Oxidized organic functional groups in aerosol particles from forest emissions measured at mid-mountain and high- elevation mountain sites in Whistler, BC

Aerosols contribute to the largest uncertainty in climate prediction (IPCC, 2007) from both direct and indirect radiative forcing; these effects are influenced by particle size and chemistry. Although organic compounds constitute a large part of aerosols, this fraction is poorly characterized. In an effort to address the complexity of organic aerosols, aerosol particles were collected in Whistler, British Columbia, at a mid-mountain site in spring 2008 and a peak site in spring and summer 2009. The organic functional group composition of the collected aerosol was measured by Fourier transform infrared (FTIR) spectroscopy. At the mid-mountain site the organic mass (OM) project mean was 1.3 ± 1.0 [mu]g m⁻³. On average, organic hydroxyl, alkane, and carboxylic acid groups represented 34%, 33%, and 23% of OM, respectively. Positive matrix factorization (PMF) analysis, which was employed with complementary elemental characterization, attributed 65% of the campaign OM to biogenic sources. The functional group composition of the biogenic factor was similar to that of secondary organic aerosol (SOA) reported from the oxidation of biogenic volatile organic compounds (BVOCs) in laboratory chamber studies, providing evidence that the magnitude and chemical composition of biogenic SOA simulated in the laboratory is similar to that found in actual atmospheric conditions. At the mountain peak site the OM project mean for all samples was 3.2 ± 3.3 [mu]g m⁻³ and reached a maximum of 13.6 [mu]g m⁻³ during severe wildfires. Both burning and non-burning forest emissions contributed to the significant ketone groups measure