The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate
Elevated nitrogen (N) deposition changes the retention, transformation, and fluxes of N in ombrotrophic peatlands. To evaluate such effects we applied a <sup>15</sup>N tracer (NH<sub>4</sub> <sup>15</sup>NO<sub>3</sub>) at a rate of 2.3 g N m<sup>...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/707/2016/bg-13-707-2016.pdf |
| _version_ | 1811338323876118528 |
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| author | K. Zając C. Blodau |
| author_facet | K. Zając C. Blodau |
| author_sort | K. Zając |
| collection | DOAJ |
| description | Elevated nitrogen (N) deposition changes the retention, transformation, and
fluxes of N in ombrotrophic peatlands. To evaluate such effects we applied a
<sup>15</sup>N tracer (NH<sub>4</sub> <sup>15</sup>NO<sub>3</sub>) at a rate of
2.3 g N m<sup>−2</sup> yr<sup>−1</sup> to mesocosms of five European peatlands with
differing long-term N deposition rates for a period of 76 days of dry and 90
days of wet conditions. We determined background N content and moss length
growth, and recovered the <sup>15</sup>N tracer from the mosses, graminoids,
shrubs, the peat, and dissolved N. Background N contents in <i>Sphagnum</i>
mosses increased from 5.5 (Degerö Stormyr, deposition < 0.2 g N m<sup>−2</sup> yr<sup>−1</sup>) up to 12.2 mg g<sup>−1</sup> (Frölichshaier
Sattelmoor, 4.7–6.0 g N m<sup>−2</sup> yr<sup>−1</sup>). In peat from Degerö,
nitrate and ammonium concentrations were below 3 mg L<sup>−1</sup>, whereas up to
30 (nitrate) and 11 mg L<sup>−1</sup> (ammonium) was found in peat from
Frölichshaier Sattelmoor. <i>Sphagnum</i> mosses (down to 5 cm below
surface) generally intercepted large amounts of <sup>15</sup>N (0.2–0.35
mg g<sup>−1</sup>) and retained the tracer most effectively relative to their
biomass. Similar quantities of the <sup>15</sup>N were recovered from the peat,
followed by shrubs, graminoids, and the dissolved pool. At the most polluted
sites we recovered more <sup>15</sup>N from shrubs (up to 12.4 %) and from
nitrate and ammonium (up to 0.7 %). However, no impact of N deposition on
<sup>15</sup>N retention by <i>Sphagnum</i> could be identified and their length
growth was highest under high N background deposition. Our experiment
suggests that the decline in N retention at levels above ca.
1.5 g m<sup>−2</sup> yr<sup>−1</sup>, as expressed by elevated near-surface peat N
content and increased dissolved N concentrations, is likely more modest than
previously thought. This conclusion is related to the finding that
<i>Sphagnum</i> species can apparently thrive at elevated long-term N
deposition rates in European peatlands. |
| first_indexed | 2024-04-13T18:09:21Z |
| format | Article |
| id | doaj.art-772071384e034983b0446db5d9db361d |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-13T18:09:21Z |
| publishDate | 2016-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-772071384e034983b0446db5d9db361d2022-12-22T02:35:58ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-02-0113370772210.5194/bg-13-707-2016The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rateK. Zając0C. Blodau1Limnological Research Station and Department of Hydrology, University of Bayreuth, Bayreuth, GermanyLimnological Research Station and Department of Hydrology, University of Bayreuth, Bayreuth, GermanyElevated nitrogen (N) deposition changes the retention, transformation, and fluxes of N in ombrotrophic peatlands. To evaluate such effects we applied a <sup>15</sup>N tracer (NH<sub>4</sub> <sup>15</sup>NO<sub>3</sub>) at a rate of 2.3 g N m<sup>−2</sup> yr<sup>−1</sup> to mesocosms of five European peatlands with differing long-term N deposition rates for a period of 76 days of dry and 90 days of wet conditions. We determined background N content and moss length growth, and recovered the <sup>15</sup>N tracer from the mosses, graminoids, shrubs, the peat, and dissolved N. Background N contents in <i>Sphagnum</i> mosses increased from 5.5 (Degerö Stormyr, deposition < 0.2 g N m<sup>−2</sup> yr<sup>−1</sup>) up to 12.2 mg g<sup>−1</sup> (Frölichshaier Sattelmoor, 4.7–6.0 g N m<sup>−2</sup> yr<sup>−1</sup>). In peat from Degerö, nitrate and ammonium concentrations were below 3 mg L<sup>−1</sup>, whereas up to 30 (nitrate) and 11 mg L<sup>−1</sup> (ammonium) was found in peat from Frölichshaier Sattelmoor. <i>Sphagnum</i> mosses (down to 5 cm below surface) generally intercepted large amounts of <sup>15</sup>N (0.2–0.35 mg g<sup>−1</sup>) and retained the tracer most effectively relative to their biomass. Similar quantities of the <sup>15</sup>N were recovered from the peat, followed by shrubs, graminoids, and the dissolved pool. At the most polluted sites we recovered more <sup>15</sup>N from shrubs (up to 12.4 %) and from nitrate and ammonium (up to 0.7 %). However, no impact of N deposition on <sup>15</sup>N retention by <i>Sphagnum</i> could be identified and their length growth was highest under high N background deposition. Our experiment suggests that the decline in N retention at levels above ca. 1.5 g m<sup>−2</sup> yr<sup>−1</sup>, as expressed by elevated near-surface peat N content and increased dissolved N concentrations, is likely more modest than previously thought. This conclusion is related to the finding that <i>Sphagnum</i> species can apparently thrive at elevated long-term N deposition rates in European peatlands.http://www.biogeosciences.net/13/707/2016/bg-13-707-2016.pdf |
| spellingShingle | K. Zając C. Blodau The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate Biogeosciences |
| title | The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate |
| title_full | The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate |
| title_fullStr | The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate |
| title_full_unstemmed | The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate |
| title_short | The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate |
| title_sort | fate of sup 15 sup n nitrate in mesocosms from five european peatlands differing in long term nitrogen deposition rate |
| url | http://www.biogeosciences.net/13/707/2016/bg-13-707-2016.pdf |
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