机动车排放颗粒物是我国城市大气PM_（2.5）重要来源。缸内直喷（gasoline direct injection,GDI）汽油机具有油耗低、CO2排放低等优点,将成为未来汽油车发展方向。然而GDI汽油机颗粒物排放高,造成的环境影响值得关注。有机物（organic ...机动车排放颗粒物是我国城市大气PM_（2.5）重要来源。缸内直喷（gasoline direct injection,GDI）汽油机具有油耗低、CO2排放低等优点,将成为未来汽油车发展方向。然而GDI汽油机颗粒物排放高,造成的环境影响值得关注。有机物（organic matters,OM）是大气颗粒物的重要组分,有着重要的健康效应和气候效应。其中可以定量检测的部分颗粒有机物（particulate organic matters,POM）有着较好的源指示作用。通过台架实验研究了GDI汽油机排放PM_（2.5）中POM的组成、排放因子等的特征,以及转速、负荷、催化剂等因素对POM组成的影响,给出汽油机排放POM源谱。定量颗粒有机物的总质量分别可以占到总有机物OM和PM_（2.5）质量浓度的14%~56%和7%~44%。多环芳烃、正构烷烃、正构烷酸、芳香酸、二元羧酸是最主要的物种。POM排放因子随转速增加而增大,对于中、低转速,POM排放因子随着负荷的增加呈现出先降低后增加的趋势;在高转速时,POM排放因子随着负荷增加而增加。三效催化剂对颗粒有机物的排放的削减作用可达到19%~64%。我国汽油车排放POM源谱与国外源谱有差异。采集和测量我国实地源样品,得到符合我国实际情况的汽油车POM源谱,对于解析我国大气颗粒物来源中的汽油车贡献至关重要。展开更多
为满足大气非甲烷烃(NMHCs)时空分布监测需求,开发出一套可用于移动观测的小型在线测量系统.环境空气经Teflon膜去除颗粒物后,以100 m L·min-1流速采样进入多床吸附剂捕集阱,样品气中的NMHCs在-10℃的温度下被捕集,之后,捕集阱经...为满足大气非甲烷烃(NMHCs)时空分布监测需求,开发出一套可用于移动观测的小型在线测量系统.环境空气经Teflon膜去除颗粒物后,以100 m L·min-1流速采样进入多床吸附剂捕集阱,样品气中的NMHCs在-10℃的温度下被捕集,之后,捕集阱经高纯氮气反吹后迅速升温至300℃,载气(高纯氮气)以1.6 m L·min-1将解吸出的样品送入GC-FID进行检测.通过系列条件实验,确定了吸附剂的最佳组合和仪器运行的最优参数,在此条件下,本系统最低检出限为0.01 nmol·mol-1(顺-2-丁烯),标准工作曲线R2为0.9991~0.9998,10次重复实验RSD<3%.本系统与现有商业化设备TH-300B的测量结果具有较好的一致性,在实际外场应用中,运行稳定性高、能准确追踪12种典型NMHCs的大气浓度变化,可为定量分析大气二次污染形成机制提供关键前体物信息.展开更多
The heterogeneous hydrolysis of dinitrogen pentoxide(N2O5)plays an important role in regulating NOx.The N2O5 uptake coefficient,γ(N2O5),was determined using an iterative box model that was constrained to observationa...The heterogeneous hydrolysis of dinitrogen pentoxide(N2O5)plays an important role in regulating NOx.The N2O5 uptake coefficient,γ(N2O5),was determined using an iterative box model that was constrained to observational data obtained in suburban Beijing from February to March 2016.The box model determined 2289 individualγ(N2O5)values that varied from<0.001 to 0.02 with an average value of 0.0046±0.0039(and a median value of 0.0032).We found the derived winterγ(N2O5)values in Beijing were relatively low as compared to values reported in previous field studies conducted during winter in Hong Kong(average value of 0.014)and the eastern U.S.coast(median value of 0.0143).In our study,field evidence of the suppression ofγ(N2O5)values due to pNO3-content,organics and the enhancement by aerosol liquid water content(ALWC)is in line with previous laboratory study results.Low ALWC,high pNO3-content,and particle morphology(inorganic core with an organic shell)accounted for the lowγ(N2O5)values in the North China Plain(NCP)during wintertime.The field-derivedγ(N2O5)values are well reproduced by a revised parameterization method,which includes the aerosol size distribution,ALWC,nitrate and organic coating,suggesting the feasibility of comprehensive parameterization in the NCP during wintertime.展开更多
文摘为满足大气非甲烷烃(NMHCs)时空分布监测需求,开发出一套可用于移动观测的小型在线测量系统.环境空气经Teflon膜去除颗粒物后,以100 m L·min-1流速采样进入多床吸附剂捕集阱,样品气中的NMHCs在-10℃的温度下被捕集,之后,捕集阱经高纯氮气反吹后迅速升温至300℃,载气(高纯氮气)以1.6 m L·min-1将解吸出的样品送入GC-FID进行检测.通过系列条件实验,确定了吸附剂的最佳组合和仪器运行的最优参数,在此条件下,本系统最低检出限为0.01 nmol·mol-1(顺-2-丁烯),标准工作曲线R2为0.9991~0.9998,10次重复实验RSD<3%.本系统与现有商业化设备TH-300B的测量结果具有较好的一致性,在实际外场应用中,运行稳定性高、能准确追踪12种典型NMHCs的大气浓度变化,可为定量分析大气二次污染形成机制提供关键前体物信息.
基金supported by the National Natural Science Foundation of China(21976006,41907185,91844301,91544225)Beijing Natural Science Foundation,China(JQ19031)China Postdoctoral Science Foundation(2018M641095,2019T120023)。
文摘The heterogeneous hydrolysis of dinitrogen pentoxide(N2O5)plays an important role in regulating NOx.The N2O5 uptake coefficient,γ(N2O5),was determined using an iterative box model that was constrained to observational data obtained in suburban Beijing from February to March 2016.The box model determined 2289 individualγ(N2O5)values that varied from<0.001 to 0.02 with an average value of 0.0046±0.0039(and a median value of 0.0032).We found the derived winterγ(N2O5)values in Beijing were relatively low as compared to values reported in previous field studies conducted during winter in Hong Kong(average value of 0.014)and the eastern U.S.coast(median value of 0.0143).In our study,field evidence of the suppression ofγ(N2O5)values due to pNO3-content,organics and the enhancement by aerosol liquid water content(ALWC)is in line with previous laboratory study results.Low ALWC,high pNO3-content,and particle morphology(inorganic core with an organic shell)accounted for the lowγ(N2O5)values in the North China Plain(NCP)during wintertime.The field-derivedγ(N2O5)values are well reproduced by a revised parameterization method,which includes the aerosol size distribution,ALWC,nitrate and organic coating,suggesting the feasibility of comprehensive parameterization in the NCP during wintertime.
