Details
| Original language | English |
|---|---|
| Pages (from-to) | 1383-1392 |
| Number of pages | 10 |
| Journal | Journal of environmental quality |
| Volume | 41 |
| Issue number | 5 |
| Publication status | Published - Sept 2012 |
Abstract
Emissions of the major greenhouse gas N2O from soils are characterized by huge spatial variability. An upscaling based on conventional small-scale chamber measurements is thus questionable and may involve a considerable amount of uncertainty.In this feasibility study, we evaluated the applicability of a large,closed tunnel for fi eld-scale measurements of N2O fl uxes from an unfertilized grassland soil. Th e tunnel, coupled to an open-path Fourier transform infrared spectrometer, covered 500 m2. During a 2-yr campaign, concurrent closed-chamber measurements (area of 0.045 m2) were performed at the tunnel plot. Th e tunnel system enabled high-density and precise N2O concentration measurements under dry, stable, nocturnal atmospheric conditions, but higher wind speeds and rain limited its application. To calculate an unbiased,predeployment N2O fl ux from the increase of N2O concentrations during tunnel deployment, we propose a novel approach based on inverse modeling (IMQ0). We show that IMQ0 is appropriate for the specifi c non-steady state tunnel setup. Compared with conventional models, which were developed for gas fl ux calculation from concentration gradients measured in vented closed chambers,IMQ0 is most accurate. Whereas N2O fl uxes obtained from the tunnel measurements were generally small and at a typical background level, the chamber measurements revealed high spatial and temporal variability of N2O emissions, including slight N2O uptake and precipitation-triggered emission peaks. Th e cumulative N2O fl uxes of both methods diff ered by one order of magnitude and were smaller for the tunnel measurements. We argue that the chambers were occasionally susceptible to detection of hotspots and hot moments of N2O emission. However, these emissions were evidently not representative for the fi eld scale. Compared with available greenhouse gas measurement techniques, we conclude that the tunnel may serve as a gap-fi lling method between smallscale chamber and ecosystem-level micrometeorological techniques,particularly during stable nocturnal conditions.
ASJC Scopus subject areas
- Environmental Science(all)
- Environmental Engineering
- Environmental Science(all)
- Water Science and Technology
- Environmental Science(all)
- Waste Management and Disposal
- Environmental Science(all)
- Pollution
- Environmental Science(all)
- Management, Monitoring, Policy and Law
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In: Journal of environmental quality, Vol. 41, No. 5, 09.2012, p. 1383-1392.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Evaluation of a closed tunnel for field-scale measurements of nitrous oxide fluxes from an unfertilized grassland soil
AU - Schäfer, Klaus
AU - Böttcher, Jürgen
AU - Weymann, Daniel
AU - Von Der Heide, Carolin
AU - Duijnisveld, Wilhelmus H.M.
N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/9
Y1 - 2012/9
N2 - Emissions of the major greenhouse gas N2O from soils are characterized by huge spatial variability. An upscaling based on conventional small-scale chamber measurements is thus questionable and may involve a considerable amount of uncertainty.In this feasibility study, we evaluated the applicability of a large,closed tunnel for fi eld-scale measurements of N2O fl uxes from an unfertilized grassland soil. Th e tunnel, coupled to an open-path Fourier transform infrared spectrometer, covered 500 m2. During a 2-yr campaign, concurrent closed-chamber measurements (area of 0.045 m2) were performed at the tunnel plot. Th e tunnel system enabled high-density and precise N2O concentration measurements under dry, stable, nocturnal atmospheric conditions, but higher wind speeds and rain limited its application. To calculate an unbiased,predeployment N2O fl ux from the increase of N2O concentrations during tunnel deployment, we propose a novel approach based on inverse modeling (IMQ0). We show that IMQ0 is appropriate for the specifi c non-steady state tunnel setup. Compared with conventional models, which were developed for gas fl ux calculation from concentration gradients measured in vented closed chambers,IMQ0 is most accurate. Whereas N2O fl uxes obtained from the tunnel measurements were generally small and at a typical background level, the chamber measurements revealed high spatial and temporal variability of N2O emissions, including slight N2O uptake and precipitation-triggered emission peaks. Th e cumulative N2O fl uxes of both methods diff ered by one order of magnitude and were smaller for the tunnel measurements. We argue that the chambers were occasionally susceptible to detection of hotspots and hot moments of N2O emission. However, these emissions were evidently not representative for the fi eld scale. Compared with available greenhouse gas measurement techniques, we conclude that the tunnel may serve as a gap-fi lling method between smallscale chamber and ecosystem-level micrometeorological techniques,particularly during stable nocturnal conditions.
AB - Emissions of the major greenhouse gas N2O from soils are characterized by huge spatial variability. An upscaling based on conventional small-scale chamber measurements is thus questionable and may involve a considerable amount of uncertainty.In this feasibility study, we evaluated the applicability of a large,closed tunnel for fi eld-scale measurements of N2O fl uxes from an unfertilized grassland soil. Th e tunnel, coupled to an open-path Fourier transform infrared spectrometer, covered 500 m2. During a 2-yr campaign, concurrent closed-chamber measurements (area of 0.045 m2) were performed at the tunnel plot. Th e tunnel system enabled high-density and precise N2O concentration measurements under dry, stable, nocturnal atmospheric conditions, but higher wind speeds and rain limited its application. To calculate an unbiased,predeployment N2O fl ux from the increase of N2O concentrations during tunnel deployment, we propose a novel approach based on inverse modeling (IMQ0). We show that IMQ0 is appropriate for the specifi c non-steady state tunnel setup. Compared with conventional models, which were developed for gas fl ux calculation from concentration gradients measured in vented closed chambers,IMQ0 is most accurate. Whereas N2O fl uxes obtained from the tunnel measurements were generally small and at a typical background level, the chamber measurements revealed high spatial and temporal variability of N2O emissions, including slight N2O uptake and precipitation-triggered emission peaks. Th e cumulative N2O fl uxes of both methods diff ered by one order of magnitude and were smaller for the tunnel measurements. We argue that the chambers were occasionally susceptible to detection of hotspots and hot moments of N2O emission. However, these emissions were evidently not representative for the fi eld scale. Compared with available greenhouse gas measurement techniques, we conclude that the tunnel may serve as a gap-fi lling method between smallscale chamber and ecosystem-level micrometeorological techniques,particularly during stable nocturnal conditions.
UR - http://www.scopus.com/inward/record.url?scp=84869413231&partnerID=8YFLogxK
U2 - 10.2134/jeq2011.0475
DO - 10.2134/jeq2011.0475
M3 - Article
C2 - 23099929
AN - SCOPUS:84869413231
VL - 41
SP - 1383
EP - 1392
JO - Journal of environmental quality
JF - Journal of environmental quality
SN - 0047-2425
IS - 5
ER -