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Summary
The chapter on “Pollutants and Pollution” provides a comprehensive overview of environmental pollution and its various forms. Pollution is defined as the undesirable changes in the physical, chemical, and biological characteristics of the environment that negatively affect living beings. The sources of pollution are both natural and man-made, often resulting from urbanization, industrial activities, and the overuse of natural resources.
Pollutants are substances or forms of energy that cause environmental degradation. They are categorized into different types based on their nature of release, biodegradability, and state (solid, liquid, or gaseous). For example, primary pollutants are directly released into the environment, such as smoke or chemicals from industrial waste, while secondary pollutants form through chemical reactions, like photochemical smog.
The chapter covers the different types of pollution, including air, water, soil, noise, and radiation pollution. Air pollution, for instance, is highlighted as a major concern in industrial cities. It is caused by both natural events, such as volcanic eruptions, and human activities like the burning of fossil fuels. The consequences include health hazards, global warming, and ozone layer depletion.
Water pollution is another critical issue discussed, arising from the discharge of harmful substances into water bodies. This pollution makes water unsafe for drinking and harmful to aquatic life. The chapter also addresses soil pollution, which occurs due to the deposition of harmful chemicals from industrial and agricultural activities. Soil pollution affects crop production and can lead to the contamination of food supplies.
Video tutorial
Textbook solutions
Multiple-Choice Questions
1. Identify biodegradable pollutants from the following.
(a) Lead
(b) Plastic
(c) Paper
(d) Pesticide
Answer: (c) Paper
2. An odourless, colourless gas produced by incomplete oxidation is
(a) Ozone
(b) Carbon dioxide
(c) Sulphur dioxide
(d) Carbon monoxide
Answer: (d) Carbon monoxide
3. The Central Pollution Control Board maintains
(a) pollution per square kilometer population.
(b) records of atmospheric pollution levels.
(c) only air pollution levels.
(d) the health of the residents of an area.
Answer: (b) records of atmospheric pollution levels.
4. Which of the following causes plasmolysis and collapse of epidermal cells of leaves and results in glazing of leaves?
(a) Ammonia
(b) Hydrogen chloride
(c) Sulphur dioxide
(d) Methane
Answer: (b) Hydrogen chloride
5. A pollutant released from the furnaces of power plants that causes soil pollution in surrounding area is
(a) Methane
(b) Fly ash
(c) Carbon monoxide
(d) Sodium chloride
Answer: (b) Fly ash
Short Answer Questions
1. Define pollution.
Answer: Pollution may be defined as the release of substances and energy (in excess of permissible limit) as waste products of human activities which result in changes, naturally harmful, within the natural environment.
2. What do you understand by a pollutant?
Answer: A pollutant can be defined as any form of energy or matter that causes degradation and pollution in the existing natural balance of ecosystems.
3. Give two examples each of solid, liquid and gaseous pollutants.
Answer:
- Solid pollutants: lead, mercury.
- Liquid pollutants: oil slicks, dissolved solids.
- Gaseous pollutants: chlorofluorocarbons, carbon dioxide.
4. What are the five types of pollution?
Answer: The five types of pollution are air pollution, water pollution, soil pollution, noise pollution, and radiation pollution.
5. What are the sources of air pollution?
Answer: The sources of air pollution are:
- Natural means: pollen grains, hydrocarbons released by vegetation, dust from deserts, storms, volcanic ash, and gases.
- Human activities: industrial activities, petroleum refineries, cement factories, thermal power stations, vehicles, pulp and paper industry, food processing units, and agricultural chemicals.
6. Give the full form of CPCB.
Answer: Central Pollution Control Board.
7. Name five important particulates that cause air pollution.
Answer: Five important particulates that cause air pollution are fluoride, cadmium, lead, mercury, and zinc.
8. What are the permissible limit of air pollution increases of RSPM and SPM?
Answer: The permissible limit for respirable suspended particulate matter (RSPM) is 60, and for suspended particulate matter (SPM) is 150.
9. Differentiate between Biodegradable and non-biodegradable pollutants.
Answer:
- Biodegradable pollutants: The pollutants which are capable of being broken down into simpler substances by the activity of microbes.
- Non-biodegradable pollutants: The pollutants which are not capable of being broken down into simpler substances by the action of microbes.
10. What are CFC’s? Give one example.
Answer: Chlorofluorocarbons (CFCs) are compounds that contain chlorine, fluorine, and carbon, and are responsible for ozone depletion. An example of a CFC is trichlorofluoromethane (trade name freon).
Long Answer Questions
1. What is the effect of various air pollutants at the global level?
Answer: At the gross level, air pollution causes two worldwide problems, namely contamination of the upper atmosphere and change of weather and climate.
Many modern environmental biologists feel that increasing particulate pollution may be reducing the amount of sunlight energy reaching the Earth’s surface, thereby, lowering solar radiation at the Earth’s surface, and producing a cooling effect on the world climate which could bring another ice age. Two of the most important consequences of air pollution at the global level are the greenhouse effect and ozone layer depletion.
The Central Pollution Control Board (CPCB) of the Government of India maintains the records of atmospheric pollution levels in many cities around the country. These data show that in many cities, air pollution reaches extremely dangerous levels on several days of the year.
The World Health Organisation has classified Delhi as one of the ten most polluted cities in the world.
2. What are the sources of water pollution?
Answer: Water pollutants are broadly divided into:
- Domestic wastes: These include waste materials from households, such as sewage and animal wastes. These wastes often contain disease-causing agents like bacteria, viruses, and parasitic worms, which can lead to water-borne diseases such as cholera, typhoid, and jaundice. Contamination of freshwater and shallow offshore seas by domestic sewage is common and poses serious health risks.
- Industrial wastes: Industries use water for various purposes like processing, cooling, and treatment of materials during production. The problem arises when the wastewater or effluents from industries are inadequately treated before being discharged into water bodies. These wastes often contain harmful chemicals, heavy metals, and other pollutants that make the water unfit for consumption and harmful to aquatic life. Major water-polluting industries include those involved in leather, pulp and paper, textiles, and chemicals.
- Agricultural wastes: The use of artificial and chemical fertilizers, pesticides, insecticides, and fungicides in agriculture leads to the contamination of soil and water. Runoff from agricultural fields carrying these chemicals is a significant source of water pollution. These chemicals can cause problems like eutrophication (excessive nutrient buildup in water bodies, leading to oxygen depletion) and bioaccumulation (the accumulation of toxic substances in the tissues of living organisms).
- Sediments: Sediments consist of soil, sand, and mineral particles that are washed into water bodies by storms and floods. These sediments can increase water turbidity, reduce sunlight penetration, and interfere with the aquatic ecosystem. They can erode pumping equipment and power turbines and reduce the amount of food available for fish. Poor soil conservation practices, deforestation, and floods contribute to the increased production of sediments in water bodies.
- Radioactive substances: Radioactive wastes come from uranium and thorium mining, refining, nuclear power plants, and industrial uses of radioactive materials. These substances can contaminate water supplies, making them hazardous to human health. Radioactive materials may enter the food chain through water and accumulate in the tissues of living organisms, leading to severe health issues. Radioactive waste dumping in oceans is particularly dangerous as it can lead to the contamination of marine life and coastal waters.
3. What is the main cause of industrial pollution?
Answer: The problem of industrial water pollution arises when inadequate measures are taken for effluent or wastewater treatment. Major water polluting industries in India include leather, pulp and paper, textiles, chemicals, etc. Methods of disposal of their wastes are primarily responsible for the risk to the environment and human health. Industries usually dump their wastes, either after treatment or without treatment, into both fresh and marine water bodies. The introduction of a wide variety of pollutants, both biodegradable and non-biodegradable, like oil, plastics, metallic, suspended solids, phenols, and various chemicals, derivatives of manufacturing processes, cannot be removed easily with available technology and this makes the freshwater unfit for consumption.
4. Write a short note on water pollution by sediments.
Answer: Sediments include soil, sand, and mineral particles which are washed into the aquatic environment by storms and flood waters. They also include large deposits of sewage, sludge, pulverized coal ash, and various industrial solids that go into the water body. The sediments erode the pumping equipment and power turbines and have the effect of increasing turbidity and consequently of reducing the amount of sunlight available to green plants which may lead to eventual asphyxiation of the fish. On the riverbeds, the sediments may interfere with the spawning sites and decrease the amount of food available for the fish.
As a result of intensive agriculture, poor soil conservation practices, deforestation, and floods, there has been an increased production of sediments and silts in streams and lakes.
5. Do you agree that nuclear waste dumping is the major cause of marine pollution?
Answer: Yes, nuclear waste dumping is a major cause of marine pollution. Radioactive substances are generated from wastes of uranium and thorium mining and refining from nuclear power plants and from industrial use of radioactive materials. The refining of uranium ore is an important source of radioactive waste producing radio nuclides of radium, bismuth, etc. Radium is the most significant waste product and is considered to be a hazard in drinking water. Water supplies must not contain radium more than the prescribed limit. Radioactive substances may cause objectionable radioactivity in marine organisms. Radioactive substances enter the human system with food and water. They accumulate in the blood, thyroid gland, liver, bone, and other muscular tissues.
At present, some low and medium-level wastes are sealed in containers and dumped into the oceans. If there is any damage to the container and it starts leaking, the nuclear waste could escape and enter the marine system. Consequently, they may be circulated by storms and ocean currents and eventually reach coastal waters with horrifying results to humans and other living organisms.
6. What are the major sources of soil pollution?
Answer: The major sources (or causes) of soil pollution can be categorised as:
- Domestic/commercial wastes: These include groceries, food scraps, food residues, vegetable remains, packing materials, cans, cardboard cartons, rags, paper, cinders, ash, broken gadgets, wood, worn-out furniture, metals, bones of dead animals, plastics, polythene bags, ceramics, glass, aluminium, rubber, leather, construction rubbish, bricks, sand, and other junks. Such wastes lying in the form of municipal wastes serve as dwelling places for disease-causing organisms. Another soil pollutant from domestic and commercial units, which carries with it the highest risk of spreading health hazards and epidemics, is human excreta.
- Modern agriculture: Modern agriculture is responsible for polluting the soil through the non-judicious use of chemical fertilisers, pesticides, insecticides, herbicides, fungicides, etc. Most of these chemicals are stable and remain in the soil for long periods without degradation. Therefore, they exhibit cumulative adverse effects. At present, around 600 different chemical compounds are being used for pest control which affect the land and subsequently, the human beings and other biota.
- Smelting and mining complexes: Smelting and mining complexes are another significant source of soil pollution. The areas around these complexes are usually found to be contaminated with heavy metals like cadmium, zinc, lead, copper, arsenic, and nickel. These metals occur in wastes resulting from smelting and mining operations. They are toxic to plants and may inhibit their growth. Their accumulation in plants makes the plants unsafe for human and animal consumption.
- Industrial wastes: The major sources of soil pollution are the industries such as paper and pulp mills, sugar mills, oil refineries, power and heating plants, chemicals and fertiliser manufacturing units, iron and steel plants, plastic and rubber-producing units, etc. These industries produce large amounts of solid wastes which are dumped on land, burnt, or emptied into rivers and seas. These solid wastes contain chemicals which affect the soil quality and life in it. Most industrial furnaces, especially power plants, produce fly ash which is the major cause of soil pollution in surrounding areas.
7. How is modern agriculture a source of soil pollution?
Answer: Modern agriculture is responsible for polluting the soil through the non-judicious use of chemical fertilisers, pesticides, insecticides, herbicides, fungicides, etc. Most of these chemicals are stable and remain in the soil for long periods without degradation. Therefore, they exhibit cumulative adverse effects. At present, around 600 different chemical compounds are being used for pest control which affect the land and subsequently, the human beings and other biota. To minimise the ill effects of pesticides, a number of countries have banned or restricted the use of many highly toxic agrochemicals. The WHO has called for an immediate ban on the use of endosulfan, a hazardous pesticide used for the rice crop. This pesticide has been found to be a cause of serious eye, kidney and liver disorders. The Government of India has already banned the use of 12 pesticides and imposed restrictions on many others to prevent environmental degradation.
8. Describe land degradation in the state of Nagaland.
Answer: Land degradation in Nagaland is a man-made as well as a natural phenomenon. Loss of vegetation due to deforestation, unsustainable fuel wood extraction, shifting cultivation (jhum), unplanned agricultural practices, encroachment into forest land for agriculture and settlements, forest fire, overgrazing, non-adoption of adequate soil conservation measures and improper crop rotation are some basic factors contributing to land degradation. The type of soil that are existing is erosion prone and the rainfall pattern is with high intensity. Thus, landslides are common. Another effect is sinking of land due to unstable geology. This has not only caused morphological changes in land, but also affected the socio-economic conditions of the people.
9. How do radioactive substances enter in the human system?
Answer: Radioactive substances enter the human system with food and water. They accumulate in the blood, thyroid gland, liver, bone and other muscular tissues. At present, some low and medium level wastes are sealed in containers and dumped into the oceans. If there is any damage to the container and it starts leaking, the nuclear waste could escape and enter the marine system. Consequently, they may be circulated by storms and ocean currents and eventually reach coastal waters with horrifying results to humans and other living organisms.
Think and Answer
Suppose you and your neighbours are being disturbed by the increasing number of generators in your locality. Apart from creating sound pollution, how does it affect your environment?
Answer: Apart from creating sound pollution, the increasing number of generators in a locality can have several negative effects on the environment:
- Air Pollution: Generators often run on diesel or petrol, emitting harmful gases like carbon monoxide, nitrogen oxides, and particulate matter into the atmosphere. This contributes to air pollution, which can have serious health effects, such as respiratory problems, and contributes to global issues like smog and climate change.
- Soil Contamination: Spills or leaks from fuel used in generators can lead to soil contamination. The chemicals in the fuel can seep into the ground, harming plant life and potentially entering the groundwater, affecting water quality.
- Water Pollution: If not managed properly, the oil and other chemicals from generators can be washed into nearby water bodies during rain, leading to water pollution. This can harm aquatic life and make the water unsafe for drinking and irrigation.
- Heat Emissions: Generators produce heat as they operate, which can contribute to localized warming, particularly in densely populated areas. This added heat can exacerbate the urban heat island effect, making the area warmer than surrounding rural areas.
- Carbon Footprint: The use of generators increases the carbon footprint of the area, as burning fossil fuels releases carbon dioxide, a major greenhouse gas that contributes to global warming and climate change.
Extras MCQs
1. What is the Latin word from which “pollution” is derived?
A. Polluere
B. Pollutio
C. Pollea
D. Pullo
Answer: A. Polluere
25. Which harmful effects are caused by pesticides and fertilizers?
A. Disruption of aquatic ecosystems
B. Reduction of air quality
C. Increase in noise pollution
D. Decrease in solar radiation
Answer: A. Disruption of aquatic ecosystems
Extra Questions and Answers
1. What is environmental pollution?
Answer: Environmental pollution is the lowering of environmental quality at local, regional, and global levels by natural and man-made processes.
94. Discuss the impact of domestic and commercial wastes on soil pollution and public health.
Answer: Domestic and commercial wastes significantly contribute to soil pollution by introducing a wide variety of pollutants, including biodegradable and non-biodegradable materials. These wastes, when not properly managed, serve as breeding grounds for disease-causing organisms, leading to the spread of health hazards and epidemics. The increasing quantity and changing composition of these wastes, with a rise in non-biodegradable materials like plastics and metals, exacerbate the problem. The contamination of soil with these materials not only affects the environment but also poses risks to public health through the contamination of air, water, and food supplies.
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