2017—2022年天津市冬季大气PM_(2.5)水溶性无机离子浓度变化特征  

Variations of water⁃soluble inorganic ions concentration in PM_(2.5)during winter of 2017-2022 in Tianjin

作　　者：李红娟 肖浩[1] 丁士元 李晓东[1] LI Hongjuan;XIAO Hao;DING Shiyuan;LI Xiaodong(School of Earth System Science,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学地球系统科学学院,天津300072

出　　处：《生态学杂志》2025年第2期566-574,共9页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(42273020,41773006);天津市自然科学基金项目(22JCQNJC00700)资助。

摘　　要：于2017—2022年连续6年采集了天津市冬季的PM_(2.5)样品,分析了8种水溶性无机离子(SO_(4)^(2-)、NO_(3)^(-)、NH_(4)^(+)、Cl^(-)、K^(+)、Ca^(2+)、Na^(+)、Mg^(2+))浓度。结果发现,2017—2022年间PM_(2.5)中SO_(4)^(2-)、NO_(3)^(-)和NH_(4)^(+)质量浓度下降明显,降幅分别为83.9%、46.2%和55.2%;NO_(3)^(-)在水溶性无机离子(WSIIs)中占比逐年升高,二次无机离子(SO_(4)^(2-)、NO_(3)^(-)和NH_(4)^(+))的主要存在形式由(NH_(4))_(2)SO_(4)逐渐向NH_(4)NO_(3)转变。此外,NO_(3)^(-)/SO_(4)^(2-)、NO_(3)^(-)/Cl^(-)及NO_(3)^(-)/K^(+)的值均呈逐年上升趋势,表明近年来相较于燃煤和生物质燃烧等固定源,机动车尾气等移动源对天津市空气质量的影响逐年增强。后向轨迹结果发现,采样期间天津市大气PM_(2.5)主要受来自西北方向、天津南部及河北中部等气团的影响,但其潜在源区域没有明显的年际差异。此外,相较于天津周边的短距离气团,来自西北方向的长距离气团所携带SO_(4)^(2-)的浓度下降明显。NO_(3)^(-)和NH_(4)^(+)的降幅较低,2020年短距离气团所携带的NO_(3)^(-)和NH_(4)^(+)浓度呈上升趋势,进一步表明未来需要加强天津及周边区域汽车尾气排放的管控。To evaluate the effectiveness of air pollution control policies in Tianjin,we collected PM_(2.5)samples over six consecutive winters from 2017 to 2022 and measured the concentration of water⁃soluble inorganic ions(SO_(4)^(2-),NO_(3)^(-),NH_(4)^(+),Cl^(-),K^(+),Ca^(2+),Na^(+),Mg^(2+)).The results revealed a marked decline in the mass concentrations of SO_(4)^(2-),NO_(3)^(-)and NH_(4)^(+)in PM_(2.5)from 2017 to 2022,with reductions of 83.9%,46.2%,and 55.2%,respectively.However,the proportion of NO_(3)^(-)within water⁃soluble inorganic ions(WSIIs)has been rising annually,with the dominant form of secondary inorganic ions(SO_(4)^(2-),NO_(3)^(-)and NH_(4)^(+))transitioning from(NH_(4))_(2)SO_(4)to NH_(4)NO_(3).The ratios of NO_(3)^(-)/SO_(4)^(2-),NO_(3)^(-)/Cl^(-)and NO_(3)^(-)/K^(+)have been increasing annually as well,indicating that com⁃pared to stationary sources such as coal combustion and biomass burning,the influence of mobile sources such as motor vehicle exhaust on air quality in Tianjin was increasing.Backward trajectory analyses showed that the PM_(2.5)in Tianjin was mainly influenced by air masses from the northwest,the southern part of Tianjin,and the central He⁃bei,without interannual differences in potential source areas.Furthermore,compared to short⁃distance air masses around Tianjin,SO_(4)^(2-)carried by long⁃distance air masses from the northwest showed a significant decrease.The re⁃ductions in NO_(3)^(-)and NH_(4)^(+)concentrations were relatively modest.Notably,NO_(3)^(-)and NH_(4)^(+)levels associated with short⁃distance air masses displayed an increasing trend in 2020,indicating the need to strengthen vehicle exhaust emissions control in Tianjin and the surrounding areas.

关 键 词：天津市 PM_(2.5) 水溶性无机离子 冬季 

分 类 号：X513[环境科学与工程—环境工程]