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Nitrous Oxide (nitrous + oxide)
Kinds of Nitrous Oxide Terms modified by Nitrous Oxide Selected AbstractsKetonization of 1,5-Cyclooctadiene by Nitrous OxideADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Dmitry Abstract The kinetics and mechanism of the liquid phase ketonization of 1,5-cyclooctadiene (COD) by nitrous oxide have been studied. The reaction proceeds without catalyst in the temperature range 473,553,K with the activation energy 113,kJ,mol,1 and is first order with respect to the initial reactants. The mechanism includes consecutive ketonization of two CC bonds in the COD molecule, with the intermediate formation of an unsaturated monoketone (MK). Further ketonization of MK leads to two isomeric diketones (DK): 1,4- and 1,5-cyclooctanedione. The 1,5-DK is a stable final product while the 1,4-DK undergoes further intramolecular aldol transformation leading to two bicyclic compounds, that retain the same number of carbon atoms. The distribution of mono- and diketones in the course of reaction is described by theoretical dependences pointing to identical reactivities of the CC double bonds residing in COD and MK molecules. The ketonization of COD by nitrous oxide exemplifies a prospective way for the preparation of valuable organic products in perfect harmony with the strategy of green chemistry. [source] DROUGHT STRESS: Comparative Time Course Action of the Foliar Applied Glycinebetaine, Salicylic Acid, Nitrous Oxide, Brassinosteroids and Spermine in Improving Drought Resistance of RiceJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2010M. Farooq Abstract Worldwide rice productivity is being threatened by increased endeavours of drought stress. Among the visible symptoms of drought stress, hampered water relations and disrupted cellular membrane functions are the most important. Exogenous use of polyamines (PAs), salicylic acid (SA), brassinosteroids (BRs), glycinebetaine (GB) and nitrous oxide (NO) can induce abiotic stresses tolerance in many crops. In this time course study, we appraised the comparative role of all these substances to improve the drought tolerance in rice (Oryza sativa L.) cultivar Super-Basmati. Plants were subjected to drought stress at four leaf stage (4 weeks after emergence) by maintaining soil moisture at 50 % of field capacity. Pre-optimized concentrations of GB (150 mg l,1), SA (100 mg l,1), NO (100 ,mol l,1 sodium nitroprusside as NO donor), BR (0.01 ,m 24-epibrassinolide) and spermine (Spm; 10 ,m) were foliar sprayed at five-leaf stage (5 weeks after emergence). There were two controls both receiving no foliar spray, viz. well watered (CK1) and drought stressed (CK2). There was substantial reduction in allometric response of rice, gas exchange and water relation attributes by drought stress. While drought stress enhanced the H2O2, malondialdehyde (MDA) and relative membrane permeability, foliar spray of all the chemicals improved growth possibly because of the improved carbon assimilation, enhanced synthesis of metabolites and maintenance of tissue water status. Simultaneous reduction in H2O2 and MDA production was also noted in the plants treated with these substances. Drought tolerance was sturdily associated with the greater tissue water potential, increased synthesis of metabolites and enhanced capacity of antioxidant system. Of all the chemicals, foliar spray with Spm was the most effective followed by BR. [source] Sir Humphry Davy; his researches in respiratory physiology and his debt to Antoine LavoisierANAESTHESIA, Issue 4 2002J. S. Sprigge Summary This article shows how the original works of the French scientist Antoine Lavoisier were developed by Humphry Davy, a trainee surgeon from Cornwall, while he was working as a physiologist. Antoine Lavoisier had worked out how oxidation involved the consumption of oxygen and the release of energy. Davy's book, Researches Chemical and Philosophical, Chiefly Concerning Nitrous Oxide, published in 1799, describes the measurement of his own lung volumes, including the first recorded measurement of the residual volume. He measured his own rates of oxygen consumption and carbon dioxide production. He is famous for his investigations into nitrous oxide, but he also investigated the effects of breathing nitric oxide and carbon monoxide. He made these observations with a gasometer and analysis of his expired air, and his work anticipates the invention of blood gas analysis. [source] Bridging Binding Modes of Phosphine-Stabilized Nitrous Oxide to Zn(C6F5)2,ANGEWANDTE CHEMIE, Issue 51 2009Rebecca Auf der Jagd nach Dr. NNO: Die Reaktion von [tBu3PN2O(B(C6H4F)3)] mit 1, 1.5 oder 2,Äquivalenten Zn(C6F5)2 führt zu den Spezies [{tBu3PN2OZn(C6F5)2}2], [{tBu3PN2OZn(C6F5)2}2Zn(C6F5)2] bzw. [tBu3PN2O{Zn(C6F5)2}2] (siehe Struktur, rot Zn (große Kugel), O (kleine Kugel), grün N, gelb P), die einzigartige Bindungsweisen von Zn an das phosphanstabilisierte N2O-Fragment zeigen. [source] Nitrous Oxide for Pain in Labor--Why Not in the United States?BIRTH, Issue 1 2007Judith P Rooks CNM No abstract is available for this article. [source] Activation of Nitrous Oxide and Selective Oxidation of Alcohols and Alkylarenes Catalyzed by the [PV2Mo10O40]5- Polyoxometalate Ion.CHEMINFORM, Issue 16 2003Revital Ben-Daniel No abstract is available for this article. [source] ChemInform Abstract: Reaction of Nitrous Oxide with Cyclopentadienyl Complexes of Cobalt, Rhodium, and Titanium.CHEMINFORM, Issue 52 2001A. V. Leont'ev Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Respiration of nitrous oxide in suboxic soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009B. Vieten Summary Reduction of nitrous oxide (N2O) is an autonomous respiratory pathway. Nitrous oxide is an alternative electron acceptor to O2 when intensive biological activity and reduced diffusivity result in an O2 deficit. Hypoxic or anoxic micro sites may form even in well-aerated soils, and provide a sink for N2O diffusing through the gas-filled pore space. We reproduced similar in vitro conditions in suboxic (0.15% O2) flow-through incubation experiments with samples from a Stagnosol and from a Histosol. Apparent half-saturation constants (km) for N2O reduction were similar for both soils and were, on average, 3.8 ,mol mol,1 at 5°C, 5.1 ,mol mol,1 at 10°C, and 6.9 ,mol mol,1 at 20°C. Respiration of N2O was estimated to contribute a maximum proportion of 1.7% to total respiration in the Stagnosol (pH 7.0) and 0.9% in the Histosol (pH 2.9). [source] Nitrous oxide as an adjunct in tumescent liposuctionJOURNAL OF COSMETIC DERMATOLOGY, Issue 4 2005Garrett Bird Summary Background, Nitrous oxide (N2O) has been used as an anesthetic for over 300 years. It is safe, easy to use, and effective. In this article we will document N2O use as an adjunct to tumescent liposuction. The history, mechanism of action, use, and safety in ambulatory surgery of N2O are reviewed. Objective, The authors intend to review the history of both tumescent liposuction and N2O in surgery, discuss the possible adverse reactions, and present guidelines for the use of N2O during tumescent liposuction. Methods, A Medline review of articles, 1966,2004, related to N2O was performed, using the search terms nitrous, oxide, safety, toxicity, mechanism, anesthetic, surgery, risks, and delivery. Articles that were cited by the authors of this subset of original articles were also used when appropriate. Articles were rated and included based on date of publication, level of evidence, and applicability to tumescent liposuction. Results and conclusions, Nitrous oxide is safe, easily administered, inexpensive, and is an effective adjunct to tumescent liposuction. It provides a high level of pain control, and is patient controlled, while not putting the patient at risk of full anesthesia. When used correctly, with proper equipment, it poses little risk to either patients or healthcare workers. [source] "Whippets"-Induced Cobalamin Deficiency Manifesting as Cervical MyelopathyJOURNAL OF NEUROIMAGING, Issue 3 2004Alan L. Diamond ABSTRACT Background. Nitrous oxide (N O) is inhaled in anesthesia and as a recreational drug from whipped cream dispensers. Its abuse reaches ,10% in some age groups. By inactivating cobalamin (Cbl) (vitamin B12), N O can cause neurologic and hematologic manifestations. We present a case of N O-induced Cbl deficiency presenting as cervical myelopathy. Case History. After regularly inhaling N O for many months, a 31-year-old man developed limb paresthesiae and ataxia over 3 months. Examination revealed finger pseudoathetosis, hyporeflexia, decreased sensation, and gait ataxia. Brain magnetic resonance imaging (MRI) was normal, but the posterior columns of the cervical and upper thoracic cord revealed patchy nonenhancing hyperintense lesions. Serum Cbl was 98 pg/mL (normal = 170,900 pg/mL). Cbl replacement led to recovery within 3 months.Discussion. This patient presented with the symptoms and signs of Cbl deficiency. The MRI lesions in the posterior columns aided the diagnosis. Physicians need to have a high level of suspicion in cases of unexplained Cbl deficiency and myelopathy. [source] The effect of nitrous oxide on cerebral blood flow velocity in children anesthetized with propofolACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2003E. Wilson-Smith Background: Propofol for maintenance of anesthesia by continuous infusion is gaining popularity for use in pediatric patients. Nitrous oxide (N2O) has been shown to increase cerebral blood flow velocity (CBFV) in both children and adults. To determine the effects of N2O on middle cerebral artery blood flow velocity (Vmca) during propofol anesthesia in children, Vmca was measured with and without N2O using transcranial Doppler (TCD) sonography. Methods: Thirty ASA I or II children aged 18 months to 6 years undergoing elective urological surgery were enrolled. Anesthesia comprised propofol aimed at producing an estimated steady-state serum concentration of 3 µg·ml,1 and a caudal epidural block. A transcranial Doppler probe was used to measure middle cerebral artery blood flow velocity. Each patient was randomized to receive a sequence of either Air/N2O/Air or N2O/Air/N2O in 35% oxygen. Fifteen min after each change in the N2O concentration, three measurements of cerebral blood flow velocity, blood pressure and heart rate were recorded. Ventilatory parameters and EtCO2 were kept constant throughout the study period. Results: CBFV increased by 12.4% when air was replaced by N2O, and returned to baseline when N2O was subsequently removed. There was a 14% decrease in CBFV when N2O was replaced with air, which increased to baseline when air was subsequently replaced with N2O. Mean heart rate and blood pressure remained constant throughout the study period. Conclusion: The effects of nitrous oxide on CBFV are preserved in children during propofol anesthesia. [source] Plant-mediated nitrous oxide emissions from beech (Fagus sylvatica) leavesNEW PHYTOLOGIST, Issue 1 2005Mari Pihlatie Summary ,,Nitrous oxide (N2O) emission estimates from forest ecosystems are based currently on emission measurements using soil enclosures. Such enclosures exclude emissions via tall plants and trees and may therefore underestimate the whole-ecosystem N2O emissions. ,,Here, we measured plant-mediated N2O emissions from the leaves of potted beech (Fagus sylvatica) seedlings after fertilizing the soil with 15N-labelled ammonium nitrate (15NH415NO3), and after exposing the roots to elevated concentrations of N2O. ,,Ammonium nitrate fertilization induced N2O + 15N2O emissions from beech leaves. Likewise, the foliage emitted N2O after beech roots were exposed to elevated concentrations of N2O. The average N2O emissions from the fertilization and the root exposure experiments were 0.4 and 2.0 µg N m,2 leaf area h,1, respectively. Higher than ambient atmospheric concentrations of N2O in the leaves of the forest trees indicate a potential for canopy N2O emissions in the forest. ,,Our experiments demonstrate the existence of a previously overlooked pathway of N2O to the atmosphere in forest ecosystems, and bring about a need to investigate the magnitude of this phenomenon at larger scales. [source] Nitrous oxide: an ageing gentlemanACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2001O. Stenqvist No abstract is available for this article. [source] Nitrous oxide for glycine encephalopathyPEDIATRIC ANESTHESIA, Issue 10 2010David A. August No abstract is available for this article. [source] The PediSedate® device, a novel approach to pediatric sedation that provides distraction and inhaled nitrous oxide: clinical evaluation in a large case seriesPEDIATRIC ANESTHESIA, Issue 2 2007WILLIAM T. DENMAN MD FRCA Summary Background:, Pediatric sedation is of paramount importance but can be challenging. Fear and anticipatory anxiety before invasive procedures often lead to uncooperativeness. A novel device (PediSedate®) provides sedation through a combination of inhaled nitrous oxide and distraction (video game). We evaluated the acceptability and safety of the PediSedate® device in children. Methods:, We enrolled children between 3 and 9 years old who were scheduled to undergo surgical procedures that required general inhalational anesthesia. After the device was applied, he/she played a video game while listening to the audio portion of the game through the earphones. Nitrous oxide in oxygen was administered via the nasal piece of the headset starting at 50% and increasing to 70%, in 10% increments every 8 min. Treatment failures, vital signs, arterial oxygen saturation, depth of sedation, airway patency, side effects, acceptance of the device and parental satisfaction were all evaluated. Results:, Of 100 children included, treatment failure occurred in 18% mainly because of poor tolerance of the device. At least 96% of the children who completed the study exhibited an excellent degree of sedation, 22% had side effects, and none experienced serious airway obstruction. Nausea and vomiting were the most common side effects and no patients had hemodynamic instability. Conclusions:, The PediSedate® device combines nonpharmacologic with pharmacologic methods of sedation. Most of the children we evaluated were able to tolerate the PediSedate® device and achieved an adequate degree of sedation. [source] Stable isotope natural abundance of nitrous oxide emitted from Antarctic tundra soils: effects of sea animal excrement depositionsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2008Renbin Zhu 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 insitu 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 , values of the soil-emitted N2O were ,15N,=,,13.5,±,3.2, and ,18O,=,26.2,±,1.4, for the penguin colony, ,15N,=,,11.5,±,5.1, and ,18O,=,26.4,±,3.5, for the skua colony and ,15N,=,,18.9,±,0.7, and ,18O,=,28.8,±,1.3, 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,µg,N2ON,kg,1). Under N2 conditions, much more N2O was formed (9.74,µg,N2ON,kg,1), and the mean ,15N and ,18O values of N2O were ,19.1,±,8.0, and 21.3,±,4.3,, respectively, from penguin colony soils, and ,17.0,±,4.2, and 20.6,±,3.5,, 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. Copyright © 2008 John Wiley & Sons, Ltd. [source] Pre-operative vitamin B infusion and prevention of nitrous oxide-induced homocysteine increaseANAESTHESIA, Issue 7 2010L. K. Rao Summary Nitrous oxide inactivates vitamin B12 with detrimental consequences for folate and methionine metabolism, detectable by an increase in total plasma homocysteine. We hypothesised that a pre-operative vitamin B12 and folate infusion prevents nitrous oxide-induced homocysteine increase. Sixty-three healthy patients having elective surgery were randomly allocated to receive either B-vitamin plus nitrous oxide; placebo plus nitrous oxide or placebo plus air. Fifty-nine patients completed the study. After intravenous B-vitamin infusion, plasma vitamin B12 and folate concentrations increased 35-fold and 12-fold, respectively, on the first postoperative measurement. Patients who received B-vitamins developed a similar increase (18%) in homocysteine after nitrous oxide (1.9 ,mol.l,1; 95% CI 0.2,3.6 ,mol.l,1) as those who did not (22%; 2.7 ,mol.l,1; 95% CI 0.6,4.8 ,mol.l,1). Patients not receiving nitrous oxide had no homocysteine change (0.5 ,mol.l,1; 95% CI ,0.8,1.9 ,mol.l,1), indicating that pre-operative intravenous B-vitamins may not prevent nitrous oxide-induced hyperhomocysteinaemia. [source] Nitrous oxide or remifentanil for the ,at risk' brainANAESTHESIA, Issue 4 2004S. M. Hancock No abstract is available for this article. [source] Survey on small animal anaesthesiaAUSTRALIAN VETERINARY JOURNAL, Issue 9 2001A NICHOLSON Objective To ascertain anaesthetic practices used currently for dogs and cats in Australia. Methods A questionnaire was distributed to 4800 veterinarians throughout Australia, seeking data on numbers of dogs and cats anaesthetised per week; drug preferences for anaesthetic premedication, induction and maintenance; use of tracheal intubation, supplemental O2, nitrous oxide and anaesthetic antagonists; and types of vaporisers, breathing systems and anaesthetic monitoring devices used or available. Additional questions concerned proportions of different animal types seen in the practice, and the respondent's university and year of graduation. Results The response rate was 19%; 95% of respondents graduated from Australian universities, about half since 1985. Most responses (79%) came from mainly small animal practices. On average 16 dogs and 12 cats were anaesthetised each week. Premedication was used more often in dogs than cats, with acepromazine and atropine most favoured in both species. For anaesthetic induction, thiopentone was most preferred in dogs and alphaxalone/alphadolone in cats. Inhaled agents, especially halothane, were preferred for maintenance in both species. Most respondents usually employed tracheal intubation when using inhalational anaesthetic maintenance, but intubation rates were lower during injectable anaesthetic maintenance and a minority of respondents provided supplemental O2. Nitrous oxide was administered regularly by 13% of respondents. The agents most frequently used to speed recovery from anaesthesia were doxapram and yohimbine. The most widely used vaporisers were the Fluotec Mark III and the Stephens machine. Most (95%) respondents used a rebreathing circuit for large dogs and a non-rebreathing system was used for small dogs by 68% of respondents. Most respondents (93%) indicated some form of aid was available to monitor general anaesthesia: the three most mentioned were an apnoea alarm, oesophageal stethoscope and electrocardiogram. Conclusion Diverse approaches were evident, but there appeared to be less variation in anaesthetising dogs: premedication was more frequent and less varied in type, while thiobarbituates dominated for induction and inhalants for maintenance. Injectable maintenance techniques had substantial use in cats, but little in dogs. Evident disparity between vaporisers available and circuits used suggested either confusion in terminology or incorrect use of some vaporisers in-circuit. While most respondents used monitoring equipment or a dedicated observer to invigilate anaesthesia, the common reliance on apnoea alarms is of concern, because of unproven reliability and accuracy. [source] Effects of sevoflurane on cognitive deficit, motor function, and histopathology after cerebral ischemia in ratsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2009E. EBERSPÄCHER Background: The volatile anesthetic sevoflurane exhibits neuroprotective properties when assessed for motor function and histopathology after cerebral ischemia in rats. Damage of hippocampal neurons after ischemia relates to a number of cognitive deficits that are not revealed by testing animals for motor function. Therefore, the present study evaluates cognitive and behavioral function as well as hippocampal damage in rats subjected to cerebral ischemia under sevoflurane compared with fentanyl/nitrous oxide (N2O)/O2 anesthesia. Methods: Thirty-four rats were trained for 10 days using a hole-board test to detect changes in cognitive and behavioral function. Rats were randomly assigned to the following groups: (A) sham/fentanyl/N2O/O2 (n=7); (B) ischemia/fentanyl/N2O/O2 (n=10); (C) sham/2.0 vol% sevoflurane in O2/air (n=7); and (D) ischemia/2.0 vol% sevoflurane in O2/air (n=10). Cerebral ischemia was produced by unilateral common carotid artery occlusion combined with hemorrhagic hypotension (mean arterial blood pressure 40 mmHg for 45 min). Temperature, arterial blood gases, and pH were maintained constant. Cerebral blood flow was measured using laser-Doppler flowmetry. After surgery, cognitive and behavioral function was re-evaluated for 10 days. On day 11, the brains were removed for histopathologic evaluation (hematoxylin/eosin-staining). Results: Cognitive testing revealed deficits in declarative and working memory in ischemic rats anesthetized with fentanyl/N2O. Rats anesthetized with sevoflurane during ischemia showed a significantly better outcome. Hippocampal damage was significantly worse with fentanyl/N2O. Conclusion: The present data add to previous investigations showing that sevoflurane prevents a deficit in cognitive function and histopathological damage induced by cerebral ischemia in rats. [source] Procedural sedation in children in the emergency department: A PREDICT studyEMERGENCY MEDICINE AUSTRALASIA, Issue 1 2009Meredith Borland Abstract Objective: To investigate current procedural sedation practice and compare clinical practice guidelines (CPG) for procedural sedation at Paediatric Research in Emergency Departments International Collaborative (PREDICT) sites. This will determine areas for improvement and provide baseline data for future multicentre studies. Methods: A questionnaire of specialist emergency physicians regarding demographics, general procedural sedation practice and specific sedation agents given to children. CPG for general sedation and sedation agents were obtained for each site. Results: Seventy-five (71%) useable surveys returned from 105 potential respondents. Most commonly used agents were nitrous oxide (N2O) (75, 100%), ketamine (total 72, 96%; i.v. 59, 83% and i.m. 22, 31%) and midazolam (total 68, 91%; i.v. 52, 81%, oral 47, 73%, intranasal 26, 41% and i.m. 6, 9%). Sedation was used for therapeutic and diagnostic procedures. Forty-three (57%) used formal sedation records and sedation checklists and thirty-one (41%) respondents reported auditing sedations. Four sites ran staff education and competency programmes. Nine sites had general sedation CPG, eight for ketamine, nine for N2O, eight for midazolam (four parenteral, five oral and six intranasal) and three for fentanyl. No site had a guideline for propofol administration. Conclusion: Procedural sedation in this research network commonly uses N2O, ketamine and midazolam for a wide range of procedures. Areas of improvement are the lack of guidelines for certain agents, documentation, staff competency training and auditing processes. Multicentre research could close gaps in terms of age cut-offs, fasting times and optimal indications for various agents. [source] Comparison of greenhouse gas fluxes and nitrogen budgets from an ombotrophic bog in Scotland and a minerotrophic sedge fen in FinlandEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2010J. Drewer Northern peatlands cover approximately 4% of the global land surface area. Those peatlands will be particularly vulnerable to environmental and climate change and therefore it is important to investigate their total greenhouse gas (GHG) budgets, to determine the feedback on the climate. Nitrogen (N) is known to influence the GHG budget in particular by affecting the methane (CH4) balance. At two peatland sites in Scotland and Finland GHG fluxes of carbon dioxide (CO2), methane and nitrous oxide (N2O) and nitrogen fluxes were measured as part of the European project ,NitroEurope'. The Scottish site, Auchencorth Moss, was a GHG sink of ,321, ,490 and ,321 g CO2 eq m,2 year,1 in 2006, 2007 and 2008, respectively, with CO2 as the dominating GHG. In contrast, the dominating GHG at the Finnish site, Lompolojänkkä, was CH4, resulting in the site being a net GHG source of +485 and +431 g CO2 eq m,2 year,1 in 2006 and 2007, respectively. Therefore, Auchencorth Moss had a negative global warming potential (GWP) whilst Lompolojänkkä had a positive GWP over the investigated time period. Initial results yielded a positive N budget for Lompolojänkkä of 7.1 kg N ha,1 year,1, meaning the site was gaining nitrogen, and a negative N budget for Auchencorth Moss of ,2.4 kg N ha year,1, meaning the site was losing nitrogen. [source] Nitrifier denitrification can be a source of N2O from soil: a revised approach to the dual-isotope labelling methodEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2010D. M. Kool Nitrifier denitrification (i.e. nitrite reduction by ammonia oxidizers) is one of the biochemical pathways of nitrous oxide (N2O) production. It is increasingly suggested that this pathway may contribute substantially to N2O production in soil, the major source of this greenhouse gas. However, although monoculture studies recognize its potential, methodological drawbacks prohibit conclusive proof that nitrifier denitrification occurs in actual soils. Here we suggest and apply a new isotopic approach to identify its presence in soil. In incubation experiments with 12 soils, N2O production was studied using oxygen (O) and nitrogen (N) isotope tracing, accounting for O exchange. Microbial biomass C and N and phospholipid fatty acid (PLFA) patterns were analysed to explain potential differences in N2O production pathways. We found that in at least five of the soils nitrifier denitrification must have contributed to N2O production. Moreover, it may even have been responsible for all NH4+ -derived N2O in most soils. In contrast, N2O as a by-product of ammonia oxidation contributed very little to total production. Microbial biomass C and N and PLFA-distinguished microbial community composition were not indicative of differences in N2O production pathways. Overall, we show that combined O and N isotope tracing may still provide a powerful tool to understand N2O production pathways, provided that O exchange is accounted for. We conclude that nitrifier denitrification can indeed occur in soils, and may in fact be responsible for the greater proportion of total nitrifier-induced N2O production. [source] Methane and nitrous oxide fluxes from a farmed Swedish HistosolEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009Å. Kasimir Klemedtsson Summary Fluxes of the greenhouse gases methane (CH4) and nitrous oxide (N2O) from histosolic soils (which account for approximately 10% of Swedish agricultural soils) supporting grassley and barley production in Sweden were measured over 3 years using static chambers. Emissions varied both over area and time. Methane was both produced and oxidized in the soil: fluxes were small, with an average emission of 0.12 g CH4 m,2 year,1 at the grassley site and net uptake of ,0.01 g CH4 m,2 year,1 at the barley field. Methane emission was related to soil water, with more emission when wet. Nitrous oxide emissions varied, with peaks of emission after soil cultivation, ploughing and harrowing. On average, the grassley and barley field had emissions of 0.20 and 1.51 g N2O m,2 year,1, respectively. We found no correlation between N2O and soil factors, but the greatest N2O emission was associated with the driest areas, with < 60% average water-filled pore space. We suggest that the best management option to mitigate emissions is to keep the soil moderately wet with permanent grass production, which restricts N2O emissions whilst minimizing those of CH4. [source] Respiration of nitrous oxide in suboxic soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009B. Vieten Summary Reduction of nitrous oxide (N2O) is an autonomous respiratory pathway. Nitrous oxide is an alternative electron acceptor to O2 when intensive biological activity and reduced diffusivity result in an O2 deficit. Hypoxic or anoxic micro sites may form even in well-aerated soils, and provide a sink for N2O diffusing through the gas-filled pore space. We reproduced similar in vitro conditions in suboxic (0.15% O2) flow-through incubation experiments with samples from a Stagnosol and from a Histosol. Apparent half-saturation constants (km) for N2O reduction were similar for both soils and were, on average, 3.8 ,mol mol,1 at 5°C, 5.1 ,mol mol,1 at 10°C, and 6.9 ,mol mol,1 at 20°C. Respiration of N2O was estimated to contribute a maximum proportion of 1.7% to total respiration in the Stagnosol (pH 7.0) and 0.9% in the Histosol (pH 2.9). [source] Methane and nitrous oxide fluxes of soils in pure and mixed stands of European beech and Norway spruceEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2006W. Borken Summary Tree species can affect the sink and source strength of soils for atmospheric methane and nitrous oxide. Here we report soil methane (CH4) and nitrous oxide (N2O) fluxes of adjacent pure and mixed stands of beech and spruce at Solling, Germany. Mean CH4 uptake rates ranged between 18 and 48 ,g C m,2 hour,1 during 2.5 years and were about twice as great in both mixed and the pure beech stand as in the pure spruce stand. CH4 uptake was negatively correlated with the dry mass of the O horizon, suggesting that this diminishes the transport of atmospheric CH4 into the mineral soil. Mean N2O emission was rather small, ranging between 6 and 16 ,g N m,2 hour,1 in all stands. Forest type had a significant effect on N2O emission only in one mixed stand during the growing season. We removed the O horizon in additional plots to study its effect on gas fluxes over 1.5 years, but N2O emissions were not altered by this treatment. Surprisingly, CH4 uptake decreased in both mixed and the pure beech stands following the removal of the O horizon. The decrease in CH4 uptake coincided with an increase in the soil moisture content of the mineral soil. Hence, O horizons may maintain the gas diffusivity within the mineral soil by storing water which cannot penetrate into the mineral soil after rainfall. Our results indicate that conversion of beech forests to beech,spruce and pure spruce forests could decrease soil CH4 uptake, while the long-term effect on N2O emissions is expected to be rather small. [source] Wavelet analysis of the scale- and location-dependent correlation of modelled and measured nitrous oxide emissions from soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2005A. E. Milne Summary We used the wavelet transform to quantify the performance of models that predict the rate of emission of nitrous oxide (N2O) from soil. Emissions of N2O and other soil variables that influence emissions were measured on soil cores collected at 256 locations across arable land in Bedfordshire, England. Rate-limiting models of N2O emissions were constructed and fitted to the data by functional analysis. These models were then evaluated by wavelet variance and wavelet correlations, estimated from coefficients of the adapted maximal overlap discrete wavelet transform (AMODWT), of the fitted and measured emission rates. We estimated wavelet variances to assess whether the partition of the variance of modelled rates of N2O emission between scales reflected that of the data. Where the relative distribution of variance in the model is more skewed to coarser scales than is the case for the observation, for example, this indicates that the model predictions are too smooth spatially, and fail adequately to represent some of the variation at finer scales. Scale-dependent wavelet correlations between model and data were used to quantify the model performance at each scale, and in several cases to determine the scale at which the model description of the data broke down. We detected significant changes in correlation between modelled and predicted emissions at each spatial scale, showing that, at some scales, model performance was not uniform in space. This suggested that the influence of a soil variable on N2O emissions, important in one region but not in another, had been omitted from the model or modelled poorly. Change points usually occurred at field boundaries or where soil textural class changed. We show that wavelet analysis can be used to quantify aspects of model performance that other methods cannot. By evaluating model behaviour at several scales and positions wavelet analysis helps us to determine whether a model is suitable for a particular purpose. [source] Aboveground plant biomass, carbon, and nitrogen dynamics before and after burning in a seminatural grassland of Miscanthus sinensis in Kumamoto, JapanGCB BIOENERGY, Issue 2 2010YO TOMA Abstract Although fire has been used for several thousand years to maintain Miscanthus sinensis grasslands in Japan, there is little information about the nutrient dynamics in these ecosystems immediately after burning. We investigated the loss of aboveground biomass; carbon (C) and nitrogen (N) dynamics; surface soil C change before and after burning; and carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes 2 h after burning in a M. sinensis grassland in Kumamoto, Japan. We calculated average C and N accumulation rates within the soil profile over the past 7300 years, which were 58.0 kg C ha,1 yr,1 and 2.60 kg N ha,1 yr,1, respectively. After burning, 98% of aboveground biomass and litter were consumed. Carbon remaining on the field, however, was 102 kg C ha,1. We found at least 43% of C was possibly lost due to decomposition. However, remaining C, which contained ash and charcoal, appeared to contribute to C accumulation in soil. There was no difference in the amount of 0,5 cm surface soil C before and after burning. The amount of remaining litter on the soil surface indicated burning appeared not to have caused a reduction in soil C nor did it negatively impact the sub-surface vegetative crown of M. sinensis. Also, nearly 50 kg N ha,1 of total aboveground biomass and litter N was lost due to burning. Compared with before the burning event, postburning CO2 and CH4 fluxes from soil appeared not to be directly affected by burning. However, it appears the short time span of measurements of N2O flux after burning sufficiently characterized the pattern of increasing N2O fluxes immediately after burning. These findings indicate burning did not cause significant reductions in soil C nor did it result in elevated CO2 and CH4 emissions from the soil relative to before the burning event. [source] Region-specific assessment of greenhouse gas mitigation with different manure management strategies in four agroecological zonesGLOBAL CHANGE BIOLOGY, Issue 12 2009SVEN G. SOMMER Abstract Livestock farming systems are major sources of trace gases contributing to emissions of the greenhouse gases (GHG) nitrous oxide (N2O) and methane (CH4), i.e. N2O accounts for 10% and CH4 for 30% of the anthropogenic contributions to net global warming. This paper presents scenario assessments of whole-system effects of technologies for reducing GHG emissions from livestock model farms using slurry-based manure management. Changes in housing and storage practice, mechanical separation, and incineration of the solid fraction derived from separation were evaluated in scenarios for Sweden, Denmark, France, and Italy. The results demonstrated that changes in manure management can induce significant changes in CH4 and N2O emissions and carbon sequestration, and that the effect of introducing environmental technologies may vary significantly with livestock farming practice and interact with climatic conditions. Shortening the in-house manure storage time reduced GHG emissions by 0,40%. The largest GHG reductions of 49 to, in one case, 82% were obtained with a combination of slurry separation and incineration, the latter process contributing to a positive GHG balance of the system by substituting fossil fuels. The amount and composition of volatile solids (VS) and nitrogen pools were main drivers in the calculations performed, and requirements to improve the assessment of VS composition and turnover during storage and in the field were identified. Nevertheless, the results clearly showed that GHG emission estimates will be unrealistic, if the assumed manure management or climatic conditions do not properly represent a given country or region. The results also showed that the mitigation potential of specific manure management strategies and technologies varied depending on current management and climatic conditions. [source] Contribution of N2O to the greenhouse gas balance of first-generation biofuelsGLOBAL CHANGE BIOLOGY, Issue 1 2009EDWARD M. W. SMEETS Abstract In this study, we analyze the impact of fertilizer- and manure-induced N2O emissions due to energy crop production on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first-generation biofuels (also taking account of other GHG emissions during the entire life cycle). We calculate the nitrous oxide (N2O) emissions by applying a statistical model that uses spatial data on climate and soil. For the land use that is assumed to be replaced by energy crop production (the ,reference land-use system'), we explore a variety of options, the most important of which are cropland for food production, grassland, and natural vegetation. Calculations are also done in the case that emissions due to energy crop production are fully additional and thus no reference is considered. The results are combined with data on other emissions due to biofuels production that are derived from existing studies, resulting in total GHG emission reduction potentials for major biofuels compared with conventional fuels. The results show that N2O emissions can have an important impact on the overall GHG balance of biofuels, though there are large uncertainties. The most important ones are those in the statistical model and the GHG emissions not related to land use. Ethanol produced from sugar cane and sugar beet are relatively robust GHG savers: these biofuels change the GHG emissions by ,103% to ,60% (sugar cane) and ,58% to ,17% (sugar beet), compared with conventional transportation fuels and depending on the reference land-use system that is considered. The use of diesel from palm fruit also results in a relatively constant and substantial change of the GHG emissions by ,75% to ,39%. For corn and wheat ethanol, the figures are ,38% to 11% and ,107% to 53%, respectively. Rapeseed diesel changes the GHG emissions by ,81% to 72% and soybean diesel by ,111% to 44%. Optimized crop management, which involves the use of state-of-the-art agricultural technologies combined with an optimized fertilization regime and the use of nitrification inhibitors, can reduce N2O emissions substantially and change the GHG emissions by up to ,135 percent points (pp) compared with conventional management. However, the uncertainties in the statistical N2O emission model and in the data on non-land-use GHG emissions due to biofuels production are large; they can change the GHG emission reduction by between ,152 and 87 pp. [source] | |||||||||||||||||||