灰霾天PM_(2.5)中水溶性有机氮污染特征比较  

Characteristics of Water-soluble Organic Nitrogen of PM_(2.5) in Xi'an During Wintertime Non-haze and Haze Periods

作　　者：程玉婷[1,2] 王格慧[1] 孙涛[1,2] 成春雷[1,2] 孟静静[1,2] 任艳芹[1,2] 李建军[1] 

机构地区：[1]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,西安710075 [2]中国科学院大学,北京100049

出　　处：《环境科学》2014年第7期2468-2476,共9页Environmental Science

基　　金：国家自然科学基金杰出青年基金项目(41325014)

摘　　要：2012年12月4-13日在西安市运用大流量大气采样器进行每小时1次PM2.5样品采集,对其进行有机碳（OC）、元素碳（EC）、水溶性有机碳（WSOC）、水溶性总氮（WSTN）、水溶性有机氮（WSON）以及无机离子分析,探讨其浓度、组成、时间变化特征和来源.结果表明,采样期间西安PM2.5中WSON小时平均浓度为（12±9.4）μg·m^-3，最高达31μg·m^-3,平均占水溶性总氮（WSTN）的47%±9.8%,而无机氮NH＋4-N和NO-3-N则平均分别占WSTN的29%±8.5%和23%±8.1%.WSON∶WSOC（N∶C）质量比值范围为0.04-0.65,平均为0.31±0.13.在非灰霾天（能见度〉10 km）、轻霾天（5 km〈能见度〈10 km）和重霾天（能见度〈5 km）,WSON分别为（1.6±0.9）、（6.5±3.9）和（23±4.7）μg·m^-3.WSOC/OC质量比值在整个观测期间无明显变化,但是WSON/WSOC（N∶C）质量比值从非灰霾天、轻霾天到重霾天呈逐步增大趋势,其均值分别为0.2±0.1、0.3±0.1和0.4±0.1,与颗粒物碱度减弱酸度增强相一致.此外,整个采样期间WSON与NH＋4、SO2-4和NO-3呈强线性相关（R^2〉0.80）,阴阳离子当量平衡进一步显示：WSON与颗粒物中和度呈负相关（R^2=0.53）.研究结果表明,大气中有机胺等气态水溶性含氮有机物可通过酸碱中和与颗粒相酸性物质反应,由气相转移到颗粒相,并且重霾天低温、高湿和静风的气象条件有利于这种酸碱中和导致的气固相转化,促使更多的WSON生成.High-volume PM2. 5samples were collected hourly from 4 December to 13 December 2012 at an urban site in Xi＇an and analyzed for organic carbon（ OC）,elemental carbon（ EC）,water-soluble organic carbon（ WSOC）,water-soluble total nitrogen（ WSTN）,water-soluble organic nitrogen（ WSON） and inorganic ions to investigate the sources and formation mechanism of WSON.The results showed that during the sampling period the averaged hourly concentration of WSON was（ 12 ± 9. 4） μg·m^-3d maximized at 31 μg·m^-3ccounting for 47% ±9.8% of WSTN with NH＋4-N and NO-3-N being 29% ± 8. 5% and 23% ± 8. 1%,respectively.WSON∶ WSOC（ N∶ C） mass ratios ranged from 0. 04 to 0. 65 with an average of 0. 31 ± 0. 13 during the observation period. WSON was（ 1.6 ±0.9） μg·m^-3（ 6.5 ±3.9） μg·m^-3 and（ 23 ± 4. 7） μg·m^-3 non-haze days（ visibility 〉10 km）,light haze days（ 5 km visibility 〈10 km） and heavy haze days（ visibility 〈5 km）,respectively. WSOC /OC mass ratio throughout the observation period showed no significant change,but WSON /WSOC（ N∶ C） mass ratio increased significantly from a lower value of 0. 2 ± 0. 1 in non-haze days to 0. 3 ± 0. 1 on light haze days and 0. 4 ± 0. 1 on heavy haze days,in consistence with the enhanced acidity of the fine particles.In addition,during the whole sampling period,WSON was strongly correlated with NH＋4,SO2-4and NO-3（ R^2〉 0. 80）,and negatively correlated with cation-anion equivalent ratio（ R^2= 0. 53）. These phenomena can be mainly ascribed to a gas-particle conversion of gaseous water-soluble nitrogen-containing organic compounds like amines via acid-base reactions,which was sharply increased under the favorable meteorological conditions（ e. g.,low temperature and high humidity） during the heavy haze days.

关 键 词：PM2.5 灰霾 水溶性有机氮 二次有机气溶胶 来源与形成机制 

分 类 号：X513[环境科学与工程—环境工程]