Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 8, issue 12
Biogeosciences, 8, 3809–3821, 2011
https://doi.org/10.5194/bg-8-3809-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Nitrogen and global change

Biogeosciences, 8, 3809–3821, 2011
https://doi.org/10.5194/bg-8-3809-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 21 Dec 2011

Research article | 21 Dec 2011

Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

A. Meijide1, G. Manca2, I. Goded1, V. Magliulo3, P. di Tommasi3, G. Seufert1, and A. Cescatti1 A. Meijide et al.
  • 1European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, Climate Change and Air Quality Unit. Via Enrico Fermi 2749 I21027 Ispra (VA) Italy
  • 2National Research Council of Italy, Institute of Atmospheric Pollution Research, Division of Rende, 87036-Rende, Italy
  • 3CNR-ISAFoM, Via Patacca, 80056 Ercolano, (Napoli), Italy

Abstract. Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem.

For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10–12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.7 g CH4 m−2 measured with chambers and EC respectively) and even greater differences are found if shorter periods with high chamber sampling frequency are compared. The differences may be a result of the combined effect of overestimation with the chambers and of the possible underestimation by the EC technique.

Publications Copernicus
Download
Citation