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Faculty of Graduate Studies Graduate Programme in Chemistry

Ibraheem Nuaaman:
A Candidate for the Degree Doctor of Philosophy

Title of Thesis:
Investigation of air pollutants near the Great Lakes in Ontario and along the coast of California

Public Talk: Monday, April 20th, 2015, 1:30 - 2:15 PM., Room 317 PSE


Carbonyl measurements in rural Ridgetown, Ontario using an AT-DNPH-HPLC system during the BAQS-Met study (2007) will be discussed. An overview of the significance, source and sinks of carbonyls will be given. Principle of operation and calibrations for the AT-DNPH-HPLC system will be presented. Total carbonyl mixing ratios were observed to be few ppb. Carbonyls accounted for 22% of the non-methane hydrocarbon (NMHC) distribution and aldehyde contribution to NMHC reactivity towards OH radical was 37%. The net photochemical formation rate (S-L) was estimated and compared to the maximum observed formation established from diurnal profiles. The HCHO to CH3CHO ratio revealed that carbonyl precursors are largely anthropogenic in nature. The highest carbonyl concentrations were observed with trans-boundary transport associated with airmasses that passed over Michigan and Illinois. Local O3 sensitivity was established using the HCHO/NO2 ratio and this area was found to be sensitive to both VOCs and NOx. Carbonyls accounted for 35% of O3 formation estimated using the MIR scale. Lake breeze events had no significant impact on carbonyl concentrations in this location.
Aerosols were measured along the coast of California using an HR-AMS during the CalNex study (2010). The significance, sources and sinks of aerosols will be presented. Principle of operation and calibrations of the HR-AMS will be discussed. Submicron aerosol concentrations and composition under land breeze and sea breeze events will be shown. The highest chloride signal (HxCl+) was observed during sea sweep experiments where artificially generated sea spray aerosols were sampled. This is despite the low sensitivity of the HR-AMS to refractory (RF) NaCl. A method is proposed to establish non-refractory p-Cl in ambient air through a subtraction of RF HxCl+ estimated using HxCl+ to Na35Cl+ ratio in sea sweeps. In ambient air, the contribution of refractory (RF) HxCl+ to HxCl+ signal was as high as 89%. A method to establish percentage chloride depletion in ambient air strictly using HR-AMS data is proposed and the results presented. The effects of relative humidity, temperature and pH on p-Cl and p-NO3 will be discussed. Finally, the organic fractionation of Pacific sea spray aerosols sampled during sea sweep experiments will be discussed.



Updated on December 7th, 2015.