重庆市不同粒径颗粒物中水溶性离子污染特征  

Characteristics ofwater-solubleionsinmulti-sizeparticlesin Chongqing

作　　者：彭超 张丹 方维凯[1,2] 王晓宸 谢耕 向英 李振亮 PENG Chao;ZHANG Dan;FANG Wei-kai;WANG Xiao-chen;XIE Geng;XIANG Ying;LI Zhen-liang(Chongqing Academy of Eco-Environmental Science,Chongqing 401147,China;Key Laboratory for Urban Atmospheric Environment Integrated Observation&Pollution Prevention and Control of Chongqing,Chongqing 401147,China;School of Chemistry and Chemical Engineering,Chongqing University,Chongqing 401331,China)

机构地区：[1]重庆市生态环境科学研究院,重庆401147 [2]城市大气环境综合观测与污染防控重庆市重点实验室,重庆401147 [3]重庆大学化学化工学院,重庆401331

出　　处：《中国环境科学》2021年第10期4529-4540,共12页China Environmental Science

基　　金：国家重点研发计划项目(2018YFC0214002);重庆市重点研发项目(cstc2018jszx-zdyfxmX0003)。

摘　　要：于2010年3月~2011年2月和2017年1~12月在重庆主城区连续采集PM1.0、PM1.0~2.5和PM_(2.5)~10样品,采用离子色谱测定了样品中9种水溶性无机离子(WSIIs)含量,研究了近年来不同粒径颗粒物中主要离子的污染特征.结果表明,2017年重庆市PM1.0、PM1.0~2.5和PM_(2.5)~10中WSIIs年均浓度和占比分别为24.10,32.89,39.11μg/m^(3)和41.8%、40.3%、38.6%,较2010年均有所下降(39.85,47.84,57.12μg/m^(3)和49.2%、46.6%、36.2%),但NO_(3)-浓度和占比呈上升趋势(分别上升12.3%~27.8%和53.1%~78.2%),且成为2017年冬季首要离子.SO_(4)^(2-)、NO_(3)-、NH_(4)^(+)、Cl^(-)、K^(+)和Na^(+)主要分布在细粒子中,F-、Mg^(2+)和Ca^(2+)主要分布在粗粒子中.重庆颗粒物呈弱碱性,其中粗粒子碱性强于细粒子,NH_(4)^(+)主要以(NH_(4))_(2)SO_(4)和NH_(4)NO_(3)的形式存在.与2010年不同,2017年细粒子中SO_(4)^(2-)和NO_(3)-浓度均随相对湿度增大而快速上升,非均相反应已成为2017年SO_(4)^(2-)和NO_(3)-形成的重要途径,且在PM1.0中尤为突出.随污染加重,不同粒径下各类WSIIs演化特征各异,其中2017年细粒子中NO_(3)-浓度及其对WSIIs贡献大幅升高,并成为重污染形成的主因,而SO_(4)^(2-)和扬尘源示踪物(Mg^(2+)、Ca^(2+))贡献呈下降趋势.与2010年相比,2017年各粒径中NO_(3)-/SO_(4)^(2-)比值随污染加重大幅升高,且重污染日比值均大于1.0.细粒子中WSIIs主要来源于二次转化,粗粒子主要来源于扬尘.2017年扬尘污染较2010年有所减缓,但二次源对WSIIs贡献上升明显,尤其是NO_(3)-的二次生成,因此对NO_(x)排放源的管控是WSIIs减排的重要途径.研究结果对了解近年来重庆市大气颗粒物污染来源及形成机制研究具有重要参考价值.PM1.0,PM_(2.5) and PM_(10) samples were collected from March 2010 to February 2011 and January 2017 to December 2017 in the urban area of Chongqing.The mass concentrations of nine water-soluble inorganic ions(WSIIs)were determined by anion chromatography,and characteristics of WSIIs inmulti-size particles during recent years were investigated.The results showed that the annualmean concentrationsof WSIIs in PM1.0,PM1.0~2.5 and PM_(2.5)~10 were 24.10,32.89 and 39.11μg/m^(3) respectively,accounting for 41.8%,40.3%and 38.6%of PM respectively in 2017.The annual mean concentrations of WSIIs in PM in 2010(39.85,47.84 and 57.12μg/m^(3) respectively)were higher than that in 2017,and so were thefractions(49.2%,46.6%and 36.2%respectively).However,the concentrations and fractions of NO_(3)-in PM increased by 12.3%~27.8%and 53.1%~8.2%respectively from 2010 to 2017,and NO_(3)-was the primary ion in 2017 winter.SO_(4)^(2-),NO_(3)-,NH_(4)^(+),Cl^(-),K^(+),and Na^(+)were mainly distributed in fine particles,while F-,Mg^(2+)and Ca^(2+)were the major WSIIs components in coarse particles.The particles in Chongqing were slightly alkaline,especially coarse particles,and NH_(4)^(+)were existed in the form of(NH_(4))_(2)SO_(4) and NH_(4)NO_(3).Compared with that in 2010,the concentrations of both SO_(4)^(2-)and NO_(3)-increased with the increase of relative humidity in fine particles in 2017.RH-dependent heterogeneous reactions contributed greatly to the formation of sulfate and nitrate in 2017,especially in PM1.0.With the aggravation of pollution,the evolution processes of different ions were differentinmulti-size particles.Among them,the concentrations and fractions of NO_(3)-in WSIIs increased significantly and NO_(3)-was the primarily driver of heavy pollution in fine particles in 2017,while the contributions of SO_(4)^(2-)and the ions from dust(Mg^(2+)and Ca^(2+))decreased.In addition,themass ratios of NO_(3)-/SO_(4)^(2-)in different particle size increased with the aggravation of pollution and were higher than 1.0 during the hea

关 键 词：水溶性无机离子 粒径分布 季节变化 演变过程 重庆 

分 类 号：X513[环境科学与工程—环境工程]