Combination of 15N Tracer and Microbial Analyses Discloses N2O Sink Potential of the Anammox Community

2021 ◽  
Author(s):  
Toshikazu Suenaga ◽  
Takumi Ota ◽  
Kohei Oba ◽  
Kentaro Usui ◽  
Toshiki Sako ◽  
...  
Keyword(s):  
15N Tracer

An in situ mesocosm method for quantifying nitrogen cycling rates in oligotrophic wetlands using 15N tracer techniques

Wetlands ◽  
2008 ◽  
Vol 28 (2) ◽  
pp. 502-512 ◽  
Author(s):  
Jeffrey R. Wozniak ◽  
Daniel L. Childers ◽  
William T. Anderson ◽  
David T. Rudnick ◽  
Christopher J. Madden
Keyword(s):  
Nitrogen Cycling ◽  
15N Tracer ◽  
Tracer Techniques

scholarly journals 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

2011 ◽  
Vol 11 (17) ◽  
pp. 9333-9342 ◽  
Author(s):  
M. Kaleem Abbasi ◽  
C. Müller
Keyword(s):  
Elevated Co2 ◽  
15N Tracer ◽  
Organic N ◽  
N2o Emissions ◽  
Ch4 Oxidation ◽  
N2o Production ◽  
N Application ◽  
Oxidation Rates ◽  
Controlled Conditions ◽  
N2o Fluxes

Abstract. Long-term field observations showed that N2O fluxes observed shortly after N application were not significantly affected by elevated CO2 in the Giessen Free Air Carbon dioxide Enrichment (FACE) study. To further investigate this unexpected result a 15N tracer study was carried out under controlled conditions where in parallel treatments either the NH4+ pool (15NH4NO3) or the NO3− pool (NH415NO3) was enriched with 15N. Fluxes of CO2, CH4, and N2O as well as the 15N enrichment of the N2O were measured. Denitrifying Enzyme Activity (DEA), total denitrification (N2 + N2O) and N2-to-N2O ratios were quantified in separate experiments. Over the 57 day incubation, N2O fluxes averaged 0.090 ng N2O-N g−1 h−1 under ambient and 0.083 ng N2O-N g−1 h−1 under elevated CO2 (not significantly different). The N2O production processes were identified by a two-source model. Results showed that N2O must have also been produced by a third source – possibly related to organic N transformation – which was stimulated by elevated CO2. Soil CO2 fluxes were approximately 20 % higher under elevated CO2 than soil from ambient but the differences were not significant. CH4 oxidation rates were on average −1.75 ng CH4-C g−1 h−1 in the elevated and −1.17 ng CH4-C g−1 h−1 in the ambient indicating that elevated CO2 increased the CH4 oxidation by 49 % compared to ambient CO2 under controlled conditions. N fertilization increased CH4 oxidation by 3-fold in both CO2 treatments. CO2 did not have any significant effect on DEA while total denitrification and N2-to-N2O ratios increased by 36 and 33 %, respectively. The results indicate that shortly after N application elevated CO2 must have stimulated both the N2O production and reduction to N2 to explain the increased N2-to-N2O ratio and at the same time explain the non-responsiveness of the N2O emissions. Thus, the observed variation of the CO2 effect on N2O emissions throughout the year is possibly governed by the dynamics of the N2O reductase activity.

scholarly journals Vertical segregation among pathways mediating nitrogen loss (N<sub>2</sub> and N<sub>2</sub>O production) across the oxygen gradient in a coastal upwelling ecosystem

2017 ◽  
Vol 14 (20) ◽  
pp. 4795-4813 ◽  
Author(s):  
Alexander Galán ◽  
Bo Thamdrup ◽  
Gonzalo S. Saldías ◽  
Laura Farías
Keyword(s):  
Coastal Upwelling ◽  
Nitrite Reduction ◽  
15N Tracer ◽  
Ammonium Oxidation ◽  
N Loss ◽  
N2o Production ◽  
Coastal System ◽  
Central Chile ◽  
N Removal ◽  
Bottom Waters

Abstract. The upwelling system off central Chile (36.5° S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30–50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N2 and/or N2O, were studied using 15N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. Incubations were developed using water retrieved from the oxycline (25 m depth) and bottom waters (85 m depth) over the continental shelf off Concepción, Chile. Results of 15N-labelled incubations revealed higher N removal activity during the austral summer, with denitrification as the dominant N2-producing pathway, which occurred together with anammox at all times. Interestingly, in both spring and summer maximum potential N removal rates were observed in the oxycline, where a greater availability of oxygen was observed (maximum O2 fluctuation between 270 and 40 µmol L−1) relative to the hypoxic bottom waters ( <  20 µmol O2 L−1). Different pathways were responsible for N2O produced in the oxycline and bottom waters, with ammonium oxidation and dissimilatory nitrite reduction, respectively, as the main source processes. Ammonium produced by dissimilatory nitrite reduction to ammonium (DNiRA) could sustain both anammox and nitrification rates, including the ammonium utilized for N2O production. The temporal and vertical variability of δ15N-NO3− confirms that multiple N-cycling processes are modulating the isotopic nitrate composition over the shelf off central Chile during spring and summer. N removal processes in this coastal system appear to be related to the availability and distribution of oxygen and particles, which are a source of organic matter and the fuel for the production of other electron donors (i.e. ammonium) and acceptors (i.e. nitrate and nitrite) after its remineralization. These results highlight the links between several pathways involved in N loss. They also establish that different mechanisms supported by alternative N substrates are responsible for substantial accumulation of N2O, which are frequently observed as hotspots in the oxycline and bottom waters. Considering the extreme variation in oxygen observed in several coastal upwelling systems, these findings could help to understand the ecological and biogeochemical implications due to global warming where intensification and/or expansion of the oceanic OMZs is projected.

scholarly journals The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate

2016 ◽  
Vol 13 (3) ◽  
pp. 707-722 ◽  
Author(s):  
K. Zając ◽  
C. Blodau
Keyword(s):  
N Deposition ◽  
15N Tracer ◽  
Deposition Rates ◽  
N Content ◽  
Near Surface ◽  
Sphagnum Mosses ◽  
Length Growth ◽  
Polluted Sites ◽  
Surface Peat

Abstract. Elevated nitrogen (N) deposition changes the retention, transformation, and fluxes of N in ombrotrophic peatlands. To evaluate such effects we applied a 15N tracer (NH4 15NO3) at a rate of 2.3 g N m−2 yr−1 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 15N tracer from the mosses, graminoids, shrubs, the peat, and dissolved N. Background N contents in Sphagnum mosses increased from 5.5 (Degerö Stormyr, deposition < 0.2 g N m−2 yr−1) up to 12.2 mg g−1 (Frölichshaier Sattelmoor, 4.7–6.0 g N m−2 yr−1). In peat from Degerö, nitrate and ammonium concentrations were below 3 mg L−1, whereas up to 30 (nitrate) and 11 mg L−1 (ammonium) was found in peat from Frölichshaier Sattelmoor. Sphagnum mosses (down to 5 cm below surface) generally intercepted large amounts of 15N (0.2–0.35 mg g−1) and retained the tracer most effectively relative to their biomass. Similar quantities of the 15N were recovered from the peat, followed by shrubs, graminoids, and the dissolved pool. At the most polluted sites we recovered more 15N from shrubs (up to 12.4 %) and from nitrate and ammonium (up to 0.7 %). However, no impact of N deposition on 15N retention by Sphagnum 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−2 yr−1, 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 Sphagnum species can apparently thrive at elevated long-term N deposition rates in European peatlands.

A novel 15N tracer model reveals: Plant nitrate uptake governs nitrogen transformation rates in agricultural soils

2013 ◽  
Vol 57 ◽  
pp. 301-310 ◽  
Author(s):  
Erich Inselsbacher ◽  
Wolfgang Wanek ◽  
Joseph Strauss ◽  
Sophie Zechmeister-Boltenstern ◽  
Christoph Müller
Keyword(s):  
Nitrate Uptake ◽  
Agricultural Soils ◽  
Nitrogen Transformation ◽  
15N Tracer ◽  
Transformation Rates

Fate of airborne nitrogen in heathland ecosystems: a 15N tracer study

2010 ◽  
Vol 17 (4) ◽  
pp. 1549-1559 ◽  
Author(s):  
UTA FRIEDRICH ◽  
KIRSTEN FALK ◽  
ENNO BAHLMANN ◽  
THORBEN MARQUARDT ◽  
HARTMUT MEYER ◽  
...  
Keyword(s):  
15N Tracer ◽  
Tracer Study

scholarly journals Management Intensity Controls Nitrogen-Use-Efficiency and Flows in Grasslands—A 15N Tracing Experiment

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 606
Author(s):  
Marcus Zistl-Schlingmann ◽  
Steve Kwatcho Kengdo ◽  
Ralf Kiese ◽  
Michael Dannenmann
Keyword(s):  
Land Use ◽  
N Balance ◽  
15N Tracer ◽  
15N Recovery ◽  
Soil N ◽  
N Losses ◽  
Soil System ◽  
Land Use Intensification ◽  
Plant Soil ◽  
Montane Grasslands

The consequences of land use intensification and climate warming on productivity, fates of fertilizer nitrogen (N) and the overall soil N balance of montane grasslands remain poorly understood. Here, we report findings of a 15N slurry-tracing experiment on large grassland plant–soil lysimeters exposed to different management intensities (extensive vs. intensive) and climates (control; translocation: +2 °C, reduced precipitation). Surface-applied cattle slurry was enriched with both 15NH4+ and 15N-urea in order to trace its fate in the plant–soil system. Recovery of 15N tracer in plants was low (7–17%), while it was considerably higher in the soil N pool (32–42%), indicating N stabilization in soil organic nitrogen (SON). Total 15N recovery was only 49% ± 7% indicating substantial fertilizer N losses to the environment. With harvest N exports exceeding N fertilization rates, the N balance was negative for all climate and management treatments. Intensive management had an increased deficit relative to extensive management. In contrast, simulated climate change had no significant effects on the grassland N balance. These results suggest a risk of soil N mining in montane grasslands under land use intensification based on broadcast liquid slurry application.

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