2017-11-01
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1. Having warmed in the air the water vapour condenses and falls to the Earth as rain, hail or snow, depending on region, climate, season and topography.
2. Seawater contains salts, including those that are useful to most land plants and animals.
3. Ocean water evaporates into atmosphere leaving salts behind, and moves across the Earth as water vapour.
4. Man's activity is accelerating the process of water pollution, the amount of fresh water available to use is increasing rapidly.
5. Irrigation can be applied to increase soil moisture, to protect plants from frosts and dry winds, to apply fertilizers.
C Translate from English into Russian in written form.
1. Deforestation upstream may cause floods or shortage downstream, while a country's hydroelectric, irrigation and public water projects may cut off its neighbour's supply
2. The ocean, which is a home to so much life, has been used as a place to dump garbage and poisonous chemicals for a long time.
3. "Acid rain" - often caused by power station emissions thousands of kilometres away - sets off a chain reaction, which kills life in vulnerable lakes and rivers.
4. Of over 200 river systems shared by two or more countries, several have already caused international conflict - and as the world grows thirstier these tensions increase.
5. Only a tiny fraction of the water, which covers the Earth, is of use to humanity: 97% is salt water, filling the oceans and seas.
D. Read the text again and answer the following questions.
1. Where does most of our fresh water come?
2. What is the never-ending cycle the article tells about?
3. Is it true that having cooled in the air the water vapour condenses and falls to the Earth as fog?
4. Can water evaporate from land sources?
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5. What is accelerating the process of water pollution?
Вариант
ECOSYSTEMS
1. Read the text and translate the extract in italic in written form.
An ecosystem consists of a number of living organisms and their physical environment. The living organisms and their non-living environment are interrelated and interact with each other.
There are 6 major components in an ecosystem:
1. inorganic substances
2. organic compounds
3. climate, temperature, wind, light and rain which affect all the processes in an ecosystem
4. producers; green plants which are able to manufacture food from simple inorganic substance in the process known photosynthesis
5. consumers; primary consumers: they obtain their energy from green plants. But secondary consumers such as dogs and cats feed on other animals.
6. decomposers, such as bacteria and fungi. Bacteria break down the flesh of dead animals. Fungi break down plant material. They enable chemical substances to return to the physical environment.
The main processes in ecosystems include:
1. food chains 2. materials cycles 3. development 4. evolution
Food chains. The Sun's energy travels through an ecosystem.
The proper transfer of energy through an ecosystem by the producers, the consumers and the decomposers is called a food chain.
Materials cycles. Materials cycles include cycles of nitrogen, carbon, oxygen, water and mineral salts. Chemical substances move from the non-living environment to living things. They are then returned to the environment.
Development. An ecosystem exists in a state of equilibrium. It can support a certain number of plants and animals of different species. If the population of one animal increased, there would not be enough food and water for all the animals. Consequently, some would die. In this way the ecosystem regulates itself and returns to its state of equilibrium. Ecosystems are not static - they change all the time. Plants and animals are able to adapt to changes in the physical environment. For example, if fire destroyed the vegetation in a region, there would be certain changes. First grass and some flowers would grow. Then insects would appear. The wind would blow the seeds of small trees. These trees would grow and birds and animals would appear.
Evolution. During long periods of time ecosystems evolve. The evolution of an ecosystem is caused by factors inside and outside it. Consider the evolution of the atmosphere: when life began there was no oxygen in the atmosphere. Consequently, the Sun's rays prevented life from developing on land. The first living organisms developed under the sea. After the evolution of photosynthesis, the oxygen in the atmosphere increased and life expanded. Complex living organisms developed. As the oxygen in the atmosphere increased, a layer of ozone was formed; life would be impossible without it on the surface of the Earth. Today life on the Earth is in danger: man himself might destroy the equilibrium of ecosystem by pollution, extinction of wildlife and unreasonable utilization of the globe's material resource.
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Ecosystems are controlled both by external and internal factors. External factors such as climate, the parent material which forms the soil and topography, control the overall structure an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. Other external factors include time and potential biota. Ecosystems are dynamic entities—invariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. The introduction of non-native species can cause substantial shifts in ecosystem function. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops. While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other internal factors include disturbance, succession and the types of species present. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.
Grammar work
