摘要
为探讨合肥市霾天气大气气溶胶粒子的组成及来源,在2012-2013年代表性月份用安德森分级采样器在合肥市区进行大气气溶胶粒子采样,并分析各样本中水溶性无机离子成分(NH_4^+、Mg^(2+)、Ca^(2+)、Na^+、K^+、NO_2^-、NO_3^-、Cl^-、SO_4^(2-))。根据同期气象资料把采样背景天气分为晴空、雾、霾、轻雾等4类,详细分析了这4种天气下大气细粒子(指PM_(2.1))和粗粒子(粒径大于2.1μm部分)的浓度、组成以及主要离子组分的异同。结果表明:(1)观测期间晴空天多对应空气质量优良,雾、霾天对应轻度到重度污染,从晴空天到雾、霾天,PM_(2.1)浓度大幅度上升,且其占总悬浮颗粒物(TSP)的比例显著上升。(2)从晴空天到雾、霾天,水溶性无机离子质量占PM_(2.1)质量浓度的比例上升,分别为46%(晴空)、67%(霾)、61%(雾)、80%(轻雾)。PM_(2.1)中水溶性无机离子浓度居前3位的雾、霾天是SO_4^(2-)、NO_3^-和NH_4^+,晴空天为SO_4^(2-)、Ca^(2+)、NO_3^-。(3)与晴空天相比,霾天PM_(2.1)中水溶性无机离子浓度变化倍数最大的是NO_3^-(为晴空的6.1倍,下同)、其次是NH_4^+(3.6倍)和SO_4^(2-)(3.0倍);雾和轻雾天PM_(2.1)中水溶性无机离子浓度变化最大的是NO_3^-(>10倍)、其次是NH_4^+(>5倍)和Cl^-(>4.0倍)。(4)4种天气下,与人为污染有关的离子(SO_4^(2-)、NO_3^-、Cl^-、NH_4^+)尺度谱存在显著差异,呈双峰型、单峰型、三峰型等;而Ca^(2+)的尺度谱无明显变化,基本上都呈双峰型。(5)在粒径3.3μm以下,阳、阴离子平衡较好,随着尺度增大变差,且晴空天比雾、霾天差。主要阴离子浓度间、Cl^-和Na^+间的比值和相关性,在晴空天和雾、霾天差异较大。
To investigate the compositions and sources of atmospheric aerosols during haze episode in Hefei,samples of atmospheric aerosol were collected using the FA-3 Andersen cascade impactor in urban Hefei in the representative months of 2012 and2013.The main water-soluble inorganic ions（WSⅡ）（NH_4~＋,Mg^（2＋）,Ca^（2＋）,Na~＋,K~＋,NO_2^-,NO_3^-,Cl^-,SO_4^（2-）） for each sample were measured.Based on the records of meteorological parameters during the observations,the samples were divided into four types：clear day,haze day,fog day and mist day.Then,the physical and chemical characteristics of aerosol under those four types of weather were analyzed and compared.The results showed that fog and haze in Hefei usually corresponded to light to heavy air pollution,and the clear day corresponded to good air quality.From clear day to fog or haze day,the concentration of fine particles（PM_（2.1） in this paper） increased evidently,with increasing percentages of WSⅡ in PM_（2.1）.The ratio of PM_（2.1） to TSP was 43%for clear days,52%for haze days,65%for fog days and 64%for mist days.The ratio of WSⅡ to PM_（2.1） was 46%（clear day）,67%（haze day）,61%（fog day）,80%（mist day）.As for mass concentration,the top three ions in PM_（2.1） was SO_4^（2-）,NO_3^- and NH_4~＋ for fog（mist） and haze days,while the top three ions were SO_4^（2-）,Ca^（2＋） and NO_3^- on clear days.The top three ratios of WSⅡ ions in PM_（2.1） on haze days,compared with the corresponding values on clear days,were 6.1 times larger for NO_3^-,3.6 for NH_4~＋ and 3.0 for SO_4^（2-）,while the top three ratios of WSII ions in PM_（2.1） on fog（mist） days with the corresponding values on clear days were over 10.0 times for NO_3^-,over 5.0 for NH_4~＋ and over 4.0 for Cl^-.Under those four types of weather,the size spectra for those ions（NH_4~＋,NO_3^-,Cl^-,SO_4^（2-）） related to anthropogenic activities were obviously different,showing double peaks,single peak and tri-peaks,while the size spectrum for natural emitted ions（e.g.,Ca^（2＋）） was almost all double peaks under the four types of weather with slight changes.The balances between cations and anions were very good for aerosols below 3.3 μm and changed worse with the increasing size,and it was better on fog,mist and haze days than on clear days.The ratios and correlations among the major anions and between Cl^- and Na~＋ show large differences between clear days and fog/haze days.
出处
《气象学报》
CAS
CSCD
北大核心
2016年第1期149-163,共15页
Acta Meteorologica Sinica
基金
公益性行业(气象)科研专项(GYHY201206011)
安徽省自然科学基金项目(1608085MD84)
关键词
气溶胶
水溶性无机离子
谱分布
雾、霾天
合肥
Aerosol
Water soluble inorganic ions
Size spectrum
Fog and haze
Hefei
