Pollutant hydrocarbons

Induction did not occur under our exposure conditions in fish exposed to water saturated with a variety of pure hydrocarbons. The compounds studied are commonly found in other pollutants besides petroleum. It is reasonable to speculate that enzyme induction may not be a common response of fish in the environment to various pollutant hydrocarbons which may be available in the water column for short periods. 

HA HAP HC HCFC HDPE HDR Humic acid Hazardous air pollutant Hydrocarbon (molecular weight 13 g/mol) Hydrochlorofluorocarbon High-density polyethylene Hot-dry-rock... 

Petroleum products undergo catalytic hydrodesulfurization and re-forming processes. Catalysts in automobile exhaust systems convert pollutants (hydrocarbons, CO, NO) to... 

Thomson S., Eglinton G. (1978) Composition and sources of pollutant hydrocarbons in the Severn Estuary. Mar. Pollut. Bull. 9, 133-6. 

Volkman JK, Revill AT, Murray AP (1997) Applications of biomarkers for identifying sources of natural and pollutant hydrocarbons in aquatic environments. In Molecular markers in Environmental Geochemistry, ACS Symp.Series 671, 110-132. 

From the standpoint of atmospheric pollution, hydrocarbon combustion is of major importance. Depending on conditions of the combustion processes, the balance of the proportions of final products may be considerable different. Particular differences are observed for mixtures containing different amounts of air. The composition of products changes also with temperature. At low temperatures (700 K) a slow combustion occurs, at temperatures from 700 to 1500 K, the process of the hydrocarbon oxidation is essentially more rapid with a tendency to explosion. In a comparison with the moderate combustion, the mechanism of the process is different. At very high temperatures (> 2300 K) an extremely rapid, explosive combustion is observed. 

Marty and Saliot (1976) gave the following values for the enrichment factor calculated for a 0.44 mm thick surface microlayer about 20 for dissolved and particulate n-alkanes for the Mediterranean Sea and between 161 and 350 for coastal samples collected along the French coast. These results are. comparable with those of Wade and Quinn (1975) who reported, for ultrasurface samples from the North Atlantic, values of the enrichment factor varying from 1.1 to 26. Analyses of sea surface samples from the Mediterranean by Morris (1974) indicated that the films collected, yielding a concentration of 40—230 mg of organic matter per m, were composed of both natural lipids in low amounts (<5% total extract) and a complex mixture of pollutant hydrocarbons. 

Tissier, M.J. and Gudin, J.L., 1973. Characteristics of naturally occurring and pollutant hydrocarbons in marine sediments. Proc. Conf. on Prevention and Control of Oil Spills. American Petroleum Institute, Washington, D.C., pp. 205—214. 

Emissions of other pollutants, hydrocarbons or CO, from hydrogen combustion in ICE become significant, if the engine bums excess lubricating oil. These emissions can be minimized by regular inspection and maintenance [69]. 

Albaig s J, Albrecht P (1979) Fingerprinting marine pollutant hydrocarbons by computerized gas chromatography-mass spectrometry. In Frei RW (ed) Recent advances in environmental analysis. Gordon and Breach, London, pp 261-280... 

It was concluded that any remedy to regulated automobile pollutants (hydrocarbons, carbon monoxide) would decrease the polynyclear aromatic hydrocarbons. 

On the other hand, it consists mainly of methane (85-95%), higher hydrocarbons, nitrogen and carbon dioxide, and thus it has inherent clean burning characteristics and a less adverse effect on the environment, with the emission of lower levels of pollutants (hydrocarbons, sulfur and nitrogen oxides, etc.), per unit of energy provided. 

Oxygen is a reactive species in the atmosphere that reacts to produce oxidation products from oxidizable gases in the atmosphere. Two such species that are particularly important are sulfur dioxide gas, SO2, and pollutant hydrocarbons. Molecular O2 does not react with these substances directly but it reacts with them indirectly through the action of reactive intermediates, especially hydroxyl radical, HO-. Atmospheric oxygen is discussed in Section 6.10. 

FIGURE 7.8 Structural formulas representative of classes of air pollutant hydrocarbons that may be introduced into the atmosphere from anthrospheric activities. 

The most abundant hydrocarbon in the atmosphere is methane, CH4, released from underground sources as natural gas and produced by the fermentation of organic matter. Methane is one of the least reactive atmospheric hydrocarbons and is produced by diffuse sources, so that its participation in the formation of pollutant photochemical reaction products is minimal. The most significant atmospheric pollutant hydrocarbons are the reactive ones produced as automobile exhaust emissions. In the presence of NO, under conditions of temperature inversion (see Chapter 16), low humidity, and sunlight, these hydrocarbons produce undesirable photochemical smog, manifested by the presence of visibility-obscuring particulate matter, oxidants such as ozone, and noxious organic species such as aldehydes. 

Organic pollutants may have a strong effect upon atmospheric quality. The effects of organic pollutants in the atmosphere can be divided into two major categories. The first consists of direct effects, such as cancer caused by exposure to vinyl chloride. The second is the formation of secondary pollutants, especially photochemical smog, discussed later in this chapter. In the case of pollutant hydrocarbons in the atmosphere, the latter is the more important effect. In some localized situations, particularly the workplace, direct effects of organic air pollutants may be equ y important. 

Figure 16.8 Potential sources of pollutant hydrocarbons from an automobile without pollution control devices.

The primary cause of unbumed hydrocarbons in the engine cylinder is wall quench, wherein the relatively cool wall in the combustion chamber of the internal combustion engine causes the flame to be extinguished within several thousandths of a centimeter from the wall. Part of the remaining hydrocarbons may be retained as residual gas in the cylinder, and part may be oxidized in the exhaust system. The remainder is emitted to the atmosphere as pollutant hydrocarbons. Engine misfire due to improper adjustment and deceleration greatly increases the emission of hydrocarbons. Turbine engines are not subject to the wall quench phenomenon because their surfaces are always hot. 

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