Session: General Posters:

Many important atmospheric aerosol processes, such as water uptake and particle cloud interactions, depend on the chemical composition of the aerosol particles. Atmospheric ageing processes, i.e. oxidation reactions, can significantly change the chemical composition of aerosol particles during their atmospheric lifetime and consequently their interaction with water. Low molecular weight dicarboxylic acids represent a significant fraction of the organic aerosol particles collected from the continental and marine atmosphere, but their ageing processes and cloud condensation nuclei (CCN) activity are often poorly understood. Therefore, maleic acid aerosol particles are employed in this study as surrogates of short unsaturated dicarboxylic acids to assess their chemical transformations in tropospheric heterogeneous chemistry as well as their impact on cloud formation.
A flow tube reactor system in conjunction with standard tools for aerosols production and characterization, a high-resolution mass spectrometer and a cloud condensation nuclei counter are utilized in this study to quantify the changes occurred in the CCN activity of maleic acid particles as a result of reaction with ozone. The reactive uptake coefficient of ozone by maleic acid is found to depend on the size of the particle and to decrease with increasing the particle diameter. In addition, the exposure of maleic acid particles in the flow tube reactor to controlled amounts of O₃ at relative humidity below 4% significantly enhanced their CCN activity. This study emphasizes the importance of investigating the rate of change in CCN activity of dicarboxylic acids under the combined effects of several atmospheric parameters as oxidants and relative humidity to accurately describe their role in cloud formation.

Dr. Denisia Popolan-Vaida

Assistant Professor, University of Central Florida

Appearances