Highly variable gase

Table 1 gives the concentration and residence time of atmospheric gases on the basis of the data of different authors. In the table the concentrations of quasipermanent and variable gases are expressed partly in parts per hundred (percent by volume) and partly in parts per million (ppm). In the case of some highly variable gases the concentrations are also expressed in /ig/m3 STP because these units are widely used in atmospheric chemical measurements. (For the conversion of ppm concentrations into /tg/m3 values see Table 4, p. 30). 

The composition of natural gas at the wellhead depends on the characteristics of the reservoir and is highly variable with respect to both the constituents present and the concentrations of these constituents. Compositions of various natural gases are given in Table 4. 

Tropospheric chemistry is strongly dependent on the concentration of the hydroxyl radical (OH), which reacts very quickly with most trace gases in the atmosphere. Owing to its short boundary layer lifetime ( 1 s), atmospheric concentrations of OH are highly variable and respond rapidly to changes in concentrations of sources and sinks. Photolysis of ozone, followed by reaction of the resulting excited state oxygen atom with water vapour, is the primary source of the OH radical in the clean troposphere ... 

Some monounsaturated fatty acids such as Clfi 1 and C1X 1 (the first number is the number of carbon atoms and the second number is the number of double bonds) are also produced biogenically, in addition to some diunsaturated species (e.g., see Sicre et al., 1990a). However, because they react fairly rapidly with tropospheric gases such as 03, OH, and NOv their concentrations are highly variable and also dependent on storage conditions after sampling. A variety of dicar-... 

Direct photochemical breakdown is the main cause of the decrease of mixing ratios with height for these trace gases at tropical and mid latitudes. In contrast, dynamic transport processes force the distribution and the high variability of tracer mixing ratios in the winter stratosphere at the poles. 

Figure 5.1 Relationship between residence time and coefficient of variation of concentrations of gas in the atmosphere. Gases with short residence times (Rn and H2O) are highly variable while those with long residence times (O2 and N2O) have less variability. (Modified from Junge, 1974.)...

Control of digester relief and blow gases is obtained by chilling, which removes a foul condensate. The uncondensed gas fraction is moved on to a gas accumulator, which smooths out the highly variable gas flow rates. The accumulator is vented at a steady rate through a shower of weak black liquor. 

The atmosphere is composed primarily of nitrogen, oxygen, and several noble gases, the concentrations of which have remained remarkably fixed over time. Also present are a number of trace gases that occur in relatively small and sometimes highly variable amounts. 

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