Biogenic and biomass burning organic aerosol in a boreal forest at Hyytiälä, Finland, during HUMPPA-COPEC 2010

Abstract

Abstract. Submicron aerosol particles were collected during July and August 2010 in Hyytiälä, Finland, to determine the composition and sources of aerosol at that boreal forest site. Submicron particles were collected on Teflon filters and analyzed by Fourier transform infrared (FTIR) spectroscopy for organic functional groups (OFGs). Positive matrix factorization (PMF) was applied to aerosol mass spectrometry (AMS) measurements and FTIR spectra to identify summertime sources of submicron aerosol mass at the sampling site. The two largest sources of organic mass (OM) in particles identified at Hyytiälä were (1) biogenic aerosol from surrounding local forest and (2) biomass burning aerosol, transported 4–5 days from large wildfires burning near Moscow, Russia, and northern Ukraine. The robustness of this apportionment is supported by the agreement of two independent analytical methods for organic measurements with three statistical techniques. FTIR factor analysis was more sensitive to the chemical differences between biogenic and biomass burning organic components, while AMS factor analysis had a higher time resolution that more clearly linked the temporal behavior of separate OM factors to that of different source tracers even though their fragment mass spectrum were similar. The greater chemical sensitivity of the FTIR is attributed to the nondestructive preparation and the functional group specificity of spectroscopy. The FTIR spectra show strong similarities among biogenic and biomass burning factors from different regions as well as with reference OM (namely olive tree burning organic aerosol and α-pinene chamber secondary organic aerosol (SOA)). The biogenic factor correlated strongly with temperature and oxidation products of biogenic volatile organic compounds (BVOCs), included more than half of the oxygenated OFGs (carbonyl groups at 29% and carboxylic acid groups at 22%), and represented 35% of the submicron OM. Compared to previous studies at Hyytiälä, the summertime biogenic OM is 1.5 to 3 times larger than springtime biogenic OM (0.64 μg m−3 and 0.4 μg m−3, measured in 2005 and 2007, respectively), even though it contributed only 35% of OM. The biomass burning factor contributed 25% of OM on average and up to 62% of OM during three periods of transported biomass burning emissions: 26–28 July, 29–30 July, and 8–9 August, with OFG consisting mostly of carbonyl (41%) and alcohol (25%) groups. The high summertime terrestrial biogenic OM (1.7 μg m−3) and the high biomass burning contributions (1.2 μg m−3) were likely due to the abnormally high temperatures that resulted in both stressed boreal forest conditions with high regional BVOC emissions and numerous wildfires in upwind regions.

Improving the simulation of global aerosol with size-segregated anthropogenic number emissions

“…GAINS underestimated the Aitken mode particle concentrations more heavily than AeroCom, by a factor of two to three in Hyytiälä, Värriö and Kpuszta, suggesting that the higher condensation sink associated with higher accumulation mode particle emissions in GAINS had a significant impact on modeled ultra-fine particle number concentrations. In addition, Hyytiälä and Värriö are regions in which BVOC emissions and clean air are the key influencing factors for new particle formation and particle growth (Ruuskanen et al, 2007;Corrigan et al, 2013;Liao et al, 2014). This was reflected in the model results: particle number size distributions in Hyytiälä and Värriö were quite similar between the two simulations based on different anthropogenic emission data sets.…”

Estimating the contribution of organic acids to northern hemispheric continental organic aerosol

“…The correlation of total organic acids to OA and m/z 44 was also observed at Hyytiälä, during the spring 2013 (Figures 1e-1h) and HUMPPA-COPEC 2010 studies (Figures 1i-1l) [Corrigan et al, 2013;Vogel et al, 2013]. In this boreal forest, 45-51% of OA mass is accounted for by organic molecules containing at least one acid group.…”

“…This is higher than that observed during BEACHON-RoMBAS. Corrigan et al [2013] note that the high OA mass concentration during HUMPPA-COPEC 2010 is due to aged biomass burning plumes advected from forest fires in central Russia, together with unusually high temperatures in Finland during the campaign period leading to enhanced biogenic SOA formation. Thus, the enhanced aging and/or biomass burning impacts may explain the higher organic acid concentration observed during the HUMPPA-COPEC 2010.…”

“…Monoterpenes and isoprene are the main biogenic VOCs emitted at this site [Yassaa et al, 2012]. During HUMPPA-COPEC 2010, organic acids were measured using an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) coupled to a miniature versatile aerosol concentration enrichment system (mVACES) [Vogel et al, 2013] while OA was measured using a compact time-of-flight AMS [Drewnick et al, 2005;Corrigan et al, 2013]. During Hyytiälä-2013, organic acids were measured using a filter inlet for gases and aerosol (FIGAERO) coupled to an HRToF-CIMS [Lopez-Hilfiker et al, 2014] and OA was measured using an aerosol chemical speciation monitor (ACSM) [Ng et al, 2011].…”

Fire Influences on Atmospheric Composition, Air Quality and Climate

“…A particularly prominent example is the fire-driven air pollution episode of summer 2010 in western Russia, which affected not only Russia itself but also other parts of Northern Europe [60] and even southern Europe [58], as mentioned earlier. For a boreal forest in Hyytiälä, Finland, using two independent analytical methods and three separate statistical methods, Corrigan et al [61] showed that biomass burning is responsible for 25 % of submicron organic aerosols in the area, especially in the relatively warm and dry months of summer.…”