Investigating the Formation of Nitrous Oxide and its Isotopic Composition in a Corona Discharge with Applications to Plasma and Atmospheric Chemistry
Abstract
Increasing atmospheric concentrations of nitrous oxide (N2O) warrant investigation, as it is a long-lived anthropogenic greenhouse gas and an ozone depleting substance. Measurements of N2O during the HIAPER Pole-to-Pole (HIPPO) mission in 2009 showed large-scale and persistent enhancements of N2O in the subtropical middle troposphere. Possible sources of the elevated N2O include biomass burning or microbial emissions that were lofted from the surface and measured before being fully mixed into the background atmosphere - both of which are globally important sources - or in situ production by lightning. In principle, the source of atmospheric N2O can be inferred by measuring its isotopic composition since, for example, biomass burning and microbial N2O production have distinct isotopic signatures. However, the isotopic composition of N2O produced by lightning is not known. In this study, N2O was produced in a positive corona discharge, which simulates low-temperature cloud-to-cloud and intra-cloud lightning and analyzed by isotope ratio mass spectrometry. The new results indicate that N2O produced in simulated laboratory lightning has an isotopic signature that is both large and distinct from microbial and combustion sources to the atmosphere, with enrichments in 15N at the central nitrogen atom and depletions in 18O. The magnitude and character of these new isotope laboratory data suggest that N2O produced by lightning could be both isotopically detectable before mixing into the background atmosphere and distinct from the combustion and microbial sources. They also provide new constraints on the kinetics and chemical mechanisms of N2O production and destruction pathways in low temperature plasmas.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A41F..08C
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE