10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Time-resolved Monitoring of Primary Intermediate/Semi-volatile Organic Species during Coal Combustion in a Representative Household Stove in Northern China
Abstract Winter household coal combustion is being increasingly held responsible for air pollution in northern China. There exist knowledge gaps with respect to quantitative contribution of household coal stove emissions to SOA, and quantitative measurements of ‘unconventional’ I/SVOCs from coal-fired stoves are thus prerequisites. Herein, high mass resolution PTR-ToF-MS was employed to examine emission of gaseous I/SVOCs and representative VOCs from a common coal-fired stove. Five common coal samples (including three bituminous coals and two anthracite coals) were investigated. Semi-quantitative source profile of 89 primary gaseous species were presented, most of these species are identified as aromatics and oxygenated aromatics. The time-resolved evolvement of representative VOCs and I/SVOCs during one single combustion cycle as well as consecutive coal stoking process were examined. In one single combustion cycle, I/SVOCs emission during the first two stages (ignition and flaming) accounted for about 70% of the total. The average I/SVOCs emission factors of single cycle combustion is ~15% higher than that of consecutive stoking process. Dramatic differences lay between source profiles of anthracites and bituminous coals. For bituminous coal, the compounds of m/z >165 (with C# > 12) account for nearly 20% of the total organic compounds (NMOCs) observed. The same group account for only ~2% of NMOCs from anthracites.
The results of this study make an important supplement to the source spectra of I/SVOCs from household coal combustion. In other studies focusing biomass burning, the compounds in the range m/z >165 accounted for only ~1.5% of the total NMOCs emissions. Our findings indicate that residential coal combustion represent an important I/SVOC emission source than biomass burning in China. Based on available values of SOA yield, I/SVOCs is estimated to account for 40-45% of SOA formed, in the case of bituminous coals. The total NMOCs and I/SVOCs emissions from residential coal combustion are projected to 153 kt and 54 kt in north China in winter, respectively. A full transition from bituminous coal to anthracite will permit a reduction of NMOCs and I/SVOCs emissions by 97% and 99%, respectively.
Current study serves as a proof of principle case quantifying gaseous I/SVOCs from stove emissions using PTR-ToF-MS. Systematical measurements of more types of coals, various types of household stoves, partitioning of I/SVOCs between gaseous and POA phase, is to be carried out.