Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study
Long-term field observations showed that N<sub>2</sub>O fluxes observed shortly after N application were not significantly affected by elevated CO<sub>2</sub> in the Giessen Free Air Carbon dioxide Enrichment (FACE) study. To further investigate this unexpected result a <s...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2011-09-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/11/9333/2011/acp-11-9333-2011.pdf |
| _version_ | 1819073158331760640 |
|---|---|
| author | C. Müller M. Kaleem Abbasi |
| author_facet | C. Müller M. Kaleem Abbasi |
| author_sort | C. Müller |
| collection | DOAJ |
| description | Long-term field observations showed that N<sub>2</sub>O fluxes observed shortly after N application were not significantly affected by elevated CO<sub>2</sub> in the Giessen Free Air Carbon dioxide Enrichment (FACE) study. To further investigate this unexpected result a <sup>15</sup>N tracer study was carried out under controlled conditions where in parallel treatments either the NH<sub>4</sub><sup>+</sup> pool (<sup>15</sup>NH<sub>4</sub>NO<sub>3</sub>) or the NO<sub>3</sub><sup>−</sup> pool (NH<sub>4</sub><sup>15</sup>NO<sub>3</sub>) was enriched with <sup>15</sup>N. Fluxes of CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O as well as the <sup>15</sup>N enrichment of the N<sub>2</sub>O were measured. Denitrifying Enzyme Activity (DEA), total denitrification (N<sub>2</sub> + N<sub>2</sub>O) and N<sub>2</sub>-to-N<sub>2</sub>O ratios were quantified in separate experiments. Over the 57 day incubation, N<sub>2</sub>O fluxes averaged 0.090 ng N<sub>2</sub>O-N g<sup>−1</sup> h<sup>−1</sup> under ambient and 0.083 ng N<sub>2</sub>O-N g<sup>−1</sup> h<sup>−1</sup> under elevated CO<sub>2</sub> (not significantly different). The N<sub>2</sub>O production processes were identified by a two-source model. Results showed that N<sub>2</sub>O must have also been produced by a third source – possibly related to organic N transformation – which was stimulated by elevated CO<sub>2</sub>. Soil CO<sub>2</sub> fluxes were approximately 20 % higher under elevated CO<sub>2</sub> than soil from ambient but the differences were not significant. CH<sub>4</sub> oxidation rates were on average −1.75 ng CH<sub>4</sub>-C g<sup>−1</sup> h<sup>−1</sup> in the elevated and −1.17 ng CH<sub>4</sub>-C g<sup>−1</sup> h<sup>−1</sup> in the ambient indicating that elevated CO<sub>2</sub> increased the CH<sub>4</sub> oxidation by 49 % compared to ambient CO<sub>2</sub> under controlled conditions. N fertilization increased CH<sub>4</sub> oxidation by 3-fold in both CO<sub>2</sub> treatments. CO<sub>2</sub> did not have any significant effect on DEA while total denitrification and N<sub>2</sub>-to-N<sub>2</sub>O ratios increased by 36 and 33 %, respectively. The results indicate that shortly after N application elevated CO<sub>2</sub> must have stimulated both the N<sub>2</sub>O production and reduction to N<sub>2</sub> to explain the increased N<sub>2</sub>-to-N<sub>2</sub>O ratio and at the same time explain the non-responsiveness of the N<sub>2</sub>O emissions. Thus, the observed variation of the CO<sub>2</sub> effect on N<sub>2</sub>O emissions throughout the year is possibly governed by the dynamics of the N<sub>2</sub>O reductase activity. |
| first_indexed | 2024-12-21T17:49:10Z |
| format | Article |
| id | doaj.art-c903766c0a6346b6ad5a7fae89740013 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-21T17:49:10Z |
| publishDate | 2011-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-c903766c0a6346b6ad5a7fae897400132022-12-21T18:55:25ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242011-09-0111179333934210.5194/acp-11-9333-2011Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE studyC. MüllerM. Kaleem AbbasiLong-term field observations showed that N<sub>2</sub>O fluxes observed shortly after N application were not significantly affected by elevated CO<sub>2</sub> in the Giessen Free Air Carbon dioxide Enrichment (FACE) study. To further investigate this unexpected result a <sup>15</sup>N tracer study was carried out under controlled conditions where in parallel treatments either the NH<sub>4</sub><sup>+</sup> pool (<sup>15</sup>NH<sub>4</sub>NO<sub>3</sub>) or the NO<sub>3</sub><sup>−</sup> pool (NH<sub>4</sub><sup>15</sup>NO<sub>3</sub>) was enriched with <sup>15</sup>N. Fluxes of CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O as well as the <sup>15</sup>N enrichment of the N<sub>2</sub>O were measured. Denitrifying Enzyme Activity (DEA), total denitrification (N<sub>2</sub> + N<sub>2</sub>O) and N<sub>2</sub>-to-N<sub>2</sub>O ratios were quantified in separate experiments. Over the 57 day incubation, N<sub>2</sub>O fluxes averaged 0.090 ng N<sub>2</sub>O-N g<sup>−1</sup> h<sup>−1</sup> under ambient and 0.083 ng N<sub>2</sub>O-N g<sup>−1</sup> h<sup>−1</sup> under elevated CO<sub>2</sub> (not significantly different). The N<sub>2</sub>O production processes were identified by a two-source model. Results showed that N<sub>2</sub>O must have also been produced by a third source – possibly related to organic N transformation – which was stimulated by elevated CO<sub>2</sub>. Soil CO<sub>2</sub> fluxes were approximately 20 % higher under elevated CO<sub>2</sub> than soil from ambient but the differences were not significant. CH<sub>4</sub> oxidation rates were on average −1.75 ng CH<sub>4</sub>-C g<sup>−1</sup> h<sup>−1</sup> in the elevated and −1.17 ng CH<sub>4</sub>-C g<sup>−1</sup> h<sup>−1</sup> in the ambient indicating that elevated CO<sub>2</sub> increased the CH<sub>4</sub> oxidation by 49 % compared to ambient CO<sub>2</sub> under controlled conditions. N fertilization increased CH<sub>4</sub> oxidation by 3-fold in both CO<sub>2</sub> treatments. CO<sub>2</sub> did not have any significant effect on DEA while total denitrification and N<sub>2</sub>-to-N<sub>2</sub>O ratios increased by 36 and 33 %, respectively. The results indicate that shortly after N application elevated CO<sub>2</sub> must have stimulated both the N<sub>2</sub>O production and reduction to N<sub>2</sub> to explain the increased N<sub>2</sub>-to-N<sub>2</sub>O ratio and at the same time explain the non-responsiveness of the N<sub>2</sub>O emissions. Thus, the observed variation of the CO<sub>2</sub> effect on N<sub>2</sub>O emissions throughout the year is possibly governed by the dynamics of the N<sub>2</sub>O reductase activity.http://www.atmos-chem-phys.net/11/9333/2011/acp-11-9333-2011.pdf |
| spellingShingle | C. Müller M. Kaleem Abbasi Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study Atmospheric Chemistry and Physics |
| title | Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study |
| title_full | Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study |
| title_fullStr | Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study |
| title_full_unstemmed | Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study |
| title_short | Trace gas fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O in a permanent grassland soil exposed to elevated CO<sub>2</sub> in the Giessen FACE study |
| title_sort | trace gas fluxes of co sub 2 sub ch sub 4 sub and n sub 2 sub o in a permanent grassland soil exposed to elevated co sub 2 sub in the giessen face study |
| url | http://www.atmos-chem-phys.net/11/9333/2011/acp-11-9333-2011.pdf |
| work_keys_str_mv | AT cmuller tracegasfluxesofcosub2subchsub4subandnsub2suboinapermanentgrasslandsoilexposedtoelevatedcosub2subinthegiessenfacestudy AT mkaleemabbasi tracegasfluxesofcosub2subchsub4subandnsub2suboinapermanentgrasslandsoilexposedtoelevatedcosub2subinthegiessenfacestudy |