Nitrification nitrous oxide

Bremner, J. M. and Blackmer, A. M. (1981). Terrestrial nitrification as a source of atmospheric nitrous oxide. In Denitrification, Nitrification, and Atmospheric Nitrous Oxide" (C. C. Delwiche, ed.). Wiley, New York. 

Zaman M, Blennerhassett JD. Effects of the different rates of urease and nitrification inhibitors on gaseous emissions of ammonia and nitrous oxide, nitrate leaching and pasture production from urine patches in an intensive grazed pasture system. Agriculture Ecosystems and Environment. 2010 136 236-246. 

Emissions of nitric and nitrous oxides are the result of microbial nitrification and denitrification in soils, controlled principally by soil water and mineral N contents, labile organic carbon, and temperature. Nitric oxide is a direct intermediate of both nitrification... 

It is thought that little net NO is produced in denitrification, it being readily reduced to N2O, and nitrification is therefore the main source of NO (Anderson and Levine, 1986 Skiba et al, 1993). Nitrous oxide is also produced in both nitrification and denitrification. At low O2 concentrations in otherwise aerobic soil, small amounts of N2O are formed as a by-product of nitrification, N2O not itself being reduced to NO,. In denitrification, the proportion of N2O produced relative to N2 increases as the availability of O2 increases and that of carbon decreases (Tiedje, 1988). In general only a small fraction of the N nitrified or denitrified in these pathways is released as NO or N2O. The emission is therefore sensitive to the amount of mineral N in the system, which is driven principally by additions of nitrogen fertilizers and deposition of nitrogen from the atmosphere. 

Skiba U, Smith KA, Fowler D. 1993. Nitrification and denitrification as sources of nitric oxide and nitrous oxide in a sandy loam soil. Soil Biology and Biochemistry 25 1527-1536. 

The 8 N- and 8 0-values of atmospheric N2O today, range from 6.4 to 7.0%c and 43 to 45.5%c (Sowers 2001). Terrestrial emissions have generally lower 8-values than marine sources. The 8 N and 8 0-values of stratospheric N2O gradually increase with altitude due to preferential photodissociation of the lighter isotopes (Rahn and Wahlen 1997). Oxygen isotope values of atmospheric nitrous oxide exhibit a mass-independent component (Cliff and Thiemens 1997 Clifif et al. 1999), which increases with altitude and distance from the source. The responsible process has not been discovered so far. First isotope measurements of N2O from the Vostok ice core by Sowers (2001) indicate large and 0 variations with time (8 N from 10 to 25%c and 8 0 from 30 to 50%c), which have been interpreted to result from in situ N2O production via nitrification. 

Nitrous oxide is important not only as a greenhouse gas but, as discussed in Chapter 12, as the major natural source of NC/ in the stratosphere, where it is transported due to its long tropospheric lifetime (Crutzen, 1970). The major sources of N20 are nitrification and denitrification in soils and aquatic systems, with smaller amounts directly from anthropogenic processes such as sewage treatment and fossil fuel combustion (e.g., see Delwiche, 1981 Khalil and Rasmussen, 1992 Williams et al., 1992 Nevison et al., 1995, 1996 Prasad, 1994, 1997 Bouwman and Taylor, 1996 and Prasad et al., 1997). The use of fertilizers increases N20 emissions. For pastures at least, soil water content at the time of fertilization appears to be an important factor in determining emissions of N20 (and NO) (Veldkamp et al., 1998). 

Delwiche, C. E., Ed., Denitrification, Nitrification, and Atmospheric Nitrous Oxide, Wiley, New York, 1981. 

Crutzen, P.J. 1981. Atmospheric chemical processes of the oxides of nitrogen, including nitrous oxide. In Delwiche, j. (ed.) Denitrification, Nitrification and Nitrous Oxide. Wiley and Sons, New York. pp. 17-44. 

T. Schlosing found that some nitrous oxide is formed during the lactic fermentations of organic substances in a soln. containing nitrates and M. E. Wollny, B. Tacke, M. W. Beyerinck and D. C. J. Minkman, and S. Suzuki observed the formation of nitrous oxide during the nitrification of organic matter by bacteria. 

Nitrification must be followed by denitrification to remove nitrogen from wastewater. It implies the reduction of nitrate to nitric oxide, nitrous oxide and nitrogen gas, coupled to the respiratory electron transport chain (because nitrates or nitrites are used as electron acceptors for the oxidation of a variety of organic or inorganic electron donors). 

Organic nitrogen is seldom completely converted to NOJ or N2 during either nitrification or denitrification. Some small fraction ends up as nitrous oxide, N2O... 

Codispoti, L. A., and Christensen, J. P. (1985). Nitrification, denitrification and nitrous oxide cycling in the Eastern Tropical South Pacific Ocean. Mar. Chem. 16, 277—300. 

Schmidt, H. L., Werner, R. A., Yoshida, N., and Well, R. (2004). Is the isotopic composition of nitrous oxide an indicator for its origin from nitrification or denitrification A theoretical approach from referred data and microbiological and enzyme kinetic aspects. Rapid Communication Mass Spectrometry 18(18), 2036—2040. 

Dore,. E., and Karl, D. M. (1996). Nitrification in the euphoric zone as a source for nitrite, nitrate, and nitrous oxide at station ALOHA. Limnology and Oceanography 41, 1619—1628. 

Dore, J. E. (1995). Microbial Nitrification in the Marine Euphoric Zone Rates and Relationships with Nitrite Distributions, Recycled Production and Nitrous Oxide Generation, Ph.D. Dissertation. University of Hawaii, Honolulu. 

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