Comparison between static chamber and tunable diode laser-based eddy covariance techniques for measuring nitrous oxide fluxes from a cotton field

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Wang , K , Zheng , X , Pihlatie , M , Vesala , T , Liu , C , Haapanala , S , Mammarella , I , Rannik , U & Liu , H 2013 , ' Comparison between static chamber and tunable diode laser-based eddy covariance techniques for measuring nitrous oxide fluxes from a cotton field ' , Agricultural and Forest Meteorology , vol. 171 , pp. 9-19 . https://doi.org/10.1016/j.agrformet.2012.11.009

Title: Comparison between static chamber and tunable diode laser-based eddy covariance techniques for measuring nitrous oxide fluxes from a cotton field
Author: Wang, Kai; Zheng, Xunhua; Pihlatie, Mari; Vesala, Timo; Liu, Chunyan; Haapanala, Sami; Mammarella, Ivan; Rannik, Ullar; Liu, Huizhi
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Date: 2013-04-15
Language: eng
Number of pages: 11
Belongs to series: Agricultural and Forest Meteorology
ISSN: 0168-1923
URI: http://hdl.handle.net/10138/40049
Abstract: Nitrous oxide (N2O) fluxes from a cotton field in northern China were measured for a year using the static chamber method based on a gas chromatograph (GC) and the eddy covariance (EC) technique based on a tunable diode laser (TDL). The aims were to compare the N2O fluxes obtained from both techniques, assess the uncertainties in the fluxes and evaluate the annual direct emission factors (EFds, i.e. the loss rate of fertilizer nitrogen via N2O emission) using the year-round datasets. During the experimental period, the hourly and daily mean chamber fluxes ranged from 0.6 to 781.8 and from 1.2 to 468.8 g N m−2 h−1, respectively. The simultaneously measured daily mean EC fluxes varied between −10.8 and 912.0 g N m−2 h−1. The EC measurements only provided trustworthy 30-min fluxes during high-emission period (a 20-day period immediately after the irrigation that followed the nitrogen fertilization event). A reliable comparison was confined to the high-emission period and showed that the chamber fluxes were 17–20% lower than the EC fluxes. This difference may implicate the magnitude of systematic underestimation in the fluxes from chamber measurements. The annual emission from the fertilized cotton field was estimated at 1.43 kg N ha−1 yr−1 by the chamber observations and 3.15 kg N ha−1 yr−1 by the EC measurements. The EFds calculated from the chamber and EC data were 1.04% and 1.65%, respectively. The chamber-based estimate was very close to the default value (1.0%) recommended by the Intergovernmental Panel on Climate Change. However, the difference in the EFds based on the two measurement techniques may vary greatly with changing environmental conditions and management practices. Further comparison studies are still needed to elucidate this issue.
Subject: Nitrous oxide
Direct emission factor
Chamber
Eddy covariance
Cropland
N2O EMISSIONS
SPATIAL VARIABILITY
QUALITY-CONTROL
NO EMISSION
GAS FLUXES
FOREST
SOILS
GRASSLAND
CO2
QUANTIFICATION
114 Physical sciences
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