Date of Award
Master of Science
Huff Hartz, Kara
Particulate matter (PM), which often consists of secondary organic aerosol (SOA), has been linked to climate change and adverse human health issues. To help reduce the negative effects of PM, the ability to predict and model SOA formation is necessary. In order to accurately predict and model SOA, understanding how the atmospheric environment affects SOA formation is critical. Not only do the effects of parameters such as temperature, UV light exposure, relative humidity, and pressure need to be known but how the identity and mass of VOCs precursors as well as the number of VOCs presence effects SOA formation needs to be addressed. In this work, the SOA yields from the ozonolysis of a Siberian fir needle oil (SFNO) and a Canadian fir needle oil (CFNO) along with various precursor mixtures containing reactive and non-reactive VOCs were investigated. The SOA yields were compared to an α-pinene two-product model and a volatility basis set (VBS) study for SFNO. Mixture studies such as these more accurately describe the atmosphere where a multitude of VOCs may exist at a given time opposed to the majority of research which involves the oxidation of single precursors such as α-pinene. The reproducibility issue usually associated with direct emission studies is also avoided for the reason that amount of each VOC within each mixture being oxidized is known. The addition of nonreactive VOCs such as bornyl acetate, camphene, and borneol had very little to no effect on SOA yields. The oxidation of VOC mixtures with VOC mass percentages similar to the SFNO produced SOA yields that became more similar to the SOA yield from SFNO as the complexity and concentration of VOCs within the mixture became more similar to overall SFNO composition. The SOA yield produced by the oxidation of CFNO was within the error the SOA yield produced by the oxidation SFNO at similar mass concentration. The composition of FNO had little to no effect on the overall SOA yield. A VBS study was conducted for the SFNO and the results of said study proved to be useful for predicting the SOA yields for a given mass oxidized for mixtures containing similar VOCs.
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