Quantification of Non-refractory Aerosol Nitrate in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy

Garner, Natasha M; Matchett, Laura C; Osthoff, Hans D

Quantification of Non-refractory Aerosol Nitrate in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy

dc.contributor.author	Garner, Natasha M
dc.contributor.author	Matchett, Laura C
dc.contributor.author	Osthoff, Hans D
dc.date.accessioned	2021-06-22T17:13:48Z
dc.date.available	2021-06-22T17:13:48Z
dc.date.issued	2020-07-08
dc.description.abstract	A thermal dissociation cavity ring-down spectrometer (TD-CRDS) for real-time quantification of non-refractory aerosol nitrate in ambient air is described. The instrument uses four parallel detection channels and heated quartz inlets to convert particulate organic nitrate (pON) (at 350 °C) and ammonium nitrate (NH4NO3) aerosol (at 540 °C) to nitrogen dioxide (NO2), whose mixing ratio is monitored via its absorption at 405 nm. Concentrations of aerosol nitrate are determined by difference relative to a parallel TD-CRDS channel in which aerosol is removed by in-line filtering. The method was validated by sampling gas streams containing laboratory-generated NH4NO3 aerosol in parallel to a scanning mobility particle sizer (SMPS). Scatter plots of TD-CRDS and SMPS data correlated (r2 > 0.9) with slopes near unity, confirming quantitative TD-CRDS response to NH4NO3 aerosol. In contrast, no response was observed when sampling (NH4)2SO4 aerosol. Instrument limits of detection (LOD; 2σ, 10 s) were 120 parts per trillion by volume (10-12, pptv) for NO2 and 148 pptv for ammonium nitrate. Partial and unsustained conversion of refractory sodium nitrate (NaNO3) was observed at the inlet temperature used for complete dissociation of HNO3 and NH4NO3, suggesting that this channel may not constitute a robust measurement of total odd nitrogen (NOy ) in environments where NaNO3 particles may be present (e.g., the polluted marine boundary layer). A potential application of the TD-CRDS is the calibration of particle counters, for which convenient methods are not currently available. Sample ambient air measurements of pON and total aerosol nitrate in Calgary are presented.	en_US
dc.description.grantingagency	Natural Sciences and Engineering Research Council (NSERC)	en_US
dc.identifier.citation	Garner, N. M., Matchett, L. C., & Osthoff, H. D. (2020). Quantification of Non-refractory Aerosol Nitrate in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy. Environmental Science & Technology, 54(16), 9854–9861. doi:10.1021/acs.est.0c01156	en_US
dc.identifier.doi	http://dx.doi.org/10.1021/acs.est.0c01156	en_US
dc.identifier.grantnumber	RGPIN/03849-2016	en_US
dc.identifier.uri	http://hdl.handle.net/1880/113523
dc.language.iso	eng	en_US
dc.publisher.department	Chemistry	en_US
dc.publisher.faculty	Science	en_US
dc.publisher.hasversion	acceptedVersion	en_US
dc.publisher.institution	University of Calgary	en_US
dc.rights	Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. 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	aerosol nitrate	en_US
dc.subject	thermal dissociation	en_US
dc.subject	cavity ring-down spectroscopy	en_US
dc.subject	nitric acid	en_US
dc.subject	ammonium nitrate	en_US
dc.subject	sodium nitrate	en_US
dc.title	Quantification of Non-refractory Aerosol Nitrate in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy	en_US
dc.type	journal article	en_US
ucalgary.item.requestcopy	true	en_US
ucalgary.scholar.level	Faculty	en_US