Real-time analysis of atmospheric aerosols using Aerosol time-of-flight mass spectrometry

Recent interest in atmospheric aerosols has stimulated development of a number of new aerosol analysis techniques. Our group has pursued the development of a single particle approach in order to gain new insight into the issues regarding internally and externally mixed particles populations. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that obtains both size and chemical composition of individual particles on a continuous basis. The instrument can obtain this data in real-time with time resolution approaching many gas-phase and meteorological measurement techniques, thus allowing for direct comparisons.

Data acquired by ATOFMS can be used for many different atmospheric applications. Particles can be emitted from a variety of both natural and anthropogenic sources. The chemical composition of the particles is reflective of the source from which it is emitted. Since ATOFMS obtains chemical composition for individual particles (essentially obtaining a chemical "fingerprint"), it is possible to identify a particle as derived from a particular source based on its observed chemical composition. The presence of particles from different sources can thus be traced in the atmosphere with temporal resolutions of 15 minutes.

ATOFMS measurements can also be correlated with ambient meteorological data. Meteorological parameters such as temperature, relative humidity, and wind direction can be compared to ATOFMS data to look for changes in the observed particle composition. Particles can be monitored during meteorological changes, such as before, during, and after a significant wind event. In addition, changes in temperature and relative humidity can be correlated with chemical composition changes due to heterogeneous processes.

This presentation will focus on the ability of ATOFMS to perform as a continuous particle measurement technique in these various applications. Emphasis will be placed on the potential advantages of having continuous chemical composition data on aerosols to integrate with gas-phase and meteorological data.