AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Evidence of the Secondary Origin of Nitrocatechols and Alkylated-Nitrocatechols in Atmospheric Aerosol Particles
Alexandre Sylvestre, Sylvain Ravier, Anaïs Detournay, Emily Bruns, Brice Temime-Roussel, Dogushan Kilic, Jay Slowik, Imad El Haddad, Stephen Platt, Andre Prévôt, NICOLAS MARCHAND, Aix Marseille Université, Laboratoire Chimie Environnement
Abstract Number: 255 Working Group: Aerosol Chemistry
Abstract Biomass burning constitutes one major sources of aerosol particles, especially during winter. However, biomass burning aerosols studies mostly focus on the primary fraction, and little is known about Secondary Organic Aerosol (SOA) formation process. Recently, methylated nitrocatechol have been identified in atmospheric particles collected in winter. These compounds are strongly associated with biomass burning markers, such as levoglucosan or dihydroabietic acid. Furthermore, they are suspected to result from secondary sources. Actually, they can be formed through the oxidation of cresol, significantly present in biomass burning emissions. In the present study, a new analytical approach, based on Direct Analysis in Real Time (DART) mass spectrometry, has been adopted.
DART offers analysis of gases, liquids and solids on surfaces, avoiding material losses and significantly reducing the sample preparation time. DART source enables soft ionization and produces simple mass spectra suitable for analysis of complex matrices, like organic aerosol, in only a few seconds. For this study, the DART source was coupled to a Q-ToF mass spectrometer (Synapt G2 HDMS, Waters), with a mass resolution up to 40 000.
The analysis of atmospheric aerosol samples, collected in Marseille during winter 2011 (APICE project), revealed the abundance of nitrocatechols and alkylated nitrocatechols. Furthermore, temporal trends very similar to those of levoglucosan or dihydroabietic acid, were observed. If this point clearly confirm their biomass burning origin, their secondary origin remains not totally clear.
Biomass smoke aging experiments were then conducted at the PSI newly developed temperature controlled smog chamber to better characterize the origin of nitrocatechols. Sample collected were analysed by DART/Q-ToF and result confirms that nitrocatechols are associated with biomass smoke and are more importantly quasi exclusively of secondary origin. Considering the abundance of biomass burning primary aerosol, and the large fraction of unexplained SOA, this result is of prime importance.