霾天气下城市气溶胶吸湿性的观测
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摘要
气溶胶吸湿性对大气能见度有重要影响,是形成霾污染的主要因素之一.利用南京信息工程大学观测获得的2014年4月17日至5月21日气溶胶吸湿增长因子(GF)、OC/EC以及水溶性无机离子资料,对南京霾日气溶胶吸湿性及主要化学组分进行分析.结果表明,随着粒径的增加,平均吸湿增长因子(GF_(mean))数值变化较小,吸湿性标准差(σ)逐渐增大,化学组分的外混合程度逐渐增强;白天气溶胶粒子的吸湿性强于夜间,但是外混合程度弱于夜晚;非霾日气溶胶吸湿性强,外混合程度高,霾日正好与之相反,且随着霾等级的增加,吸湿性和外混合程度都进一步减小;非霾日气溶胶主要水溶性无机离子为NH_4~+、NO_3~-和SO_4~(2-),而霾日OC/EC的含量占比较高;含量相对丰富的OC/EC是造成低湿背景霾天气下小尺度气溶胶吸湿性变弱的主要原因,霾日所处环境相对湿度的高低也是影响气溶胶吸湿能力的重要因素;整个观测期间,南京市气溶胶化学组分中(NH_4)_2SO_4和OC等不可溶物质含量最多,NH_4NO_3含量次之;利用化学组分计算得到的平均吸湿性参数κ_(chem)和利用H-TDMA仪器实际观测计算得出的κ_(mean)存在较好的一致性,两者的相关性在霾天气下进一步增强,因此可以利用气溶胶主要化学组分来预报气溶胶吸湿性.
The hygroscopicity of aerosols has an important influence on atmospheric visibility and is one of the main causes of haze pollution. Based on observations of the aerosol hygroscopic growth factor(GF),water soluble inorganic ions,and organic carbon/elemental carbon(OC/EC) data during haze weather from April 17 to May 21,in 2014,the hygroscopic properties of aerosols and corresponding effects on haze in Nanjing were analyzed. The results showed that the distribution of GF was bimodal and varied from 1. 12 to 1. 64. With the increase of particle size,the average hygroscopic growth factor(GF_(mean)) changed less and the standard deviation of wettability(σ) increased gradually; meanwhile,the degree of external mixing of chemical components increased gradually. The hygroscopicity of aerosol particles in the day was better than that at night,but the mixing degree was weaker than that at night; in non-haze weather,the hygroscopicity of aerosol particles was stronger and the degree of external mixing was higher,while the hygroscopicity and mixing degree of haze particles showed opposite trends. With the increase of haze levels,the hygroscopicity of aerosol particles grew weaker and the degree of external mixing decreased further. Relative humidity can have a significant impact on the chemical components of aerosols and their hygroscopic capacity. Under a low humidity background,the main chemical components of aerosols included NH_4~+ ,NO_3~-,SO_4~(2-),OC,and EC,and the content of OC/EC in aerosols during haze days was more abundant; in haze weather with low relative humidity,abundant organic matter was the main reason for the decrease of the moisture absorption capacity of small-scale aerosols. The level of relative humidity in the haze weather was also an important factor affecting the hygroscopic capacity of aerosols. The contents of(NH_4)_2SO_4,OC,and insoluble substances in aerosols were the highest,followed by NH_4NO_3.The contents of these chemical components showed obvious diurnal variation characteristics,which resulted in significant diurnal variation of the hygroscopicity of the aerosols. κchemcalculated by the chemical composition and κmeanacquired by observations using HTDMA showed good consistency,and the correlation coefficient was 0. 890 3. In haze weather,the correlation between them was further enhanced. Therefore,the major chemical components of aerosols could be used to predict the hygroscopic properties of aerosols.
The hygroscopicity of aerosols has an important influence on atmospheric visibility and is one of the main causes of haze pollution. Based on observations of the aerosol hygroscopic growth factor(GF),water soluble inorganic ions,and organic carbon/elemental carbon(OC/EC) data during haze weather from April 17 to May 21,in 2014,the hygroscopic properties of aerosols and corresponding effects on haze in Nanjing were analyzed. The results showed that the distribution of GF was bimodal and varied from 1. 12 to 1. 64. With the increase of particle size,the average hygroscopic growth factor(GF_(mean)) changed less and the standard deviation of wettability(σ) increased gradually; meanwhile,the degree of external mixing of chemical components increased gradually. The hygroscopicity of aerosol particles in the day was better than that at night,but the mixing degree was weaker than that at night; in non-haze weather,the hygroscopicity of aerosol particles was stronger and the degree of external mixing was higher,while the hygroscopicity and mixing degree of haze particles showed opposite trends. With the increase of haze levels,the hygroscopicity of aerosol particles grew weaker and the degree of external mixing decreased further. Relative humidity can have a significant impact on the chemical components of aerosols and their hygroscopic capacity. Under a low humidity background,the main chemical components of aerosols included NH_4~+ ,NO_3~-,SO_4~(2-),OC,and EC,and the content of OC/EC in aerosols during haze days was more abundant; in haze weather with low relative humidity,abundant organic matter was the main reason for the decrease of the moisture absorption capacity of small-scale aerosols. The level of relative humidity in the haze weather was also an important factor affecting the hygroscopic capacity of aerosols. The contents of(NH_4)_2SO_4,OC,and insoluble substances in aerosols were the highest,followed by NH_4NO_3.The contents of these chemical components showed obvious diurnal variation characteristics,which resulted in significant diurnal variation of the hygroscopicity of the aerosols. κchemcalculated by the chemical composition and κmeanacquired by observations using HTDMA showed good consistency,and the correlation coefficient was 0. 890 3. In haze weather,the correlation between them was further enhanced. Therefore,the major chemical components of aerosols could be used to predict the hygroscopic properties of aerosols.
引文
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[14]张程,于兴娜,安俊琳,等.南京北郊霾天气溶胶化学组分粒径分布特征[J].中国环境科学,2018,38(8):2873-2881.Zhang C,Yu X N,An J L,et al. Distribution characteristics of chemical components in aerosol during haze days in north suburban Nanjing[J]. China Environmental Science,2018,38(8):2873-2881.
[15]宋秀瑜,曹念文,赵成,等.南京地区相对湿度对气溶胶含量的影响[J].中国环境科学,2018,38(9):3240-3246.Song X Y,Cao N W,Zhao C,et al. Effect of relative humidity on aerosol content in Nanjing[J]. China Environmental Science,2018,38(9):3240-3246.
[16] Liu Q F,Jing B,Peng C,et al. Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance[J]. Atmospheric Environment,2016,125:69-77.
[17] Gysel M, Mc Figgans G B, Coe H. Inversion of tandem differential mobility analyser(TDMA)measurements[J].Journal of Aerosol Science,2009,40(2):134-151.
[18] Petters M D,Kreidenweis S M. A single parameter representation of hygroscopic growth and cloud condensation nucleus activity[J]. Atmospheric Chemistry and Physics,2013,13(2):1081-1091.
[19] Gysel M,Crosier J,Topping D O,et al. Closure study between chemical composition and hygroscopic growth of aerosol particles during TORCH2[J]. Atmospheric Chemistry and Physics,2007,7(24):6131-6144.
[20]陈卉,杨素英,李艳伟,等.黄山夏季气溶胶吸湿性及与化学组分闭合[J].环境科学,2016,37(6):2008-2016.Chen H,Yang S Y,Li Y W,et al. Hygroscopic properties and closure of aerosol chemical composition in Mt. Huang in summer[J]. Environmental Science,2016,37(6):2008-2016.
[21] Liu H J, Zhao C S, Nekat B, et al. 2014. Aerosol hygroscopicity derived from size-segregated chemical composition and its parameterization in the North China Plain[J].Atmospheric Chemistry and Physics, 2014, 14(5):2525-2539.
[22] QX/T 113-2010,霾的观测和预报等级[S].
[23]庄智一.上海地区霾的统计分析研究[D].上海:华东师范大学,2012. 1-60.
[24]汤莉莉,祝愿,牛生杰,等.南京北郊大气细粒子中黑碳气溶胶的观测研究[J].环境科学学报,2011,31(4):709-716.Tang L L,Zhu Y,Niu S J,et al. Observation of black carbon in fine particulate matter in the north suburb of Nanjing[J]. Acta Scientiae Circumstantiae,2011,31(4):709-716.
[25] Jiang R X,Hao B T,Li L L,et al. Comparison of aerosol hygroscopicity and mixing state between winter and summer seasons in Pearl River Delta region,China[J]. Atmospheric Research,2016,169:160-170.
[26]钱小东,张启磊,徐学哲,等.气溶胶吸湿和挥发特性测量的VH-TDMA装置研究[J].中国环境科学,2017,37(4):1269-1275.Qian X D,Zhang Q L,Xu X Z,et al. Development of a Volatility Hygroscopic Tandem Differential Mobility Analyzer(VH-TDMA)for the measurement of aerosol thermal and hygroscopic properties[J]. China Environmental Science,2017,37(4):1269-1275.
[27] Liu P F,Zhao C S,Gbel T,et al. Hygroscopic properties of aerosol particles at high relative humidity and their diurnal variations in the North China Plain[J]. Atmospheric Chemistry and Physics,2011,11(7):3479-3494.
[28]李琦,银燕,顾雪松,等.南京夏季气溶胶吸湿增长因子和云凝结核的观测研究[J].中国环境科学,2015,35(2):337-346.Li Q,Yin Y,Gu X S,et al. An observational study of aerosol hygroscopic growth factor and cloud condensation nuclei in Nanjing in summer[J]. China Environmental Science,2015,35(2):337-346.
[29]闫璐璐,刘焕武,黄学敏,等.利用SPAMS研究西安市重污染天气细颗粒物污染特征及来源[J].环境科学研究,2018,31(11):1841-1848.Yan L L,Liu H W,Huang X M,et al. Characteristics and source apportionment of fine particles in Xi'an Using a Single Particle Aerosol Mass Spectrometer(SPAMS)during heavy pollution[J]. Research of Environmental Sciences,2018,31(11):1841-1848.
[2] Cao Y Q, Zhang W, Wang W J, et al. Spatial-temporal characteristics of haze and vertical distribution of aerosols over the Yangtze River Delta of China[J]. Journal of Environmental Sciences,2018,66:12-19.
[3]张小曳,廖宏,王芬娟.对IPCC第五次评估报告气溶胶-云对气候变化影响与响应结论的解读[J].气候变化研究进展,2014,10(1):37-39.Zhang X Y,Liao H,Wang F J. The effects of aerosols and clouds on climate change and their responses[J]. Progressus Inquisitiones de Mutatione Climatis,2014,10(1):37-39.
[4] Qi X F,Sun J Y,Zhang L,et al. Aerosol hygroscopicity during the haze red-alert period in december 2016 at a rural site of the North China Plain[J]. Journal of Meteorological Research,2018,32(1):38-48.
[5]吴兑,廖碧婷,陈慧忠,等.珠江三角洲地区的灰霾天气研究进展[J].气候与环境研究,2014,19(2):248-264.Wu D,Liao B T,Chen H Z,et al. Advances in studies of haze weather over Pearl River Delta[J]. Climatic and Environmental Research,2014,19(2):248-264.
[6]江文华,刘德,陈勇航,等. 1980~2012年重庆地区霾日时空变化特征[J].干旱气象,2015,33(4):602-606.Jiang W H,Liu D,Chen Y H,et al. Temporal and spatial variations of haze days in Chongqing from 1980 to 2012[J].Journal of Arid Meteorology,2015,33(4):602-606.
[7]宋宇,唐孝炎,方晨,等.北京市大气细粒子的来源分析[J].环境科学,2002,23(6):11-16.Song Y,Tang X Y,Fang C,et al. Source apportionment on fine particles in Beijing[J]. Environmental Science,2002,23(6):11-16.
[8] Pitchford M L,Mc Murry P H. Relationship between measured water vapor growth and chemistry of atmospheric aerosol for Grand Canyon, Arizona, in winter 1990[J]. Atmospheric Environment,1994,28(5):827-839.
[9] Tan H B,Yin Y,Gu X S,et al. An observational study of the hygroscopic properties of aerosols over the Pearl River Delta region[J]. Atmospheric Environment,2013,77:817-826.
[10]颜鹏,潘小乐,汤洁,等.北京市区大气气溶胶散射系数亲水增长的观测研究[J].气象学报,2008,66(1):111-119.Yan P,Pan X L,Tang J,et al. An experimental study on the influence of relative humidity on the atmospheric aerosol scattering coefficient at an urban site in Beijing[J]. Acta Meteorologica Sinica,2008,66(1):111-119.
[11]吴奕霄,银燕,顾雪松,等.南京北郊大气气溶胶的吸湿性观测研究[J].中国环境科学,2014,34(8):1938-1949.Wu Y X,Yin Y,Gu X F,et al. An observational study of the hygroscopic properties of aerosols in north suburb of Nanjing[J].China Environmental Science,2014,34(8):1938-1949.
[12]张茹,汤莉莉,许汉冰,等.冬季南京城市大气气溶胶吸湿性观测研究[J].环境科学学报,2018,38(1):32-40.Zhang R,Tang L L,Xu H B,et al. Hygroscopic properties of urban aerosol in Nanjing during wintertime[J]. Acta Scientiae Circumstantiae,2018,38(1):32-40.
[13]徐彬,张泽锋,李艳伟,等.南京北郊春季气溶胶吸湿性分析[J].环境科学,2015,36(6):1911-1918.Xu B,Zhang Z F,Li Y W,et al. Hygroscopic properties of aerosol particles in north suburb of Nanjing in spring[J].Environmental Science,2015,36(6):1911-1918.
[14]张程,于兴娜,安俊琳,等.南京北郊霾天气溶胶化学组分粒径分布特征[J].中国环境科学,2018,38(8):2873-2881.Zhang C,Yu X N,An J L,et al. Distribution characteristics of chemical components in aerosol during haze days in north suburban Nanjing[J]. China Environmental Science,2018,38(8):2873-2881.
[15]宋秀瑜,曹念文,赵成,等.南京地区相对湿度对气溶胶含量的影响[J].中国环境科学,2018,38(9):3240-3246.Song X Y,Cao N W,Zhao C,et al. Effect of relative humidity on aerosol content in Nanjing[J]. China Environmental Science,2018,38(9):3240-3246.
[16] Liu Q F,Jing B,Peng C,et al. Hygroscopicity of internally mixed multi-component aerosol particles of atmospheric relevance[J]. Atmospheric Environment,2016,125:69-77.
[17] Gysel M, Mc Figgans G B, Coe H. Inversion of tandem differential mobility analyser(TDMA)measurements[J].Journal of Aerosol Science,2009,40(2):134-151.
[18] Petters M D,Kreidenweis S M. A single parameter representation of hygroscopic growth and cloud condensation nucleus activity[J]. Atmospheric Chemistry and Physics,2013,13(2):1081-1091.
[19] Gysel M,Crosier J,Topping D O,et al. Closure study between chemical composition and hygroscopic growth of aerosol particles during TORCH2[J]. Atmospheric Chemistry and Physics,2007,7(24):6131-6144.
[20]陈卉,杨素英,李艳伟,等.黄山夏季气溶胶吸湿性及与化学组分闭合[J].环境科学,2016,37(6):2008-2016.Chen H,Yang S Y,Li Y W,et al. Hygroscopic properties and closure of aerosol chemical composition in Mt. Huang in summer[J]. Environmental Science,2016,37(6):2008-2016.
[21] Liu H J, Zhao C S, Nekat B, et al. 2014. Aerosol hygroscopicity derived from size-segregated chemical composition and its parameterization in the North China Plain[J].Atmospheric Chemistry and Physics, 2014, 14(5):2525-2539.
[22] QX/T 113-2010,霾的观测和预报等级[S].
[23]庄智一.上海地区霾的统计分析研究[D].上海:华东师范大学,2012. 1-60.
[24]汤莉莉,祝愿,牛生杰,等.南京北郊大气细粒子中黑碳气溶胶的观测研究[J].环境科学学报,2011,31(4):709-716.Tang L L,Zhu Y,Niu S J,et al. Observation of black carbon in fine particulate matter in the north suburb of Nanjing[J]. Acta Scientiae Circumstantiae,2011,31(4):709-716.
[25] Jiang R X,Hao B T,Li L L,et al. Comparison of aerosol hygroscopicity and mixing state between winter and summer seasons in Pearl River Delta region,China[J]. Atmospheric Research,2016,169:160-170.
[26]钱小东,张启磊,徐学哲,等.气溶胶吸湿和挥发特性测量的VH-TDMA装置研究[J].中国环境科学,2017,37(4):1269-1275.Qian X D,Zhang Q L,Xu X Z,et al. Development of a Volatility Hygroscopic Tandem Differential Mobility Analyzer(VH-TDMA)for the measurement of aerosol thermal and hygroscopic properties[J]. China Environmental Science,2017,37(4):1269-1275.
[27] Liu P F,Zhao C S,Gbel T,et al. Hygroscopic properties of aerosol particles at high relative humidity and their diurnal variations in the North China Plain[J]. Atmospheric Chemistry and Physics,2011,11(7):3479-3494.
[28]李琦,银燕,顾雪松,等.南京夏季气溶胶吸湿增长因子和云凝结核的观测研究[J].中国环境科学,2015,35(2):337-346.Li Q,Yin Y,Gu X S,et al. An observational study of aerosol hygroscopic growth factor and cloud condensation nuclei in Nanjing in summer[J]. China Environmental Science,2015,35(2):337-346.
[29]闫璐璐,刘焕武,黄学敏,等.利用SPAMS研究西安市重污染天气细颗粒物污染特征及来源[J].环境科学研究,2018,31(11):1841-1848.Yan L L,Liu H W,Huang X M,et al. Characteristics and source apportionment of fine particles in Xi'an Using a Single Particle Aerosol Mass Spectrometer(SPAMS)during heavy pollution[J]. Research of Environmental Sciences,2018,31(11):1841-1848.