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Button ES, Marsden KA, Nightingale PD, Dixon ER, Chadwick DR, Jones DL, Cárdenas LM. Separating N 2O production and consumption in intact agricultural soil cores at different moisture contents and depths. EUROPEAN JOURNAL OF SOIL SCIENCE 2023; 74:e13363. [PMID: 38529015 PMCID: PMC10962597 DOI: 10.1111/ejss.13363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/29/2023] [Accepted: 04/01/2023] [Indexed: 03/27/2024]
Abstract
Agricultural soils are a major source of the potent greenhouse gas and ozone depleting substance, N2O. To implement management practices that minimize microbial N2O production and maximize its consumption (i.e., complete denitrification), we must understand the interplay between simultaneously occurring biological and physical processes, especially how this changes with soil depth. Meaningfully disentangling of these processes is challenging and typical N2O flux measurement techniques provide little insight into subsurface mechanisms. In addition, denitrification studies are often conducted on sieved soil in altered O2 environments which relate poorly to in situ field conditions. Here, we developed a novel incubation system with headspaces both above and below the soil cores and field-relevant O2 concentrations to better represent in situ conditions. We incubated intact sandy clay loam textured agricultural topsoil (0-10 cm) and subsoil (50-60 cm) cores for 3-4 days at 50% and 70% water-filled pore space, respectively. 15N-N2O pool dilution and an SF6 tracer were injected below the cores to determine the relative diffusivity and the net N2O emission and gross N2O emission and consumption fluxes. The relationship between calculated fluxes from the below and above soil core headspaces confirmed that the system performed well. Relative diffusivity did not vary with depth, likely due to the preservation of preferential flow pathways in the intact cores. Gross N2O emission and uptake also did not differ with depth but were higher in the drier cores, contrary to expectation. We speculate this was due to aerobic denitrification being the primary N2O consuming process and simultaneously occurring denitrification and nitrification both producing N2O in the drier cores. We provide further evidence of substantial N2O consumption in drier soil but without net negative N2O emissions. The results from this study are important for the future application of the 15N-N2O pool dilution method and N budgeting and modelling, as required for improving management to minimize N2O losses.
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Affiliation(s)
- Erik S. Button
- School of Natural SciencesBangor UniversityBangorGwyneddUK
| | | | - Philip D. Nightingale
- Plymouth Marine Laboratory, Prospect Pl, Marine Biogeochemical ObservationsPlymouthDevonUK
| | - Elizabeth R. Dixon
- Rothamsted Research North Wyke, Net Zero and Resilient FarmingOkehamptonDevonUK
| | | | - David L. Jones
- School of Natural SciencesBangor UniversityBangorGwyneddUK
- Centre for Sustainable Farming Systems, Food Futures InstituteMurdochWestern AustraliaAustralia
| | - Laura M. Cárdenas
- Rothamsted Research North Wyke, Net Zero and Resilient FarmingOkehamptonDevonUK
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O. S. van Cleef F, B. Dubeux JC, M. Ciriaco F, Henry DD, Ruiz-Moreno M, M. Jaramillo D, Garcia L, S. Santos ER, DiLorenzo N, B. Vendramini JM, Naumann HD, Sollenberger LE. Inclusion of a tannin-rich legume in the diet of beef steers reduces greenhouse gas emissions from their excreta. Sci Rep 2022; 12:14220. [PMID: 35987790 PMCID: PMC9392745 DOI: 10.1038/s41598-022-18523-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 08/16/2022] [Indexed: 11/09/2022] Open
Abstract
The objectives of this study were to determine the emission of nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), as well as the isotopic composition of N2O from excreta of beef steers fed ‘AU Grazer’ sericea lespedeza hay [SL; Lespedeza cuneata (Dum. Cours.) G. Don]. Fifteen Brahman × Angus crossbred steers were fed one of three experimental diets: 0, 50, or 100% inclusion of SL into ‘Tifton 85’ bermudagrass hay (Cynodon spp.). Gas sampling occurred on days 0, 1, 3, 5, 7, 14, 18, 25, and 32 after urine or feces application to static chambers for two experimental periods. Effect of the day after feces application (P < 0.001), while day × inclusion of SL interaction was observed in urine (P < 0.001) for all greenhouse gases (GHG) analyzed. Peaks of emission of all GHG in urine and feces occurred in the first days (P < 0.001), with days 3 and 5 being most depleted in 15N-N2O in feces, and days 3, 5, and 7, in urine (P < 0.001). Feeding SL to beef steers was effective in mitigating the emission of GHG from the excreta, but further research is necessary to investigate the mechanisms behind the reductions.
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Gao D, Hou L, Liu M, Zheng Y, Yin G, Niu Y. N 2O emission dynamics along an intertidal elevation gradient in a subtropical estuary: Importance of N 2O consumption. ENVIRONMENTAL RESEARCH 2022; 205:112432. [PMID: 34843720 DOI: 10.1016/j.envres.2021.112432] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/09/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
Studying nitrous oxide (N2O) production and consumption processes along an intertidal elevation gradient can improve the understanding of N2O dynamics among coastal wetlands. A natural-abundance isotope technique was applied to characterize the processes responsible for N2O emission in high, middle and low intertidal zones in the Yangtze Estuary. The results showed that N2O emission rates in high tidal zones (0.84 ± 0.35 nmol g-1 h-1) were significantly higher than those in middle (0.21 ± 0.04 nmol g-1 h-1) and low tidal zones (0.26 ± 0.05 nmol g-1 h-1). Gross N2O production and consumption rates were greater in high and low tidal zones than in middle tidal zones, whereas N2O consumption proportions generally increased from high to low tidal zones. N2O consumption was quite pronounced, implying that N2O emission in estuarine wetlands accounts for only a small fraction of the total production. Higher degrees of N2O consumption were the pivotal driver of less N2O emission in low tidal zones. Bacterial denitrification (>84%) was the dominant pathway, although hydroxylamine (NH2OH) oxidation/fungal denitrification contributed substantially to N2O production in high tidal flats. The contribution to N2O production exhibited a decrease in NH2OH oxidation/fungal denitrification and an increase in bacterial denitrification with decreasing elevation. Changes in N2O dynamics along the elevation gradient were affected by carbon and nitrogen substrate availabilities as well as the redox environments. Overall, our findings highlight the importance of N2O consumption in controlling N2O emission in intertidal wetlands, especially with higher inundation frequencies and durations.
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Affiliation(s)
- Dengzhou Gao
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China; Key Laboratory of Geographic Information Science of the Ministry of Education, College of Geographical Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China.
| | - Min Liu
- Key Laboratory of Geographic Information Science of the Ministry of Education, College of Geographical Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Yanling Zheng
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China; Key Laboratory of Geographic Information Science of the Ministry of Education, College of Geographical Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Guoyu Yin
- Key Laboratory of Geographic Information Science of the Ministry of Education, College of Geographical Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Yuhui Niu
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
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Wu YF, Whitaker J, Toet S, Bradley A, Davies CA, McNamara NP. Diurnal variability in soil nitrous oxide emissions is a widespread phenomenon. GLOBAL CHANGE BIOLOGY 2021; 27:4950-4966. [PMID: 34231289 DOI: 10.1111/gcb.15791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Manual measurements of nitrous oxide (N2 O) emissions with static chambers are commonly practised. However, they generally do not consider the diurnal variability of N2 O flux, and little is known about the patterns and drivers of such variability. We systematically reviewed and analysed 286 diurnal data sets of N2 O fluxes from published literature to (i) assess the prevalence and timing (day or night peaking) of diurnal N2 O flux patterns in agricultural and forest soils, (ii) examine the relationship between N2 O flux and soil temperature with different diurnal patterns, (iii) identify whether non-diurnal factors (i.e. land management and soil properties) influence the occurrence of diurnal patterns and (iv) evaluate the accuracy of estimating cumulative N2 O emissions with single-daily flux measurements. Our synthesis demonstrates that diurnal N2 O flux variability is a widespread phenomenon in agricultural and forest soils. Of the 286 data sets analysed, ~80% exhibited diurnal N2 O patterns, with ~60% peaking during the day and ~20% at night. Contrary to many published observations, our analysis only found strong positive correlations (R > 0.7) between N2 O flux and soil temperature in one-third of the data sets. Soil drainage property, soil water-filled pore space (WFPS) level and land use were also found to potentially influence the occurrence of certain diurnal patterns. Our work demonstrated that single-daily flux measurements at mid-morning yielded daily emission estimates with the smallest average bias compared to measurements made at other times of day, however, it could still lead to significant over- or underestimation due to inconsistent diurnal N2 O patterns. This inconsistency also reflects the inaccuracy of using soil temperature to predict the time of daily average N2 O flux. Future research should investigate the relationship between N2 O flux and other diurnal parameters, such as photosynthetically active radiation (PAR) and root exudation, along with the consideration of the effects of soil moisture, drainage and land use on the diurnal patterns of N2 O flux. The information could be incorporated in N2 O emission prediction models to improve accuracy.
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Affiliation(s)
- Yuk-Faat Wu
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, UK
- Department of Environment and Geography, University of York, Heslington, York, UK
| | - Jeanette Whitaker
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, UK
| | - Sylvia Toet
- Department of Environment and Geography, University of York, Heslington, York, UK
| | - Amy Bradley
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, UK
| | - Christian A Davies
- Shell International Exploration and Production Inc., Shell Technology Centre Houston, Houston, TX, USA
| | - Niall P McNamara
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, UK
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Toyoda S, Yoshida N, Koba K. Isotopocule analysis of biologically produced nitrous oxide in various environments. MASS SPECTROMETRY REVIEWS 2017; 36:135-160. [PMID: 25869149 DOI: 10.1002/mas.21459] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 01/13/2015] [Accepted: 01/13/2015] [Indexed: 06/04/2023]
Abstract
Natural abundance ratios of isotopocules, molecules that have the same chemical constitution and configuration, but that only differ in isotope substitution, retain a record of a compound's origin and reactions. A method to measure isotopocule ratios of nitrous oxide (N2 O) has been established by using mass analysis of molecular ions and fragment ions. The method has been applied widely to environmental samples from the atmosphere, ocean, fresh water, soils, and laboratory-simulation experiments. Results show that isotopocule ratios, particularly the 15 N-site preference (difference between isotopocule ratios 14 N15 N16 O/14 N14 N16 O and 15 N14 N16 O/14 N14 N16 O), have a wide range that depends on their production and consumption processes. Observational and laboratory studies of N2 O related to biological processes are reviewed and discussed to elucidate complex material cycles of this trace gas, which causes global warming and stratospheric ozone depletion. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:135-160, 2017.
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Affiliation(s)
- Sakae Toyoda
- Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
| | - Naohiro Yoshida
- Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Keisuke Koba
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-City, Tokyo 183-8509, Japan
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Verhoeven E, Pereira E, Decock C, Suddick E, Angst T, Six J. Toward a Better Assessment of Biochar-Nitrous Oxide Mitigation Potential at the Field Scale. JOURNAL OF ENVIRONMENTAL QUALITY 2017; 46:237-246. [PMID: 28380558 DOI: 10.2134/jeq2016.10.0396] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Through meta-analysis, we synthesize results from field studies on the effect of biochar application on NO emissions and crop yield. We aimed to better constrain the effect of biochar on NO emissions under field conditions, identify significant predictor variables, assess potential synergies and tradeoffs between NO mitigation and yield, and discuss knowledge gaps. The response ratios for yield and NO emissions were weighted by one of two functions: (i) the inverse of the pooled variance or (ii) the inverse of number of observations per field site. Significant emission reductions were observed when weighting by the inverse of the pooled variance (-18.1 to -7.1%) but not when weighting by the number of observations per site (-17.1 to +0.8%), thus revealing a bias in the existing data by sites with more observations. Mean yield increased by 1.7 to 13.8%. Our study shows yield benefits but no robust evidence for NO emission reductions by biochar under field conditions. When weighted by the inverse of the number of observations per site, NO emission reductions were not significantly affected by cropping system, biochar properties of feedstock, pyrolysis temperature, surface area, pH, ash content, application rate, or site characteristics of N rate, N form, or soil pH. Uneven coverage in the range of these predictor variables likely underlies the failure to detect effects. We discuss the need for future biochar field studies to investigate effects of fertilizer N form, sustained and biologically relevant changes in soil moisture, multiple biochars per site, and time since biochar application.
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Murray RH, Erler DV, Eyre BD. Nitrous oxide fluxes in estuarine environments: response to global change. GLOBAL CHANGE BIOLOGY 2015; 21:3219-3245. [PMID: 25752934 DOI: 10.1111/gcb.12923] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 02/02/2015] [Indexed: 06/04/2023]
Abstract
Nitrous oxide is a powerful, long-lived greenhouse gas, but we know little about the role of estuarine areas in the global N2 O budget. This review summarizes 56 studies of N2 O fluxes and associated biogeochemical controlling factors in estuarine open waters, salt marshes, mangroves, and intertidal sediments. The majority of in situ N2 O production occurs as a result of sediment denitrification, although the water column contributes N2 O through nitrification in suspended particles. The most important factors controlling N2 O fluxes seem to be dissolved inorganic nitrogen (DIN) and oxygen availability, which in turn are affected by tidal cycles, groundwater inputs, and macrophyte density. The heterogeneity of coastal environments leads to a high variability in observations, but on average estuarine open water, intertidal and vegetated environments are sites of a small positive N2 O flux to the atmosphere (range 0.15-0.91; median 0.31; Tg N2 O-N yr(-1) ). Global changes in macrophyte distribution and anthropogenic nitrogen loading are expected to increase N2 O emissions from estuaries. We estimate that a doubling of current median NO3 (-) concentrations would increase the global estuary water-air N2 O flux by about 0.45 Tg N2 O-N yr(-1) or about 190%. A loss of 50% of mangrove habitat, being converted to unvegetated intertidal area, would result in a net decrease in N2 O emissions of 0.002 Tg N2 O-N yr(-1) . In contrast, conversion of 50% of salt marsh to unvegetated area would result in a net increase of 0.001 Tg N2 O-N yr(-1) . Decreased oxygen concentrations may inhibit production of N2 O by nitrification; however, sediment denitrification and the associated ratio of N2 O:N2 is expected to increase.
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Affiliation(s)
- Rachel H Murray
- Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Dirk V Erler
- Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Bradley D Eyre
- Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
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Snider DM, Venkiteswaran JJ, Schiff SL, Spoelstra J. From the ground up: global nitrous oxide sources are constrained by stable isotope values. PLoS One 2015; 10:e0118954. [PMID: 25811179 PMCID: PMC4374930 DOI: 10.1371/journal.pone.0118954] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 01/08/2015] [Indexed: 11/18/2022] Open
Abstract
Rising concentrations of nitrous oxide (N2O) in the atmosphere are causing widespread concern because this trace gas plays a key role in the destruction of stratospheric ozone and it is a strong greenhouse gas. The successful mitigation of N2O emissions requires a solid understanding of the relative importance of all N2O sources and sinks. Stable isotope ratio measurements (δ15N-N2O and δ18O-N2O), including the intramolecular distribution of 15N (site preference), are one way to track different sources if they are isotopically distinct. ‘Top-down’ isotope mass-balance studies have had limited success balancing the global N2O budget thus far because the isotopic signatures of soil, freshwater, and marine sources are poorly constrained and a comprehensive analysis of global N2O stable isotope measurements has not been done. Here we used a robust analysis of all available in situ measurements to define key global N2O sources. We showed that the marine source is isotopically distinct from soil and freshwater N2O (the continental source). Further, the global average source (sum of all natural and anthropogenic sources) is largely controlled by soils and freshwaters. These findings substantiate past modelling studies that relied on several assumptions about the global N2O cycle. Finally, a two-box-model and a Bayesian isotope mixing model revealed marine and continental N2O sources have relative contributions of 24–26% and 74–76% to the total, respectively. Further, the Bayesian modeling exercise indicated the N2O flux from freshwaters may be much larger than currently thought.
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Affiliation(s)
- David M. Snider
- National Water Research Institute, Canada Centre for Inland Waters, Environment Canada, Burlington, ON, L7R 4A6, Canada
- * E-mail: (DMS); (JJV)
| | - Jason J. Venkiteswaran
- Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
- * E-mail: (DMS); (JJV)
| | - Sherry L. Schiff
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - John Spoelstra
- National Water Research Institute, Canada Centre for Inland Waters, Environment Canada, Burlington, ON, L7R 4A6, Canada
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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Raynaud X, Nunan N. Spatial ecology of bacteria at the microscale in soil. PLoS One 2014; 9:e87217. [PMID: 24489873 PMCID: PMC3905020 DOI: 10.1371/journal.pone.0087217] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 12/26/2013] [Indexed: 11/18/2022] Open
Abstract
Despite an exceptional number of bacterial cells and species in soils, bacterial diversity seems to have little effect on soil processes, such as respiration or nitrification, that can be affected by interactions between bacterial cells. The aim of this study is to understand how bacterial cells are distributed in soil to better understand the scaling between cell-to-cell interactions and what can be measured in a few milligrams, or more, of soil. Based on the analysis of 744 images of observed bacterial distributions in soil thin sections taken at different depths, we found that the inter-cell distance was, on average 12.46 µm and that these inter-cell distances were shorter near the soil surface (10.38 µm) than at depth (>18 µm), due to changes in cell densities. These images were also used to develop a spatial statistical model, based on Log Gaussian Cox Processes, to analyse the 2D distribution of cells and construct realistic 3D bacterial distributions. Our analyses suggest that despite the very high number of cells and species in soil, bacteria only interact with a few other individuals. For example, at bacterial densities commonly found in bulk soil (10(8) cells g(-1) soil), the number of neighbours a single bacterium has within an interaction distance of ca. 20 µm is relatively limited (120 cells on average). Making conservative assumptions about the distribution of species, we show that such neighbourhoods contain less than 100 species. This value did not change appreciably as a function of the overall diversity in soil, suggesting that the diversity of soil bacterial communities may be species-saturated. All in all, this work provides precise data on bacterial distributions, a novel way to model them at the micrometer scale as well as some new insights on the degree of interactions between individual bacterial cells in soils.
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Affiliation(s)
- Xavier Raynaud
- Sorbonne Universités, UPMC Univ Paris 06, Institute of Ecology and Environmental Sciences – Paris, Paris, France
| | - Naoise Nunan
- CNRS, Institute of Ecology and Environmental Sciences – Paris, Campus AgroParisTech, Thiverval-Grignon, France
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Research advances on source/sink intensities and greenhouse effects of CO 2, CH 4 and N 2O in agricultural soils. ACTA ACUST UNITED AC 2011. [DOI: 10.3724/sp.j.1011.2011.00966] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Goldberg SD, Knorr KH, Gebauer G. N(2)O concentration and isotope signature along profiles provide deeper insight into the fate of N(2)O in soils. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2008; 44:377-391. [PMID: 19061068 DOI: 10.1080/10256010802507433] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Nitrous oxide is an important greenhouse gas and its origin and fate are thus of broad interest. Most studies on emissions of nitrous oxide from soils focused on fluxes between soil and atmosphere and hence represent an integration of physical and biological processes at different depths of a soil profile. Analysis of N(2)O concentration and isotope signature along soil profiles was suggested to improve the localisation of sources and sinks in soils as well as underlying processes and could therefore extend our knowledge on processes affecting surface N(2)O fluxes. Such a mechanistic understanding would be desirable to improve N(2)O mitigation strategies and global N(2)O budgets. To investigate N(2)O dynamics within soil profiles of two contrasting (semi)natural ecosystem types (a temperate acidic fen and a Norway spruce forest), soil gas samplers were constructed to meet the different requirements of a water-saturated and an unsaturated soil, respectively. The samplers were installed in three replicates and allowed soil gas sampling from six different soil depths. We analysed soil air for N(2)O concentration and isotope composition and calculated N(2)O net turnover using a mass balance approach and considering diffusive fluxes. At the fen site, N(2)O was mainly produced in 30-50 cm soil depth. Diffusion to adjacent layers above and below indicated N(2)O consumption. Values of delta(15)N and delta(18)O of N(2)O in the fen soil were always linearly correlated and their qualitative changes within the profile corresponded with the calculated turnover processes, suggesting further reduction of N(2)O. In the spruce forest, highest N(2)O production occurred in the topsoil, but there was also notable production occurring in the subsoil at a depth of 70 cm. Changes in N(2)O isotope composition as to be expected from local production and consumption processes within the soil profile did hardly occur, though. This was presumably caused by high diffusive fluxes and comparatively low net turnover, as isotope signatures approached values measured for ambient N(2)O towards the topsoil. Our results demonstrate a highly variable influence of diffusive versus production/consumption processes on N(2)O concentration and isotope composition, depending on the type of ecosystem. This finding indicates the necessity of further N(2)O concentration and isotope profile investigations in different types of natural and anthropogenic ecosystems in order to generalise our mechanistic understanding of N(2)O exchange between soil and atmosphere.
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Affiliation(s)
- Stefanie Daniela Goldberg
- Laboratory of Isotope Biogeochemistry, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
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Zhu R, Liu Y, Li X, Sun J, Xu H, Sun L. Stable isotope natural abundance of nitrous oxide emitted from Antarctic tundra soils: effects of sea animal excrement depositions. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:3570-3578. [PMID: 18932270 DOI: 10.1002/rcm.3762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nitrous oxide (N2O), a greenhouse gas, is mainly emitted from soils during the nitrification and denitrification processes. N2O stable isotope investigations can help to characterize the N2O sources and N2O production mechanisms. N2O isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of N2O emitted from Antarctic tundra ecosystems have been reported although the coastal ice-free tundra around Antarctic continent is the largest sea animal colony on the global scale. Here, we report for the first time stable isotope composition of N2O emitted from Antarctic sea animal colonies (including penguin, seal and skua colonies) and normal tundra soils using in situ field observations and laboratory incubations, and we have analyzed the effects of sea animal excrement depositions on stable isotope natural abundance of N2O. For all the field sites, the soil-emitted N2O was 15N- and 18O-depleted compared with N2O in local ambient air. The mean delta values of the soil-emitted N2O were delta15N = -13.5 +/- 3.2 per thousand and delta18O = 26.2 +/- 1.4 per thousand for the penguin colony, delta15N = -11.5 +/- 5.1 per thousand and delta18O = 26.4 +/- 3.5 per thousand for the skua colony and delta15N = -18.9 +/- 0.7 per thousand and delta18O = 28.8 +/- 1.3 per thousand for the seal colony. In the soil incubations, the isotopic composition of N2O was measured under N2 and under ambient air conditions. The soils incubated under the ambient air emitted very little N2O (2.93 microg N2O--N kg(-1)). Under N2 conditions, much more N2O was formed (9.74 microg N2O--N kg(-1)), and the mean delta15N and delta18O values of N2O were -19.1 +/- 8.0 per thousand and 21.3 +/- 4.3 per thousand, respectively, from penguin colony soils, and -17.0 +/- 4.2 per thousand and 20.6 +/- 3.5 per thousand, respectively, from seal colony soils. The data from in situ field observations and laboratory experiments point to denitrification as the predominant N2O source from Antarctic sea animal colonies.
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Affiliation(s)
- Renbin Zhu
- Institute of Polar Environment, University of Science and Technology of China, Hefei City, Anhui Province 230026, PR China.
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Boontanon N, Ueda S, Wada E. Estimation of pathways of the production of greenhouse gases in the tropical swamp forest in Thailand by stable isotope investigation. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2008; 44:253-265. [PMID: 18763183 DOI: 10.1080/10256010802309764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Dynamics of greenhouse gases (N(2)O and CH(4)) with the dry-wet cycle along with the variation of oxidation-reduction boundaries were investigated in the tropical wetland in monsoon Asia. It was clarified that the production of N(2)O and CH(4) was closely related to the development of a redox boundary in the Bang Nara River systems. An intermittent increase in N(2)O was observed at the beginning of the rainy season, when a large amount of easily decomposable organic matter was introduced into the river. After 10 days, when dissolved oxygen was consumed completely at the middle reaches, the emission of CH(4) became maximal due to the possible occurrence of denitrification. The distribution of stable isotope ratios in N(2)O clearly demonstrated that nitrification is the major process for its production. Furthermore, the production of N(2)O in this study area was found to vary in time and space with changes in the redox boundary along the water flow.
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Affiliation(s)
- Narin Boontanon
- Faculty of Environment and Resource Studies, Mahidol University, Nakhon Pathom, Thailand.
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Rock L, Ellert BH, Mayer B, Norman AL. Isotopic composition of tropospheric and soil N2O from successive depths of agricultural plots with contrasting crops and nitrogen amendments. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd008330] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Kool DM, Wrage N, Oenema O, Dolfing J, Van Groenigen JW. Oxygen exchange between (de)nitrification intermediates and H2O and its implications for source determination of NO3- and N2O: a review. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2007; 21:3569-3578. [PMID: 17935120 DOI: 10.1002/rcm.3249] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Stable isotope analysis of oxygen (O) is increasingly used to determine the origin of nitrate (NO(3)-) and nitrous oxide (N(2)O) in the environment. The assumption underlying these studies is that the (18)O signature of NO(3)- and N(2)O provides information on the different O sources (O(2) and H(2)O) during the production of these compounds by various biochemical pathways. However, exchange of O atoms between H(2)O and intermediates of the (de)nitrification pathways may change the isotopic signal and thereby bias its interpretation for source determination. Chemical exchange of O between H(2)O and various nitrogenous oxides has been reported, but the probability and extent of its occurrence in terrestrial ecosystems remain unclear. Biochemical O exchange between H(2)O and nitrogenous oxides, NO(2)- in particular, has been reported for monocultures of many nitrifiers and denitrifiers that are abundant in nature, with exchange rates of up to 100%. Therefore, biochemical O exchange is likely to be important in most soil ecosystems, and should be taken into account in source determination studies. Failing to do so might lead to (i) an overestimation of nitrification as NO(3)- source, and (ii) an overestimation of nitrifier denitrification and nitrification-coupled denitrification as N(2)O production pathways. A method to quantify the rate and controls of biochemical O exchange in ecosystems is needed, and we argue this can only be done reliably with artificially enriched (18)O compounds. We conclude that in N source determination studies, the O isotopic signature of especially N(2)O should only be used with extreme caution.
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Affiliation(s)
- D M Kool
- Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands.
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