Net soil–atmosphere fluxes mask patterns in gross production and consumption of nitrous oxide and methane in a managed ecosystem

Abstract. Nitrous oxide (N2O) and methane (CH4) are potent greenhouse gases that are both produced and consumed in soil. Production and consumption of these gases are driven by different processes, making it difficult to infer their controls when measuring only net fluxes. We used the trace gas pool dilution technique to simultaneously measure gross fluxes of N2O and CH4 throughout the growing season in a cornfield in northern California, USA. Net N2O fluxes ranged from 0–4.5 mg N m−2 d−1 with the N2O yield averaging 0.68 ± 0.02. Gross N2O production was best predicted by net nitrogen (N) mineralization, soil moisture, and soil temperature (R2 = 0.60, n = 39, p < 0.001). Gross N2O reduction was correlated with the combination of gross N2O production rates, net N mineralization rates, and CO2 emissions (R2 = 0.74, n = 39, p < 0.001). Overall, net CH4 fluxes averaged −0.03 ± 0.02 mg C m−2 d−1. The methanogenic fraction of carbon mineralization ranged from 0 to 0.27 % and explained 40 % of the variability in gross CH4 production rates (n = 37, p < 0.001). Gross CH4 oxidation exhibited a strong positive relationship with gross CH4 production rates (R2 = 0.67, n = 37, p < 0.001), which reached as high as 5.4 mg C m−2 d−1. Our study is the first to demonstrate the simultaneous in situ measurement of gross N2O and CH4 fluxes, and results highlight that net soil–atmosphere fluxes can mask significant gross production and consumption of these trace gases.

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Net soil–atmosphere fluxes mask patterns in gross production and consumption of nitrous oxide and methane in a managed ecosystem

Biogeosciences ◽

10.5194/bg-13-1705-2016 ◽

2016 ◽

Vol 13 (5) ◽

pp. 1705-1715 ◽

Cited By ~ 16

Author(s):

Wendy H. Yang ◽

Whendee L. Silver

Keyword(s):

Nitrous Oxide ◽

N Mineralization ◽

Carbon Mineralization ◽

Net N Mineralization ◽

Production Rates ◽

N2o Production ◽

Ch4 Production ◽

Soil Atmosphere ◽

Strong Positive Relationship ◽

Production And Consumption

Abstract. Nitrous oxide (N2O) and methane (CH4) are potent greenhouse gases that are both produced and consumed in soil. Production and consumption of these gases are driven by different processes, making it difficult to infer their controls when measuring only net fluxes. We used the trace gas pool dilution technique to simultaneously measure gross fluxes of N2O and CH4 throughout the growing season in a cornfield in northern California, USA. Net N2O fluxes ranged 0–4.5 mg N m−2 d−1 with the N2O yield averaging 0.68 ± 0.02. Gross N2O production was best predicted by net nitrogen (N) mineralization, soil moisture, and soil temperature (R2 = 0.60, n = 39, p< 0.001). Gross N2O reduction was correlated with the combination of gross N2O production rates, net N mineralization rates, and CO2 emissions (R2 = 0.74, n = 39, p< 0.001). Overall, net CH4 fluxes averaged −0.03 ± 0.02 mg C m−2 d−1. The methanogenic fraction of carbon mineralization ranged from 0 to 0.27 % and explained 40 % of the variability in gross CH4 production rates (n = 37, p< 0.001). Gross CH4 oxidation exhibited a strong positive relationship with gross CH4 production rates (R2 = 0.67, n = 37, p< 0.001), which reached as high as 5.4 mg C m−2 d−1. Our study is the first to demonstrate the simultaneous in situ measurement of gross N2O and CH4 fluxes, and results highlight that net soil–atmosphere fluxes can mask significant gross production and consumption of these trace gases.

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Carbon and nitrogen mineralization in soil amended with non-tabletized and tabletized poultry manure

Canadian Journal of Soil Science ◽

10.4141/s99-101 ◽

2000 ◽

Vol 80 (2) ◽

pp. 271-276 ◽

Cited By ~ 5

Author(s):

T. Paré ◽

H. Dinel ◽

M. Schnitzer

Keyword(s):

Nitrogen Mineralization ◽

N Mineralization ◽

Organic Fertilizer ◽

Carbon Mineralization ◽

Poultry Manure ◽

Net N Mineralization ◽

N Accumulation ◽

Suitable Alternative ◽

C And N Mineralization ◽

C And N

The recycling of poultry (Gallus gallus domesticus) manure (PM) needs to be done in a manner that will not only improve soil physical, chemical and biological properties but also minimize environmental risks. Untreated PM is more difficult to handle and more expensive to apply than granular fertilizers; the application of PM in the form of tablets may be a suitable alternative. It is necessary to determine whether C and N mineralization in tabletized PM (T-PM) differs from non-tabletized PM (NT-PM). Net C and N mineralization from a Brandon loam soil (Typic Endoaquoll) amended with NT-PM and T-PM, were measured in an incubation study at 25 °C. After 60 d of incubation, about 62 and 77% of total PM carbon was mineralized in NT-PM and T-PM amended soils, respectively. Carbon mineralization was not stimulated by the addition of PM tablets containing NPK to soil, while in soils mixed with NT-PM + NPK, soil respiration was reduced. Net N mineralization was similar in soils amended with T-PM and NT-PM, although changes in ammonium (NH4+–N) concentrations during incubation differed. Generally more NH4+–N accumulated in soil amended with T-PM and T-PM + NPK than with NT-PM and NT-PM + NPK The concentrations of nitrate (NO3−–N) did not differ in soils amended with T-PM and NT-PM, indicating a reduction in nitrification and NH4+–N accumulation in soils amended with PM tablets. Key words: Poultry manure, tablets, carbon mineralization, nitrogen mineralization, organic fertilizer

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Nitrous oxide dynamics in low oxygen regions of the Pacific: insights from the MEMENTO database

Biogeosciences ◽

10.5194/bg-9-5007-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 5007-5022 ◽

Cited By ~ 32

Author(s):

L. M. Zamora ◽

A. Oschlies ◽

H. W. Bange ◽

K. B. Huebert ◽

J. D. Craig ◽

...

Keyword(s):

Nitrous Oxide ◽

N2o Emissions ◽

Low Oxygen ◽

N2o Production ◽

Oxygen Minimum Zones ◽

A Value ◽

The Pacific ◽

Production And Consumption ◽

The Relationship ◽

Oxygen Minimum

Abstract. The eastern tropical Pacific (ETP) is believed to be one of the largest marine sources of the greenhouse gas nitrous oxide (N2O). Future N2O emissions from the ETP are highly uncertain because oxygen minimum zones are expected to expand, affecting both regional production and consumption of N2O. Here we assess three primary uncertainties in how N2O may respond to changing O2 levels: (1) the relationship between N2O production and O2 (is it linear or exponential at low O2 concentrations?), (2) the cutoff point at which net N2O production switches to net N2O consumption (uncertainties in this parameterisation can lead to differences in model ETP N2O concentrations of more than 20%), and (3) the rate of net N2O consumption at low O2. Based on the MEMENTO database, which is the largest N2O dataset currently available, we find that N2O production in the ETP increases linearly rather than exponentially with decreasing O2. Additionally, net N2O consumption switches to net N2O production at ~ 10 μM O2, a value in line with recent studies that suggest consumption occurs on a larger scale than previously thought. N2O consumption is on the order of 0.01–1 mmol N2O m−3 yr−1 in the Peru-Chile Undercurrent. Based on these findings, it appears that recent studies substantially overestimated N2O production in the ETP. In light of expected deoxygenation and the higher than previously expected point at which net N2O production switches to consumption, there is enough uncertainty in future N2O production that even the sign of future changes is still unclear.

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Nitrous oxide dynamics in low oxygen regions of the Pacific: insights from the MEMENTO database

Biogeosciences Discussions ◽

10.5194/bgd-9-10019-2012 ◽

2012 ◽

Vol 9 (8) ◽

pp. 10019-10056 ◽

Cited By ~ 2

Author(s):

L. M. Zamora ◽

A. Oschlies ◽

H. W. Bange ◽

J. D. Craig ◽

K. B. Huebert ◽

...

Keyword(s):

Nitrous Oxide ◽

Low Oxygen ◽

N2o Production ◽

Oxygen Minimum Zones ◽

A Value ◽

Regional Production ◽

The Pacific ◽

Production And Consumption ◽

The Relationship ◽

Oxygen Minimum

Abstract. The Eastern Tropical Pacific (ETP) is believed to be one of the largest marine sources of the greenhouse gas nitrous oxide N2O). Future N2Oemissions from the ETP are highly uncertain because oxygen minimum zones are expected to expand, affecting both regional production and consumption of N2O. Here we assess three primary uncertainties in how N2O may respond to changing O2 levels: (1) the relationship between N2O production and O2 (is it linear or exponential at low O2 concentrations?), (2) the cutoff point at which net N2O production switches to net N2O consumption (uncertainties in this parameterization can lead to differences in model ETP N2O concentrations of more than 20%), and (3) the rate of net N2O consumption at low O2. Based on the MEMENTO database, which is the largest N2O dataset currently available, we find that N2O production in the ETP increases linearly rather than exponentially with decreasing O2. Additionally, net N2O consumption switches to net N2O production at ~ 10 μM O2, a value in line with recent studies that suggest consumption occurs on a larger scale than previously thought. N2O consumption is on the order of 0.129 mmol N2O m−3 yr−1 in the Peru–Chile Undercurrent. Based on these findings, it appears that recent studies substantially overestimated N2O production in the ETP. In light of expected deoxygenation, future N2O production is still uncertain, but due to higher-than-expected consumption levels, it is possible that N2Oconcentrations may decrease rather than increase as oxygen minimum zones expand.

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Alteration of nitrous oxide emissions from floodplain soils by aggregate size, litter accumulation and plant soil interactions

10.5194/bg-2018-281 ◽

2018 ◽

Author(s):

Martin Ley ◽

Moritz F. Lehmann ◽

Pascal A. Niklaus ◽

Jörg Luster

Keyword(s):

Nitrous Oxide ◽

Aggregate Size ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

N2o Production ◽

Litter Accumulation ◽

Plant Soil ◽

Floodplain Soils ◽

Production And Consumption ◽

Drying Conditions

Abstract. Abstract. Semi–terrestrial soils such as floodplain soils are considered potential hotspots of nitrous oxide (N2O) emissions. Microhabitats in the soil, such as within and outside of aggregates, in the detritusphere, and/or in the rhizosphere, are considered to promote and preserve specific redox conditions. Yet, our understanding of the relative effects of such microhabitats and their interactions on N2O production and consumption in soils is still incomplete. Therefore, we assessed the effect of aggregate size, buried organic matter, and rhizosphere processes on the occurrence of enhanced N2O emissions under simulated flooding/drying conditions in a mesocosm experiment. We used two model soils with equivalent structure and texture, comprising macroaggregates (4000–250 µm) or microaggregates (

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Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O

Biogeosciences ◽

10.5194/bg-7-2159-2010 ◽

2010 ◽

Vol 7 (7) ◽

pp. 2159-2190 ◽

Cited By ~ 214

Author(s):

S. W. A. Naqvi ◽

H. W. Bange ◽

L. Farías ◽

P. M. S. Monteiro ◽

M. I. Scranton ◽

...

Keyword(s):

Nitrous Oxide ◽

Bottom Water ◽

Coastal Upwelling ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

Quantitative Prediction ◽

The Black Sea ◽

N2o Production ◽

Ch4 Production ◽

Subsurface Waters

Abstract. We review here the available information on methane (CH4) and nitrous oxide (N2O) from major marine, mostly coastal, oxygen (O2)-deficient zones formed both naturally and as a result of human activities (mainly eutrophication). Concentrations of both gases in subsurface waters are affected by ambient O2 levels to varying degrees. Organic matter supply to seafloor appears to be the primary factor controlling CH4 production in sediments and its supply to (and concentration in) overlying waters, with bottom-water O2-deficiency exerting only a modulating effect. High (micromolar level) CH4 accumulation occurs in anoxic (sulphidic) waters of silled basins, such as the Black Sea and Cariaco Basin, and over the highly productive Namibian shelf. In other regions experiencing various degrees of O2-deficiency (hypoxia to anoxia), CH4 concentrations vary from a few to hundreds of nanomolar levels. Since coastal O2-deficient zones are generally very productive and are sometimes located close to river mouths and submarine hydrocarbon seeps, it is difficult to differentiate any O2-deficiency-induced enhancement from in situ production of CH4 in the water column and its inputs through freshwater runoff or seepage from sediments. While the role of bottom-water O2-deficiency in CH4 formation appears to be secondary, even when CH4 accumulates in O2-deficient subsurface waters, methanotrophic activity severely restricts its diffusive efflux to the atmosphere. As a result, an intensification or expansion of coastal O2-deficient zones will probably not drastically change the present status where emission from the ocean as a whole forms an insignificant term in the atmospheric CH4 budget. The situation is different for N2O, the production of which is greatly enhanced in low-O2 waters, and although it is lost through denitrification in most suboxic and anoxic environments, the peripheries of such environments offer most suitable conditions for its production, with the exception of enclosed anoxic basins. Most O2-deficient systems serve as strong net sources of N2O to the atmosphere. This is especially true for coastal upwelling regions with shallow O2-deficient zones where a dramatic increase in N2O production often occurs in rapidly denitrifying waters. Nitrous oxide emissions from these zones are globally significant, and so their ongoing intensification and expansion is likely to lead to a significant increase in N2O emission from the ocean. However, a meaningful quantitative prediction of this increase is not possible at present because of continuing uncertainties concerning the formative pathways to N2O as well as insufficient data from key coastal regions.

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Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils

10.5194/bg-2021-228 ◽

2021 ◽

Author(s):

Jenie A. Gil ◽

Maija E. Marushchak ◽

Tobias Rütting ◽

Elizabeth M. Baggs ◽

Tibisay Pérez ◽

...

Keyword(s):

Nitrous Oxide ◽

Water Content ◽

N Mineralization ◽

N2o Emission ◽

The Arctic ◽

High Water Content ◽

N2o Emissions ◽

Gross Nitrification ◽

N2o Production ◽

Bare Peat

Abstract. Nitrous oxide (N2O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in subarctic tundra emitting N2O at high rates, such as bare peat surfaces on permafrost peatlands. The processes behind N2O production in these high-emitting habitats are, however, poorly understood. In this study, we established an in situ 15N-labelling experiment with the main objectives to partition the microbial sources of N2O emitted from bare peat surfaces (BP) on permafrost peatlands and to study the fate of ammonium and nitrate in these soils and in adjacent vegetated peat surfaces (VP) showing low N2O emissions. Our results confirm the hypothesis that denitrification is mostly responsible for the high N2O emissions from BP surfaces. During the study period denitrification contributed with ~79 % of the total N2O emission in BP, while the contribution of ammonia oxidation was less, about 19 %. However, nitrification is a key process for the overall N2O production in these soils with negligible external nitrogen (N) load because it is responsible for nitrite/nitrate supply for denitrification, as also supported by relatively high gross nitrification rates in BP. Generally, both gross N mineralization and gross nitrification rates were much higher in BP with high N2O emissions than in VP, where the high C / N ratio together with low water content was likely limiting N mineralization and nitrification and, consequently, N2O production. Also, competition for mineral N between plants and microbes was additionally limiting N availability for N2O production in VP. Our results show that multiple factors control N2O production in permafrost peatlands, the absence of plants being a key factor together with inter-mediate to high water content and low C / N ratio, all factors which also impact on gross N turnover rates. The intermediate to high soil water content which creates anaerobic microsites in BP is a key N2O emission driver for the prevalence of denitrification to occur. This knowledge is important for evaluating future permafrost –N feedback loops from the Arctic.

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Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽

10.3390/w13030320 ◽

2021 ◽

Vol 13 (3) ◽

pp. 320

Author(s):

Qianyao Si ◽

Mary G. Lusk ◽

Patrick W. Inglett

Keyword(s):

Removal Efficiency ◽

N Mineralization ◽

Inorganic Nitrogen ◽

Dry Season ◽

Pollutant Removal ◽

Net N Mineralization ◽

Wet Season ◽

Inorganic N ◽

N Removal ◽

Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

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Biological nitrous oxide consumption in oxygenated waters of the high latitude Atlantic Ocean

Communications Earth & Environment ◽

10.1038/s43247-021-00104-y ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Andrew P. Rees ◽

Ian J. Brown ◽

Amal Jayakumar ◽

Gennadi Lessin ◽

Paul J. Somerfield ◽

...

Keyword(s):

Nitrous Oxide ◽

Atlantic Ocean ◽

High Latitude ◽

Bacterial Communities ◽

Stratospheric Ozone ◽

Intermediate Step ◽

Anoxic Environments ◽

Production And Consumption ◽

Net Flux ◽

Traditional Understanding

AbstractNitrous oxide (N2O) is important to the global radiative budget of the atmosphere and contributes to the depletion of stratospheric ozone. Globally the ocean represents a large net flux of N2O to the atmosphere but the direction of this flux varies regionally. Our understanding of N2O production and consumption processes in the ocean remains incomplete. Traditional understanding tells us that anaerobic denitrification, the reduction of NO3− to N2 with N2O as an intermediate step, is the sole biological means of reducing N2O, a process known to occur in anoxic environments only. Here we present experimental evidence of N2O removal under fully oxygenated conditions, coupled with observations of bacterial communities with novel, atypical gene sequences for N2O reduction. The focus of this work was on the high latitude Atlantic Ocean where we show bacterial consumption sufficient to account for oceanic N2O depletion and the occurrence of regional sinks for atmospheric N2O.

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Microbial N2O consumption in and above marine N2O production hotspots

The ISME Journal ◽

10.1038/s41396-020-00861-2 ◽

2020 ◽

Author(s):

Xin Sun ◽

Amal Jayakumar ◽

John C. Tracey ◽

Elizabeth Wallace ◽

Colette L. Kelly ◽

...

Keyword(s):

Kinetic Parameters ◽

Substrate Affinity ◽

N2o Production ◽

Anoxic Waters ◽

Production And Consumption ◽

Consumption Rates ◽

Anoxic Zones ◽

First Time ◽

Microbial N

AbstractThe ocean is a net source of N2O, a potent greenhouse gas and ozone-depleting agent. However, the removal of N2O via microbial N2O consumption is poorly constrained and rate measurements have been restricted to anoxic waters. Here we expand N2O consumption measurements from anoxic zones to the sharp oxygen gradient above them, and experimentally determine kinetic parameters in both oxic and anoxic seawater for the first time. We find that the substrate affinity, O2 tolerance, and community composition of N2O-consuming microbes in oxic waters differ from those in the underlying anoxic layers. Kinetic parameters determined here are used to model in situ N2O production and consumption rates. Estimated in situ rates differ from measured rates, confirming the necessity to consider kinetics when predicting N2O cycling. Microbes from the oxic layer consume N2O under anoxic conditions at a much faster rate than microbes from anoxic zones. These experimental results are in keeping with model results which indicate that N2O consumption likely takes place above the oxygen deficient zone (ODZ). Thus, the dynamic layer with steep O2 and N2O gradients right above the ODZ is a previously ignored potential gatekeeper of N2O and should be accounted for in the marine N2O budget.

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