Research interests

Knowledge of the chemical composition of individual aerosol particles is essential for our understanding of aerosol dynamics and chemistry in the atmosphere. Size resolved composition on the single particle level can provide detailed information on processes such as the formation, transformation and deposition of aerosols.

My work has been focused on techniques to enable quantification of the alkali content in single aerosol particles. A newly developed aerosol mass spectrometer, AMS, based on surface ionization technique has provided the tool for on-line studies of submicron particles and the subsequent chemical analysis with respect to their alkali content. Special attention to instrumental design during the construction, calibration, and optimization phase of the project has resulted in an instrument applicable for field studies.

AMS has proved useful during field measurements and data sampled from different aerosol sources has added detailed information on the alkali metal content in individual particles. Submicron combustion particles from large-scale biomass combustion were found to consist of almost pure potassium salt for particle diameters < 100 nm. As larger biomass particles were sampled, the fraction of fly ash particles with a thin coating of alkali salt on the surface increased. The potassium content in particles from coal combustion was in general low, but sodium was detected in higher concentrations in this fuel compared to the biomass fuel. Alkali concentrations in ambient air showed large variations in particle size and number distributions. Elevated sodium number concentrations could be linked to air masses with a marine contribution to the aerosol.

The quadrupole MS in the AMS was recently replaced and an orthogonal acceleration time-of-flight MS was installed to allow simultaneous detection of multiple elements in single particles.

Selected publications