Week #8 Report

This week a lot of sample and data analysis is happening on ambient urban aerosols. The following pictures shows some data we found interesting and hopefully you would find them intriguing as well.


The three mass spectra displayed right here are all from the urban aerosol samples collected in Toronto, Canada, though at different times. The red pin in the map shows the location of the sampling site. As you may see, the three spectra are very different from each other despite they are collected in the same space. After some literature research, we speculate that such difference in spectral pattern is caused by the difference in the major source of organics for these samples. Notice that Toronto is a city located by a lake, and the first spectrum possesses a strong signature of aerosols with lake/marine origin: the ion species CH3SO2+. Therefore, we believe that this particular sample may be influenced by aerosols brought by the east winds from the lake.

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For the second spectrum, we can see spikes at high mass numbers, such as C6H9O2+, C7H5O+, and C4H9O2+. These ion species can generally be found in mass spectrum of aerosol with influence from the burning of diesels (for example, from the emissions of buses). Hence, we may conclude that this aerosol sample has an urban source, rather than a lake/marine one. Furthermore, for the third spectrum, we can see small spikes for the signature ions of both urban and waters source. This sample is probably influenced by both aerosol sources. These three samples demonstrate the importance of considering the geography surrounding the sample sites while analyzing the source of aerosol samples.

Next week will be my last week for summer research and I will take off on Friday, July 26th. A major amount of samples and data, including biomass burning and ambient urban aerosols, are still waiting for me to analyze. Hopefully you will stay with me for my last post!