Carbon and Oxygen Cycles

Lesson 1

MATTER AND ENERGY CYCLING IN ECOSYSTEMS

Блок 7

Forests

Forests have a lower albedo (<0.10 for conifers) than most other vegetated surfaces (0.20–0.25). Their vertical structure produces
a number of dis­tinct microclimatic layers, particularly in tropical rainforests. Wind speeds are characteristically low in forests and trees form important shelter belts. Unlike short vegetation, various types of tree exhibit a variety of rates of evapotranspiration and thereby differentially affect local tem­peratures and forest humidity. The effect of forests on precipitation has not yet been resolved but they may have a marginal topographic effect under convective conditions in temperate regions. The disposition of forest moisture is very much affected by canopy interception and evaporation, but forested catchments appear to have greater evapotranspiration losses than ones with a grass cover. Another major feature of forest micro­climates is their lower temperatures and smaller diurnal ranges' compared with surrounding areas.

Упражнение 1.

Прочитайте заголовок приводимого ниже текста. Подумайте, о чем в нем может идти речь. Приведите 10–15 слов, которые могут, с Вашей точки зрения, встретиться в тексте.

Прочитайте и переведите текст.

Carbon is the basic building block of the large organic molecules necessary for life, including simple carbonhydrates or sugars (such as glucose), complex carbonhydrates, fats, proteins, and nucleic acids such as DNA. DNA molecules in the cells of plants and animals carry genetic information and chemical instructions for manufacturing various proteins living organisms need.

Most land plants obtain their carbon by absorbing carbon dioxide gas, which makes up 0,03% of the atmosphere, through pores in leaves. They obtain the oxygen atoms they need from the oxygen in carbon dioxide and from water molecules in soil or bodies of water. The ocean’s microscopic floating plants, known collectively as phytoplankton, get their carbon from atmospheric carbon dioxide that dissolved in ocean water.

Chlorophyll molecules and some other pigments in the cells of green plants absorb solar energy and use it to combine carbon dioxide with water to form glucose along with oxygen gas. This complex process in which radiant energy from the sun is converted into chemical energy stored in plant tissue is called photosynthesis.

Plants and animals transform a portion of glucose and other, more complex, carbon-containing molecules they synthesise (plants) or eat (consumers) back into carbon dioxide and water by the process of cellular respiration. The chemical energy released in this complex process drives the physical and chemical changes needed for plants and animals to survive, grow and reproduce.

The carbon dioxide released by cellular respiration in all plants and animals is returned to the atmosphere and water for reuse by producers. Although the overall chemical reaction involved in cellular respiration is the reverse of that for photosynthesis, many of the detailed chemical reactions involved in the processes are different.

Photosynthesis and respiration are the basis of carbon and oxygen cycles. Through these two interconnected cycles, plants produce food and oxygen needed by animals and absorb carbon dioxide given off by animals.

Some of the earth’s carbon is tied up for long periods in fossil fuels – coal, petroleum, natural gas, peat, oil shale, tar sands, and lignite – formed over millions of years in lithosphere. The carbon in these mineral deposits remains locked deed in the earth’s crust until it is released to the atmosphere as carbon dioxide when fossil fuels are extracted and burned. Some of the earth’s carbon is also locked for millions of years in deposits of carbonate rocks below the seafloor until movements of the earth’s crust expose these rocks as part of an island or a continent. The carbon then reenters the cycle very slowly through erosion and other physical and chemical weathering processes that release it as carbon dioxide into the atmosphere.

Human beings intervene in the carbon and oxygen cycles in two ways that increase the average amount of carbon dioxide in the atmosphere. First, we remove forests and other vegetation without sufficient replanting, so that fewer plants are available worldwide to convert carbon dioxide in the atmosphere to organic nutrients. Second, we burn fossil fuels and wood.

Упражнение 2.

Прочитайте следующие слова и определите их соответствия
в русском языке:

Cycle, organic, molecule, nucleic, genetic, information, chemical, physical, organism, gas, atom, pore, ocean, atmospheric, microscopic, phytoplankton, pigment, form, glucose, energy, photosynthesis, transform, synthesise, complex, detailed, process, period, mineral, lithosphere, continent.

Упражнение 3.

Какие части речи обозначаются в словарях следующими сокращениями:

v., adv., n., adj., conj., num., part., prep., pron.?

Упражнение 4.

Определите, к каким частям речи относятся следующие слова; напишите соответствующие английские сокращения для каждого из них:

Animal, first, respiration, for, cellular, they, in, and, widely, is, extracted, million, remove.

Упражнение 5.

Найдите в тексте Carbon and Oxygen Cycles примеры этих частей речи.

v.	n.	adj.	adv.	num.	prep.	part.

Упражнение 6.

Заполните пропуски, используя суффиксы: ~able, ~al/~ial, ~ful, ~ic, ~ine, ~ish, ~ive, ~less.

Diamond is a form of pure … (crystal) carbon which has been formed under great heat and pressure and brought to the surface of the Earth by … (volcano) activity. It is the hardest … (nature) substance in the world with a very high … (refract) power giving specific … (optic) properties, above all, a particularly clear and brilliant reflection of light. The most … (value) diamonds are completely … (without colour) They are, however, extremely rare; the majority having a … (slightly yellow) or … (slightly green) colour caused by different mineral impurities and gases. Diamond feels cold to the touch as it dissipates heat very quickly, hence, checking thermal conductivity is a … (rely) method of detection. Cheaper synthetic diamonds are now being made for … (industry) applications. These are particularly … (use) for cutting tools.

Упражнение 7.

В правой колонке найдите русские эквиваленты следующих английских словосочетаний из текста Carbon and Oxygen Cycles:

1. carbon dioxide 2. living organism 3. plant tissues 4. radiant energy 5. cellular respiration 6. interconnected cycles 7. mineral deposits 8. fossil fuel 9. weathering process 10. average amount

a. ископаемое топливо b. процесс выветривания c. клеточное дыхание d. ткани растений e. углекислый газ f. среднее количество g. живой организм h. лучистая энергия i. взаимосвязанные циклы j. минеральные отложения

Упражнение 8.

Прочитайте текст и найдите в нем ответы на следующие вопросы:

1. От чего зависит важность того или иного элемента для живых организмов?

2. Что способствует круговороту элементов?

3. Что произошло бы без биогеохимических циклов?

(Контрольное время – 7 минут)

Дата добавления: 2014-12-27