An Introduction to Environmental Chemistry

atmosphere at about 1.7 ppm (Box 3.1). Methane could be imagined to react with O 2 in the following way: eqn. 3.2 The reaction c ...

9.75 years. This represents the average lifetime of a CH 4 molecule in the atmos- phere (at least, it would if the atmosphere wa ...

a long residence time, then it will have ample time to become well mixed in the atmosphere and thus would be expected to show gr ...

fossil fuel by human activities. This has given rise to a continuing increase in the CO 2 concentration in the atmosphere. The p ...

is released in a single event than for many years previously. The eruptions occur in very specific locations where there are act ...

3.4.2 Biological sources Unlike the geological sources, biology does not appear to be a large direct source of particles to the ...

reactions of nitrogen compounds in soils that produce the gases: NH 3 , N 2 , N 2 O and nitric oxide (NO). Microorganisms in the ...

phide (OCS). This can be produced by reaction between carbon disulphide (CS 2 ) and water: eqn. 3.11 and, although the flux to t ...

3.5 Reactivity of trace substances in the atmosphere Gases with short residence times in the atmosphere are clearly those that c ...

OCS, N 2 O and even CH 4 have long residence times. The CFCs (chlorofluoro- carbons, Fig. 3.4b: refrigerants and aerosol propell ...

between two quite distinct types of air pollution that affect major cities of the world. 3.6.1 London smog—primary pollution Urb ...

eqn. 3.19 There are other impurities in fuels too, but sulphur has always been seen as most characteristic of the air pollution ...

48 Chapter Three Fig. 3.5The London smog of 1952. Photograph courtesy of Popperfoto Northampton, UK. Victorian England realized ...

Photochemical smog was first noticed in Los Angeles during the Second World War. Initially it was assumed to be similar to the a ...

Although air pollution and smoke have traditionally been closely linked, there were always those who thought there was more to a ...

The Atmosphere 51 Box 3.6 Reactions in photochemical smog Reactions involving nitrogen oxides (NO and NO 2 ) and ozone (O 3 ) li ...

3.6.3 21st-century particulate pollution It is valid to ask what might be different about pollution in the early 21st century. O ...

cities. The diesel engine can emit very small particles, perhaps only 0.1mm across, but these readily coagulate into somewhat la ...

The two gases that particularly characterize photochemical smog, O 3 and nitrogen oxides, caused particular concern because of t ...

importance of other sources of benzene to humans, for example tobacco smoke. Toluene (C 6 H 5 CH 3 ; Fig. 3.4d) is another aroma ...