Methane emissions of rice increased by elevated carbon dioxide and temperature
| Autor: | Jeffrey T. Baker, Stephen A. Covell, Wilfredo Colón-Guasp, Kenneth J. Boote, Deyun Pan, Leon Hartwell Allen, Stephan L. Albrecht |
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| Rok vydání: | 2003 |
| Předmět: |
Greenhouse Effect
Environmental Engineering Hot Temperature Growing season Management Monitoring Policy and Law Methane chemistry.chemical_compound Humans Poaceae Waste Management and Disposal Water Science and Technology Air Pollutants Atmosphere Air Global warming Environmental engineering Temperature Oryza Radiative forcing Carbon Dioxide Environment Controlled Pollution chemistry Greenhouse gas Environmental chemistry Carbon dioxide Paddy field |
| Zdroj: | Journal of environmental quality. 32(6) |
| ISSN: | 0047-2425 |
| Popis: | Methane (CH 4 ) effluxes by paddy-culture rice (Oryza saliva L.) contribute about 16% of the total anthropogenic emissions. Since radiative forcing of CH 4 at current atmospheric concentrations is 21 times greater on a per mole basis than that of carbon dioxide (CO 2 ), it is imperative that the impact of global change on rice CH 4 emissions be evaluated. Rice (cv. IR72) was planted in sunlit, closed-circulation, controlled-environment chambers in which CH 4 efflux densities were measured daily. The CO 2 concentration was maintained at either 330 or 660 μmol mol -1 . Air temperatures were controlled to daily maxima and minima of 32/23, 35/26, and 38/29°C at each CO 2 treatment. Emissions of CH 4 each day were determined during a 4-h period after venting and resealing the chambers at 0800 h. Diurnal CH 4 effluxes on 77, 98, and 119 d after planting (DAP) were obtained similarly at 4-h intervals. Emissions over four-plant hills and over flooded bare soil were measured at 53, 63, and 100 DAP. Emissions were negligible before 40 DAP. Thereafter, emissions were observed first in high-CO 2 , high-temperature treatments and reached a sustained maximum efflux density of about 7 mg m -2 h -1 (0.17 g m -2 d -1 ) near the end of the growing season. Total seasonal CH 4 emission was fourfold greater for high-CO 2 , high-temperature treatments than for the low-CO 2 , low-temperature treatment, probably due to more root sloughing or exudates, since about sixfold more acetate was found in the soil at 71 DAP. Both rising CO 2 and increasing temperatures could lead to a positive feedback on global warming by increasing the emissions of CH 4 from rice. |
| Databáze: | OpenAIRE |
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