18.6 POLLUTION
Pollution is the contamination of the natural environment by anythingthat has a negative impact. The contaminants are usually chemical substances but may also beenergies, such as noise or heat. Pollution is dangerous to human health. It alsodamages the ecosystemswhich all life, including our own, depends on.
Air pollutionis mainly caused by burning fossil fuels (Modules 13.11/12) in motor vehicles, thermal power stations (for making electricity), and other industrial processes. These includethe smelting of iron and steel (Module 13.15) and the manufacture of concrete and bricks (Module 13.16). The main pollutants are carbon monoxide which is toxic (poisonous), carbon dioxide which contributes to global warming, oxides of sulphur and nitrogen which cause breathing problems and acid rain and fine particles of many dangerous substances. Air can also be contaminated by fine particles of dangerous radio-active materials as a result of accidents at nuclear power stations or the explosion of atomic bombs. Air pollution produced in one place can spread quickly to affect other places far away.
Land pollutionis mainly caused by the waste bi-products of industry and mining, by chemicals that leak or spill from containers or pipes, and by the litterof human communities, especially plastic litter. Soil may also be polluted by pesticides and other chemicals used in agriculture.Badly contaminated land may not be usable for human habitation or farming for a very long time.
Water pollution has the same causes as land pollution. Huge volumes of water are taken from rivers, lakes and seas to use in industrial and mining processes. When thiswater is returned to the environment, most of it is contaminated. The pollutants includeheat as well astoxic or radio-active substances; these all have adverse effects onfish and other aquatic life. Water can also be polluted by untreated human sewage, leading to the spread of diseases such as cholera. Polluted water is no good for drinking;it may also make fishing impossible or make fish dangerous to eat.
Preventing and cleaning up pollution. Most ‘developed’ countries have strict laws to prevent pollution. These laws also force polluters to clean up any damage they cause to the environment.
18 - 6
- 1. List the main contaminants that are likely to be found in (i) polluted air, (ii) polluted water. List the dangersassociated with each contaminant.
- 2. Look up, and report on, one of these notorious examples of pollution: Bhopal, Chernobyl, Fukushima, Exxon Valdez, Deepwater Horizon.
18 - 6