Geography
Oxides of Nitrogen
Oxides of nitrogen are a group of chemical compounds containing nitrogen and oxygen. They are primarily produced by human activities such as industrial processes and vehicle emissions. These compounds contribute to air pollution and can have harmful effects on human health and the environment, including contributing to the formation of acid rain and smog.
Written by Perlego with AI-assistance
Related key terms
1 of 5
10 Key excerpts on "Oxides of Nitrogen"
eBook - PDF- L. Grant, T. Schneider(Authors)
- 2013(Publication Date)
- Elsevier Science(Publisher)
Consequently, Oxides of Nitrogen are rarely present alone in polluted air masses. Both nitric oxide (NO) and nitrogen dioxide (NO2) can either be toxic to or metabolized by plants. The rate of uptake of the pollutants and the physio-logical state of the plant determine whether the NOx will be injurious or beneficial. Oxides of Nitrogen are less phytotoxic than S02 or 03 and the concentrations of NOx that presently occur in most agricultural areas do not pose a threat to crop productivity. However, exposure to NOx in combination with SO2 and/or O3 can alter plant metabolism and productivity at concentrations that would not produce such effects if the pollutants were present alone. Consequently, the effects of NOx on crop growth and yield are minimal in comparison with the effects of NOx in combination with SO2 and O3. INTRODUCTION The lower atmosphere is composed of a relatively homogeneous mixture of nitrogen and oxygen, which constitutes approximately 99 percent of the air surrounding the earth. The remaining 1 percent is composed of argon, other inert gases, and a host of biologically active gases such as CO2 and H2O. Biologically active gases from anthropogenic sources--Oxides of Nitrogen (NOx), oxides of sulfur (SOx), and ozone (03)—are considered to be the air pollutants that pose the most serious threat to crop productivity. Sources of NOx The major anthropogenic sources of NOx are automobiles, fossil fuel power generating facilities, furnaces, incinerators, and specific industrial processes such as nitric acid production. Nitric oxide (NO) emissions from these sources are converted to nitrogen dioxide (NO2) in the atmosphere. It has been estimated that ten times more NO is produced from biological activity worldwide than from human activity (ref. 1); however, concentrations of NO produced by natural sources (e.g., denitrifying bacteria) are low and nearly constant due to their low emission rates and wide dispersion.
eBook - ePubNitrogen and Climate Change
An Explosive Story
- D. Reay(Author)
- 2015(Publication Date)
- Palgrave Macmillan(Publisher)
5 Airborne Nitrogen and Climate Change Nitrogen oxide sourcesNitric oxide (NO) and nitrogen dioxide (NO2 ) are both gases and are commonly grouped together as NOx (pronounced ‘nox’). Like nitrous oxide, the NOx gases are oxidised forms of nitrogen, with fossil fuel burning, biomass burning and cultivated soils being their largest anthropogenic sources1, 2 (Figure 5.1 ). Unlike nitrous oxide, these gases are highly reactive, with short atmospheric lifetimes and the ability to cause severe illness and even death in humans. Early fossil fuel-driven emissions of these NOx gases were dominated by the release of the trace amounts of reactive nitrogen contained in coal as it was burned3 . With the advent of higher temperature boilers and the rapid spread of the internal combustion engine, more and more NOx was produced by the direct reaction of dinitrogen gas with oxygen – the high temperatures in power station furnaces and vehicle engines breaking apart the twin atoms of nitrogen gas and combining them with oxygen. The NOx gases that flow from exhausts and chimneys are usually in the highly reactive form of nitric oxide. Being so very reactive, this gas quickly combines with more oxygen and is converted into the brownish, acrid-smelling gas called nitrogen dioxide. The amounts released from burning fossil fuels have rocketed over the past century, especially since the Second World War. As the sulphur-enriched smogs of the 1950s began to clear, the injections of NOx into the atmosphere became more intense4 . Between the 1960s and 1980s these human-made emissions more than doubled to 25 million tonnes of nitrogen per year and today make up over half of all the NOx produced across the planet5 .Much of the world’s soil-derived NOx now also has the fertile fingerprints of humankind upon it6 . The busy microbial push-me pull-you of the nitrifiers and denitrifiers leads to NOx being produced and a small proportion of this key stepping stone in each process leaks away into the atmosphere. With more ammonium for the nitrifiers and more nitrate for the denitrifiers, fertilised-soil NOx emissions have kept on climbing, and now make up around half of all soil emissions globally7
eBook - PDF- J.B. Mudd(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
6 Oxides of Nitrogen O. C. Taylor, C. R. Thompson, D. T. Tingey, and R. A. Reinert I. Formation of Nitrogen Oxides 122 II. Factors Affecting Injury 123 III. Mechanism Causing Plant Injury 124 IV. Effects on Higher Plants 125 V. Combined Effects of NO, and SO, 135 VI. Evaluation of Air Quality Standards for Vegetation Effects ... 136 References 138 Of the several Oxides of Nitrogen which may be found in the atmosphere, the most important as air pollutants are nitric oxide (NO) and nitrogen dioxide (N0 2 ). According to Robinson and Robbins (1970) the major component of worldwide atmospheric nitrogen oxides is biologically pro-duced NO. These, primarily bacteria produced oxides, amount to about 50 X 10 7 tons per year, and by comparison man-made sources emit about 5 X 10 7 tons per year. The biological sources are widely distributed over the face of the earth, while man-made sources are concentrated in a rela-tively few densely populated areas. Consequently, natural sources are usu-ally not considered seriously when an inventory of sources of Oxides of Nitrogen is being compiled. 121 122 O. C. TAYLOR, C. R. THOMPSON, D. T. TINGEY, R. A. REINERT I. Formation of Nitrogen Oxides During combustion some of the nitrogen in the air is oxidized to NO and a comparatively small amount of N0 2 . The rate of NO formation in-creases in proportion to the temperature of combustion. Rate of NO de-composition decreases rapidly as temperature of the gaseous by-products of combustion falls. Both NO and N0 2 are formed at combustion tempera-tures above 2000°F, but N0 2 accounts for less than 1 % of the total nitro-gen oxides in these gases. Within a few seconds after the combustion gases are ejected into the atmosphere they are diluted, and part of the NO, per-haps as much as 10%, is oxidized to N0 2 . Once the NO has been diluted to about one part per million (ppm) parts of air it no longer reacts readily with oxygen to produce N0 2 .
eBook - PDFEmerging Pollutants
Some Strategies for the Quality Preservation of Our Environment
- Sonia Soloneski, Marcelo L. Larramendy, Sonia Soloneski, Marcelo L. Larramendy(Authors)
- 2018(Publication Date)
- IntechOpen(Publisher)
This phenomenon represents an alarming threat for human health, as a major cause of respiratory and cardiovascular pathologies as well as infertility. Moreover, those atmo-spheric pollutants have severe impacts on the environment and participate in climatic change, © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. acidification, eutrophication, and ecosystem disturbances. Several international and national organizations (e.g. WHO, EEA, and INERIS) aim at reducing the global emission of pollut-ants, thanks to environmental policies as Kyoto and Gothenburg protocols signed in 1997 and 1999, respectively. After that, an encouraging decrease in air pollutants’ levels was measured between 2000 and 2015 [1]. Atmospheric pollutants can be classified into four families: classical, indoor, and organic or inorganic air pollutants. Among the classical ones, which are the principle in amount, sulfur dioxide (SO 2 ), particle matter, ozone (O 3 ), and nitrogen oxide (NOx) species are found [2]. The term NOx refers to a wide range of nitrogen-derived compounds, where nitric oxide (NO) and nitrogen dioxide (NO 2 ) are predominant [3]. Those compounds can be naturally produced at low level by lightnings [4] and volcanic eruptions [5]. However, NOx is mainly generated by anthropogenic activity (e.g., road transport, energy production, industry, and agriculture) ( Figure 1 ) [6]. Even if NO and NO 2 represent the main species of NOx, nitrogen exists in several oxidation states in the environment, from N (−III) to N (+V). NO takes a central place in the series of reactive nitrogen species (RNS) [7]. Oxidation and reduction of NO result in the formation of several RNS, including nitrate or ammonium.
- W S Wilson, A S Ball, R H Hinton(Authors)
- 1999(Publication Date)
- Woodhead Publishing(Publisher)
The anthropogenic contribution to the oxidized nitrogen emissions to the atmo- sphere now represent the dominant component of the total and effects of these emissions are detectable throughout the global atmosphere. The effects include modification of the oxidizing capacity of the atmosphere, acidic deposition, the formation of photochemical oxidants (and ozone in particular), radiative forcing of climate and eutrophication of terrestrial and marine ecosystems. Thus the emissions of oxidized nitrogen contribute directly to many of the regional and global environmental problems of the late 20th century. Similarly, the emission of reduced nitrogen as NH3, from intensive animal production and also from fertilized cropland and industrial processes, is now a major contribution to the atmospheric transport and deposition of fixed nitrogen globally (Dentener, 1993). The current scale of anthropogenic fluxes of fixed nitrogen to the atmosphere now exceed the natural fluxes at a global scale and taken together with the industrial fixation of nitrogen for agriculture, there is justification for the view that human activities have taken over the global nitrogen cycle. 121 122 The Atmospheric Nitrogen Cycle und the Role of Anthropogenic Activity This paper summarizes the current understanding of the global nitrogen cycle and considers in more detail the current atmospheric budgets of oxidized and reduced nitrogen over the UK. The fate of UK emissions and the consequences of deposited nitrogen of terrestrial ecosystems are also briefly reviewed. 1.1 Emissions The emissions of NO,, largely as NO from the combustion of fossil fuel, occurs both from oxidation of the N in the fuel and also the combination of atmospheric oxygen and nitrogen in the combustion processes. The global emissions have increased from approximately 2 Tg NO,-N y-l at the turn of the century to 20 Tg NO,-N y-' by 1980 (Dignon & Hamseed, 1989).
eBook - PDFThe Chemistry of Environmental Tobacco Smoke
Composition and Measurement, Second Edition
- Roger A. Jenkins, Bruce Tomkins, Michael R. Guerin(Authors)
- 2000(Publication Date)
- CRC Press(Publisher)
9 Field Studies— Oxides of Nitrogen INTRODUCTION The Oxides of Nitrogen, commonly abbreviated NO x, are principally formed by the combustion of nitrogen-containing constituents of fuels and by the high temperature oxidation of nitrogen. The majority of the N O x, (NO, N 20 , and N 0 2) in tobacco smoke arises by oxidation of nitrogen bound in a variety of nitrogen-containing tobacco components such as nicotine alkaloids, amino acids, and proteins and by the thermal decomposition of nitrate. NO plus N 0 2 comprise more than 90% of the Oxides of Nitrogen in cigarette smoke. As such, NO, is taken to mean NO plus N 0 2 in describing Oxides of Nitrogen produced by tobacco smoking. The Kentucky reference 1R4F filter cigarette delivers approximately 230 jug of NO in its mainstream smoke and 900 /ug of NO in its sidestream (Chap. 3, Table 3.1). Commercial nonfilter cigarettes are reported to deliver from 100-600 yUg/cigarette of NO in their mainstream smoke and to exhibit sidestream-to-mainstreamratios ranging from4-10 (Chap. 3, Table 3.2). More than 95% by weight of the NOx in both mainstream (Norman et al. 1983, Jenkins and Gill 1980) and sidestream (Norman et al. 1983) smoke is present as nitric oxide (NO). Martin et al. (1997) have completed a detailed analysis of NO and N 0 2 emissions as ETS for the 50 top-selling brand styles of cigarettes in the United States. Average NO and N 0 2 emissions for all brand styles were 1645 and 198 yag/cigarette, respectively. Note that in ETS chamber measurements, N 0 2represents ~11% of the N Ox, reflective the conversion of NO to N 0 2 through reaction with ambient oxygen. The acute and chronic health effects of NO include bronchitis, irritation of the nose and throat, increased susceptibility to respiratory infections, blocking of oxygen transfer in blood, and irritation of the skin and eyes at concentrations below the federal outdoor air standard of 53 ppb (ASHRAE 1989).
eBook - PDFEnvironmental Science and Technology
A Sustainable Approach to Green Science and Technology, Second Edition
- Stanley E. Manahan(Author)
- 2006(Publication Date)
- CRC Press(Publisher)
For example, NO pollution and the formation of photochemical smog. For example, NO 2 is readily is readily dissociated photochemically to NO and reactive atomic oxygen by electromagnetic dissociated photochemically to NO and reactive atomic oxygen by electromagnetic radiation of less than 398 nm wavelength: radiation of less than 398 nm wavelength: NO NO 2 + + h ν → NO + O (8.10.4) NO + O (8.10.4) This reaction is the most important primary photochemical process involved in This reaction is the most important primary photochemical process involved in smog formation. smog formation. Air Pollutant Nitrogen Compounds Air Pollutant Nitrogen Compounds Nitrogen compounds, especially nitrogen oxides, are among the most significant Nitrogen compounds, especially nitrogen oxides, are among the most significant air pollutants. The three Oxides of Nitrogen normally encountered in the atmosphere air pollutants. The three Oxides of Nitrogen normally encountered in the atmosphere are nitrous oxide (N are nitrous oxide (N 2 O), nitric oxide (NO), and nitrogen dioxide (NO O), nitric oxide (NO), and nitrogen dioxide (NO 2 ). Microbially ). Microbially generated nitrous oxide is relatively unreactive and probably does not significantly generated nitrous oxide is relatively unreactive and probably does not significantly influence important chemical reactions in the lower atmosphere. However, colorless, influence important chemical reactions in the lower atmosphere. However, colorless, odorless nitric oxide and pungent red-brown nitrogen dioxide, collectively designated odorless nitric oxide and pungent red-brown nitrogen dioxide, collectively designated NO NO x , are very important in polluted air. Regionally high pollutant NO , are very important in polluted air. Regionally high pollutant NO 2 concentra-concentra-tions can result in severe air quality deterioration. Practically all anthropogenic NO tions can result in severe air quality deterioration.
- John R Barker(Author)
- 1995(Publication Date)
- World Scientific(Publisher)
In this chapter, we have discussed the results of a number of ob-servational and theoretical studies designed to establish the climatology of reactive nitrogen species, to evaluate the O3 production potential 246 Progress and Problems in Atmospheric Chemistry spatially and/or temporally, and to test our understanding of tropospheric photochemistry. In particular, although this discussion has focussed on the non-urban troposphere, it is clear that areas that include high sources or reservoirs of NO x and NMHCs, such as highly populated urban regions, vegetated suburban areas, and the high latitude troposphere, and regions directly downwind or above (aided by convection) such sources, represent likely zones of O3 formation. However, with the relatively few measurements that have been made, it is not surprising that a number of the scientific questions relating to NO x climatology and O3 formation remain unanswered. We have not yet fully characterized the distribution of background levels of NO^ and NO y compounds nor is it well understood what fraction of the observed levels can be attributed to local versus remote human activities. A detailed assessment of natural variability of and anthropogenic perturbations to the marine atmosphere and the determination of the sources and distribution of ozone and the processes controlling its chemical precursors and its production and loss is needed. For example, the CITE-2, CITE-3, MLOPEX, and SAGA-3 campaigns have improved our understanding of chemistry in the remote marine environments, but lightning NO in the NO x budget remains unquantified. Because of uncertainties in the NO^ budget and its natural variability, it is difficult to calculate the distribution of O3.
eBook - PDF- J.L. Hatfield, R.F. Follett(Authors)
- 2008(Publication Date)
- Academic Press(Publisher)
NO x . Upon its emission into the atmosphere, NO x plays a central role in tropospheric chemistry (Williams et al., 1992). The NO x interacts in a series of concentration-dependent cycles with atmospheric oxidants, ozone (O 3 ), hydroxyl radicals (OH) during the oxidation of carbon monoxide (CO), methane (CH 4 ), and nonmethane hydrocarbons. The oxidizing capacity of the atmosphere is regulated by NO x through regulation of OH and O 3 production and loss (Holland et al., 1997). Increasing NO x concentrations are contributing substantially to observed increases in O 3 concentrations in the Northern Hemisphere (Chameides et al., 1994). Detailed descriptions of the complex interactive cycles of NO x in the atmosphere can be Exchange of Gaseous Nitrogen Compounds 457 found in many references (e.g., Ehhalt et al., 1992; Liu et al., 1992; Williams et al., 1992; Holland and Lamarque, 1997). As a general simple description (Figure 7), when NO enters the atmosphere it reacts rapidly with O 3 to form NO 2 . In the sunlight, part of NO 2 – in a complex set of reactions that involve hydrocarbons, ozone, and CO – dissociates to reform NO and O 3 . In the presence of NO x , CO is oxidized to produce CO 2 and O 3 . The NO 2 is further oxidized to a mixture of products referred to as NO y (NO x organic nitrates, inorganic nitrates and nitrites). During the daytime this set of reactions takes place within a few hours when the sun is bright but may require a few days when clouds block the sun (Williams et al., 1992). At night NO 2 accumulates. At very low NO x concentrations ( 0.08 ppbv) there is net O 3 consumption. As NO x concen-trations increase from 0.08 ppbv to about 1 ppbv, OH and O 3 production increases proportionately with increasing NO x . At NO x concentrations above 1.1 ppbv there is a decline in OH and O 3 production (Holland and Lamarque, 1997). Nitric acid production becomes the dominant end product.
eBook - PDF- Warneck(Author)
- 1988(Publication Date)
- Academic Press(Publisher)
9.4.1 NITROGEN OXIDE CHEMISTRY Figure 9-6 summarizes our current understanding of the chemical reac- tions involving nitrogen oxides in the troposphere. Photolytically induced Fig. 9-6. Oxidation scheme for nitrogen oxides and related compounds. Photochemical processes are indicated by bold arrows. 9.4 NITROGEN DIOXIDE, NO2, AND RELATED COMPOUNDS 455 Table 9-10. Reactions Involving Nitrogen Oxides and Their Oxidation Products Reaction Reactant 0 3 + N 0 + NO,+O, RO2 + NO + NO,+ RO OH+NO -+ HNO, HNO,+hv - OH+NO NO,+hv -+ NO+O 0 3 + N 0 2 - NO,+O, NO,+ hv NO,+O NO,+HCHO -+ H N 0 3 + H C 0 N,O, + hv - NO3+ NO, N 0 3 + N 0 2 - N,O, N,O,+H,O -+ 2HN03 N,O,+ H,O hz 2HN0, O H + N 0 2 + HNO, OH + HNO, -+ H,O+ NO3 HNO,+hv - OH+NO, HNO,, wet deposition HN03, dry deposition 2NO,+ H,O - HN03+ HNO, NO+ NO,+ H,O - 2HN0, 0 3 RO2 OH hv hv 0 3 hv HCHO NO2 hv H2O Rural aerosol OH OH hv - - H2O H2O NO2 m 30 ppbv 0.1 ppbv - - - 30 ppbv - 1 PPbV 6 PPbV - 2.5% - - - - - - 2.5% 2.5% 6 PPbV k', j d 1.8 (-14) 5 (-12) 8 (-12) 8.4 (-4) 3.5 (-3) 3.2 (-17) 1.6 (-1) 6 (-15) 7 (-13) 6 (-6) 12 (-21) - 1.3 (-11) 1.5 (-13) 1(-7) - - 8 (-38) 4.4 (-40) 7.5 (1) 5 (1) 1(5) 1.2 (3) 2.8 (2) 4.2 (4) 6.2 6.7 (3) 9.5 1.7 ( 5 ) >8.3 (2) 1.2 (2) 3.8 (4) 3.3 (6) 1(7) 4.7 ( 5 ) e 3.3 (5)' 7 (7)' 2.5 (10)' a The associated time constants are obtained from the respective rate or photodissociation coefficients and reactant concentrations for ground-level rural atmospheric conditions. Data are based in part on a compilation of Ehhalt and Drummond (1982). Orders of magnitude are shown in parentheses. * In units of mo~ecu~es/cm'. In units of cm3/mo~ecules. In units of s-'. Half-lifetime. ' Assumes uniform vertical distribution. pathways are indicated by bolL arrows. These processes are active only during the day, whereas the others occur at all times. Table 9-10 is added to show time constants associated with the individual reaction steps.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
