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Natural Nitrogen Isotope Ratios as a Potential Indicator of N2O Production Pathways in a Floodplain Fen. WATER 2020. [DOI: 10.3390/w12020409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitrous oxide (N2O), a major greenhouse gas and ozone depleter, is emitted from drained organic soils typically developed in floodplains. We investigated the effect of the water table depth and soil oxygen (O2) content on N2O fluxes and their nitrogen isotope composition in a drained floodplain fen in Estonia. Measurements were done at natural water table depth, and we created a temporary anoxic environment by experimental flooding. From the suboxic peat (0.5–6 mg O2/L) N2O emissions peaked at 6 mg O2/L and afterwards decreased with decreasing O2. From the anoxic and oxic peat (0 and >6 mg O2/L, respectively) N2O emissions were low. Under anoxic conditions the δ15N/δ14N ratio of the top 10 cm peat layer was low, gradually decreasing to 30 cm. In the suboxic peat, δ15N/δ14N ratios increased with depth. In samples of peat fluctuating between suboxic and anoxic, the elevated 15N/14N ratios (δ15N = 7–9‰ ambient N2) indicated intensive microbial processing of nitrogen. Low values of site preference (SP; difference between the central and peripheral 15N atoms) and δ18O-N2O in the captured gas samples indicate nitrifier denitrification in the floodplain fen.
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Wu D, Well R, Cárdenas LM, Fuß R, Lewicka-Szczebak D, Köster JR, Brüggemann N, Bol R. Quantifying N 2O reduction to N 2 during denitrification in soils via isotopic mapping approach: Model evaluation and uncertainty analysis. ENVIRONMENTAL RESEARCH 2019; 179:108806. [PMID: 31627026 DOI: 10.1016/j.envres.2019.108806] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/05/2019] [Accepted: 10/06/2019] [Indexed: 06/10/2023]
Abstract
The last step of denitrification, i.e. the reduction of N2O to N2, has been intensively studied in the laboratory to understand the denitrification process, predict nitrogen fertiliser losses, and to establish mitigation strategies for N2O. However, assessing N2 production via denitrification at large spatial scales is still not possible due to lack of reliable quantitative approaches. Here, we present a novel numerical "mapping approach" model using the δ15Nsp/δ18O slope that has been proposed to potentially be used to indirectly quantify N2O reduction to N2 at field or larger spatial scales. We evaluate the model using data obtained from seven independent soil incubation studies conducted under a He-O2 atmosphere. Furthermore, we analyse the contribution of different parameters to the uncertainty of the model. The model performance strongly differed between studies and incubation conditions. Re-evaluation of the previous data set demonstrated that using soils-specific instead of default endmember values could largely improve model performance. Since the uncertainty of modelled N2O reduction was relatively high, further improvements to estimate model parameters to obtain more precise estimations remain an on-going matter, e.g. by determination of soil-specific isotope fractionation factors and isotopocule endmember values of N2O production processes using controlled laboratory incubations. The applicability of the mapping approach model is promising with an increasing availability of real-time and field based analysis of N2O isotope signatures.
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Affiliation(s)
- Di Wu
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China; Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
| | - Reinhard Well
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116, Braunschweig, Germany
| | | | - Roland Fuß
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116, Braunschweig, Germany
| | | | - Jan Reent Köster
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116, Braunschweig, Germany
| | - Nicolas Brüggemann
- Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Roland Bol
- Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
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Li Y, Yan W, Wang F, Lv S, Li Q, Yu Q. Nitrogen pollution and sources in an aquatic system at an agricultural coastal area of Eastern China based on a dual-isotope approach. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:23807-23823. [PMID: 31209747 DOI: 10.1007/s11356-019-05665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 06/03/2019] [Indexed: 06/09/2023]
Abstract
Nitrogen (N) pollution of water courses is a major concern in most coastal watersheds in eastern China with intensive agricultural production. We use hydrogeological and dual-isotopic approaches to analyze the N concentrations, pollution, transformations, and sources of surface water and groundwater in an agricultural watershed of the Jiaozhou Bay (JZB) area. Results showed that dissolved total N (DTN) concentrations in sub-rivers (SRs) ranged from 6.0 to 25.3 mg N L-1 in the dry season and 9.1-26.7 mg N L-1 in the wet season, which indicated a positive relationship with the percentages of agricultural land. Meanwhile, the dominant dissolved N species in SRs changed from nitrate (NO3-, 64-100%) to dissolved organic N (DON, 52-77%) from the dry season to the wet season and the increased DON concentrations showed a positive relationship with the planted proportions of vegetable production systems. The NO3- concentrations of groundwaters ranged from 10.6 to 121.4 mg N L-1, which were over the limit for drinking water by the World Health Organization. Isotopic analysis indicated that most NO3- originated from the microbiological conversion via nitrification, whereas the deletion of denitrification was insignificant in this area. The results of the stable isotope analysis in R mixing model showed the contributions of potential NO3- sources which were in order of manure fertilizers (20.6-69.0%) > soil organic matter (19.5-53.2%) > chemical fertilizers (5.5-34.3%) > atmospheric deposition (1.3-18.8%). This study suggests that the management of crop productions and reasonable manure fertilizer application should be implemented to protect the quality of aquatic systems in the JZB area.
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Affiliation(s)
- Yanqiang Li
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Weijin Yan
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Fang Wang
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Shucong Lv
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Qingqian Li
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Qibiao Yu
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
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4
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Castellano‐Hinojosa A, Loick N, Dixon E, Matthews GP, Lewicka‐Szczebak D, Well R, Bol R, Charteris A, Cardenas L. Improved isotopic model based on 15 N tracing and Rayleigh-type isotope fractionation for simulating differential sources of N 2 O emissions in a clay grassland soil. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:449-460. [PMID: 30561863 PMCID: PMC6492082 DOI: 10.1002/rcm.8374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/12/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
RATIONALE Isotopic signatures of N2 O can help distinguish between two sources (fertiliser N or endogenous soil N) of N2 O emissions. The contribution of each source to N2 O emissions after N-application is difficult to determine. Here, isotopologue signatures of emitted N2 O are used in an improved isotopic model based on Rayleigh-type equations. METHODS The effects of a partial (33% of surface area, treatment 1c) or total (100% of surface area, treatment 3c) dispersal of N and C on gaseous emissions from denitrification were measured in a laboratory incubation system (DENIS) allowing simultaneous measurements of NO, N2 O, N2 and CO2 over a 12-day incubation period. To determine the source of N2 O emissions those results were combined with both the isotope ratio mass spectrometry analysis of the isotopocules of emitted N2 O and those from the 15 N-tracing technique. RESULTS The spatial dispersal of N and C significantly affected the quantity, but not the timing, of gas fluxes. Cumulative emissions are larger for treatment 3c than treatment 1c. The 15 N-enrichment analysis shows that initially ~70% of the emitted N2 O derived from the applied amendment followed by a constant decrease. The decrease in contribution of the fertiliser N-pool after an initial increase is sooner and larger for treatment 1c. The Rayleigh-type model applied to N2 O isotopocules data (δ15 Nbulk -N2 O values) shows poor agreement with the measurements for the original one-pool model for treatment 1c; the two-pool models gives better results when using a third-order polynomial equation. In contrast, in treatment 3c little difference is observed between the two modelling approaches. CONCLUSIONS The importance of N2 O emissions from different N-pools in soil for the interpretation of N2 O isotopocules data was demonstrated using a Rayleigh-type model. Earlier statements concerning exponential increase in native soil nitrate pool activity highlighted in previous studies should be replaced with a polynomial increase with dependency on both N-pool sizes.
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Affiliation(s)
- Antonio Castellano‐Hinojosa
- Department of Microbiology, Faculty of PharmacyUniversity of Granada. Campus Cartuja18071GranadaSpain
- Department of Soil Microbiology and Symbiotic SystemsEstación Experimental del Zaidín18080GranadaSpain
| | - Nadine Loick
- Rothamsted Research, North WykeOkehamptonEX20 2SBUK
| | | | - G. Peter Matthews
- School of Geography, Earth and Environmental SciencesUniversity of PlymouthDavy Building, Drake CircusPlymouthPL4 8AAUK
| | | | - Reinhard Well
- Thünen Institute of Climate‐Smart AgricultureBundesallee 6538116BraunschweigGermany
| | - Roland Bol
- Agrosphere (IBG‐3)Institute of Bio‐ and GeosciencesForschungszentrum Jülich52428JülichGermany
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Lenhart K, Behrendt T, Greiner S, Steinkamp J, Well R, Giesemann A, Keppler F. Nitrous oxide effluxes from plants as a potentially important source to the atmosphere. THE NEW PHYTOLOGIST 2019; 221:1398-1408. [PMID: 30303249 DOI: 10.1111/nph.15455] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 08/19/2018] [Indexed: 05/12/2023]
Abstract
The global budget for nitrous oxide (N2 O), an important greenhouse gas and probably dominant ozone-depleting substance emitted in the 21st century, is far from being fully understood. Cycling of N2 O in terrestrial ecosystems has traditionally exclusively focused on gas exchange between the soil surface (nitrification-denitrification processes) and the atmosphere. Terrestrial vegetation has not been considered in the global budget so far, even though plants are known to release N2 O. Here, we report the N2 O emission rates of 32 plant species from 22 different families measured under controlled laboratory conditions. Furthermore, the first isotopocule values (δ15 N, δ18 O and δ15 Nsp ) of N2 O emitted from plants were determined. A robust relationship established between N2 O emission and CO2 respiration rates, which did not alter significantly over a broad range of changing environmental conditions, was used to quantify plant-derived emissions on an ecosystem scale. Stable isotope measurements (δ15 N, δ18 O and δ15 Nsp ) of N2 O emitted by plants clearly show that the dual isotopocule fingerprint of plant-derived N2 O differs from that of currently known microbial or chemical processes. Our work suggests that vegetation is a natural source of N2 O in the environment with a large fraction released by a hitherto unrecognized process.
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Affiliation(s)
- Katharina Lenhart
- Bingen University of Applied Sciences, Berlinstr. 109, Bingen, 55411, Germany
- Center for Organismal Studies, Im Neuenheimer Feld 360, Heidelberg, 69120, Germany
- Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, Heidelberg, D-69120, Germany
| | - Thomas Behrendt
- Max-Planck-Institute for Biogeochemistry, Hans Knöll Str. 10, Jena, 07745, Germany
| | - Steffen Greiner
- Center for Organismal Studies, Im Neuenheimer Feld 360, Heidelberg, 69120, Germany
| | - Jörg Steinkamp
- Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, Frankfurt am Main, 60325, Germany
- Johannes Gutenberg-Universität, Anselm-Franz-von-Bentzel-Weg 12, D-55128 Mainz, Germany
| | - Reinhard Well
- Thünen-Institute of Climate-Smart Agriculture, Bundesallee 50, Braunschweig, D-38116, Germany
| | - Anette Giesemann
- Thünen-Institute of Climate-Smart Agriculture, Bundesallee 50, Braunschweig, D-38116, Germany
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, Heidelberg, D-69120, Germany
- Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, D-69120, Germany
- Max-Planck-Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, D-55128, Germany
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Wang A, Fang Y, Chen D, Phillips O, Koba K, Zhu W, Zhu J. High nitrogen isotope fractionation of nitrate during denitrification in four forest soils and its implications for denitrification rate estimates. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 633:1078-1088. [PMID: 29758860 DOI: 10.1016/j.scitotenv.2018.03.261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Denitrification is a major process contributing to the removal of nitrogen (N) from ecosystems, but its rate is difficult to quantify. The natural abundance of isotopes can be used to identify the occurrence of denitrification and has recently been used to quantify denitrification rates at the ecosystem level. However, the technique requires an understanding of the isotopic enrichment factor associated with denitrification, which few studies have investigated in forest soils. Here, soils collected from two tropical and two temperate forests in China were incubated under anaerobic or aerobic laboratory conditions for two weeks to determine the N and oxygen (O) isotope enrichment factors during denitrification. We found that at room temperature (20°C), NO3- was reduced at a rate of 0.17 to 0.35μgNg-1h-1, accompanied by the isotope fractionation of N (15ε) and O (18ε) of 31‰ to 65‰ (48.3±2.0‰ on average) and 11‰ to 39‰ (18.9±1.7‰ on average), respectively. The N isotope effects were, unexpectedly, much higher than reported in the literature for heterotrophic denitrification (typically ranging from 5‰ to 30‰) and in other environmental settings (e.g., groundwater, marine sediments and agricultural soils). In addition, the ratios of Δδ18O:Δδ15N ranged from 0.28 to 0.60 (0.38±0.02 on average), which were lower than the canonical ratios of 0.5 to 1 for denitrification reported in other terrestrial and freshwater systems. We suggest that the isotope effects of denitrification for soils may vary greatly among regions and soil types and that gaseous N losses may have been overestimated for terrestrial ecosystems in previous studies in which lower fractionation factors were applied.
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Affiliation(s)
- Ang Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China; Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China; Qingyuan Forest CERN, Chinese Academy of Sciences, Shenyang 110016, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yunting Fang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China; Qingyuan Forest CERN, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Dexiang Chen
- Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China.
| | | | - Keisuke Koba
- Center for Ecological Research, Kyoto University, Shiga 520-2113, Japan
| | - Weixing Zhu
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China; Department of Biological Sciences, Binghamton University, The State University of New York, Binghamton, NY 13902, USA
| | - Jiaojun Zhu
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China; Qingyuan Forest CERN, Chinese Academy of Sciences, Shenyang 110016, China
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Van Nguyen Q, Jensen LS, Bol R, Wu D, Triolo JM, Vazifehkhoran AH, Bruun S. Biogas Digester Hydraulic Retention Time Affects Oxygen Consumption Patterns and Greenhouse Gas Emissions after Application of Digestate to Soil. JOURNAL OF ENVIRONMENTAL QUALITY 2017; 46:1114-1122. [PMID: 28991980 DOI: 10.2134/jeq2017.03.0117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Knowledge about environmental impacts associated with the application of anaerobic digestion residue to agricultural land is of interest owing to the rapid proliferation of biogas plants worldwide. However, virtually no information exists concerning how soil-emitted NO is affected by the feedstock hydraulic retention time (HRT) in the biogas digester. Here, the O planar optode technique was used to visualize soil O dynamics following the surface application of digestates of the codigestion of pig slurry and agro-industrial waste. We also used NO isotopomer analysis of soil-emitted NO to determine the NO production pathways, i.e., nitrification or denitrification. Two-dimensional images of soil O indicated that anoxic and hypoxic conditions developed at 2.0- and 1.5-cm soil depth for soil amended with the digestate produced with 15-d (PO15) and 30-d (PO30) retention time, respectively. Total NO emissions were significantly lower for PO15 than PO30 due to the greater expansion of the anoxic zone, which enhanced NO reduction via complete denitrification. However, cumulative CO emissions were not significantly different between PO15 and PO30 for the entire incubation period. During incubation, NO emissions came from both nitrification and denitrification in amended soils. Increasing the HRT of the biogas digester appears to induce significant NO emissions, but it is unlikely to affect the NO production pathways after application to soil.
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Lewicka-Szczebak D, Well R, Bol R, Gregory AS, Matthews GP, Misselbrook T, Whalley WR, Cardenas LM. Isotope fractionation factors controlling isotopocule signatures of soil-emitted N₂O produced by denitrification processes of various rates. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:269-282. [PMID: 26411625 DOI: 10.1002/rcm.7102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/14/2014] [Accepted: 11/17/2014] [Indexed: 06/05/2023]
Abstract
RATIONALE This study aimed (i) to determine the isotopic fractionation factors associated with N2O production and reduction during soil denitrification and (ii) to help specify the factors controlling the magnitude of the isotope effects. For the first time the isotope effects of denitrification were determined in an experiment under oxic atmosphere and using a novel approach where N2O production and reduction occurred simultaneously. METHODS Soil incubations were performed under a He/O2 atmosphere and the denitrification product ratio [N2O/(N2 + N2O)] was determined by direct measurement of N2 and N2O fluxes. N2O isotopocules were analyzed by mass spectrometry to determine δ(18)O, δ(15)N and (15)N site preference within the linear N2O molecule (SP). An isotopic model was applied for the simultaneous determination of net isotope effects (η) of both N2O production and reduction, taking into account emissions from two distinct soil pools. RESULTS A clear relationship was observed between (15)N and (18)O isotope effects during N2O production and denitrification rates. For N2O reduction, diverse isotope effects were observed for the two distinct soil pools characterized by different product ratios. For moderate product ratios (from 0.1 to 1.0) the range of isotope effects given by previous studies was confirmed and refined, whereas for very low product ratios (below 0.1) the net isotope effects were much smaller. CONCLUSIONS The fractionation factors associated with denitrification, determined under oxic incubation, are similar to the factors previously determined under anoxic conditions, hence potentially applicable for field studies. However, it was shown that the η(18)O/η(15)N ratios, previously accepted as typical for N2O reduction processes (i.e., higher than 2), are not valid for all conditions.
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Affiliation(s)
- Dominika Lewicka-Szczebak
- Thünen Institute of Climate-Smart Agriculture, Federal Research Institute for Rural Areas, Forestry and Fisheries, Bundesallee 50, D-38116, Braunschweig, Germany
- Institute of Geological Sciences, University of Wrocław, Cybulskiego 30, PL-50-205, Wroclaw, Poland
| | - Reinhard Well
- Thünen Institute of Climate-Smart Agriculture, Federal Research Institute for Rural Areas, Forestry and Fisheries, Bundesallee 50, D-38116, Braunschweig, Germany
| | - Roland Bol
- Forschungszentrum Jülich IBG-3, Wilhelm-Johnen-Straße, 52428, Jülich, Germany
| | | | - G Peter Matthews
- Faculty of Science & Environment, University of Plymouth, Plymouth, PL4 8AA, UK
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Mander U, Well R, Weymann D, Soosaar K, Maddison M, Kanal A, Lõhmus K, Truu J, Augustin J, Tournebize J. Isotopologue ratios of N2O and N2 measurements underpin the importance of denitrification in differently N-loaded riparian alder forests. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11910-11918. [PMID: 25264900 DOI: 10.1021/es501727h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Known as biogeochemical hotspots in landscapes, riparian buffer zones exhibit considerable potential concerning mitigation of groundwater contaminants such as nitrate, but may in return enhance the risk for indirect N2O emission. Here we aim to assess and to compare two riparian gray alder forests in terms of gaseous N2O and N2 fluxes and dissolved N2O, N2, and NO3(-) in the near-surface groundwater. We further determine for the first time isotopologue ratios of N2O dissolved in the riparian groundwater in order to support our assumption that it mainly originated from denitrification. The study sites, both situated in Estonia, northeastern Europe, receive contrasting N loads from adjacent uphill arable land. Whereas N2O emissions were rather small at both sites, average gaseous N2-to-N2O ratios inferred from closed-chamber measurements and He-O laboratory incubations were almost four times smaller for the heavily loaded site. In contrast, groundwater parameters were less variable among sites and between landscape positions. Campaign-based average (15)N site preferences of N2O (SP) in riparian groundwater ranged between 11 and 44 ‰. Besides the strong prevalence of N2 emission over N2O fluxes and the correlation pattern between isotopologue and water quality data, this comparatively large range highlights the importance of denitrification and N2O reduction in both riparian gray alder stands.
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Affiliation(s)
- Ulo Mander
- Institute of Ecology and Earth Sciences, University of Tartu , 51014 Tartu, Estonia
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10
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Rohe L, Anderson TH, Braker G, Flessa H, Giesemann A, Lewicka-Szczebak D, Wrage-Mönnig N, Well R. Dual isotope and isotopomer signatures of nitrous oxide from fungal denitrification--a pure culture study. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1893-1903. [PMID: 25088133 DOI: 10.1002/rcm.6975] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/27/2014] [Accepted: 06/27/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE The contribution of fungal denitrification to the emission of the greenhouse gas nitrous oxide (N2O) from soil has not yet been sufficiently investigated. The intramolecular (15)N site preference (SP) of N2O could provide a tool to distinguish between N2O produced by bacteria or fungi, since in previous studies fungi exhibited much higher SP values than bacteria. METHODS To further constrain isotopic evidence of fungal denitrification, we incubated six soil fungal strains under denitrifying conditions, with either NO3(-) or NO2(-) as the electron acceptor, and measured the isotopic signature (δ(18)O, δ(15)Nbulk and SP values) of the N2O produced. The nitrogen isotopic fractionation was calculated and the oxygen isotope exchange associated with particular fungal enzymes was estimated. RESULTS Five fungi of the order Hypocreales produced N2O with a SP of 35.1 ± 1.7 ‰ after 7 days of anaerobic incubation independent of the electron acceptor, whereas one Sordariales species produced N2O from NO2(-) only, with a SP value of 21.9 ± 1.4 ‰. Smaller isotope effects of (15)Nbulk were associated with larger N2O production. The δ(18)O values were influenced by oxygen exchange between water and denitrification intermediates, which occurred primarily at the nitrite reduction step. CONCLUSIONS Our results confirm that SP of N2O is a promising tool to differentiate between fungal and bacterial N2O from denitrification. Modelling of oxygen isotope fractionation processes indicated that the contribution of the NO2(-) and NO reduction steps to the total oxygen exchange differed among the various fungal species studied. However, more information is needed about different biological orders of fungi as they may differ in denitrification enzymes and consequently in the SP and δ(18)O values of the N2O produced.
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Affiliation(s)
- Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, D-38116, Braunschweig, Germany; University of Göttingen, Department of Crop Sciences, Institute of Grassland Science, von-Siebold-Straße 8, D-37075, Göttingen, Germany
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11
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Rohe L, Anderson TH, Braker G, Flessa H, Giesemann A, Wrage-Mönnig N, Well R. Fungal oxygen exchange between denitrification intermediates and water. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:377-384. [PMID: 24395505 DOI: 10.1002/rcm.6790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 11/14/2013] [Accepted: 11/20/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Fungi can contribute greatly to N2O production from denitrification. Therefore, it is important to quantify the isotopic signature of fungal N2O. The isotopic composition of N2O can be used to identify and analyze the processes of N2O production and N2O reduction. In contrast to bacteria, information about the oxygen exchange between denitrification intermediates and water during fungal denitrification is lacking, impeding the explanatory power of stable isotope methods. METHODS Six fungal species were anaerobically incubated with the electron acceptors nitrate or nitrite and (18)O-labeled water to determine the oxygen exchange between denitrification intermediates and water. After seven days of incubation, gas samples were analyzed for N2O isotopologues by isotope ratio mass spectrometry. RESULTS All the fungal species produced N2O. N2O production was greater when nitrite was the sole electron acceptor (129 to 6558 nmol N2O g dw(-1) h(-1)) than when nitrate was the electron acceptor (6 to 47 nmol N2O g dw(-1) h(-1)). Oxygen exchange was complete with nitrate as electron acceptor in one of five fungi and with nitrite in two of six fungi. Oxygen exchange of the other fungi varied (41 to 89% with nitrite and 11 to 61% with nitrate). CONCLUSIONS This is the first report on oxygen exchange with water during fungal denitrification. The exchange appears to be within the range previously reported for bacterial denitrification. This adds to the difficulty of differentiating N2O producing processes based on the origin of N2O-O. However, the large oxygen exchange repeatedly observed for bacteria and now also fungi could lead to less variability in the δ(18)O values of N2O from soils, which could facilitate the assessment of the extent of N2O reduction.
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Affiliation(s)
- Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, D-38116, Braunschweig, Germany; University of Göttingen, Department of Crop Sciences, Institute of Grassland Science, von-Siebold-Str. 8, D-37075, Göttingen, Germany
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Köster JR, Well R, Dittert K, Giesemann A, Lewicka-Szczebak D, Mühling KH, Herrmann A, Lammel J, Senbayram M. Soil denitrification potential and its influence on N2O reduction and N2O isotopomer ratios. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2363-2373. [PMID: 24097392 DOI: 10.1002/rcm.6699] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/27/2013] [Accepted: 07/29/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE N2O isotopomer ratios may provide a useful tool for studying N2O source processes in soils and may also help estimating N2O reduction to N2. However, remaining uncertainties about different processes and their characteristic isotope effects still hamper its application. We conducted two laboratory incubation experiments (i) to compare the denitrification potential and N2O/(N2O+N2) product ratio of denitrification of various soil types from Northern Germany, and (ii) to investigate the effect of N2O reduction on the intramolecular (15)N distribution of emitted N2O. METHODS Three contrasting soils (clay, loamy, and sandy soil) were amended with nitrate solution and incubated under N2 -free He atmosphere in a fully automated incubation system over 9 or 28 days in two experiments. N2O, N2, and CO2 release was quantified by online gas chromatography. In addition, the N2O isotopomer ratios were determined by isotope-ratio mass spectrometry (IRMS) and the net enrichment factors of the (15)N site preference (SP) of the N2O-to-N2 reduction step (η(SP)) were estimated using a Rayleigh model. RESULTS The total denitrification rate was highest in clay soil and lowest in sandy soil. Surprisingly, the N2O/(N2O+N2) product ratio in clay and loam soil was identical; however, it was significantly lower in sandy soil. The IRMS measurements revealed highest N2O SP values in clay soil and lowest SP values in sandy soil. The η(SP) values of N2O reduction were between -8.2 and -6.1‰, and a significant relationship between δ(18)O and SP values was found. CONCLUSIONS Both experiments showed that the N2O/(N2O+N2) product ratio of denitrification is not solely controlled by the available carbon content of the soil or by the denitrification rate. Differences in N2O SP values could not be explained by variations in N2O reduction between soils, but rather originate from other processes involved in denitrification. The linear δ(18)O vs SP relationship may be indicative for N2O reduction; however, it deviates significantly from the findings of previous studies.
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Affiliation(s)
- Jan Reent Köster
- Institute of Plant Nutrition and Soil Science, Kiel University, Hermann-Rodewald-Str. 2, D-24118, Kiel, Germany
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Köster JR, Well R, Tuzson B, Bol R, Dittert K, Giesemann A, Emmenegger L, Manninen A, Cárdenas L, Mohn J. Novel laser spectroscopic technique for continuous analysis of N2O isotopomers--application and intercomparison with isotope ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:216-222. [PMID: 23239336 DOI: 10.1002/rcm.6434] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 10/03/2012] [Accepted: 10/08/2012] [Indexed: 06/01/2023]
Abstract
RATIONALE Nitrous oxide (N(2)O), a highly climate-relevant trace gas, is mainly derived from microbial denitrification and nitrification processes in soils. Apportioning N(2)O to these source processes is a challenging task, but better understanding of the processes is required to improve mitigation strategies. The N(2)O site-specific (15)N signatures from denitrification and nitrification have been shown to be clearly different, making this signature a potential tool for N(2)O source identification. We have applied for the first time quantum cascade laser absorption spectroscopy (QCLAS) for the continuous analysis of the intramolecular (15)N distribution of soil-derived N(2)O and compared this with state-of-the-art isotope ratio mass spectrometry (IRMS). METHODS Soil was amended with nitrate and sucrose and incubated in a laboratory setup. The N(2)O release was quantified by FTIR spectroscopy, while the N(2)O intramolecular (15)N distribution was continuously analyzed by online QCLAS at 1 Hz resolution. The QCLAS results on time-integrating flask samples were compared with those from the IRMS analysis. RESULTS The analytical precision (2σ) of QCLAS was around 0.3‰ for the δ(15)N(bulk) and the (15)N site preference (SP) for 1-min average values. Comparing the two techniques on flask samples, excellent agreement (R(2)= 0.99; offset of 1.2‰) was observed for the δ(15)N(bulk) values while for the SP values the correlation was less good (R(2 )= 0.76; offset of 0.9‰), presumably due to the lower precision of the IRMS SP measurements. CONCLUSIONS These findings validate QCLAS as a viable alternative technique with even higher precision than state-of-the-art IRMS. Thus, laser spectroscopy has the potential to contribute significantly to a better understanding of N turnover in soils, which is crucial for advancing strategies to mitigate emissions of this efficient greenhouse gas.
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Affiliation(s)
- Jan Reent Köster
- Institute of Plant Nutrition and Soil Science, Kiel University, Hermann-Rodewald-Str. 2, D-24118, Kiel, Germany.
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The Isotopomers of Nitrous Oxide: Analytical Considerations and Application to Resolution of Microbial Production Pathways. ADVANCES IN ISOTOPE GEOCHEMISTRY 2012. [DOI: 10.1007/978-3-642-10637-8_23] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Kool DM, Van Groenigen JW, Wrage N. Source Determination of Nitrous Oxide Based on Nitrogen and Oxygen Isotope Tracing. Methods Enzymol 2011; 496:139-60. [DOI: 10.1016/b978-0-12-386489-5.00006-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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