AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Ambient Biomass Burning Influenced Fog and Aerosol Samples: Molecular Insights on Aging
MATTHEW BREGE, Marco Paglione, Stefania Gilardoni, Stefano Decesari, M. Cristina Facchini, Lynn Mazzoleni, Michigan Technological University
Abstract Number: 184 Working Group: There Must be Something in the Water: Cloud, Fog and Aerosol Aqueous Chemistry for Aerosol Production
Abstract Ambient samples of fog and aerosol influenced by regional biomass burning emissions and secondary processes were collected in the Italian Po Valley during the 2013 Supersito field campaign. Two samples of fog water and two samples of PM1 aerosol were selected for ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometric analysis after the extent of “fresh” vs “aged” biomass burning influence was determined from factor analysis of 1H-NMR results and analysis of AMS mass spectra. Over 4300 distinct molecular formulas were assigned and sorted into 4 elemental groups (CHO, CHNO, CHOS and CHNOS) and 64 subclasses. These samples had an atypically large frequency of molecular formulas containing nitrogen and sulfur, attributed to nucleophilic substitution reactions with nitrate and sulfate ions in the aqueous phase of fog and aerosol water. Samples with significant influence of “aged” biomass burning emissions contained highly oxygenated (O/C > 0.6) and more saturated (H/C > 1.2) molecular formulas compared to those with primarily “fresh” emissions. Averages of the molecular formula double bond equivalents and carbon numbers were higher in the “fresh” biomass burning influenced samples, whereas the average O/C and H/C values were higher in samples influenced by “aged” biomass burning. Several molecular formulas detected in the Po Valley samples were identical to those from ambient biomass burning emission samples previously studied, however a large fraction were not previously observed, highlighting the importance of additional studies with respect to biomass burning aging in atmospheric aerosol.