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Chapter 17

Sources of Pollution

Class 9 - Total Geography Morning Star


Short Answer Questions

Question 1

Name any three air pollutants and the sources of each of them.

Answer

Three air pollutants are-

  1. Carbon Monoxide — It is produced by gasoline fuel, motor vehicles fuel, burning of wood and coal, solid waste disposal and industrial processes.

  2. Nitrogen Oxides — Its primary sources are motor vehicles and power generation stations, combustion of organic matters, furnace stacks and incinerators.

  3. Hydrocarbons — These are produced by motor vehicles, industrial processes, garbage and agricultural waste.

Question 2

What are natural sources of air pollution? Name one industry which pollutes the atmosphere with gaseous as well as with particulate matter.

Answer

Natural sources of air pollution produce air pollutants as a result of natural phenomena. These include volcanic eruptions, deflation of sand and dust as well as forest, or wild fires of natural vegetation, etc.

Automobile industry pollutes the atmosphere with gaseous as well as with particulate matter.

Question 3

What is known as smog? What harm is done by smog especially in winter?

Answer

Smog is a combination of smoke and fog.

During the winter months, due to severe cold, the use of coal and fossil fuels to heat homes and for other purposes increases. These lead to the formation of smog. Smog is harmful for health as it causes asthma, bronchitis, shortness of breath, eye and nose irritation, etc. It also reduces visibility and leads to problems in traffic movement.

Question 4

Name three gases emitted during burning of garbage.

Answer

Three gases emitted during burning of garbage are-

  1. Carbon dioxide
  2. Sulphur dioxide
  3. Nitrogen oxides

Question 5

Mention any two sources of water pollution.

Answer

Two sources of water pollution are-

  1. Domestic sources, like phosphates from detergents and fertilisers.
  2. Industrial sources, like heavy metals and synthetic organic compounds.

Question 6

Name two heavy metals from industries that pollute water.

Answer

Two heavy metals from industries that pollute water are-

  1. Lead
  2. Manganese

Question 7

Mention any two sources of soil pollution.

Answer

Two sources of soil pollution are-

  1. Chemical fertilisers
  2. Biomedical waste

Question 8

Why are radioactive pollutants very dangerous?

Answer

Radioactive pollutants are very dangerous because of the following reasons-

  1. Radioactive wastes from atomic reactors are hazardous to living organisms.
  2. Even if radioactive wastes are buried underground, they may escape into the surroundings.
  3. Inert gases escape as vapours and pollute the environment.
  4. The radioactive wastes emitted during the testing of nuclear weapons makes the surrounding materials radioactive.
  5. Radioactive materials are carried away to distant places by winds. They are brought down by rain. Raindrops containing these radioactive particles fall on earth,and affect the soil causing soil pollution.
  6. The radioactive materials in the soil reach water sources, where the aquatic organisms absorb and accumulate them through the food chains and pass them on to human beings.

Structured Questions

Question 1(a)

With reference to noise pollution, answer the following:

When does sound become a source of noise pollution?

Answer

Noise pollution refers to an unwanted sound which produces unpleasant effects and discomfort. Sound becomes unwanted when it interferes with normal activities such as sleeping, conversation or disrupts one's quality of life.

Question 1(b)

With reference to noise pollution, answer the following:

How does traffic contribute to noise pollution?

Answer

The rapidly increasing number of vehicles on the roads are a big source of noise pollution. Increasing traffic jams in congested areas lead to repeated hooting of horns by impatient drivers causing noise pollution.

Question 1(c)

With reference to noise pollution, answer the following:

Why are the construction sites considered as worse than factories in their contribution to noise pollution?

Answer

The construction sites are considered as worse than factories in their contribution to noise pollution because whatever construction takes place noise emissions levels are higher as well as the equipment is inherently noisy.

In the era of fast urbanisation the demolition and the repair activities along with the huge machines used for the purposes create a great deal of noise to the annoyance of the people living near the sites of construction.

Question 1(d)

With reference to noise pollution, answer the following:

How do the airplanes cause noise pollution? Why is there more noise pollution during landing as compared to during take-off?

Answer

The airplanes cause noise pollution as the noise made by the jet planes is more disturbing than that of the old propeller driven aircraft because it is of far higher pitch. Jet noise is caused by the violent mixing of the jet of gases from the engine with the surrounding air. It is at maximum level during take-off when the engine delivers maximum thrust, and reduces rapidly as the aircraft climbs.

During landing, the main source of high-frequency noise is the sound made by the air compressor and turbine blades. Air crafts pass close to the ground for quite a distance during landing operation and this noise often constitutes a more sustained environmental nuisance than the intense noise of shorter duration produced during take-off. Hence, there is more noise pollution during landing as compared to during take-off.

Question 2(a)

Air pollution is the contamination of air by pollutants. In this context answer the following:

Based on their origin, how can air pollutants be classified?

Answer

Air pollutants can be classified as-

  1. Primary Pollutants
  2. Secondary Pollutants

Question 2(b)

Air pollution is the contamination of air by pollutants. In this context answer the following:

How does the use of automobiles cause air pollution?

Answer

Vehicles are mainly responsible for more than 80% of total air pollution. The major pollutants released from automobiles, locomotives, aircraft etc., include carbon monoxide, unburnt hydrocarbons and nitrogen monoxide. In the major metropolitan cities like Delhi, Mumbai and Kolkata, vehicular exhaust accounts for 75% of all CO, 45% of all hydrocarbons, 40% of all oxides and 30% of all suspended particulate matter.

Air pollution is also caused by the gaseous and volatile hydrocarbons such as methane, acetylene and ethylene. Some hydrocarbons like ethylene, which undergo chemical reactions in the presence of sunlight and nitrogen oxide form photochemical oxidants that are harmful. Fuel combustion in automobiles also produces nitrogen dioxide.

Question 2(c)

Air pollution is the contamination of air by pollutants. In this context answer the following:

How do industries pollute the air?

Answer

Industries such as chemical industries, paper and pulp mills, cotton mills and petroleum refineries produce most air pollution. The cement factories emit dust, which is potential health hazard. The smoke coming out from the factories has small particles of dust, carbon, metals, other solids, liquids and radioactive materials which get mixed in smoke and pollute the air.

The burning of sulphur in coal or heavy oil in thermal power plants releases sulphur dioxide in the air. Sulphur dioxide combines with oxygen and water to form sulphuric acid in the atmosphere which is a health hazard. Besides, it produces acid rain.

Question 2(d)

Air pollution is the contamination of air by pollutants. In this context answer the following:

Mention any three air pollutants and two sources of each.

Answer

Three air pollutants are-

  1. Carbon monoxide — It is produced by gasoline fuel and motor vehicles fuel.
  2. Nitrogen oxides — Its primary sources are motor vehicles and power generation stations.
  3. Hydrocarbons — These are produced by motor vehicles and industrial processes.

Question 3(a)

With reference to the sources of water pollutants answer the following:

What are the domestic sources of water pollution?

Answer

Man uses water for drinking, preparation of food, bathing, for cleaning the house, etc. Most of the used water is drained out through municipal drains and poured into a river or lake. Domestic waste water that is mixed with other wastes such as plastic, detergents, animal dung and human faecal material is known as municipal waste.

Many detergents and fertilisers contain phosphates. When phosphates are discharged into waterways, their remnants promote rapid growth of algae. Such enrichment process is known as eutrophication. Aquatic weeds multiply rapidly in many water bodies. They interfere with fishing, navigation and irrigation.

Question 3(b)

With reference to the sources of water pollutants answer the following:

Why is it harmful to dispose of household detergents in water bodies?

Answer

Many detergents contain phosphates. When phosphates are discharged into waterways, their remnants promote rapid growth of algae. Such enrichment process is known as eutrophication. Aquatic weeds multiply rapidly in many water bodies. They interfere with fishing, navigation and irrigation.

Question 3(c)

With reference to the sources of water pollutants answer the following:

In what way does the industrial waste pollute water?

Answer

Industries dealing with chemicals, pulp and paper, food processing, etc. produce waste material such as heavy metals or synthetic organic compounds. These reach water bodies either through direct discharge or by leaching from waste dumps. Among the heavy metals, cadmium, lead, mercury, copper, chromium etc., get into water.

The industrial waste mixed with water makes it poisonous and unhygienic. It may also cause various diseases in humans and animals, if consumed without treatment.

Question 3(d)

With reference to the sources of water pollutants answer the following:

What are the sources of radioactive pollution? Describe each of them.

Answer

The two main sources of radioactive pollution are-

  1. Natural sources — These sources are cosmic rays with energetic radiations reaching the earth from outer space. Though they are a major hazard in space, they are not dangerous for organisms on earth.
  2. Man made sources — The following sources cause radioactive pollution-
    1. X-rays waste — The use of X-rays is common for detecting skeletal disorders. Cancer patients undergo radium and other isotope radiations. The X-rays pass through genetic cells and affect the chromosomes, resulting in mutations.
    2. Radioactive fallout from nuclear plants — In a nuclear power establishment, both fuel elements and coolants are sources of radiation pollution. Radioactive wastes from atomic reactors are hazardous to living organisms. Even if radioactive wastes are buried underground they may escape into the surroundings. Inert gases escape as vapours and pollute the environment.
    3. Nuclear weapons — Testing of nuclear weapons involves using radioactive substances like Uranium 235 and Plutonium 239 for fission. The radioactive waste emitted during these tests makes the surrounding materials radioactive.
      Radioactive particles are carried away to distant places by wind. They are brought down by rain. Raindrops containing these radioactive particles fall on earth and affect the soil causing pollution. From the soil, the radioactive materials reach water sources, where the aquatic organisms absorb and accumulate them through the food chains and pass them on to human beings.
    4. Radioactive isotopes — Radioactive isotopes are used in research laboratories. When the waste water from these laboratories reaches the rivers, streams, lakes etc., through the sewers they cause water pollution.
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