Pollution of Air and Water Class 8 Notes Science

What is Pollution? 

Types of PollutionThese substances or materials, known as pollutants, can come from natural sources, such as volcanic eruptions or forest fires, but are mostly caused by human activities, including industrial processes, transportation, and waste disposal.

• Pollutants: A substance that causes pollution is called a pollutant. Pollutants can be in liquid, solid or gaseous form.
• Types of pollution: Air pollution, water pollution, soil pollution, sound pollution, light pollution, etc.

Air Pollution 

Air pollution is the presence of harmful substances in the air that have a negative impact on both living and non-living things. 

Air Pollution

• During winter, a dense fog-like layer in the atmosphere called smog is formed by the combination of smoke and fog. 
• The smoke contains nitrogen oxides which mix with other pollutants in the air and with fog to create smog. 
• This can cause respiratory problems like asthma, coughing, and wheezing in children.

Air Pollutants and Causes of Air Pollution

Air PollutantsSome of the most common air pollutants include:

• Carbon monoxide (CO): A colorless, odorless gas produced by the incomplete combustion of fossil fuels.
• Sulfur dioxide (SO₂): A gas that is released during the combustion of sulfur-containing fuels, such as coal and oil.  Pollutants like sulphur dioxide and nitrogen dioxide are released in large quantities by petroleum refineries.
• Nitrogen oxides (NO_x): Gases that are produced during high-temperature combustion processes, such as those in motor vehicles and power plants.
• Particulate matter (PM): Tiny particles that can be inhaled and cause respiratory and cardiovascular problems.
• Ozone (O₃): A gas that is formed when nitrogen oxides and volatile organic compounds (VOCs) react in the presence of sunlight.
• Volatile organic compounds (VOCs): Gases that are released from products like paints, solvents, and cleaners.
• Chlorofluorocarbons (CFCs): CFCs or chlorofluorocarbons are synthetic products that contain carbon, chlorine and fluorine. They were formerly used as a refrigerant and as a propellant in aerosol or air sprays. CFCs contribute to the depletion of the ozone layer that protects us from the harmful ultraviolet rays of the sun.
• Smog: Smog is a mix, in the air, of smoke and chemicals with fog. The chemical components of smog can include ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. Smog can trigger breathing difficulties like asthma and coughing.

Smog

•  Soot: Soot is released when automobiles burn fossil fuels, like petrol and diesel. Pollutants like sulphur dioxide and nitrogen dioxide, which are produced by industries like rubber processing, automobile chemicals and the Mathura oil refinery near Agra, are responsible for the decolourisation of the Taj Mahal.

There are many causes of air pollution, including:

• Transportation: Vehicles, airplanes, and ships all emit pollutants into the air.
• Incomplete burning of fossil fuels, like petrol and diesel, results in the production of colourless, odourless and toxic carbon monoxide gas.
• Industrial processes: Factories and power plants release a wide range of pollutants into the atmosphere.
• Agriculture: Pesticides and fertilizers can release harmful gases into the air.
• Natural events: Volcanic eruptions, wildfires, and dust storms can all contribute to air pollution.
• Household activities: Burning wood, coal, and other fuels for heating and cooking can also release pollutants into the air.
• Climate change: Rising temperatures can lead to the formation of more ground-level ozone, which is a harmful air pollutant.

It's important to reduce the amount of air pollution we create by using cleaner forms of energy, reducing our reliance on fossil fuels, and using environmentally friendly products. By working together to reduce air pollution, we can create a healthier and more sustainable world.

Effects of Air Pollution on the Taj Mahal

Pollution on Taj Mahal

CO2(g) + 2H2O(l)→2H2CO3(aq)
2SO2(g) + O2(g) + 2H2O(l)→2H2SO4(aq)
4NO2(g) + O2(g) + 2H2O(l)→4HNO3(aq)            

The Taj Mahal is adversely affected by acid rain, which corrodes its marble surface. The air pollution is causing the white marble to gradually turn black, causing damage to this iconic monument.

Understanding Global Warming: Causes and Effects

Global warming is a significant environmental issue that has far-reaching effects on the planet's climate. It refers to the gradual increase in the average temperature of the earth's atmosphere and oceans, primarily due to the increase in greenhouse gases caused by human activities.

Global Warming and Environmental Changes

• Greenhouse Gases: Greenhouse gases are the primary culprits behind global warming. These gases trap heat in the earth's atmosphere, causing the planet to warm up. The most common greenhouse gases are water vapor, nitrous oxide, carbon dioxide, and methane.
• Greenhouse Effect: The greenhouse effect is a natural process that helps maintain the livable temperature on the earth's surface. Most of the solar radiation passes through the atmosphere and is absorbed by the earth's surface. The earth then radiates heat back towards space, but a portion of it is trapped by the greenhouse gases in the atmosphere, which helps regulate the temperature.
• Global Warming: Global warming occurs when excess greenhouse gases, primarily carbon dioxide, trap more heat in the atmosphere than is necessary, leading to a gradual increase in the earth's average temperature. The main human activities that contribute to global warming include deforestation, industries, oil refineries, power plants, and the excessive burning of fossil fuels like natural gas, oil, and coal.
• Effects of Global Warming: The effects of global warming are far-reaching and can have devastating consequences for the planet. Some of the significant effects include:

1. Warmer Climate: On average, the earth's temperature has become warmer than earlier, leading to severe heat waves and droughts.
2. Natural Calamities: Global warming has caused an increase in the occurrence and severity of natural calamities such as floods, cyclones, and earthquakes.
3. Rise of Sea Level: Due to global warming, the polar ice caps are melting, leading to a rise in sea levels, which can cause flooding in coastal areas.
4. Severe Weather Events: The shifting of the climatic pattern has been observed across the globe, leading to more severe weather events like hurricanes, tornadoes, and typhoons.

Effective Measures to Reduce Air Pollution

Air pollution is a serious environmental concern that requires immediate attention. The following measures can help in reducing air pollution and promoting a cleaner and healthier environment:

• Encourage the use of CNG: Compressed Natural Gas (CNG) is a cleaner and more eco-friendly fuel than petrol and diesel. Encouraging the use of CNG as an alternative fuel can significantly reduce air pollution levels.
• Use unleaded petrol: Unleaded petrol contains fewer harmful chemicals and emissions, making it a better alternative to traditional petrol. Promoting the use of unleaded petrol can help reduce air pollution levels and protect the environment.
• Proper waste management: Proper waste management is critical in reducing air pollution levels. Disposing of waste in landfills or burning it can lead to harmful emissions. Proper waste management practices, such as recycling and composting, can help reduce air pollution levels and maintain hygiene.
• Use of public transport or carpooling: Encouraging the use of public transport or carpooling can significantly reduce emissions and ease congestion on roads. Using public transport is also an economical option and helps reduce air pollution levels.

Water Pollution

Water pollution occurs when harmful waste and substances contaminate water bodies, making it unsuitable for human consumption and harmful to aquatic life. The causes of water pollution include urbanization, industrial activities, agriculture, and religious and social practices.

Water Pollution

• Water Pollutants
  Substances that pollute water are called water pollutants. Examples of water pollutants include detergents, chemicals dumped by hospitals, insecticides, and herbicides
• Effects of Water Pollution on the River Ganga
  Towns and cities throw large quantities of garbage, untreated sewage, dead bodies, and other harmful things into the river. Pollution in the Ganga is choking aquatic life and hindering the growth of plants. Ganga is one of the ten most endangered rivers in the world.
• Potable Water
  Water suitable for drinking is called potable water. Potable water is free from contaminants and harmful bacteria. Water that is not potable or fit for drinking is called raw water.
• Methods to Make Water Potable Boiling water kills all the microbes and protects us from waterborne diseases.
  Filtration is the process of separating suspended solid matter from a liquid and can remove impurities up to a certain extent.
  Chlorination is done by adding chlorine tablets or bleaching powder to the water, which kills certain bacteria and other microbes in tap water.
  Water treatment plants Laws should be strictly implemented so that polluted water isn’t disposed of directly into rivers and lakes. Water treatment plants should be installed in all industrial areas.
  Recycle Water: At an individual level, one should consciously save water and not waste it. Reduce, reusing and recycling should be used diligently as a method. Reusing water used for washing and for other household tasks, water used for washing vegetables can be used to water plants in the garden, while brushing your teeth or washing utensils the taps should be turned off.

Frequently Asked Questions (FAQs) Related to Pollution of Air and Water

Q1: What is air pollution?

Ans: Air pollution is the presence of harmful substances in the air that can have a negative impact on human health and the environment. Examples of air pollutants include carbon monoxide, sulfur dioxide, nitrogen oxides, and particulate matter.

Q2: What are the major sources of air pollution?

Ans: The major sources of air pollution include transportation (cars, trucks, planes), industrial activity (factories, power plants), agriculture (livestock farming, fertilizer use), and residential heating and cooking.

Q3: What are the effects of air pollution on human health?

Ans: Air pollution can cause a range of health problems, including respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD), heart disease, stroke, and lung cancer. It can also exacerbate existing health conditions and cause premature death.

Q4: What is water pollution?

Ans: Water pollution is the presence of harmful substances in water bodies, such as rivers, lakes, and oceans. Examples of water pollutants include chemicals from industrial and agricultural activities, sewage and wastewater, and plastic waste.

Q5: What are the sources of water pollution?

Ans: The sources of water pollution include industrial and agricultural activities, sewage and wastewater, oil spills, and plastic waste.