Overlooked nitrous oxide emissions driven by bedrock weathering

2020 ◽  
Author(s):  
Jiamin Wan ◽  
Tetsu Tokunaga ◽  
Kenneth Williams ◽  
Wendy Brown ◽  
Alexander Newman ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Field Studies ◽  
Nitrous Oxide Emissions ◽  
Release Rates ◽  
Global Estimate ◽  
N Release ◽  
Bedrock Weathering ◽  
Reactive N ◽  
Biological Nitrogen ◽  
N Pool

Abstract Atmospheric nitrous oxide (N2O) contributes directly to global warming, yet current models1-5 overlook bedrock-contained nitrogen (rock-N), the largest terrestrial N pool6, as a N2O source. Although rock-N release rates are large6-9, incomplete understanding on the fate of released rock-N has obscured connections between rock-N and atmospheric N2O. This connection emerged through our field studies of a hillslope underlain by marine shale. Bedrock weathering within the zone of the seasonally fluctuating water table controls the weathering depth, hence the release of rock-N. At this site, rock-N weathering contributes 78% of the subsurface reactive-N, with ~22% derived from atmospheric deposition and biological nitrogen fixation, commonly regarded as the sole sources of reactive-N in pristine environments10,11. About 56% of reactive-N denitrifies, including 14% emitted as N2O into the atmosphere. The remaining reactive-N discharges in porewaters to a floodplain where additional denitrification likely occurs. Using global rock-N releases of 11–18 Tg y-1 8, our measurements extrapolate to a weathering driven efflux of 1.3–2.1 Tg N-N2O y-1, consistent with a flux of 1.0–1.7 Tg N- N2O y-1 solely derived from the literature. Thus, bedrock weathering contributes approximately 10-17 % of nitrous oxide to the current global estimate of ~10 Tg y-1.

scholarly journals Global soil nitrous oxide emissions in a dynamic carbon–nitrogen model

2015 ◽  
Vol 12 (3) ◽  
pp. 3101-3143 ◽  
Author(s):  
Y. Y. Huang ◽  
S. Gerber
Keyword(s):  
Nitrous Oxide ◽  
Elevated Co2 ◽  
Pore Space ◽  
Stratospheric Ozone ◽  
Co2 Enrichment ◽  
Field Studies ◽  
Global Scale ◽  
N2o Emission ◽  
Nitrous Oxide Emissions ◽  
Moisture Regime

Abstract. Nitrous oxide (N2O) is an important greenhouse gas that also contributes to the depletion of stratospheric ozone. With high temporal and spatial heterogeneity, a quantitative understanding of terrestrial N2O emission, its variabilities and reponses to climate change is challenging. We added a soil N2O emission module to the dynamic global land model LM3V-N, and tested its sensitivity to soil moisture regime and responses to elevated CO2 and temperature. The model was capable of reproducing the average of cross-site observed annual mean emissions, although differences remained across individual sites if stand-level measurements were representative of gridcell emissions. Modelled N2O fluxes were highly sensitive to water filled pore space (WFPS), with a global sensitivity of approximately 0.25 Tg N year−1 per 0.01 change in WFPS. We found that the global response of N2O emission to CO2 fertilization was largely determined by the response of tropical emissions, whereas the extratropical response was weaker and different, highlighting the need to expand field studies in tropical ecosystems. Warming generally enhanced N2O efflux, and the enhancement was greatly dampened when combined with elevated CO2, although CO2 alone had a small effect. Our analysis suggests caution when extrapolation from current field CO2 enrichment and warming studies to the global scale.

scholarly journals Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

2016 ◽  
Author(s):  
Philipp Porada ◽  
Ulrich Pöschl ◽  
Axel Kleidon ◽  
Christian Beer ◽  
Bettina Weber
Keyword(s):  
Nitrous Oxide ◽  
Atmospheric Deposition ◽  
Net Primary Productivity ◽  
Climatic Conditions ◽  
Nitrous Oxide Emissions ◽  
Emission Rates ◽  
Vegetation Model ◽  
Empirical Relationships ◽  
Global Estimate ◽  
Photosynthesis And Respiration

Abstract. Nitrous oxide is a strong greenhouse gas and atmospheric ozone-depleting agent, which is largely emitted by soils. Recently, also lichens and bryophytes have been shown to release significant amounts of nitrous oxide. This finding relies on empirical relationships between nitrous oxide emissions, respiration and net primary productivity of lichens and bryophytes, which are combined with ecosystem-scale values of their productivity. Here we obtain an alternative estimate of nitrous oxide emissions which is based on a global process-based non-vascular vegetation model of lichens and bryophytes. The model quantifies photosynthesis and respiration of lichens and bryophytes directly as a function of environmental conditions, such as light and temperature. Nitrous oxide emissions are then derived from simulated respiration assuming a fixed relationship between the two fluxes. This approach yields a global estimate of 0.27 (0.19–0.35) Tg yr−1 of nitrous oxide released by lichens and bryophytes. This is lower than previous estimates, but corresponds to about 50 % of the atmospheric deposition of N2O into the oceans or 25 % of the atmospheric deposition on land. Uncertainty in our simulated estimate results from large variation in emission rates due to both physiological differences between species and spatial heterogeneity of climatic conditions. To constrain our predictions, field observations of respiration in combination with a more process-based approach for relating nitrous oxide emissions to respiration may be helpful.

scholarly journals Fate of N in a peatland, Whim bog: N immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

2012 ◽  
Vol 9 (7) ◽  
pp. 8141-8171 ◽  
Author(s):  
L. J. Sheppard ◽  
I. D. Leith ◽  
S. R. Leeson ◽  
N. van Dijk ◽  
C. Field ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Deposition ◽  
Soil Water ◽  
Nitrogen Availability ◽  
N Deposition ◽  
Nitrous Oxide Emissions ◽  
Ombrotrophic Peatland ◽  
Pleurocarpous Mosses ◽  
Peat Surface ◽  
Reactive N

Abstract. Peatlands' vast carbon reserves accumulated under low nitrogen availability. Carbon and nitrogen cycling are inextricably linked, so what are the consequences of increased reactive nitrogen deposition for the sustainability and functioning of peatlands, and does the form of the nitrogen deposition make a difference? We have addressed these questions for an ombrotrophic peatland, Whim bog in SE Scotland, using a globally unique field simulation of reactive N deposition as dry deposited ammonia and wet deposited reduced N, ammonium and oxidised N, nitrate, added as ammonium chloride or sodium nitrate. The effects of 10 yr of reactive N additions, 56 kg N ha−1 yr−1, depended on the N form. Ammonia-N deposition caused the keystone Sphagnum species, together with the main shrub Calluna and the pleurocarpous mosses to disappear, exposing up to 30% of the peat surface. This led to a significant increase in soil water nitrate and nitrous oxide emissions. By contrast wet deposited N, despite significantly reducing the cover of Sphagnum and Pleurozium moss, did not have a detrimental effect on Calluna cover nor did it significantly change soil water N concentrations or nitrous oxide emissions. Importantly 10 yr of wet deposited N did not bare the peat surface nor significantly disrupt the vegetation, enabling the N to be retained within the carbon rich peatland ecosystems. However, given the significant role of Sphagnum in maintaining conditions that retard decomposition this study suggests that all nitrogen forms will eventually compromise carbon sequestration by peatlands through loss of some keystone Sphagnum species.

scholarly journals Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

2013 ◽  
Vol 10 (1) ◽  
pp. 149-160 ◽  
Author(s):  
L. J. Sheppard ◽  
I. D. Leith ◽  
S. R. Leeson ◽  
N. van Dijk ◽  
C. Field ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Water ◽  
Nitrogen Availability ◽  
N Deposition ◽  
Nitrous Oxide Emissions ◽  
Carbon And Nitrogen ◽  
Ombrotrophic Peatland ◽  
Pleurocarpous Mosses ◽  
Peat Surface ◽  
Reactive N

Abstract. Peatlands represent a vast carbon reserve that has accumulated under conditions of low nitrogen availability. Given the strong coupling between the carbon and nitrogen cycles, we need to establish the consequences of the increase in reactive nitrogen deposition for the sustainability of peatlands, and whether the form in which the nitrogen is deposited makes a difference. We have addressed these questions using a globally unique field simulation of reactive N deposition as dry deposited ammonia and wet deposited reduced N, ammonium and oxidised N, nitrate, added as ammonium chloride or sodium nitrate, to an ombrotrophic peatland, Whim bog in SE Scotland. Here we report the fate of 56 kg N ha−1 yr−1 additions over 10 yr and the consequences. The effects of 10 yr of reactive N additions depended on the form in which the N was applied. Ammonia-N deposition caused the keystone Sphagnum species, together with the main shrub Calluna and the pleurocarpous mosses, to disappear, exposing up to 30% of the peat surface. This led to a significant increase in soil water nitrate and nitrous oxide emissions. By contrast wet deposited N, despite significantly reducing the cover of Sphagnum and Pleurozium moss, did not have a detrimental effect on Calluna cover nor did it significantly change soil water N concentrations or nitrous oxide emissions. Importantly 10 yr of wet deposited N did not bare the peat surface nor significantly disrupt the vegetation enabling the N to be retained within the carbon rich peatland ecosystems. However, given the significant role of Sphagnum in maintaining conditions that retard decomposition, this study suggests that all nitrogen forms will eventually compromise carbon sequestration by peatlands through loss of some keystone Sphagnum species.

scholarly journals Nitrite build-up effect on nitrous oxide emissions in a laboratory-scale anaerobic/aerobic/anoxic/aerobic sequencing batch reactor

2021 ◽  
Vol 16 (2) ◽  
pp. 1
Author(s):  
Larissa Coelho Auto Gomes ◽  
Barbara Costa Pereira ◽  
Renato Pereira Ribeiro ◽  
Jaime Lopes da Mota Oliveira
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Removal ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Mitigation Strategies ◽  
Nitrous Oxide Emissions ◽  
Biological Nitrogen Removal ◽  
N2o Emissions ◽  
N2o Production ◽  
Biological Nitrogen

Biological wastewater treatment processes with biological nitrogen removal are potential sources of nitrous oxide (N2O) emissions. It is important to expand knowledge on the controlling factors associated with N2O production, in order to propose emission mitigation strategies. This study therefore sought to identify the parameters that favor nitrite (NO2-) accumulation and its influence on N2O production and emission in an anaerobic/aerobic/anoxic/aerobic sequencing batch reactor with biological nitrogen removal. Even with controlled dissolved oxygen concentrations and oxidation reduction potential, the first aerobic phase promoted only partial nitrification, resulting in NO2- build-up (ranging from 29 to 57%) and consequent N2O generation. The NO2- was not fully consumed in the subsequent anoxic phase, leading to even greater N2O production through partial denitrification. A direct relationship was observed between NO2- accumulation in these phases and N2O production. In the first aerobic phase, the N2O/NO2- ratio varied between 0.5 to 8.5%, while in the anoxic one values ranged between 8.3 and 22.7%. Higher N2O production was therefore noted during the anoxic phase compared to the first aerobic phase. As a result, the highest N2O fluxes occurred in the second aerobic phase, ranging from 706 to 2416 mg N m-2 h-1, as soon as aeration was triggered. Complete nitrification and denitrification promotion in this system was proven to be the key factor to avoid NO2- build-up and, consequently, N2O emissions.

Characteristics of Nitrous Oxide Emissions from Partial Nitrification Process Treating High Ammonium Wastewater

2014 ◽  
Vol 1073-1076 ◽  
pp. 844-848
Author(s):  
Ming Chuan Zhang ◽  
Xuan Gong ◽  
Xin Yang Xu
Keyword(s):  
Nitrous Oxide ◽  
Loading Rate ◽  
Granular Sludge ◽  
Nitrogen Loading ◽  
Partial Nitrification ◽  
Nitrous Oxide Emissions ◽  
Aerobic Granular Sludge ◽  
Intermittent Aeration ◽  
Nitrification Process ◽  
Biological Nitrogen

Nitrous oxide is a greenhouse gas, and biological nitrogen removal leads to nitrous oxide generation and emissions. In this study, the emission of nitrous oxide from partial nitrification process was investigated in two intermittently aerated SBRs (IASBRs). Activated sludge floc and aerobic granular sludge were feed into two IASBRs, respectively. In the steady state, partial nitrification was successfully achieved under intermittent aeration control strategy. Nitrous oxide emissions were 6.5% and 8.9% of the total influent nitrogen loading rate in IASBR1 and IASBR2, respectively. Nitrous oxide was mainly generated in non-aeration periods, but aeration period contributed to 91.8% and 90.6% of nitrous oxide emissions in two IASBRs, respectively. PHB can be used as the carbon source for heterotrophic denitrification, causing more nitrous oxide generated in IASBR2 which was seeded with aerobic granular sludge.

scholarly journals Estimating global nitrous oxide emissions by lichens and bryophytes with a process-based productivity model

2017 ◽  
Vol 14 (6) ◽  
pp. 1593-1602 ◽  
Author(s):  
Philipp Porada ◽  
Ulrich Pöschl ◽  
Axel Kleidon ◽  
Christian Beer ◽  
Bettina Weber
Keyword(s):  
Nitrous Oxide ◽  
Atmospheric Deposition ◽  
Net Primary Productivity ◽  
Climatic Conditions ◽  
Nitrous Oxide Emissions ◽  
Emission Rates ◽  
Vegetation Model ◽  
Empirical Relationships ◽  
Global Estimate ◽  
Photosynthesis And Respiration

Abstract. Nitrous oxide is a strong greenhouse gas and atmospheric ozone-depleting agent which is largely emitted by soils. Recently, lichens and bryophytes have also been shown to release significant amounts of nitrous oxide. This finding relies on ecosystem-scale estimates of net primary productivity of lichens and bryophytes, which are converted to nitrous oxide emissions by empirical relationships between productivity and respiration, as well as between respiration and nitrous oxide release. Here we obtain an alternative estimate of nitrous oxide emissions which is based on a global process-based non-vascular vegetation model of lichens and bryophytes. The model quantifies photosynthesis and respiration of lichens and bryophytes directly as a function of environmental conditions, such as light and temperature. Nitrous oxide emissions are then derived from simulated respiration assuming a fixed relationship between the two fluxes. This approach yields a global estimate of 0.27 (0.19–0.35) (Tg N2O) year−1 released by lichens and bryophytes. This is lower than previous estimates but corresponds to about 50 % of the atmospheric deposition of nitrous oxide into the oceans or 25 % of the atmospheric deposition on land. Uncertainty in our simulated estimate results from large variation in emission rates due to both physiological differences between species and spatial heterogeneity of climatic conditions. To constrain our predictions, combined online gas exchange measurements of respiration and nitrous oxide emissions may be helpful.

scholarly journals Nitrous oxide emissions from grass–clover swards as influenced by sward age and biological nitrogen fixation

2020 ◽  
Vol 75 (4) ◽  
pp. 372-384 ◽  
Author(s):  
Thorsten Reinsch ◽  
Carsten Malisch ◽  
Ralf Loges ◽  
Friedhelm Taube
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Nitrous Oxide Emissions ◽  
Biological Nitrogen

Estimates of nitrous oxide emissions from agricultural fields over 28 months

1997 ◽  
Vol 77 (2) ◽  
pp. 135-144 ◽  
Author(s):  
C. Wagner-Riddle ◽  
G. W. Thurtell ◽  
G. K. Kidd ◽  
E. G. Beauchamp ◽  
R. Sweetman
Keyword(s):  
Nitrous Oxide ◽  
Field Studies ◽  
Kentucky Bluegrass ◽  
Animal Manure ◽  
Tunable Diode Laser ◽  
Nitrous Oxide Emissions ◽  
Research Station ◽  
Long Term Effects ◽  
Key Words Nitrous Oxide

Field studies conducted throughout the calendar year are needed to improve flux estimates for the greenhouse gas nitrous oxide (N2O). In this study, we report monthly N2O emissions measured using micrometeorological techniques and a Tunable Diode Laser Trace Gas Analyzer (TDLTGA). Nitrous oxide fluxes were measured at the Elora Research Station (20 km north of Guelph, Ontario) from July to November 1992, and from March 1993 to February 1995, giving a total of 2445 daily averages obtained during the full length of the experiment. The soil at the experimental site was a Conestogo silt loam (Gleyed melanic brunisol). Several fields were monitored including fallow, manured fallow, Kentucky bluegrass, alfalfa, barley, canola, soybeans and corn plots. Spring thaw emissions from fallow or ploughed plots measured from March to April ranged from 1.5 to 4.3 kg N ha−1, corresponding to approximately 65% of the total annual emission. Similar effects were not observed on the vegetated (alfalfa and grass) plots. The lowest total annual N2O emissions were measured for second year alfalfa (1 kg N ha−1 yr−1) and bluegrass (0 to 0.5 kg N ha−1 yr−1). Higher annual emissions (2.5 to 4.0 kg N ha−1 yr−1) were observed for corn, barley, canola, and fallow plots. Highest annual emissions were measured after addition of nitrogen in the form of animal manure on a fallowed plot (5.7 to 7.4 kg N ha−1 yr−1), and alfalfa residue by fall-ploughing (6.1 kg N ha−1 yr−1). Plot management during the previous year affected N2O emissions, particularly on the soybean plot (5.9 kg N ha−1 yr−1) that followed a manured fallow treatment. The micrometeorological technique used in this study was successful at quasi-continuous monitoring of N2O fluxes from several plots, and therefore, useful for detecting long-term effects of management on emissions. Key words: Nitrous oxide, N2O fluxes, trace gases, agriculture, greenhouse gases

scholarly journals Bedrock weathering contributes to subsurface reactive nitrogen and nitrous oxide emissions

2021 ◽  
Author(s):  
Jiamin Wan ◽  
Tetsu K. Tokunaga ◽  
Wendy Brown ◽  
Alexander W. Newman ◽  
Wenming Dong ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrous Oxide Emissions ◽  
Reactive Nitrogen ◽  
Bedrock Weathering
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