为了解冬季不同污染等级下NH_(3)和AWC(Aerosol Water Content,气溶胶液态水含量)对PM_(2.5)中水溶性二次离子形成的影响,对保定市冬季颗粒物浓度、二次离子及前体物(SO_(2)、NO_(2)、NH_(3))浓度进行了分析,并利用ISORROPIA-Ⅱ计算了PM...为了解冬季不同污染等级下NH_(3)和AWC(Aerosol Water Content,气溶胶液态水含量)对PM_(2.5)中水溶性二次离子形成的影响,对保定市冬季颗粒物浓度、二次离子及前体物(SO_(2)、NO_(2)、NH_(3))浓度进行了分析,并利用ISORROPIA-Ⅱ计算了PM_(2.5)中的AWC和pH.结果表明:①2017—2018年冬季保定市重污染期(AQI>200)ρ(PM_(2.5))、ρ(SO_(2))、ρ(NO_(2))和ρ(NH_(3))较优良期(AQI<100)分别升高了3.0、1.1、1.3和0.8倍,气态前体物的二次转化是污染形成的重要原因之一.重污染期ρ(NH_(4)^(+))、ρ(SO_(4)^(2-))、ρ(NO_(3)-)较冬季平均值分别升高了1.2、0.9、1.3倍,其中ρ(NO_(3)-)升幅最大,其次为ρ(NH_(4)^(+)).②保定市大气中过剩NH_(3)指数为0.1μmol m^(3),采样期间为富氨环境,NO_(3)-的生成主要受HNO_(3)限制.③重污染期PM_(2.5)中AWC高达93.6μg m^(3),是优良期的20.6倍,观测期间保定市SO_(4)^(2-)的二次生成以颗粒物表面液相氧化为主,即SO_(2)被NO_(2)和NH_(3)氧化,NO_(3)-的二次生成包括NH_(3)参与的非均相转化和N_(2)O_(5)的非均相水解过程.④整体而言,pH变化的敏感性表现为TA(总氨)浓度>TS(总硫)浓度>TN(总氮)浓度≈TA+TS+TN浓度(同时改变相同比例的总氨、总硫、总氮浓度),随污染等级的升高,pH对TS、TA浓度变化的敏感性减弱,对TN浓度变化的敏感性增强;单独改变TS、TN、TA浓度时AWC敏感性弱,同时改变TS、TN、TA浓度时AWC敏感性较强,AWC变化与二次离子浓度密切相关.研究显示,保定市冬季污染期SNA的形成以液态水参与的液相氧化为主,NH_(3)可以维持颗粒物的高pH,保持氧化过程.展开更多
Fog simulation and prediction are becoming increasingly important in China because of the great impact of fog on traffic and other human activities. More studies are needed to have a better understanding of the format...Fog simulation and prediction are becoming increasingly important in China because of the great impact of fog on traffic and other human activities. More studies are needed to have a better understanding of the formation mechanisms and life cycles of fogs. This work uses data from two fog cases observed in Wuqing, Tianjin, in 2009. The data include aerosol size distribution, fog droplet size distribution, fog liquid water content, and meteorological properties. The results show that increasing aerosols can increase the number concentration of fog droplets and decrease fog droplet size, which is consistent with the first aerosol indirect effect found in clouds. It is also shown that increased aerosols can lead to lower visibility in fogs. This work demonstrates that the first aerosol indirect effect plays an important role in fogs.展开更多
文摘为了解冬季不同污染等级下NH_(3)和AWC(Aerosol Water Content,气溶胶液态水含量)对PM_(2.5)中水溶性二次离子形成的影响,对保定市冬季颗粒物浓度、二次离子及前体物(SO_(2)、NO_(2)、NH_(3))浓度进行了分析,并利用ISORROPIA-Ⅱ计算了PM_(2.5)中的AWC和pH.结果表明:①2017—2018年冬季保定市重污染期(AQI>200)ρ(PM_(2.5))、ρ(SO_(2))、ρ(NO_(2))和ρ(NH_(3))较优良期(AQI<100)分别升高了3.0、1.1、1.3和0.8倍,气态前体物的二次转化是污染形成的重要原因之一.重污染期ρ(NH_(4)^(+))、ρ(SO_(4)^(2-))、ρ(NO_(3)-)较冬季平均值分别升高了1.2、0.9、1.3倍,其中ρ(NO_(3)-)升幅最大,其次为ρ(NH_(4)^(+)).②保定市大气中过剩NH_(3)指数为0.1μmol m^(3),采样期间为富氨环境,NO_(3)-的生成主要受HNO_(3)限制.③重污染期PM_(2.5)中AWC高达93.6μg m^(3),是优良期的20.6倍,观测期间保定市SO_(4)^(2-)的二次生成以颗粒物表面液相氧化为主,即SO_(2)被NO_(2)和NH_(3)氧化,NO_(3)-的二次生成包括NH_(3)参与的非均相转化和N_(2)O_(5)的非均相水解过程.④整体而言,pH变化的敏感性表现为TA(总氨)浓度>TS(总硫)浓度>TN(总氮)浓度≈TA+TS+TN浓度(同时改变相同比例的总氨、总硫、总氮浓度),随污染等级的升高,pH对TS、TA浓度变化的敏感性减弱,对TN浓度变化的敏感性增强;单独改变TS、TN、TA浓度时AWC敏感性弱,同时改变TS、TN、TA浓度时AWC敏感性较强,AWC变化与二次离子浓度密切相关.研究显示,保定市冬季污染期SNA的形成以液态水参与的液相氧化为主,NH_(3)可以维持颗粒物的高pH,保持氧化过程.
基金supported by the Chinese National Public Benefit Research Foundation of Meteorology(Grants Nos. GYHY200906025 and GYHY201006011)
文摘Fog simulation and prediction are becoming increasingly important in China because of the great impact of fog on traffic and other human activities. More studies are needed to have a better understanding of the formation mechanisms and life cycles of fogs. This work uses data from two fog cases observed in Wuqing, Tianjin, in 2009. The data include aerosol size distribution, fog droplet size distribution, fog liquid water content, and meteorological properties. The results show that increasing aerosols can increase the number concentration of fog droplets and decrease fog droplet size, which is consistent with the first aerosol indirect effect found in clouds. It is also shown that increased aerosols can lead to lower visibility in fogs. This work demonstrates that the first aerosol indirect effect plays an important role in fogs.
