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Nitrogen Cycle

  1. Biogeochemical Cycles
  2. Carbon and Oxygen Cycles
  3. Phosphorus Cycle
  4. The oceans and the global carbon cycle

Living things need nitrogen to manufacture proteins. Thus the growth of many plants can be limited by a lack of nitrogen available from the soil. Too little nitrogen can also cause malnutrition in people, because many of the body's essential functions require nitrogen-containing molecules such as proteins, DNA, and some vitamins.

The nitrogen gas that makes up about 78% of the volume of the earth's atmosphere is useless to most plants and animals. Fortunately, nitrogen gas is converted into water-soluble ionic compounds containing nitrate ions, which are taken up by plant roots as part of the nitrogen cycle. This nitrogen fixation - that is, the conversation of atmospheric nitrogen gas into forms useful to plants - is accomplished by (1) soil bacteria; (2) rhizobium bacteria living in small swellings; (3) blue-green algae in water and soil; (4) lightning, which converts nitrogen gas and oxygen gas in the atmosphere to forms that return to the earth as nitrate ions in rainfall and other types of precipitation.

Plants convert nitrates obtained from soil water into large, nitrogen-containing molecules such as the proteins and nucleic acids necessary for life and good health. Animals get most of the proteins and other nitrogen-containing molecules they need by eating plants or other animals that have eaten plants. When plants and animals die, decomposers break down the nitrogen-containing molecules into ammonia gas and water-soluble salts containing ammonium ions. Other specialized groups of bacteria then convert these forms of nitrogen back into nitrate ions in the soil and into nitrogen gas, which is released to the atmosphere to begin the cycle again.

Human beings intervene in the nitrogen cycle in several important ways. First, large quantities of NO and NO2 are added to the atmosphere when fossil fuels are burned in power plants and vehicles. These oxides of nitrogen can react with other chemicals in the atmosphere under the influence of sunlight to form photochemical smog and nitric acid, a major component of acid deposition, commonly known as acid rain. Second, nitrogen gas and hydrogen gas are converted by an industrial process into ammonia gas, which is then converted to ammonium compounds used as commercial fertilizer. Third, mineral deposits of compounds containing nitrate ions are mined and used as commercial fertilizers. Fourth, excess nitrate ions are added to aquatic ecosystems via the runoff of animal wastes from livestock feedlots, the runoff of commercial nitrate fertilizers from cropland, and the discharge of untreated and treated municipal sewage. This excess supply of nitrate plant nutrients can stimulate extremely rapid growth of algae and other aquatic plants, which can deplete the water of dissolved oxygen gas and cause massive fish kills.

Вправа 2.

Складіть 5 спеціальних питань до тексту Nitrogen Cycle.

Вправа 3.

(Парна робота) Дайте відповідь на питання, складені у вправі 2.

Вправа 4.

Виберіть з тексту Nitrogen Cycle 10-15 ключових слів. Які з Ваших припущень виправдалися?

Вправа 5.

Визначте, до яких частин мови відносяться обрані Вами слова.

Вправа 6.

Знайдіть в тексті Nitrogen Cycleприклади цих частин мови.

 v.  n.  adj.  adv.  prep.
         

Вправа 7.

Використовуючи суфікси, утворіть дієслова або іменники і заповніть пропуски в пропозиціях: ~ (At) ion, ~ sion, ~ ise.

приклади: To vary - variation; to divide - division; character - to characterise.

Verbs Nouns
 1. It is cheaper to regulate the temperature automatically. 2. If gases ... very rapidly cryogenic temperatures are attained. 3. The committee was set up to standardise civil aviation procedures. 4. People get old because the body ... genetic damage. 5. The first atomic bomb exploded on August 6, 1945. 6. The astronauts are provided with a 14-day supply of pressurised oxygen. 7. Solar energy is ... from hydrogen. 8. Heat losses can be ... by thermal protection. 9. It was necessary to extend the research facilities  Automatic temperature .... is more economical. Rapid expansion of the gases produces temperatures of below 120 Kelvin. His job involves the ... of aviation safety procedures. Ageing is a result of the accumulationof genetic damage. 80,000 people were killed in the Hiroshima ... The oxygen supply is stored under ... The generation of solar energy involves the conversion of hydrogen. Efficient insulation reduces heat losses to a minimum. Because of the increase in staff, an ... had to be built

Вправа 8.

У тексті Nitrogen Cycle знайдіть слова з суфіксами ~ (At) ion, ~ sion, ~ ise.

Вправа 9.

У правій колонці знайдіть російські еквіваленти наступних англійських словосполучень:

 1. lack of nitrogen2. essential functions3. make up4. plant roots5. rapid growth6. blue-green algae7. nucleic acids8. water-soluble salts9. power plants10. nitric acid11. photochemical smog12. commercial fertilizers13. municipal sewage  a. розчинні у воді соліb. швидкий ростc. азотна кіслотаd. синьо-зелені водоросліe. життєво важливі функцііf. електростанцііg. міські стічні водиh. фотохімічний смогi. промислові (хімічні) удобреніяj. коріння растенійk. составлятьl. недолік азотаm. нуклеїнові кислоти

Вправа 10. Прочитайте текст. (Контрольний час - 5 хвилин)

Слова, які зустрінуться в тексті:

conventional removal - стандартне видалення;

reside in - покладатися;

replenish - наповнювати.

Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil. This process was discovered by the Russian microbiologist, Sergei Winogradsky.

Nitrifying organisms are chemoautotrophs, and use carbon dioxide as their carbon source for growth.

Nitrification also plays an important role in the removal of nitrogen from municipal wastewater. The conventional removal is nitrification, followed by denitrification. The cost of this process resides mainly in aeration (bringing oxygen in the reactor) and the addition of an external carbon source (e.g. methanol) for the denitrification.

Together with ammonification, nitrification forms a mineralisation process which refers to the complete decomposition of organic material, with the release of available nitrogen compounds. This replenishes the nitrogen cycle.

Вправа 11.

Дайте відповідь на наступні питання, виходячи з інформації
в тексті з вправи 10:

1. Що таке нітрифікація?

2. Де нітрифікація грає важливу роль?

3. За що відповідає процес мінералізації?

Вправа 12.

Випишіть 10 ключових слів з тексту у вправі 10.

Вправа 13.

Знайдіть в тексті вправи 10 слова з суфіксами ~ (At) ion, ~ sion, ~ ise і переведіть їх.

Вправа 14.

Письмово переведіть текст. (Контрольний час - 15 хвилин)




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