基于分级采样的大气颗粒相硝酸盐浓度测定正负偏差  

The deviation in size-resolved atmospheric particulate phase nitrate determination

作　　者：骆亮 刘喆 王红燕 刘佳 田世丽 邵鹏 LUO Liang;LIU Zhe;WANG Hongyan;LIU Jia;TIAN Shi;SHAO Peng(Institute of Analysis and Testing Beijing Academy of Science and Technology(Beijing Center for Physical and Chemical Analysis),Beijing 100089,China;Department of Chemistry,Capital Normal University,Beijing 100048,China)

机构地区：[1]北京市科学技术研究院分析测试研究所(北京市理化分析测试中心),北京100089 [2]首都师范大学化学系,北京100048

出　　处：《环境工程学报》2023年第12期4126-4130,共5页Chinese Journal of Environmental Engineering

基　　金：北京市自然科学基金资助项目(8222044,8232025);北京市科学技术研究院创新工程项目(23CA005-05);创新培育项目(23CB030)。

摘　　要：为确定前体物吸附和硝酸铵挥发造成的分粒径段硝酸盐测定的正负偏差,基于安德森分级采样器,通过采样器前置扩散管和后置滤膜等方法来确定夏季颗粒相硝酸盐浓度测定的偏差。首先,通过条件实验,确定了夏季采样过程中质量分数5%KOH和10%甘油甲醇为前置扩散管的最佳涂层溶液浓度,其对硝酸气体的吸附率可达到92.1%。前置扩散管串联采样器和单独采样器的同步采样确定了前体物吸附造成的各粒径段硝酸盐正偏差平均值为4.4%±2.6%,0.65~1.1μm的偏差最大(为8.4%±4.5%),>9μm的偏差最小(为0.9%±0.6%),即细粒径段偏差大于粗粒径段。通过后置滤膜确认了硝酸铵挥发造成的夏季总悬浮颗粒物中硝酸盐测定负偏差为27.5%±10.2%。利用PM1、PM2.5和PM10采样器分别加后置滤膜将这一负偏差分配到不同粒径段,PM1、PM1-2.5和PM2.5-10的硝酸盐负偏差分别为35.6%±8.4%、28.3%±9.3%和14.8%±6.6%。不考虑正负偏差的校正,造成的细颗粒物和粗颗粒物硝酸盐低估比率分别为19.1%±5.6%和10.9%±6.7%,对细颗粒物的低估更多。具体到各个粒径段,<0.43μm的低估程度最高(为21.2%±4.4%),4.7~5.8μm的低估程度最低(为10.7%±3.7%)。该研究结果有利于优化分粒径段硝酸盐的监测方案,并提高硝酸盐数据准确性。tTo investigate the deviation in size-resolved nitrate determination,the experiments for determining the optimal concentrations of annular denuders coatings were performed,and size-resolved nitrate samples were collected by a 9-stage Andersen sampler with pre-denuder and post-filter membrane in Beijing in the summer of 2022.The results showed that when the concentration of KOH coating solution was 5%,the removal rate of acid gases in the atmosphere reached 92.1%.The positive deviation caused by precursor absorption was 4.4%±2.6%,the maximum deviation was 8.4%±4.5%in the size fraction of 0.65~1.1μm,and the minimum deviation was 0.9%±0.6%in the size fraction of>9μm.The negative deviation of nitrate determination in total suspended particulates caused by volatilization of ammonium nitrate was 27.5%±10.2%.This negative deviation was assigned to different size fractions by using PM,PM2.s and PMio samplers with post-filter membrane,respectively.The negative deviations of nitrate determination were 35.6%±8.4%,28.3%±9.3%and 14.8%±6.6%in PM,PM-2.5 and PM2.5-1o,respectively.Without considering the correction of positive and negative deviations,the nitrate underestimation rates of fine and coarse particles were 19.1%and 10.9%respectively.These results are beneficial to optimize the monitoring scheme of nitrate in size-resolved particles and improve the data accuracy.

关 键 词：硝酸盐 分粒径段 正负偏差 前体物吸附 硝酸铵挥发 

分 类 号：X513[环境科学与工程—环境工程]