摘要
近年来,无机盐尤其是硝酸盐对我国大气PM_(2.5)的贡献日益凸显,而其如何影响颗粒物的重要理化性质尚待深入研究.于2021年1~12月期间,在镇江市开展了连续观测,获得了大气PM_(2.5)中硫酸铵[(NH_(4)_(2)SO_(4))]和硝酸铵(NH_(4)NO_(3))浓度,系统讨论了二者对颗粒物消光、吸湿增长和酸度的影响.结果表明,2021年镇江市ρ[(NH_(4)_(2)SO_(4)]和ρ(NH_(4)NO_(3))的年均值分别为(6.5±4.5)μg·m^(-3)和(15.0±13.3)μg·m^(-3),对PM_(2.5)浓度的平均贡献率分别为(20.5±18.2)%和(34.5±18.4)%;PM_(2.5)的总消光系数为(224.5±194.2)Mm-1,其中NH_(4)NO_(3)的贡献率为(40.1±20.9)%,(NH_(4)_(2)SO_(4)为(19.1±10.8)%;(NH_(4)_(2)SO_(4)和NH_(4)NO_(3)是PM_(2.5)吸湿增长的主要贡献者,在污染条件下NH_(4)NO_(3)对颗粒物液态水的贡献率为(53.8±13.4)%~(61.6±14.6)%;NH_(4)NO_(3)是未来镇江市能见度和空气质量改善的关键污染物,但削减NH_(4)NO_(3)前体物可能会导致颗粒物酸度增加,尤其对春冬季节颗粒物酸度的影响较为明显.研究结果对理解空气质量变化及二次影响具有重要意义,并对镇江市空气质量的持续改善提供了重要参考.
Recently,the contribution of inorganic salts(nitrates in particular)to the mass concentration of particulate matter with an aerodynamic diameter of less than 2.5μm(PM_(2.5))has been increasing across China.However,it is urgent to understand how the increased inorganic salts affect the crucial properties of PM_(2.5).Here,we conducted continuous field observations at Zhenjiang Ecology and Environment Protection Bureau from January 1 to December 31,2021.The mass concentrations of ammonium sulfate[(NH_(4)_(2)SO_(4)]and ammonium nitrate(NH_(4)NO_(3))were calculated using different methods.The contributions of(NH_(4)_(2)SO_(4)and NH_(4)NO_(3)to the extinction coefficient,hygroscopic growth,and acidity of PM_(2.5)were discussed in detail.Our results demonstrated that the mean mass concentrations of(NH_(4)_(2)SO_(4)and NH_(4)NO_(3)during the study period were(6.5±4.5)and(15.0±13.3)μg·m^(-3),which contributed(20.5±18.2)%and(34.5±18.4)%to the mass concentration of PM_(2.5),respectively.The total extinction coefficient of PM_(2.5)was(224.5±194.2)Mm-1,in which NH_(4)NO_(3)was the largest contributor[(40.1±20.9)%]followed by(NH_(4)_(2)SO_(4)[(19.1±10.8)%].(NH_(4)_(2)SO_(4)and NH_(4)NO_(3)were also the dominant contributors to the hygroscopic growth of PM_(2.5).In particular,NH_(4)NO_(3)contributed from(53.8±13.4)%to(61.6±14.6)%to the aerosol water content of PM_(2.5)under pollution conditions.Thus,NH_(4)NO_(3)was a key air pollutant to be targeted for further improving the visibility and air quality in Zhenjiang in the future.However,the reduction in the precursors of NH_(4)NO_(3)would lead to an increase in aerosol acidity,particularly in the spring and winter seasons.Our results help us understand the evolution of air quality and the related impacts and also provide important information on air quality improvement in Zhenjiang in the future.
作者
曹军
谢佳丽
孙娟
李锦雯
徐政
华陈杰
张雨生
宋柏颖
刘永春
CAO Jun;XIE Jia-li;SUN Juan;LI Jin-wen;XU Zheng;HUA Chen-jie;ZHANG Yu-sheng;SONG Bo-ying;LIU Yong-chun(Jiangsu Environmental Monitoring Centre,Nanjing 210019,China;Aerosol and Haze Laboratory,Advanced Innovation Center for Soft Matter Science and Engineering,Beijing University of Chemical Technology,Beijing 100029,China;Nanjing Environmental Monitoring Centre of Jiangsu Province,Nanjing 210019,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2023年第10期5356-5369,共14页
Environmental Science
基金
国家自然科学基金项目(92044301,42275117,41975154)。
