Understanding the effects of atmospheric conditions on climate change and human health is a major challenge facing scientists today. Due to the large global emissions (~1000 Tg/year) of biogenic volatile organic compounds (BVOCs), their oxidation in the atmosphere is a large source of secondary organic aerosol (SOA), an important component of fine mode particulate matter that plays a critical and complex role in the atmosphere.
Near the Earth's surface, SOA threatens human health through respiratory and cardiovascular damage, and contributes substantially to poor air quality. In the upper troposphere, aerosols not only exhibit a direct radiative forcing (i.e. impact on global temperature), but also participate in a complex water vapor feedback cycle by affecting cloud formation and precipitation patterns, resulting in indirect climate forcing.
The Claeys group develops and applies bio-organic mass spectrometric methods to better understand complex systems, including both biochemical and biogeochemical systems. Since about 15 years the group focuses on the chemical characterization of SOA formed from volatile organic compounds (VOCs) that are of biogenic or anthropogenic origin. As VOCs undergo oxidation and/or photolysis in the atmosphere, compounds can be produced with higher functionality, greater reactivity, and lower volatility. This contributes to the growth of SOA mostly through increased solubility in aqueous-phase aerosols.
Emphasis is given to the chemical characterization of marker compounds or tracers that are formed from a certain VOC and are present in fine ambient aerosol, so that their detection allows one to obtain information on aerosol sources (i.e. precursors) and source processes. For the chemical characterization of SOA tracers use is made of organic mass spectrometric and chromatographic approaches and synthesis of reference compounds.
Current projects concern the investigation of the mechanisms leading to SOA formation from isoprene, monoterpenes (e.g. α-pinene) and green leaf volatiles (e.g. 3-Z-hexenal) through the chemical characterization of tracers. To this aim, SOA is generated in environmental chambers under controlled conditions and compared with fine ambient aerosol collected from vegetated regions during summer.
In addition, emphasis is also given to the characterization of regional fine aerosol collected in Flanders, Belgium, with focus on the impact of biomass burning and traffic. In this research the impact of biomass burning is assessed through the measurement of a primary tracer, levoglucosan, which is formed via pyrolysis of celllulose, whereas the impact of traffic is assessed through the measurement of the elemental carbon.