scholarly journals Nitrification is a minor source of nitrous oxide (N 2 O) in agricultural landscapes and declines with increasing management intensity

2021 ◽  
Author(s):  
Di Liang ◽  
G. Philip Robertson
Keyword(s):  
Nitrous Oxide ◽  
Agricultural Landscapes ◽  
Management Intensity ◽  
A Minor

scholarly journals Representing composition, spatial structure and management intensity of European agricultural landscapes: A new typology

2016 ◽  
Vol 150 ◽  
pp. 36-49 ◽  
Author(s):  
Emma H. van der Zanden ◽  
Christian Levers ◽  
Peter H. Verburg ◽  
Tobias Kuemmerle
Keyword(s):  
Spatial Structure ◽  
Agricultural Landscapes ◽  
Management Intensity

scholarly journals Widespread nitrous oxide undersaturation in farm waterbodies creates an unexpected greenhouse gas sink

2019 ◽  
Vol 116 (20) ◽  
pp. 9814-9819 ◽  
Author(s):  
Jackie R. Webb ◽  
Nicole M. Hayes ◽  
Gavin L. Simpson ◽  
Peter R. Leavitt ◽  
Helen M. Baulch ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Inorganic Nitrogen ◽  
Generalized Additive Models ◽  
Regional Analysis ◽  
Freshwater Ecosystems ◽  
Agricultural Landscapes ◽  
Additive Models ◽  
Water Column Stability ◽  
Flowing Waters

Nitrogen pollution and global eutrophication are predicted to increase nitrous oxide (N2O) emissions from freshwater ecosystems. Surface waters within agricultural landscapes experience the full impact of these pressures and can contribute substantially to total landscape N2O emissions. However, N2O measurements to date have focused on flowing waters. Small artificial waterbodies remain greatly understudied in the context of agricultural N2O emissions. This study provides a regional analysis of N2O measurements in small (<0.01 km2) artificial reservoirs, of which an estimated 16 million exist globally. We show that 67% of reservoirs were N2O sinks (−12 to −2 μmol N2O⋅m−2⋅d−1) in Canada’s largest agricultural area, despite their highly eutrophic status [99 ± 289 µg⋅L−1 chlorophyll-a (Chl-a)]. Generalized additive models indicated that in situ N2O concentrations were strongly and nonlinearly related to stratification strength and dissolved inorganic nitrogen content, with the lowest N2O levels under conditions of strong water column stability and high algal biomass. Predicted fluxes from previously published models based on lakes, reservoirs, and agricultural waters overestimated measured fluxes on average by 7- to 33-fold, challenging the widely held view that eutrophic N-enriched waters are sources of N2O.

Nitrous Oxide from Heterogeneous Agricultural Landscapes: Source Contribution Analysis by Eddy Covariance and Chambers

2011 ◽  
Vol 75 (5) ◽  
pp. 1829-1838 ◽  
Author(s):  
Marina Molodovskaya ◽  
Jon Warland ◽  
Brian K. Richards ◽  
Gunilla Öberg ◽  
Tammo S. Steenhuis
Keyword(s):  
Nitrous Oxide ◽  
Eddy Covariance ◽  
Agricultural Landscapes ◽  
Source Contribution ◽  
Contribution Analysis

Effects of climate and management intensity on nitrous oxide emissions in grassland systems across Europe

2007 ◽  
Vol 121 (1-2) ◽  
pp. 135-152 ◽  
Author(s):  
C.R. Flechard ◽  
P. Ambus ◽  
U. Skiba ◽  
R.M. Rees ◽  
A. Hensen ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrous Oxide Emissions ◽  
Management Intensity

Effect of Water Injection on Emission Characteristics of a Turbocharged Diesel Engine

2009 ◽  
Author(s):  
R. K. Sullerey ◽  
Ankur Agarwal
Keyword(s):  
Nitrous Oxide ◽  
Diesel Engine ◽  
Water Injection ◽  
Nitrous Oxide Emissions ◽  
Small Scale ◽  
Common Source ◽  
Low Carbon ◽  
Direct Water Injection ◽  
A Minor ◽  
Humidified Air

The diesel engine is a very common source of small-scale power generation. While diesel engines are efficient with low carbon monoxide and hydrocarbon emissions, they have high nitrous oxide emissions. One approach to reduce the formation of nitrous oxides is by introducing water in the diesel engine system. The present paper is a study of effects on performance of direct water injection in the cylinder during the compression stroke and humidifying air prior to its entry to the engine by use of suitable models for various processes. It is observed that nitrous oxide concentrations are substantially reduced by both direct water injection as well as by use of humidified air. Use of humid air however also increases the power output of the engine with a minor loss in efficiency.

Influence of Anesthetics—Nitrous Oxide in Particular—on Electromyographic Response Evoked by Transcranial Electrical Stimulation of the Cortex

Neurosurgery ◽  
1989 ◽  
Vol 24 (2) ◽  
pp. 253-256 ◽  
Author(s):  
Josef Zentner ◽  
Ivan Kiss ◽  
Alois Ebner
Keyword(s):  
Nitrous Oxide ◽  
Motor Evoked Potentials ◽  
Transcranial Electrical Stimulation ◽  
Minor Effect ◽  
Oxide Mixture ◽  
Similar Reduction ◽  
Anterior Tibial ◽  
Oxygen Nitrous Oxide ◽  
A Minor ◽  
Electrical Stimuli

Abstract The influence of anesthetics usually used for neuroleptic anesthesia—nitrous oxide, fetanyl, flunitrazepam, and thiopental sodium—on motor evoked potentials (MEP) was examined in 15 patients during neurosurgical operations on the spinal cord, in 16 patients in traumatic coma, and in 6 healthy volunteers. MEP were recorded from the contralateral thenar and anterior tibial muscles in response to single transcranial electrical stimuli on the motor cortex. Intraoperatively, during neuroleptic anesthesia we found the amplitudes to be reduced to an average of 11% of the preoperative baselines for the thenar potentials, and to 7% of the preoperative baselines for the anterior tibial muscle potentials, despite a maximum stimulus strength of 750 V. A similar reduction of MEP amplitudes was observed in 6 volunteers during breathing of an oxygen/nitrous oxide mixture (34%/66%), whereas fentanyl, flunitrazepam, and thiopental had only a minor effect on MEP. We conclude that with respect to anesthesia-related suppression of amplitudes, an average of 5 to 15 electromyographic responses should be evaluated for intraoperative monitoring of MEP using the technique described here.

Nitrous oxide emissions from agricultural soils challenge climate sustainability in the US Corn Belt

2021 ◽  
Vol 118 (46) ◽  
pp. e2112108118
Author(s):  
Nathaniel C. Lawrence ◽  
Carlos G. Tenesaca ◽  
Andy VanLoocke ◽  
Steven J. Hall
Keyword(s):  
Nitrous Oxide ◽  
Soil Carbon ◽  
Agricultural Soils ◽  
Agricultural Landscapes ◽  
Nitrous Oxide Emissions ◽  
Corn Belt ◽  
Agricultural Practice ◽  
Mean Values ◽  
The Us ◽  
Soil Emissions

Agricultural landscapes are the largest source of anthropogenic nitrous oxide (N2O) emissions, but their specific sources and magnitudes remain contested. In the US Corn Belt, a globally important N2O source, in-field soil emissions were reportedly too small to account for N2O measured in the regional atmosphere, and disproportionately high N2O emissions from intermittent streams have been invoked to explain the discrepancy. We collected 3 y of high-frequency (4-h) measurements across a topographic gradient, including a very poorly drained (intermittently flooded) depression and adjacent upland soils. Mean annual N2O emissions from this corn–soybean rotation (7.8 kg of N2O–N ha−1⋅y−1) were similar to a previous regional top-down estimate, regardless of landscape position. Synthesizing other Corn Belt studies, we found mean emissions of 5.6 kg of N2O–N ha−1⋅y−1 from soils with similar drainage to our transect (moderately well-drained to very poorly drained), which collectively comprise 60% of corn–soybean-cultivated soils. In contrast, strictly well-drained soils averaged only 2.3 kg of N2O–N ha−1⋅y−1. Our results imply that in-field N2O emissions from soils with moderately to severely impaired drainage are similar to regional mean values and that N2O emissions from well-drained soils are not representative of the broader Corn Belt. On the basis of carbon dioxide equivalents, the warming effect of direct N2O emissions from our transect was twofold greater than optimistic soil carbon gains achievable from agricultural practice changes. Despite the recent focus on soil carbon sequestration, addressing N2O emissions from wet Corn Belt soils may have greater leverage in achieving climate sustainability.

Nitrogen removal and nitrous oxide emissions in woodchips biofilters treating agricultural drainage waters

2020 ◽  
Author(s):  
Joachim Audet ◽  
Dominik Zak ◽  
Carl Christian Hoffmann
Keyword(s):  
Gas Chromatography ◽  
Nitrous Oxide ◽  
Nitrogen Removal ◽  
Drainage Water ◽  
Agricultural Landscapes ◽  
Nitrous Oxide Emissions ◽  
Temperate Climate ◽  
Closed Chamber ◽  
Total N ◽  
N Removal

&lt;p&gt;Eutrophication of aquatic ecosystems provoked by excess nitrogen (N) concentration is still a major concern worldwide with severe consequences such as hypoxia, biodiversity loss, and degradation of drinking water quality. To face these challenges, a novel N mitigation measure has emerged in the last decades consisting of biofilters made of woodchips. Drainage water from agricultural areas infiltrate through a layer of woodchips before it discharges to an aquatic recipient such as a ditch or a stream. The goal with this technique is to provide optimal conditions for denitrification i.e. an easy degradable carbon source (the woodchips) and an anaerobic environment. There is, however, some concerns regarding the emissions of the greenhouse gas nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) which can be a by-product of denitrification.&lt;/p&gt;&lt;p&gt;Here, we present results on N removal and N&lt;sub&gt;2&lt;/sub&gt;O emissions from 9 biofilters differing in age (1&amp;#8211;8 years) and representing a total of 18 years of monitoring. The biofilters were all located in agricultural catchments in Denmark (temperate climate conditions). Nitrogen removal in the biofilters was estimated using a mass balance approach measuring N species dissolved in the water (total N, nitrate, nitrite, ammonium) using time proportional automated samplers placed at inlet and outlet of the biofilters. Nitrous oxide emissions were measured every third week both as gaseous form at the surface of the biofilters (closed chamber technique and gas chromatography) and in dissolved form in the water phase at inlet and outlet of the biofilters (headspace technique and gas chromatography). We take advantage of this unique dataset to identify the factors enabling to maximize N removal while minimizing N&lt;sub&gt;2&lt;/sub&gt;O emissions. Furthermore, we make a first assessment of the potential impact of the increasing number of biofilters on N&lt;sub&gt;2&lt;/sub&gt;O emissions in agricultural landscapes.&lt;/p&gt;

scholarly journals Nitrous oxide generation, denitrification, and nitrate removal in a seepage wetland intercepting surface and subsurface flows from a grazed dairy catchment

Soil Research ◽  
2008 ◽  
Vol 46 (7) ◽  
pp. 565 ◽  
Author(s):  
M. Zaman ◽  
M. L. Nguyen ◽  
A. J. Gold ◽  
P. M. Groffman ◽  
D. Q. Kellogg ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Sulfur Hexafluoride ◽  
Nitrate Removal ◽  
Agricultural Landscapes ◽  
Subsurface Water ◽  
Wetland Soil ◽  
N2o Emissions ◽  
Full Potential ◽  
Gaseous Emissions ◽  
Agricultural Catchments

Little is known about seepage wetlands, located within agricultural landscapes, with respect to removing nitrate (NO3−) from agricultural catchments, mainly through gaseous emissions of nitrous oxide (N2O) and dinitrogen (N2) via denitrification. These variables were quantified using a push–pull technique where we introduced a subsurface water plume spiked with 15N-enriched NO3− and 2 conservative tracers [bromide (Br−) and sulfur hexafluoride (SF6)] into each of 4 piezometers and extracted the plume from the same piezometers throughout a 48-h period. To minimise advective and dispersive flux, we placed each of these push–pull piezometers within a confined lysimeter (0.5 m diameter) installed around undisturbed wetland soil and vegetation. Although minimal dilution of the subsurface water plumes occurred, NO3−-N concentration dropped sharply in the first 4 h following dosing, such that NO3−-limiting conditions (<2 mg/L of NO3-N) for denitrification prevailed over the final 44 h of the experiment. Mean subsurface water NO3− removal rates during non-limiting conditions were 15.7 mg/L.day. Denitrification (based on the generation of isotopically enriched N2O plus N2) accounted for only 7% (1.1 mg/L.day) of the observed groundwater NO3− removal, suggesting that other transformation processes, such as plant uptake, were responsible for most of the NO3− removal. Although considerable increases in 15N-enriched N2O levels were initially observed following NO3− dosing, no net emissions were generated over the 48-h study. Our results suggest that this wetland may be a source of N2O emissions when NO3− concentrations are elevated (non-limited), but can readily remove N2O (function as a N2O sink) when NO3− levels are low. These results argue for the use of engineered bypass flow designs to regulate NO3− loading to wetland denitrification buffers during high flow events and thus enhance retention time and the potential for NO3−-limiting conditions and N2O removal. Although this type of management may reduce the full potential for wetland NO3− removal, it provides a balance between water quality goals and greenhouse gas emissions.

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