 |
| Titel |
Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy |
| VerfasserIn |
A. Meijide, G. Manca, I. Goded, V. Magliulo, P. Tommasi, G. Seufert, A. Cescatti |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 12 ; Nr. 8, no. 12 (2011-12-21), S.3809-3821 |
| Datensatznummer |
250006258
|
| Publikation (Nr.) |
 copernicus.org/bg-8-3809-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
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. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|