Air Pollutants Measurement Technology

Author: | published date:2013-11-30

As required by the in-depth characterization and analysis of the complicated air pollution processes in China, we developed a series of measurement techniques such as gas samplers for plume detection, and on-line analyzers for criteria pollutants. We therefore updated our measurement platforms from off-line to on-line, from criteria pollutants to a spectrum of reactive trace compounds (VOCs, Hg, HONO, TOC, WSOC, EC/OC), from single parameter analysis to integrated measurements of multi-components and the measurements of both gas- and aerosol- phase compounds simultaneously. 

We developed the on-line VOCs measurement system based on “Electric refrigeration and cryogenic (-155 oC) air trapping technique” and developed the on-line measurement device for gas and water soluble aerosol analysis and the on-line Hg analyzer. With these developments we have been issued more than 20 patents in developing ambient monitoring instruments. All of these developed systems were tested and examined in field measurements. Some of those instruments are commercially available in market, such as  (1) gas and aerosol collector (GAC), (2) on-line VOCs detection system, (3) CES-124 on-line Hg analyzer, (4) dilution chamber, (5) on-line OC/EC analyzer, (6) off-line and on-line measurements of CH4, NMHCs, CO and CO2based on GC-FID, (7) on-line NH3 analyzer based on chemical enrichment, (8) on-line dimethylsulfoxide (DMS) analyzer, (9) NOx measurements based on photolytic converter, (10) aerosol humidity controller, (11) multi-channels gas sampling tube, and (12) on-line PANs analyzer. Details of (1) and (2) are further provided below:

a)        On-line analyzer for atmospheric volatile organic compounds (VOCs). The newly developed continuous monitor for VOCs couples a cryogenic trap and thermal extraction device and a gas chromatography column with FID and MS detectors. Our instrument is capable of providing on-line measurements for about 100 VOC species with high time resolution and high sensitivity. It also performs well in long-term monitoring. We made this monitor commercially available through Wuhan Tianhong instruments Co., Ltd. In the past three years, Wuhan Tianhong instruments Co., Ltd. sold out 40 on-line VOC analyzers with gross income of 60 million RMB.

b)        Gas and Aerosol Collector (GAC). The Gas and Aerosol Collector provides accurate on-line measurements with 30-min time resolution for inorganic trace compounds in both gaseous and aerosol phase such as SO2, NH3, HNO3, HONO, HCl, Cl-, SO42-, NO3-, NH4+, etc. Compared to filter sampling, this new sampling technique solved the problem of losing volatile and semi-volatile compounds during sampling. We have been issued two invention patentsfor this instrument. The field measurement results of GAC were published in international journals such as ACP and AE. GAC is currently being commercialized by Wuhan Yuhong Environmental Protection Development Co., Ltd.

        Both on-line VOC analyzer and GAC were utilized and compared to other instruments with different principles in several field measurements during 2008 and 2011. Those field campaigns include PRIDE-PRD2008 (October-November), CAREBEIJNG2008 for Beijing Olympic Games in summer time, the Asian Game in Heshan, Guangzhou during November 2010, in Changdao Island in Shandong province and Sihong in Jiangsu province for LTP project in April 2011, and Beijing in August 2011. Both systems performed well in different seasons.