Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field
Straw incorporation generally increases CH<sub>4</sub> emission from rice fields, but its effects on the mechanism of CH<sub>4</sub> emission, especially on the pathway of CH<sub>4</sub> production and the fraction of CH<sub>4</sub> oxidized, are not w...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2013-05-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/10/3375/2013/bg-10-3375-2013.pdf |
| _version_ | 1819195451620982784 |
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| author | G. B. Zhang Y. Ji J. Ma G. Liu H. Xu K. Yagi |
| author_facet | G. B. Zhang Y. Ji J. Ma G. Liu H. Xu K. Yagi |
| author_sort | G. B. Zhang |
| collection | DOAJ |
| description | Straw incorporation generally increases CH<sub>4</sub> emission from rice fields, but its effects on the mechanism of CH<sub>4</sub> emission, especially on the pathway of CH<sub>4</sub> production and the fraction of CH<sub>4</sub> oxidized, are not well known. To investigate the methanogenic pathway, the fraction of CH<sub>4</sub> oxidized as well as the stable carbon isotope fractionation during the oxidation and transport of CH<sub>4</sub> as affected by straw incorporation, observations were conducted of production and oxidation of CH<sub>4</sub> in paddy soil and rice roots and δ<sup>13</sup>C-values of produced CH<sub>4</sub> and CO<sub>2</sub>, and emitted CH<sub>4</sub> in incubation and field experiments. Straw incorporation significantly enhanced CH<sub>4</sub> production potentials of the paddy soil and rice roots. However, it increased the relative contribution of acetate to total CH<sub>4</sub> production (<i>F</i><sub>ac</sub>) in the paddy soil by ∼10–30%, but decreased <i>F</i><sub>ac</sub>-value of the rice roots by ∼5–20%. Compared with rice roots, paddy soil was more important in acetoclastic methanogenesis, with <i>F</i><sub>ac</sub>-value being 6–30% higher. Straw incorporation highly decreased the fraction of CH<sub>4</sub> oxidized (<i>F</i><sub>ox</sub>) by 41–71%, probably attributed to the fact that it increased CH<sub>4</sub> oxidation potential whereas CH<sub>4</sub> production potential was increased to a larger extent. There was little CH<sub>4</sub> formed during aerobic incubation, and the produced CH<sub>4</sub> was more <sup>13</sup>C-enriched relative to that of anaerobic incubation. Assuming δ<sup>13</sup>C-values of CH<sub>4</sub> aerobically produced in paddy soil to be the δ<sup>13</sup>C-values of residual CH<sub>4</sub> after being oxidized, (<i>F</i><sub>ox</sub>-value still appeared to be 45–68% lower when straw was incorporated. Oxidation fractionation factor (α<sub>ox</sub>) was higher with straw incorporation (1.033) than without straw incorporation (1.025). The δ<sup>13</sup>C-values of CH<sub>4</sub> emitted after cutting of the plants (−50 to −43‰) were more positive than those of before (−58 to −55‰), suggesting a transport fractionation factor (ϵ<sub>transport</sub>) was −8.0‰ with straw incorporation and −12.0‰ without straw incorporation. Causes of this difference may be related to the diffusion process in transport as affected by growth of rice plants and pressure in the rhizosphere. The experiment shows that straw incorporation increases the contribution of acetate to total methanogenesis in paddy soil but decreases it on rice roots, and it significantly decreases the fraction of CH<sub>4</sub> oxidized in the field and expands oxidation fractionation while reducing transport fractionation. |
| first_indexed | 2024-12-23T02:12:58Z |
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| id | doaj.art-ef8f2fcc62f34e9fa3176bb214b741e5 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-23T02:12:58Z |
| publishDate | 2013-05-01 |
| publisher | Copernicus Publications |
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| series | Biogeosciences |
| spelling | doaj.art-ef8f2fcc62f34e9fa3176bb214b741e52022-12-21T18:03:44ZengCopernicus PublicationsBiogeosciences1726-41701726-41892013-05-011053375338910.5194/bg-10-3375-2013Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice fieldG. B. ZhangY. JiJ. MaG. LiuH. XuK. YagiStraw incorporation generally increases CH<sub>4</sub> emission from rice fields, but its effects on the mechanism of CH<sub>4</sub> emission, especially on the pathway of CH<sub>4</sub> production and the fraction of CH<sub>4</sub> oxidized, are not well known. To investigate the methanogenic pathway, the fraction of CH<sub>4</sub> oxidized as well as the stable carbon isotope fractionation during the oxidation and transport of CH<sub>4</sub> as affected by straw incorporation, observations were conducted of production and oxidation of CH<sub>4</sub> in paddy soil and rice roots and δ<sup>13</sup>C-values of produced CH<sub>4</sub> and CO<sub>2</sub>, and emitted CH<sub>4</sub> in incubation and field experiments. Straw incorporation significantly enhanced CH<sub>4</sub> production potentials of the paddy soil and rice roots. However, it increased the relative contribution of acetate to total CH<sub>4</sub> production (<i>F</i><sub>ac</sub>) in the paddy soil by ∼10–30%, but decreased <i>F</i><sub>ac</sub>-value of the rice roots by ∼5–20%. Compared with rice roots, paddy soil was more important in acetoclastic methanogenesis, with <i>F</i><sub>ac</sub>-value being 6–30% higher. Straw incorporation highly decreased the fraction of CH<sub>4</sub> oxidized (<i>F</i><sub>ox</sub>) by 41–71%, probably attributed to the fact that it increased CH<sub>4</sub> oxidation potential whereas CH<sub>4</sub> production potential was increased to a larger extent. There was little CH<sub>4</sub> formed during aerobic incubation, and the produced CH<sub>4</sub> was more <sup>13</sup>C-enriched relative to that of anaerobic incubation. Assuming δ<sup>13</sup>C-values of CH<sub>4</sub> aerobically produced in paddy soil to be the δ<sup>13</sup>C-values of residual CH<sub>4</sub> after being oxidized, (<i>F</i><sub>ox</sub>-value still appeared to be 45–68% lower when straw was incorporated. Oxidation fractionation factor (α<sub>ox</sub>) was higher with straw incorporation (1.033) than without straw incorporation (1.025). The δ<sup>13</sup>C-values of CH<sub>4</sub> emitted after cutting of the plants (−50 to −43‰) were more positive than those of before (−58 to −55‰), suggesting a transport fractionation factor (ϵ<sub>transport</sub>) was −8.0‰ with straw incorporation and −12.0‰ without straw incorporation. Causes of this difference may be related to the diffusion process in transport as affected by growth of rice plants and pressure in the rhizosphere. The experiment shows that straw incorporation increases the contribution of acetate to total methanogenesis in paddy soil but decreases it on rice roots, and it significantly decreases the fraction of CH<sub>4</sub> oxidized in the field and expands oxidation fractionation while reducing transport fractionation.http://www.biogeosciences.net/10/3375/2013/bg-10-3375-2013.pdf |
| spellingShingle | G. B. Zhang Y. Ji J. Ma G. Liu H. Xu K. Yagi Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field Biogeosciences |
| title | Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field |
| title_full | Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field |
| title_fullStr | Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field |
| title_full_unstemmed | Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field |
| title_short | Pathway of CH<sub>4</sub> production, fraction of CH<sub>4</sub> oxidized, and <sup>13</sup>C isotope fractionation in a straw-incorporated rice field |
| title_sort | pathway of ch sub 4 sub production fraction of ch sub 4 sub oxidized and sup 13 sup c isotope fractionation in a straw incorporated rice field |
| url | http://www.biogeosciences.net/10/3375/2013/bg-10-3375-2013.pdf |
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