Effects of elevated temperature and atmospheric carbon dioxide concentration on the emissions of methane and nitrous oxide from Portuguese flooded rice fields

Pereira, J.; Figueiredo, N.; Goufo, P.; Carneiro, J.; Morais, R.; Carranca, C.; Coutinho, J.; Trindade, H.

http://hdl.handle.net/10400.19/1775

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Abstract(s)

Methane (CH4) and nitrous oxide (N2O) emissions from ﬂooded rice ﬁelds have been rarely measured in Europe. A ﬁeld study was carried out in an intermittent ﬂooded rice ﬁeld at central Portugal to investigate if global warming under Mediterranean conditions, elevated soil temperature (þ2 $C) and atmospheric [CO2] (550 ppm), could lead to signiﬁcant effects in CH4 and N2O emissions. The experimental design consisted of three treatments arranged in a randomized complete block design with three replicates. To assess the effects of ambient temperature and actual atmospheric [CO2] (375 ppm), plots were laid under open-ﬁeld rice conditions. Using open-top chambers, two other treatments were established: one to assess the effect of elevated temperature and actual atmospheric [CO2] and a third treatment to evaluate the combined effect of elevated temperature and atmospheric [CO2]. Measurements of CH4 and N2O ﬂuxes were made throughout two consecutive growing seasons in the ﬁeld using the closed chamber technique. Elevation of temperature with or without elevated atmospheric [CO2] increased CH4 emissions by 50%, but this increase was not signiﬁcant compared to the open-ﬁeld condition. As for N2O, elevated temperature alone or combined with elevated atmospheric [CO2] had no signiﬁcant effect on emissions relative to the open-ﬁeld treatment. The estimated seasonal CH4 EF for the Portuguese ﬂooded rice ﬁelds was 10.0 g CH4 m"2 , while the EF for N2O emissions was 1.4% of N input. These results suggested that default seasonal CH4 and N2O EFs currently used by the Portuguese inventory were not appropriated.

Keywords

CO2 enrichment Emission factors GHGs emissions Intermittent ﬂooded rice Open-ﬁeld Temperature

URI

http://hdl.handle.net/10400.19/1775

Citation

Pereira J., Figueiredo N., Goufo P., Carneiro J., Morais R., Carranca C., Coutinho J., Trindade H., 2013. Effects of elevated temperature and atmospheric carbon dioxide concentration on the emissions of methane and nitrous oxide from Portuguese flooded rice fields. Atmospheric Environment 80, 464-471.