Dr. Markus Kalberer (Chemistry)
Chemistry of atmospheric aerosols and their effects on human health
Atmospheric aerosol particles (with a size range of a few nanometers to tens of micrometers) are key components in the climate system and are associated with respiratory and cardio-vascular diseases. In both areas the chemical composition and reactivity of aerosol particles are important.
Our research activities include:
Analysis of the composition of organic aerosols
About 30-50% of atmospheric aerosol particles are composed of organic material. The chemical composition, formation pathways, and reactions of this organic material are poorly characterised.
To gain more detailed insights into the chemical composition of organic aerosols, we are using a number of state-of-the-art analytical-chemical techniques, including ultra- high resolution mass spectrometry, NMR and chromatographic methods. Changes in the organic composition of the aerosols due to atmospheric oxidation reactions are investigated, and the corresponding changes in the climate forcing and toxicity of the aerosol are explored. We are generating and reacting aerosol particles in laboratory experiments or analyse particles collected from the ambient atmosphere.
The emphasis of these analyses is currently on elucidating the role of the recently discovered high molecular weight organic oligomers and humic-like substances that are often found in atmospheric aerosol.
(a) Mass spectrum (MS) of organic aerosol particles, generated and oxidized in a laboratory set-up. Hundreds of small oligomers are generated with masses up to 1000 m/z (Kalberer et al., Science, 2004).
(b) If measured with a high resolution mass spectrometer, the elemental composition of all compounds in a MS can be determined. The oxygen to carbon atom ratios are shown here for all higher molecular weight compounds in the MS of another laboratory aerosols sample (dots represent peaks in the original MS), which allows the deduction of possible formation mechanisms and structures of oligomers and monomers (Reinhardt et al., Anal.Chem., 2007).
Development of analytical-chemical instrumentation
To advance our knowledge of the chemical composition of aerosols novel analytical methods and instrumentation are required. Recently we have introduced a number of new analytical techniques to the field of atmospheric sciences, most notable in the field of mass spectrometry. We are currently developing analytical methods and instruments to identify and quantify the components of aerosol that are relevant to human health effects.
Interactions of aerosol particles with the lung
Epidemiological studies have shown correlations between aerosol particle exposure and a range of adverse health effects. However, the interaction of particles with the lung, the main pathway of undesired particle uptake, are not well known and a mechanistic understanding of particle effects in lung cells is lacking. We recently built a particle deposition chamber, which allows for an accurate deposition of nanometer sized aerosol particles on lung cell cultures mimicking accurately the in vivo physiological conditions. In collaboration with cell biologists and toxicologists we are investigating the effects of particle composition and particle source on the biochemical and physiological responses of lung cells.
- Dr. Markus Kalberer: Group leader in the Atmospheric Laboratory Studies sector of CAS