Laboratory Investigation of ClNO2 Production from Environmental Samples Collected Near the Great Salt Lake

JAMES CHRISTIE, Sean O'Connel-Lopez, Kevin Perry, Kerri Pratt, Cassandra Gaston, University of Miami

     Abstract Number: 282
     Working Group: Aerosol Chemistry

Abstract
In recent years, Salt Lake City has experienced increased wintertime ozone (O3), which is a criteria air pollutant and greenhouse gas. A potential source of wintertime O3 is thought to be the nighttime reaction between chloride containing aerosols and dinitrogen pentoxide (N2O5) which leads to the production of nitryl chloride (ClNO2). In the daytime, ClNO2 will then photolyze to produce chlorine radicals (Cl•), which is a precursor to O3. However, the sources of these chloride containing aerosols in the Great Salt Lake Basin, and their subsequent reaction kinetics remain unclear. To better understand this, we analyzed environmental samples collected near the Great Salt Lake and Salt Lake City to investigate their ClNO2 forming potential. To simulate realistic wintertime conditions where chloride containing aerosols react with N2O5 we used an aerosol kinetic flow tube under varying relative humidities. To analyze the kinetic uptake of N2O5 and propensity to generate ClNO2 of our samples, we utilized chemical ionization mass spectrometry (CIMS) coupled to an aerodynamic particle sizer (APS) and scanning mobility particle sizer to determine our surface area concentrations and calculate the reactive uptake of N2O5. Coupling the CIMS with aerosol time of flight mass spectrometry (ATOFMS), we were able to simultaneously determine the chemical composition of our samples and explore how aerosol size-resolved composition impact ClNO2 production. This work highlights how the varied chemical composition of our samples affects the formation of ClNO2 while simultaneously calling attention to potential sources of wintertime O3 in Salt Lake City.