Secondary component, atmospheric

The secondary component results from atmospheric chemical reactions that produce inorganic ionic species of which the most important are NH. and NOJ. Organic vapors also react in the atmosphere to form condensable products. For example, cyclic olefins react with ozone to form less volatile dicarboxyiic acids. The secondary chemical species nomially reported in studies ofaliiiospheric aerosol composition are relatively stable reaction products they have usually survived in the atmosphere and on filter or impactor... 

The atmosphere is polluted either in the release of different substances into the air or during processes occurring directly in the air (e.g. chemical reactions). The substances polluting the air may be divided into primary and secondary ones, depending on the site of their production. In contrast to primary pollutants, which enter the atmosphere from natural sources or by the action of human activity, the secondary components are formed directly in the air during atmospheric reactions. These reactions occur as a result of mutual interactions between elements and compounds or by the action of different types of the energy. 

The sea level cosmic ray dose is 300 millirad-yr and the sea level ionization is 2.2 x 10 ion pairs m s l The sea level flux has a soft component, which can be absorbed in about 100 mm of lead (about 100 g-cm of absorber) and a more penetrating (largely muon) hard component. The sea level radiation is Icirgely produced in the atmosphere and is a secondary component from interactions of the primary particles. The steep primary energy spectrum means that most secondaries at sea level are from rather low energy primaries. Thus the secondary flux is dependent on the solar cycle and the geomagnetic latitude of the observer. 

Particles in the atmosphere arise from natural sources, such as windborne dust, sea spray, and volcanoes, and from anthropogenic activities, such as combustion of fuels. Whereas an aerosol is technically defined as a suspension of fine solid or liquid particles in a gas, common usage refers to the aerosol as the particulate component only (Table 2.17). Emitted directly as particles (primary aerosol) or formed in the atmosphere by gas-to-particle conversion processes (secondary aerosol), atmospheric aerosols are generally considered to be the particles that range in size from a few nanometers (nm) to tens of micrometers... 

Sulfate—a secondary component, usually originated from atmospheric oxidation of SO2. 

It has been established that the principal growth mechanism for urban atmospheric aerosols in the 0.1-1.0 ym diameter size range (the so-called Accxamulation Mode) is gas-to-particle conversion (68,71) The major secondary components in atmospheric aerosols have been identified as sulfates, nitrates and particulate organic species (68,71,72,73). The qualitative picture of polluted... 

Air pollution can be considered to have three components sources, transport and transformations in the atmosphere, and receptors. The source emits airborne substances that, when released, are transported through the atmosphere. Some of the substances interact with sunlight or chemical species in the atmosphere and are transformed. Pollutants that are emitted directiy to the atmosphere are called primary pollutants pollutants that are formed in the atmosphere as a result of transformations are called secondary pollutants. The reactants that undergo transformation are referred to as precursors. An example of a secondary pollutant is O, and its precursors are NMHC and nitrogen oxides, NO, a combination of nitric oxide [10102-43-9] NO, and NO2. The receptor is the person, animal, plant, material, or ecosystem affected by the emissions. 

The gas chromatograph (GC) resembles the MS in providing both qualitative and quantitative EGA but is significantly slower in operation. The interval between analyses is normally controlled by the retention time of the last component to be eluted from the column such delay may permit the occurrence of secondary reactions between primary products [162]. Several systems and their applications have been described [144,163— 167] sample withdrawal can be achieved [164] without the necessity for performing the reaction in an atmosphere of carrier gas. By suitable choice of separation column or combination of columns [162], it is possible to resolve species which are difficult to measure in a small low-resolution MS, e.g. H20, NH3, CH4, N2 and CO. Wiedemann [168] has made a critical comparison of results obtained by MS and GC techniques and adjudged the quality of data as being about equal. 

It must be also considered that the reaction rates of different thermal processes which can occur simultaneously are influenced by the treatment conditions (temperature, heating rate, pressure, static or dynamic atmosphere). This will affect the relative quantities of the products formed and in some cases also their nature, when recombination reactions give rise to secondary degradation products. On account of its sensitivity and resolution power Py-GC/MS will also provide useful information on minor components present in a material, including low molecular weight additives and pigments. 

Fig. 12.11 shows the structure of a rocket plume generated downstream of a rocket nozzle. The plume consists of a primary flame and a secondary flame.Fil The primary flame is generated by the exhaust combustion gas from the rocket motor without any effect of the ambient atmosphere. The primary flame is composed of oblique shock waves and expansion waves as a result of interaction with the ambient pressure. The structure is dependent on the expansion ratio of the nozzle, as described in Appendix C. Therefore, no diffusional mixing with ambient air occurs in the primary flame. The secondary flame is generated by mixing of the exhaust gas from the nozzle with the ambient air. The dimensions of the secondary flame are dependent not only on the combustion gas expelled from the exhaust nozzle, but also on the expansion ratio of the nozzle. A nitropolymer propellant composed of nc(0-466), ng(0-369), dep(0104), ec(0 029), and pbst(0.032) is used as a reference propellant to determine the effect of plume suppression. The burning rate characteristics of the propellants are shown in Fig. 6-31. Since the nitropolymer propellant is fuel-rich, the exhaust gas forms a combustible gaseous mixture with the ambient air. This gaseous mixture is ignited and afterburning occurs somewhat downstream of the nozzle exit. The major combustion products in the combustion chamber are CO, Hj, CO2, N2, and HjO. The fuel components are CO and H2, the mole fractions of which at the nozzle throat are co(0.47) and iH2(0.24).

The addition of phosphine to 5,6-dideoxy-l,2-0-isopropylidene-D-xylo-hex-5-enfuranose 14) takes place when the reaction mixture is irradiated with UV-light. A mixture of 5,6-dideoxy-l, 2-0-isopropylidene-o -D-xylo-hexa-furanose-phosphine 15) and bis-6-(5,6-dideoxy-l, 2-0-isopropylidene-a-D-xylo hexanose)phosphine (f 6) is probably formed but the components could not be separated. In the presence of atmospheric oxygen these are converted to the corresponding phosphonous acid 17) and the secondary phosphine oxide (25), respectively... 

After release from fires, organic and some inorganic components undergo rapid or more delayed chemical transformation in the atmosphere. The physical properties as well as chemical composition of smoke particles may alter on the way from the source areas (biomass burning areas) to the measurement sites in Northern Europe. There are several reasons why particle properties change. Chemical components can, e.g., become oxidized or substituted in particles, but also the condensation of secondary material onto the LRT particles during the transport changes the particle properties. 

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