大气PM_(2.5)在线监测仪对SO_4^(2-)、NO_3^-和NH_4^+的测定评价  

Evaluation of SO_4^(2-),NO_3^- and NH_4^+ measurements using ambient PM_(2.5) real-time monitoring instruments

作　　者：袁超[1,2] 王韬[1,2] 高晓梅[1,2] 聂玮[1,2] 雷国强 徐政[1,2] 王文兴[1] 

机构地区：[1]山东大学环境研究院,济南250100 [2]香港理工大学土木及环境工程系 [3]香港特区政府环境保护署

出　　处：《环境化学》2012年第11期1808-1815,共8页Environmental Chemistry

基　　金：香港环境及自然保育基金项目(2009-07);香港理工大学Niche Area Development(1-BB94)资助

摘　　要：通过两套大气细颗粒物(PM2.5)水溶性离子在线监测仪与蜂巢式固气分离器膜采样系统作对比,评估了在线监测仪器对主要水溶性组分SO24-、NO3-和NH4+的测定结果.美国URG公司生产的在线连续监测分析系统(AIM URG-9000B)对NH4+和NO3-的监测结果较好,但对SO24-的测定结果存在明显高估,其原因是AIM的平板溶蚀器系统无法完全去除大气中高浓度SO2,从而对SO24-的测定结果有干扰.为解决这一问题,进行了一系列实验,结果表明采用两个溶蚀器串联并用5 mmol.L-1H2O2+5 mmol.L-1NaOH混合溶液作吸收液时,高浓度的SO2(甚至达到260μg.m-3)可以被完全吸收而对SO24-的测定结果不产生影响.由荷兰能源研究所(ECN)、Metrohm和Applikon共同研制的在线气体组分及气溶胶监测系统(MARGA,ADI2080)对NH4+和SO24-的监测结果较好,可以满足实验要求;但NO3-的测定结果偏高,其准确性需作进一步评估.新型监测仪器在不同大气环境中投入使用前需进行对比测试,以确定其准确性和精确性.Field studies were conducted in Hong Kong to assess two different real-time techniques for measuring SO42- , NOr and NH~ in PM2.5 by comparison with a honeycomb denuder filter-pack system. An ambient ion monitor （AIM, URG9000B ） showed good performance for NO3- and NH4＋, but obvious overestimation for SO^-, which was attributed to the positive interference by high ambient SO2 concentrations which could not be totally eliminated in the parallel denuder. To overcome this problem, a series of experiments were conducted, which lead to an improved system including two denuders working in series and with the use of a new denuder liquid （5 mmol＂ L-1 H202 ＋ 5 mmol-L-1 NaOH）. The new system could absorb high concentration of SO2 （even up to 260 p^g-m-3） so that the SO^- measurement results would not be affected. Another monitor for measuring aerosols and gases （ MARGA, Model ADI 2080）, developed by ECN, Metrohm and Applikon, was also evaluated. MARGA showed excellent performance for the measurements of SO^- and NI-I~ , but exhibited high NO3- measurement results. The accuracy of NO^- measurements should be evaluated further. This study demonstrated the need for evaluating new measurement techniques in different atmospheric environments to determine the accuracy and precision of the measurements.

关 键 词：PM25在线监测系统 AIM MARGA NH4+ NO3- SO24- 

分 类 号：X831[环境科学与工程—环境工程]