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Summary
Environment Class 12

Fly Ash: (1:54 PM)

  • What is Fly Ash? 
  • Fly ash is the byproduct of coal burning, mainly produced from thermal power plants.
  • The particles of Fly Ash are finer than cement. 
  • And vary between 10 to 100 microns. 
  • It is made up of various compounds including Silicon Dioxide (SiO2), Aluminium Oxide, Ferric Oxide, Calcium Oxide, and many minor metals. 

Effects of Fly Ash: 

  • Health Issues: 
  • Stroke, respiratory diseases, cancer, heart problems, eye irritation, etc. 
  • Impact on plants: 
  • Reduced photosynthetic activity. 
  • Absorption of metals and biomagnification. 
  • Impact on the topography, such as land degradation, and changes in Albedo.
  • Water Pollution: 
  • Through the leaching of heavy metals underground. 

Handling of Fly Ash: (2:01 PM)

  • It is collected by using electrostatic precipitators from flue gas.
  • Handling involves: 
  • 1) Wet disposal. With the help of Fly Ash ponds. 
  • 2) Dry disposal. Through burial, or covering with a soil layer. 

Utilization of Fly Ash: 

  • Utilized in Fly Ash bricks.
  • Cement manufacturing.
  • Road construction. 
  • Soil stabilization.
  • Landfilling.
  • Advantages of Fly Ash Bricks: 
  • 1) Cheaper than normal bricks. 
  • 2) Lighter in weight. 
  • 3) Higher strength. 
  • 4) Finer in texture.
  • 5) Good sound insulation. 
  • If it is poorly made, it will be of lower strength. 
  • It is not good for winters and very cold conditions. 

Secondary Pollutant: 

  • Acid Rain: 
  • It is a precipitation with a pH of less than 5.6%.
  • It is majorly due to the reaction of Sulphur and Nitrogen Oxides with water or water vapour. 
  • The oxides of sulphur and nitrogen are released by industrial emissions and volcanic eruptions.

Types of Acid Rain: (2:32 PM)

  • Wet precipitation: 
  • When it falls down in the form of rain.
  • It deposits on the surfaces, along with water. 
  • Dry depositions: 
  • In the form of dry powder, as they get attached to dust and smoke particles.
  • And falls down to the surface, to be washed down by further rainfall. 

Impacts: 

  • It results in a foul smell.
  • Reduces visibility.
  • Eye irritation, skin irritation, respiratory issues, and reduced plant productivity, negatively impact buildings and monuments and corrode them. 
  • Causes soil leaching. 
  • Reduces soil fertility. 

Smog: (2:35 PM)

  • Smog is a secondary pollutant formed in the atmosphere due to the reaction of various chemical compounds released through the burning of hydrocarbons, fossil fuels and other industrial emissions. 
  • The primary pollutants which are responsible for the formation of smog are: 
  • 1) NOx (vehicular emission)
  • 2) SOx (industrial emissions)
  • 3) Particulate Matter (stubble burning and construction industry)
  • 4) Volatile organic compounds (VOCs) (burning of biomass and solid waste). 

There are 2 types of Smog:  

Classical Smog

Photochemical Smog

This is formed due to the buildup of sulphur oxide.

It involves smoke and fog.

It occurs in cool humid climates (winter).

This type of smog was first observed in London in 1952.

It has high SOx.

It causes bronchitis and irritation. 

This is formed due to the photochemical reaction of sunlight on the nitrogen oxides and hydrocarbons produced by automobiles and factories. 

It does not involve any smoke or fog.

It occurs in warm dry and sunny climates.

This type of smog was first observed in Los Angeles. 

It has oxidizing agents. 

Causes eye irritation.

Components of Smog: (2:55 PM)

  • Ozone,
  • Paroxy Acetyle Nitrate.
  • Acrolein, 
  • Formaldehyde,

Impacts of Smog: (2:57 PM)

  • Health issues: 
  • Headache,
  • Nausea, 
  • Eye irritation, 
  • Cough, 
  • Chest pain,
  • Breathing problem,
  • Damage to plant life through reduced photosynthesis, reduced plant productivity, impact on structures and buildings, and corrosion of metals. 
  • Corrosion of building material.
  • Cracking of rubber and painted surface. 
  • Impact on visibility, 
  • Disruption of transportation, roadways, rail, and airways.
  • Increase in accidents, etc. 
  • Decreases temperature. 
  • Smog helps in maintaining low temperatures.

Common Sources of Air Pollution: 

  • 1) Vehicular Emission.
  • 2) Construction Dust. 
  • 3) Industrial Emissions. 
  • 4) Thermal Power Plant. 
  • 5) Burning of diesel generators. 
  • 6) Restaurants (tandoor, coal), etc. 

Air Pollution in Delhi: (3:13 PM)

  • Located far from the coastal region, the winds are not very strong.
  • Basin surrounded by mountains. It has a bowl-shaped depression located between the mountains, which can trap air for a longer duration. 
  • Time: October and November months. 
  • The calm winds created in the transition period between South West and North East Monsoon.
  • Radiation Inversion is formed due to the cooling of air near the surface. 
  • The temperature inversion prevents convection and dispersal of pollutants released near the surface. 
  • Due to the limited time between rice harvest and wheat sowing, and limitations on early rice transplantation in Punjab and Haryana.
  • Burning of crackers during festivals.

Land Degradation: (3:47 PM)

  • IPCC defines land as the terrestrial portion of the biosphere that comprises natural resources, ecological processes, topography, human settlements, and infrastructure that operates within that system.
  • A negative trend in land conditions is caused by direct or indirect human-induced processes expressed as a long-term reduction of biological productivity, ecological integrity or value to humans. 
  • Desertification is land degradation in Arid, Semi-Arid and dry subhumid areas resulting from climatic variations and human activities leading to long-term loss of productive ecosystems. 

Topic for the next class: Land Degradation, continued.