Investigating reactive tropospheric nitrogen oxides by thermal-dissociation cavity ring-down spectroscopy

Gingerysty, Nicholas John Louis

Investigating reactive tropospheric nitrogen oxides by thermal-dissociation cavity ring-down spectroscopy

dc.contributor.advisor	Osthoff, Hans D.
dc.contributor.author	Gingerysty, Nicholas John Louis
dc.contributor.committeemember	Gailer, Jürgen G.
dc.contributor.committeemember	Kimura, Susana Y.
dc.date	2021-06
dc.date.accessioned	2021-01-26T16:01:32Z
dc.date.available	2021-01-26T16:01:32Z
dc.date.issued	2021-01-18
dc.description.abstract	The nitrogen oxides are important trace constituents of the troposphere that originate mainly from anthropogenic sources. Accurate quantification techniques are needed to characterize their abundance and to assess their impact on air quality. This thesis describes a compact and portable source that delivers nitrous acid (HONO) in high purity (>95%). HONO is produced dynamically by reacting a gas stream containing < 1 part per million (by volume) HCl gas at relative humidity of 30% - 40% with solid sodium nitrite. The production of HONO and absence of impurities such as nitric oxide (NO), nitrogen dioxide (NO2) and nitrosyl chloride (ClNO) were verified by Fourier transform infrared (FTIR) and thermal dissociation cavity ring-down spectroscopy (TD CRDS). The interference from HONO in the measurement of NO2 by photolytic conversion with chemiluminescence detection (P-CL) was investigated in two prototype converters. The first used radiation centred around 395 nm, common in P-CL. The second utilized 415 nm light, where the overlap with the HONO absorption spectrum and expected HONO interference are lower. Mixing ratios of NO2, NOx and HONO entering and exiting the converters were quantified by TD-CRDS. Both converters exhibited high NO2 conversion efficiency (CFNO2 >90%). Plots of CF against flow rate delivered photolysis frequencies of 4.2 s-1 and 2.9 s-1 for NO2 and 0.25 s-1 and 0.10 s-1 for HONO at 395 nm and 415 nm, respectively. The CFHONO was larger than predicted implying that measurements of NO2 by P-CL overestimate NO2 concentrations. Mixing ratios of nitrogen oxides were quantified during the SNOWDOGS campaign in Fort MacKay, AB, in January 2020. The group's TD-CRDS was modified to simultaneously quantify mixing ratios of NO2, HNO3, gas phase NOy, and total NOy (including particulate nitrate). High nitrogen oxide concentrations at night and faster than expected daytime conversion of NO2 to nitric acid (HNO3) and particulate nitrate were observed, indicating that the nitrogen oxides are processed primarily by photochemical reactions in polluted regions at high latitude during winter.	en_US
dc.identifier.citation	Gingerysty, N. J. L. (2021). Investigating reactive tropospheric nitrogen oxides by thermal-dissociation cavity ring-down spectroscopy (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/38580
dc.identifier.uri	http://hdl.handle.net/1880/113012
dc.language.iso	eng	en_US
dc.publisher.faculty	Science	en_US
dc.publisher.institution	University of Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.subject	Chemistry	en_US
dc.subject	nitrogen oxides	en_US
dc.subject	nitrous acid	en_US
dc.subject	cavity ring-down spectroscopy	en_US
dc.subject	photolytic conversion	en_US
dc.subject	Athabasca oil sands	en_US
dc.subject.classification	Chemistry--Analytical	en_US
dc.subject.classification	Atmospheric Science	en_US
dc.title	Investigating reactive tropospheric nitrogen oxides by thermal-dissociation cavity ring-down spectroscopy	en_US
dc.type	master thesis	en_US
thesis.degree.discipline	Chemistry	en_US
thesis.degree.grantor	University of Calgary	en_US
thesis.degree.name	Master of Science (MSc)	en_US
ucalgary.item.requestcopy	true	en_US