Gas–particle partitioning of semivolatile organic compounds when wildfire smoke comes to town

Abstract

Abstract. Wildfires have become an increasingly important source of organic gases and particulate matter in the western USA. A large fraction of organic particulate matter emitted in wildfires is semivolatile, and the oxidation of organic gases in smoke can form lower-volatility products that then condense on smoke particulates. In this research, we measured the gas- and particle-phase concentrations of semivolatile organic compounds (SVOCs) during the 2017 northern California wildfires in a downwind urban area, using semivolatile thermal desorption aerosol gas chromatography (SV-TAG), and measured SVOCs in a rural site affected by biomass burning using cTAG (comprehensive thermal desorption aerosol gas chromatography mass spectrometry) in Idaho in 2018. Commonly used biomass burning markers such as levoglucosan, mannosan, and nitrocatechols were found to stay predominantly in the particle phase, even when the ambient organic aerosol (OA) was relatively low. The phase partitioning of SVOCs is observed to be dependent on their saturation vapor pressure, while the equilibrium absorption model underpredicts the particle-phase fraction of most of the compounds measured. Wildfire organic aerosol enhanced the condensation of polar compounds into the particle phase but not some nonpolar compounds, such as polycyclic aromatic hydrocarbons.

Hygroscopicity and Volatility of Biomass Burning Aromatic and Nitroaromatic Compounds

“…Based on these observations, it is reasonable to assume that these compounds will remain particle-bound throughout their atmospheric lifetime, even in aqueous solution. Indeed, this is consistent with observations of wildfire smoke particles that show 4NC is primarily particle bound even when aerosol mass concentrations are low following plume dilution . This also indicates favorable gas-to-particle partitioning of compounds with similar volatility in the BB plume.…”

“…Indeed, this is consistent with observations of wildfire smoke particles that show 4NC is primarily particle bound even when aerosol mass concentrations are low following plume dilution. 54 This also indicates favorable gas-to-particle partitioning of compounds with similar volatility in the BB plume.…”

Molecular Characterization of Gaseous Organic Acids and Nitrogen‐Containing Compounds From Crop Straw and Wood Burning

“…However, the gas-phase C 6 H 10 O 5 is not expected to be the most abundant species from fresh crop straw and wood burning emissions in this study, attributing to the fact that C 6 H 12 O 5 is more enriched in the particle phase rather than the gas phase due to fast gas-particle partitioning. Consistently, Liang et al (2023) evaluated the phase partitioning behaviors of biomass burning markers and found that levoglucosan, mannosan and nitrocatechols mainly stay in the particle phase.…”