Nitrous oxide concentration

Machida, T., Nakazawa, T., Fujji, Y. et al. (1995). Increase in atmospheric nitrous oxide concentration during the last 250 years. Geophys. Res. Lett. 22, 2921-2924. 

Problems may arise when the atmospheric concentration of greenhouse gases increases. Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth s atmosphere. 

A similar phenomenon can be observed in the cuffs and balloons of tracheal tubes, flotation catheters, etc. Increases in cuff pressure may be sufficient to cause mucosal ischaemia with subsequent damage to the tracheal mucosa. In the case of pulmonary flotation catheters, there is a risk of cuff rupture followed by gas embolism and infarction. A number of factors affect the rate of volume and pressure change—time, permeability, elasticity, initial volume and pressure, nitrous oxide concentration, temperature. 

The global atmospheric nitrous oxide concentration increased from a preindustrial value of about 270 ppb to 319 ppb in 2005. The growth rate has been approximately constant since 1980 and more than 30% of all nitrous oxide emissions are primarily due to agriculture. 

Barnes, J., and Owens, N. J. P. (1998). Denitrification and Nitrous Oxide concentrations in the Humber Estuary, U.K., and adjacent coastal zones. Mar. Poll. Bull. 37, 247—260. 

PlOC-3 See The decomposition of nitrous oxide on neodymium oxide, dysprosium oxide and erbium oxide, J. Catal., 28, 428 (1973). Some investigators have reported the rate of this reaction to be independent of oxygen concentration and first-order in nitrous oxide concentration, while others have reported the reaction to be first-order in nitrous oxide concentration and negative one-half-order in oxygen concentration. Can you propose a mechanism that is consistent with both observations ... 

As stated above, most users of the headspace technique make no distinction between dynamic HS and PT. In one of the few publications that distinguished and compared these two HS modes, dynamic HS and PT were assessed as steps preceding high-resolution GC-electron capture detection for the determination of nitrous oxide in sea water. The process was found to exhibit a first-order kinetics in both cases and the matrix to exert a significant effect that was proportional to the nitrous oxide concentration in bidistilled water, as well as in synthetic and natural sea water. As expected, PT provided better extraction recovery, sensitivity and limits of detection — which fell in the pico-mole-per-millilitre range [46]. 

Effect of Nitrous Oxide on Benzene-2-Butene Solutions. The yield of nitrogen increased with increasing concentration of nitrous oxide, in agreement with the work of Sato and co-workers (43). The isomerization showed a marked decrease at low nitrous oxide concentrations. Figure 4 summarizes the results. 

Figure 4> GN2 and Gteom vs. nitrous oxide concentration for cis-2-butene (0.25M) in benzene. X, Gisom O, GA 2...

The yield of nitrogen may be increased at higher nitrous oxide concentrations by (39) ... 

Figure 3. Yields of nitrogen in molecules/100 e.v. as a function of nitrous oxide concentration in cyclohexane, O, and in 2,2,4-trimethylpentane. Solid line represents theoretical yields of electrons scavenged hy nitrous oxide (7)...

Barnes J and Owens NJP (1998) Denitrification and nitrous oxide concentrations in the Humber estuary, UK and adjacent coastal zones. Marine Pollution Bulletin 37 247-260. 

An alternative procedure that has been tested by us is that of measuring the area of the derivative signal between pre-set points such as its zero crossings, that might be expected to yield comparable results. There were found no significant differences between relative concentrations evaluated fi om line peak and area measurements of oxygen in air mixtures. Results for nitrous oxide and air mixtures (Figure 4.1) showed, however, a marked curvature of the peak measurements as a function of nitrous oxide concentration, whereas area measure-... 

Fig. 17.32 The concentrations of methane in ice of the Dome-C core (EPICA) between 380 x 10 years and 650x10 years in the past vary in-step with the 5D values and hence with the average annual surface temperatures at Dome C. The warm and cold climatic intervals are identified by the MIS (marine isotope stages) numbers from Fig. 17.30 where up means warm and down means cold. The profile of nitrous oxide concentrations also mirrors the fluctuations of 6D. Data for the upper part of the core...

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