Nitrogen tracers

A rather complete picture of what happens to fertilizer nitrogen added to cropped soil in greenhouse pots is shown in Table 23.11, taken from the data of Legg and Allison (1959, 1960). Immobilization of added tracer nitrogen increased 4—5 times as the nitrogen addition increased 16-fold. Soil nitrogen mineralization (column 9) was essentially a constant as fertilizer nitrogen additions were increased. 

BARTHOLOMEW W.V. 1964. Guides in extending the use of tracer nitrogen in soils and fertilizer research. Proceedings of the Nitrogen Research Symposium. TVA Report number T64-45F, 81-96. 

Fogel, M., Tuross, N. and Owsley, D.W. 1989 Nitrogen isotope tracers of human lactation in modem and archaeological populations. Annual report of the Director Geophysical Laboratory, 1988-1989. Washington, D.C., Carnegie Institution ofWashington 111-117. 

Steele, K.W. and Daniel, R.M.J 1978 Fractionation of nitrogen isotopes by animals a further complication to the use of variations in the natural abundance of for tracer studies. Journal of Agricultural Science, Cambridge 90 7-9. 

To further test the model, calculations were performed to simulate the isotopic tracer experiments presented in Figs. 9 and 10. It should be noted that while the tracer experiments were performed at 438K, the rate coefficients used in the model were chosen to fit the experiments in which chemisorbed NO was reduced at 423 K. Figures 21 and 22 illustrate the nitrogen partial pressure and surface coverage responses predicted for an experiment in which 5 0 is substituted for l NO at the same time that H2 is added to the NO flow. Similar plots are shown in Figs. 23 and 24 for an experiment in which NO is substituted for during steady-state reduction. 

Thermal Degradation of Secondary Nitramines - A Nitrogen-15 Tracer Study of HMX (l,3,5,7-tetranitro-l,3,5,7-tetrazazcyclooctane). 

The molar fraction ratio between helium and nitrogen in the flue gas was determined from gas chromatographic measurements. The molar flow of the tracer gas of helium was measured. Because Rogers applied batch methods to measure water vapour in flue gas and the helium-nitrogen ratio, the overall method become a semi-continuous method. The water vapour of the flue gas was measured batchwise by freezing it out in an U-tube placed in an acetone-dry ice mixture. 

Introduction of a fluorine-18 in )0-position to the pyridine nitrogen has been carried out in 37 % radiochemical yield by nucleophilic exchange for NO2 in the synthesis of a potential MAO-B imaging tracer (Scheme 48) [205]. 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of urea production, urea recycling, and interorgan nitrogen transfer in living systems. 

The process of reductive dechlorination requires the presence of a readily oxidizable substrate or electron donor. The addition of nitrogen and phosphorous nutrients may be required. Because oxygen is detrimental to an anaerobic process, oxygen scavengers may be required to drive the process. Tracers to monitor the biological process may also be necessary. 

---