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There is the idea that there is an inherent equilibrium most ecosystems with plants and animals interacting so as to produce a stable continuing system of life on Earth. Organisms in the ecosystem are adapter to each other – for example, waste products produced by one species are used by another and resources used by some are replenished by others; the oxygen needed by animals is produced by plants while the waste product of animal aspiration, carbon dioxide, is used by plants as a raw material in photosynthesis. The nitrogen cycle, the water cycle, and the control of animal populations by natural predators are other examples. The activities of human beings can, and frequently do, disrupt the balance of nature. The idea of a balance of nature is also expressed in the Gaia hypothesis, which likens the Earth to a living organism, constantly adjusting itself to circumstances so as to increase its chances of survival.
Pollution is the harmful effect on the environment of by-products of human activity, principally industrial and agricultural processes – for example, noise, smoke, car emission, chemical and radioactive effluents in air, seas, and rivers, pesticides, radiation, sewage and household waste. Pollution contributes to the greenhouse effect. Pollution control involves higher production costs for the industries concerned, but failure to implement adequate controls may result in irreversible environmental damage and an increase in the incidence of diseases such as cancer. Radioactive pollution results from inadequate nuclear safety.
Transboundary pollution is when the pollution generated in one country affects another, for example as occurs with acid rain. Natural disaster may also cause pollution; volcanic eruptions, for example, cause ash to be ejected into the atmosphere and deposited on land surfaces.
Greenhouse Effect is the phenomenon of the Earth’s atmosphere by which solar radiation, trapped by the Earth and re-emitted from the surface, is prevented from escaping by various gases in the air. The result is a rise in the Earth’s temperature.
Acid Rain is an acidic precipitation thought to be caused principally by the release into the atmosphere of sulphur dioxide and oxides of nitrogen. Sulphur dioxide is formed by the burning of fossil fuels, such as coal, that contain high quantities of sulphur; nitrogen oxides are contributed from various industrial activities and from car exhaust fumes.
The main effect of acid rain is to damage the chemical balance of soil, causing leaching of important minerals including magnesium and aluminium.
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