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II. Объясните, каким образом происходит естественное загрязнение атмосферы.
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III. Найдите в тексте абзац, в котором говориться об источниках загрязнения атмосферы в настоящее время.
IV. Охарактеризуйте основные группы компонентов выхлопных газов.
WATER POLLUTION
Ever since man progressed from a hunting to an agricultural society, with the corresponding development of stable communities, as agricultural methods improved a smaller percentage of the population produced all food needed, larger communities and diverse secondary industries developed and grew into the present modern society. Concurrent with this growth, however, was the increasing percentage of waste materials and the problems of disposal. When the total volume of waste from a community was relatively small, the easiest method of disposal was to “throw it away”, usually into the nearest receptacle. Since man cannot exist without water, community development and city growth centered in areas where the water supplies were adequate and continuous. Initially this meant development in river valleys, and thus the nearest receptacle for wastes was the river.
The term “pollution” has been variously defined by many people, but if it may be described here as “the detrimental effects on a localized ecological structure by the addition of the waste products of a society “, then it is apparent that the first noticeable pollution problems should have involved the supply of drinking water.
It is in this particular area that the question of pollution takes on a new meaning. Is a body of water polluted when it directly affects man, or should it be classified as polluted when the ecological structure is first upset? The hydrosphere is a dynamic system containing physiochemical and biological equilibria, and there is no doubt that a normally active waterway has a large capacity to assimilate wastes. However, in many areas this capacity is now being reached or exceeded so that many waterways are becoming increasingly contaminated. Before this contamination becomes readily noticeable however, equilibria are changed and the ecological structure may be seriously affected. Some examples of water systems where the effects of pollution have become or are becoming increasingly apparent are the Adriatic, Baltic and Mediterranean seas; the Thames, Rhine and Seine rivers; and the Great Lakes in America and Canada. But dynamic systems have a remarkable capacity for regeneration, and with careful planning even the most seriously polluted waterways may be brought back into full use. An example of river regeneration on a large scale is the successful attempt to restore the Thames estuary.
I. Закончите следующие предложения соответствующими фразами из текста:
1. As agricultural methods improved, ………..
2. Concurrent with this growth, however, was the increasing percentage of …………...
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3. Since man cannot exist without water, ………….
4.It is in this particular area that the question of ……..
5. The hydrosphere is a dynamic system containing ……...
6. But dynamic systems have a remarkable capacity for ………..
Protection of water.
The water and the air the most important elements in physical and chemical processes on the surface of the earth. Resources of river, lake and underground fresh waters are distributed very unevenly on the continents.
Russia is one of the richest countries in the world in water resources. The main source of fresh water comes from river discharge estimated at 4,700 km a year. In addition, Russia has many lakes, the total area of which is larger than Great Britain and useable reserves of underground waters are extensive. nevertheless, the question of the rational use of water resources and their protection from pollution is acquiring growing importance in Russia.
Water use. Shortage of water in different areas of the world is due not only to uneven distribution of water resources but also to its more varied and intensive use.
The Law on Conservation of Nature of the Russian Federation states that all rivers, lakes and underground waters are to be protected from depletion and pollution as water supply resources, a source of energy and means of treatment. Rivers and lakes are also used as transport routes, fisheries, hunting areas and recreation sites.
It is obvious that the exploitation of water resources is extremely varied at the present time. It should be added that the scope of water resource exploitation is growing rapidly due to population growth, fast development of industry and expansion of irrigated land area.
An enormous amount of water is used in industry. To manufacture one ton of paper, 100 m of water is required, one ton of synthetic fibres-from2,500 to 5,000 m of water and so on. It has been estimated that industry consumes about 15 per cent for the daily needs of the people.
A sharp increase in water consumption on the planet may lead to a water shortage in the near future. In view of this, measures are being worked out to increase water resources and rationally exploit them.
Redistribution of water. There are two ways to redistribute river water by means of reservoirs and through canals.
Reservoirs. In recent decades, cascades of hydroelectric power plants have been built with reservoirs, the largest on the Volga, Kama, Dnieper, Angara and Yenisei.
Reservoirs are an example of how man intervenes to a considerable extent in natural processes over large areas. Reservoirs help solve energy problems, irrigate agricultural land, improve water transport, supply large enterprises, cities and other populated areas with water fisheries and form the basis for recreation and tourist zones.
Canals are important not only for redistributing water but also as transport routes, as such they are artificial rivers built by mighty excavating machines.
Use of underground water. Supplies of underground waters are considerable, and, therefore, their rational use helps to compensate for moisture shortages. Academician Karpinsky called water the most precious natural resource. Unlike mineral deposits, water resources are renewed in the course of exploitation.
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Geothermal (hot) waters are a kind of ground water source, the water being obtained from the earth's interior by deep drilling. These hot waters are used to generate electricity (geothermal electric plants), heat homes and livestock breeding farms, and also in hot-houses. Recently, geothermal waters have been used for breeding fish in ponds in Siberia.
I. Ответьте на вопросы по тексту:
1. Как можно объяснить неравномерное распределение водных ресурсов?
2. Каковы масштабы эксплуатации водных ресурсов?
3. Каковы последствия резкого увеличения потребления воды?
4. Какие существуют возможности использования подземной воды?
II. Прочтите и определите значения следующих слов по сходству со словами того же корня в русском языке:
planet [ ]n, rational [ ] a, decade [ ] n, cascade [ ] n, territory [ ]n, compensate [ ]v, geothermal [ ] a.
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