Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

Journal Article · Fri Nov 27 00:00:00 EST 2009 · Atmospheric Chemistry and Physics, 9(22):8949-8966

DOI:https://doi.org/10.5194/acp-9-8949-2009· OSTI ID:972958

lewis, Kristen A; Arnott, W P; Moosmuller, H; Chakrabarti, Raj; Carrico, Christian M; Kreidenweis, Sonia M; Day, Derek E; Malm, William C; Laskin, Alexander; Jimenez, Jose L; Ulbrich, Ingrid M; Huffman, John A; Onasch, Timothy B; Trimborn, Achim; Liu, Li; Mishchenko, M

Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 972958
• Report Number(s): PNNL-SA-67663; 19793; KP1704020; TRN: US201005%%470
• Journal Information: Atmospheric Chemistry and Physics, 9(22):8949-8966, Vol. 9, Issue 22
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ABSORPTION
AEROSOLS
AQUEOUS SOLUTIONS
BIOFUELS
BIOMASS
CARBON
CHEMICAL COMPOSITION
COATINGS
COMBUSTION
CROSS SECTIONS
EVAPORATION
HEAT TRANSFER
HUMIDITY
HYGROSCOPICITY
LASERS
LIGHT SCATTERING
MASS SPECTROMETERS
MASS TRANSFER
MONOMERS
PARTICLE PROPERTIES
SHIELDING
Environmental Molecular Sciences Laboratory