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Light-absorbing carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions
Citation:
Hays, M., M. Xie, AND A. Holder. Light-absorbing carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions. American Association for Aerosol Research, Raleigh, NC, October 16 - 20, 2017.
Impact/Purpose:
The OC generated from BB or gasoline vehicle emissions shows strong light absorption and wavelength dependence; the biomass fuel type may also play a role in the light-absorbing properties of OC generated from BB. How biomass fuel type affects the light absorption of OC from BB is uncertain and merits further study. Gasoline vehicles tend to emit stronger light-absorbing OC in winter than in summer. Compared to BB, the light absorption of OC from gasoline vehicle emissions was of the same magnitude but weaker, suggesting the importance of gasoline vehicle emissions as a BrC source in urban regions.
Description:
Carbonaceous aerosols are ubiquitous in the atmosphere and can directly affect Earth’s climate by absorbing and scattering incoming solar radiation. Both field and laboratory measurements have confirmed that biomass burning (BB) is an important primary source of light absorbing organic carbon (OC), also termed as “BrC”, which is also clearly observed in BB-impacted atmospheres. However, chemical and optical information about the BrC emitted from prescribed or controlled burning is scant. Prescribed burning is a less intensive fire technique used in forest and agricultural land management, or for land restoration objectives. Prescribed agricultural burns prepare fields for planting, stimulate plant growth and yields, and control pests, whereas prescribed forest burning is used to abate aggressive wildfire and promote ecological succession and sustainability. In addition, motor vehicles are also a primary source of PM2.5 emissions to urban atmospheres. While direct measurements of BrC from primary vehicle emissions are still lacking. This study attempts to address limitations in understanding BrC as it relates to primary source combustion emissions. In that vein, UV-Vis spectrometry was applied to measure the light-absorbing properties of OC in methanol extracts of prescribed and laboratory BB and gasoline vehicle aerosol emissions. The gasoline vehicle emissions were sampled during different seasons (winter and summer) while also examining vehicle class (truck and car) and model year variables.