Text В Water Pollution

Water in its natural state is never 100 percent pure. As soon as it condenses as rain, water begins gathering impurities until purified or until it evaporates. Much of this impurity is not sufficient to spoil the usefulness of water; some materials and substances, however, do limit its usefulness.

By definition «water pollution» we mean the presence in water of any
substance that interferes with any of its legitimate uses - for public
water supplies, recreation, agriculture, industry, the preservation of fish
and esthetic purposes. ^ '^;!'-^;'^ '. (/ ^ ' ^{r,/V i/} *" I ^

The principal forms of water pollution are domestic, industrial and
agricultural wastes. Domestic wastes include sewage, detergents and
everything else going down the chains of a city into its sewer system -
used water from toilets, bathtubg, Virira and washings from restaurants,
laundries, hospitals and hotels and other businesses: • '.м'^л

Industrial wastes are the acids, oils, greases, other jCj^micals and
animal and vegetable matter discharged by factories. These wastes are
discharged either through sewer system or through separate outlets di­
rectly into waterways. Agricultural wastes include pesticides (insecti­
cides, fungicides and herbicides), fertilizers (mainly nitrates and phos­
phates) and animal wastes. In addition to these principal forms, other
pollutants such as heat and radioactive substances, can contribute to
water pollution. -> /< - ^ ' 1\,

The extent of pollution in a given body of water can be measured to some degree by the amount of organic wastes it contains. Organic wastes can generally be destroyed by biochemical action, either naturally in a free-flowing stream or artificially in a waste treatment plant. Not all pollutants can be removed by such action, however; examples include minerals and acids from industrial operations or mining. Such pollut­ants as radioactive substances, pesticides, detergents and various oil prod­ucts are highly resistant to breakdown and must be specially treated.

Упражнение З. Прочтите нижеприведенные суждения. Найдите в тексте предложения, более полно выражающие мысль данных суждений, и прочтите их вслух.

Lesson 22 О 215

1. Natural water is never 100 per cent pure. 2. «Water pollution» means the presence in water of the substance that interferes with its legitimate uses. 3. Agricultural wastes include pesticides, fertilizers, etc. 4. There are some forms pf water pollution. 5. The extent of water pollution can be measured by the amount of organic wastes in it. 6. Some wastes can be destroyed but others cannot.