Environment Pollution- Introduction, Types and Sources



  • Pollution is the introduction of contaminants into the natural environment that cause adverse change
    • Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light).
    • Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants
  • Environmental pollution is one of the most serious problems facing humanity and other life forms on our planet today
    • Environmental pollution is defined as “the contamination of the physical and biological components of the earth/atmosphere system to such an extent that normal environmental processes are adversely affected”



  • The major forms of pollution are listed below along with the particular contaminants relevant to each of them:
Types Detail/Pollutants involved
Air pollution ·         Air pollution is a mixture of solid particles and gases in the air.

·         Car emissions, chemicals from factories, dust, and pollen and mold spores may be suspended as particles

·         Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry and motor vehicles

Water pollution ·         Water pollution occurs when toxic substances enter water bodies such as lakes, rivers, oceans and so on, getting dissolved in them, lying suspended in the water or depositing on the bed

·         Common pollutants include discharges of untreated sewage, and chemical contaminants, release of waste and contaminants into surface runoff flowing to surface waters, groundwater pollution from waste disposal and leaching into the ground

Soil pollution ·         It is the presence of toxic chemicals (pollutants or contaminants) in soil, in high enough concentrations to pose a risk to human health and/or the ecosystem

·         The  contaminants include metals, inorganic ions and salts (e.g. phosphates, carbonates, sulfates, nitrates), and many organic compounds (such as lipids, proteins, DNA, fatty acids, hydrocarbons, PAHs, alcohols, etc.).

Thermal pollution ·         Thermal pollution, sometimes called “thermal enrichment,” is the degradation of water quality by any process that changes ambient water temperature.

·         A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers

·         Deforestation eliminates shade, which exposes the water to


·         Water on hot paved surfaces gets hot, then runs off into nearby bodies of water, raising the water temperature. Retention ponds can also be a source of thermal shock because the relatively small and shallow bodies of water can absorb quite a bit of heat energy from the sun

 Noise pollution ·         Noise pollution happens when the sound coming from planes, industry or other sources reaches harmful levels

·         WHO Noise Environmental Burden on Disease working group found that noise pollution may contribute to hundreds of thousands of deaths per year by increasing the rates of coronary heart disease

·         Underwater noise pollution coming from ships has been shown to upset whales’ navigation systems and kill other species that depend on the natural underwater world

Light pollution ·         Light pollution is the excess amount of light in the night sky.

·         Light pollution, also called photo-pollution, is almost always found in urban areas.

·         Light pollution can disrupt ecosystems by confusing the distinction between night and day.

Land Pollution ·         This involves the decline in the quality of the earth’s land surfaces in terms of use, landscape, and ability to support life forms

·         Land pollution takes place when waste and garbage is not disposed of in the right manner thus, introducing toxins and chemicals on the land

·         Also, Mineral exploitation equally leads to a decline in the quality of the earth’s land surfaces.


Sources of Pollution

  • Nature of pollution sources
    • Point source pollution enters a water body at a specific site and is generally readily identified.
      • Potential point sources of pollution include effluent discharges from sewage treatment works and industrial sites, power stations, landfill sites, fish farms, and oil spillage via a pipeline from industrial sites.
    • Diffuse pollution arises where substances are widely used and dispersed over an area as a result of land-use activities such as urban development, amenity, farming and forestry.
      • These activities may be recent or have been carried out in the past.
      • It is often difficult to identify specific sources of such pollution and therefore take immediate action to prevent it, since prevention often requires major changes to land use and management practices.
      • Examples of diffuse pollution include the leaching to surface water and groundwater of contaminants from roads, manures, nutrients and pesticides used in agriculture and forestry, and atmospheric deposition of contaminants arising from industry
  • Substances that may cause pollution
    • Nutrients
      • The main potentially-polluting nutrients in relation to water are nitrogen, ammonia (a gas containing nitrogen and hydrogen), phosphorus and sulphur.
      • They arise from the natural breakdown of crop residues and soil organic matter, rainfall, fertilisers, urine and manure, silage, landfill sites, wastewater and industrial effluents, power generation and other fuel-burning activities.
      • For example, nutrients are the principal cause of eutrophication which is the enrichment of lakes, rivers and the marine environment leading to increased plant growth and the occurrence of algae.
    • Pesticides
      • These include herbicides, insecticides and fungicides that are used in gardens, in agriculture, in roadside and trackside (railway) maintenance, and in parkland and golf courses.
    • Heavy metals
      • These are widely-used ingredients for chemical compounds used in industry
      • Industrial contaminated land can be a source of heavy metals leaching into the environment
      • They also exist naturally in soils at low concentrations. They can be found in fuel, chemicals, waste materials and batteries.
      • In high concentrations they are toxic to humans, animals, fish and plants.
    • Suspended solids
      • Suspended solids are mineral and organic particles that remain suspended in water. They sink only very slowly or are easily resuspended by water turbulence.
      • Suspended solids might be eroded soil or decayed leaves. Wastewater from sewage works and industry might also carry suspended solids into water bodies
    • Pathogens
      • These are present in faeces from human and animal sources, including wildlife.
      • They can enter water through poor wastewater management or poor handling of manures, slurry and other farm wastes.
      • They may also be carried directly off fields by heavy rainfall or enter water bodies where stock and wildlife have direct access for drinking purposes
    • Hydrocarbons
      • These include vegetable and mineral oils (including petrol, diesel, white spirit, heating and lubricating oil), and chlorinated solvents such as dry cleaning fluids
    • Persistent organic pollutants (POPs)
      • These are chemicals that are capable of long-range transport, accumulate in human and animal tissue, and have a significant impact on human health and the environment, even at low concentrations.
      • They include substances such as dioxin and polychlorinated biphenyls (PCBs).


Examples of common sources of pollution

Examples of

sources of pollution

Point source or diffuse Potential pollutant
Effluent discharges from sewage treatment works Point source Nitrogen (N) and Phosphorus (P), persistent organic pollutants, pathogens, litter, oxygen-depleting substances, suspended solids and settleable solids
Industrial effluent discharges Point source N, oxygen-depleting substances and a broad spectrum of chemicals, suspended solids, etc.
Industrial processes Point source Broad spectrum of chemicals released to air and water
Oil storage facilities Point source Hydrocarbons
Urban stormwater discharges Point source – arising from storm water runoff (from paved areas and roofs in towns and cities) entering the sewer network N, P, oxygen-depleting substances, heavy metals, hydrocarbons, pathogens, persistent organic pollutants, suspended solids, settle able solids, litter
Landfill sites Point source


N, ammonia, oxygen-depleting substances, broad spectrum of chemicals
Pesticide use Diffuse Broad spectrum of chemicals
Mining Point/Diffuse Heavy metals, acid mine drainage, suspended and settle able solids