Micrometeorological measurements of nitrous oxide exchange above a cropland

Li, J; Tong, X; Yu, Q; Dong, Y; Peng, C

Micrometeorological measurements of nitrous oxide exchange above a cropland

Li, J Tong, X Yu, Q

Dong, Y Peng, C

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Publication Type:: Journal Article
Citation:: Atmospheric Environment, 2008, 42 (29), pp. 6992 - 7001
Issue Date:: 2008-09-01

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Field	Value	Language
dc.contributor.author	Li, J	en_US
dc.contributor.author	Tong, X	en_US
dc.contributor.author	Yu, Q https://orcid.org/0000-0001-6950-1821	en_US
dc.contributor.author	Dong, Y	en_US
dc.contributor.author	Peng, C	en_US
dc.date.issued	2008-09-01	en_US
dc.identifier.citation	Atmospheric Environment, 2008, 42 (29), pp. 6992 - 7001	en_US
dc.identifier.issn	1352-2310	en_US
dc.identifier.uri	http://hdl.handle.net/10453/9365
dc.description.abstract	N2O fluxes in a wheat/maize rotation system were measured using flux gradient methods combined with gas chromatograph (GC) technique. The mean precision of two repeated GC analyses for N2O concentration achieved to 0.27-0.46 ppbv, which could resolve N2O concentration differences in a low range of 0.39-0.65 ppbv. To maximize measurable N2O concentration differences, gradient measurements were conducted only after fertilization or under low wind conditions. During observation period, N2O flux ranged from -4.41 to 4.84 mgN2O m-2 h-1 for maize field, and from -2.82 to 3.59 mgN2O m-2 h-1 for wheat field. When gradient observation changed from two layers to four layers, the temporal variation of N2O flux reduced but the mean value changed less. Many negative N2O fluxes were found in maize and wheat fields even after fertilization. Nearly all of them were caused by negative N2O concentration differences. During four days' observation in maize field, a mean N2O flux of -0.75 mgN2O m-2 h-1 was found in the daytime and could not be simply attributed to the temporal variation of N2O flux. N2O flux determined by the aerodynamic method (Fa) and the Bowen ratio/energy balance method (Fb) were in a good agreement and statistically significant. The ratio of Fa to Fb increased linearly with energy balance ratio (EBR) obtained by the aerodynamic method in the daytime when EBR is larger than 0.3. It is the first time to give a quantitative description for the impact of energy closure on N2O flux, and show a possible way to improve the data quality under the condition of poor energy balance. © 2008 Elsevier Ltd. All rights reserved.	en_US
dc.relation.ispartof	Atmospheric Environment	en_US
dc.relation.isbasedon	10.1016/j.atmosenv.2008.04.040	en_US
dc.subject.classification	Meteorology & Atmospheric Sciences	en_US
dc.title	Micrometeorological measurements of nitrous oxide exchange above a cropland	en_US
dc.type	Journal Article
utslib.citation.volume	29	en_US
utslib.citation.volume	42	en_US
utslib.for	0907 Environmental Engineering	en_US
utslib.for	0104 Statistics	en_US
utslib.for	040104 Climate Change Processes	en_US
utslib.for	0401 Atmospheric Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	closed_access
pubs.declined	1970-01-01T00:00:00.0+1000
pubs.issue	29	en_US
pubs.publication-status	Published	en_US
pubs.volume	42	en_US

Abstract:

N2O fluxes in a wheat/maize rotation system were measured using flux gradient methods combined with gas chromatograph (GC) technique. The mean precision of two repeated GC analyses for N2O concentration achieved to 0.27-0.46 ppbv, which could resolve N2O concentration differences in a low range of 0.39-0.65 ppbv. To maximize measurable N2O concentration differences, gradient measurements were conducted only after fertilization or under low wind conditions. During observation period, N2O flux ranged from -4.41 to 4.84 mgN2O m-2 h-1 for maize field, and from -2.82 to 3.59 mgN2O m-2 h-1 for wheat field. When gradient observation changed from two layers to four layers, the temporal variation of N2O flux reduced but the mean value changed less. Many negative N2O fluxes were found in maize and wheat fields even after fertilization. Nearly all of them were caused by negative N2O concentration differences. During four days' observation in maize field, a mean N2O flux of -0.75 mgN2O m-2 h-1 was found in the daytime and could not be simply attributed to the temporal variation of N2O flux. N2O flux determined by the aerodynamic method (Fa) and the Bowen ratio/energy balance method (Fb) were in a good agreement and statistically significant. The ratio of Fa to Fb increased linearly with energy balance ratio (EBR) obtained by the aerodynamic method in the daytime when EBR is larger than 0.3. It is the first time to give a quantitative description for the impact of energy closure on N2O flux, and show a possible way to improve the data quality under the condition of poor energy balance. © 2008 Elsevier Ltd. All rights reserved.

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