Chemicals in the environment

Vocabulary

Chemicals химикалии

Stem from происходить из

Sustain поддерживать

Lane тропинка, улица

Emission control контроль за выбросами

Text 1

Read the text below and render it in Russia or English, as you like.

Do you agree with the idea that some environmental problems have arisen from poorly controlled discharges of wastes or chemicals?

In recent years there has been increasing concern around the world over chemicals in the environment. Such concern has arisen in response to information on the widespread distribution of chemicals stemming from human activities and the potentially harmful effects of those chemicals on humans or on the ecological systems which sustain humans. Some environmental problems, such as contaminated lane, have arisen from poorly controlled discharges of wastes or chemicals whilst others, such as air pollution, have arisen from poor emission controls on energy generation and motor vehicles.

Other problems have arisen from the release of chemical into the environment over many years where insufficient attention had been given to an analysis of their behavior in soils, air and water and to their effects on humans and other species. Chlorinated organo-compounds illustrate this problem. For example, groups of chemicals such as polychlorinated biphenyls (PCBs) and dichlorodyphenyl trichloroethane (DDT) were developed as relatively stable substances so it is not surprising today that as a result of their widespread use and release into the environment they can be detected in Arctic and Antarctic snow and surrounding ecosystems.

Read the text and make the resume of it:

Text 2

Hazards and chemical fertilizers

The great expansion of the fertilizers use has benefited mankind enormously, but the benefits are not unalloyed (not without drawbacks). The runoff of chemical fertilizers into rivers, lakes and underground waters creates two important hazards. One is the chemical pollution of drinking water. In certain areas in Illinois and California the nitrate can cause the physiological disorder (methomoglobinemia) which reduces the blood’s oxygen-carrying capacity and can be particularly dangerous to children under five. This hazard is only of local dimension and can be handled by finding alternative sources of drinking water. A much more extensive hazard, profound in its effects on the biosphere is well-known phenomenon called eutrophication. Inorganic nitrates and phosphates discharged into lakes and other bodies of fresh water provide a rich medium for the growth of algae; the massive growth of algae in turn depletes the water of oxygen and thus kills off the fish life. In the end eutrophication and overfertilization of the lake slow bring about its death as a body of fresh water converting it into swamp. Lake Erie is a prime example of the process now under way.

Undoubtedly the runoff of nitrates and phosphates from farmlands plays a large part. There are also other important contributes, however. Considerable amount of phosphate coming mainly from detergents are discharged into rivers and lakes from sewers carrying municipal and industrial wastes. And there is reason to believe that in some rivers and lakes most of the nitrate may come from not fertilizers but from the internal-combustion engine.

It is estimated that in the state of New Jersey, which has heavy automobile traffic, nitrous oxide products of gasoline combustion, picked up by rainfall contribute as much as 20 pounds of nitrogen per acre per year to the land. Some of this nitrogen washes into many rivers and lakes of New Jersey and its adjoining states. A way must be found to deal with the eutrophication problem because even in the short run it can have damaging effects affecting as it does the supply of potable water, the cycle of aquatic life and consequently man’s food supply.

Notes:

Hazard риск, опасность

Fertilizer удобрение

Eutrophication евтрофикация, загрязнение водорослями

Algae водоросли

internal-combustion engine двигатель внутреннего сгорания

detergent дезинфицирующее средство

potable пригодный для питья

UNIT V

RADIOACTIVITY

WARM UP

What do you know about radioactivity? It is safe?