10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Molecular Insights from Ultrahigh Resolution Orbitrap Mass Spectrometry on Aqueous Phase Processing of Ambient Biomass Burning Emissions Influenced Po Valley Fog and Aerosol
MATTHEW BREGE, Tyler Leverton, Stefania Gilardoni, Stefano Decesari, Marco Paglione, M. Cristina Facchini, Lynn Mazzoleni, Michigan Technological University
Abstract Number: 1367 Working Group: Aerosol Chemistry
Abstract Ambient samples of fog water and PM1 aerosol were collected in the Po Valley (Italy) over four consecutive days in the winter of 2015. The Po Valley has an established history of regional biomass burning emissions influence and aqueous aging processes resulting in significant concentrations of brown carbon. Four samples of fog water and eight samples of extracted PM1 aerosol filters (day and night samples) were analyzed by ultrahigh resolution Orbitrap mass spectrometry using both electrospray ionization and atmospheric pressure photoionization methods. The water-soluble organic matter of the samples was fractionated prior to analysis using a 2-step solid phase extraction procedure for HULIS. This fractionation method facilitated the observation of additional less easily ionized condensed aromatic species. Thousands of distinct molecular formulas were assigned to the monoisotopic masses of each sample, and were categorized into elemental groups and sub-classes based on the observed number of oxygen, nitrogen and/or sulfur atoms in the formulas. An atypically large frequency of molecular formulas containing nitrogen and sulfur were observed. Many of which could be attributed to multifunctional organonitrates and organosulfates, however aromatic species with lower numbers of oxygen abundant in atmospheric pressure photoionization could not. In general, higher numbers of CHNO species were observed in aerosol samples and higher numbers of CHOS species were found in fog water. The observed molecular trends were related to the atmospheric conditions to determine their likely origins. The overlapping collection time periods between the two sample types, and the progressive chronological sampling, allowed for a unique perspective on chemical transformations within this humid atmosphere.