Mobile Near-Field Measurements of Biomass Burning Volatile Organic Compounds: Emission Ratios and Factor Analysis

Comprehensive measurements of volatile
organic compounds (VOCs)
and oxygenated VOCs that are emitted from wildfires are important
inputs for constraining ozone and secondary organic aerosol formation
potential in chemical transport models. Using Vocus proton-transfer
reaction mass spectrometer and tunable infrared laser direct absorption
spectroscopy instruments on a mobile laboratory during the Fire Influence
on Regional to Global Environments and Air Quality (FIREX-AQ) 2018
and 2019 campaigns, seven different fires over two years were sampled
from <10 km away providing extensive chemical composition and aging
information about emissions of VOCs and oxidized VOCs from fires.
Several of these fires were sampled <300 m from burning fuels,
yielding insight into relatively fresh smoke measurements. The emission
ratios reported here are statistically consistent with measurements
of controlled fires in a laboratory setting. Chemically unique mass
spectral signatures of low- and high-temperature pyrolysis are determined
from factor analysis while sampling real-world fires burning in heterogeneous
stages.