Pollution explained: Types, Causes and effects

 What is Pollution?

    Pollution is the introduction of harmful substances or products into the environment, negatively affecting our air, soil and land. But not all pollutants are toxic in every context.

In other words:

    An adverse change in the natural environment caused by any toxic substance is called pollution.

Pollutant:

     A substance that causes pollution, even a beneficial substance one when present beyond a specific concentration, is called pollutant. These can include chemical, heat or other agents. For example carbon dioxide is a gas important for life cycle but by increasing its original value it causes pollution. These are harmful for environment. A substance which makes anything impure is called contaminants.

Sources of pollutants:

     Major air pollutant is caused by human beings. Pollutant contain metal ions, nitrogen and oxides. Even a low concentration of these substances has harmful effects. These pollutants come from volcanic eruptions, burning of fossil fuels, emission from transportation sources, agricultures chemicals.

Types of pollution:

    There are several types of pollution including:

• Air pollution 
• Water pollution
• Land pollution

1. Air Pollution:

     Air pollution occurs when harmful substances contaminate the air and these substances are known as air pollutant.  

Causes:

    Major air pollutant include oxides of nitrogen (NOx), sulfur, hydrocarbons and volatile organic compounds.

Sources:

• Volcanic eruption and decomposition of organic matter
•  Naturally or by humans burning of woods  
• Burning of fossil fuels for energy
• Automobiles emit (CO₂ and CO)
  

Impacts on human health:

    It has a negative impact on human health. It causes many dangerous disease such as asthma, emphysema, tracheal and lung cancer, stroke and other common illnesses. 

Impacts on ecosystem:   

    Air pollution has adverse effect both ecosystem and human health. Air pollution cause:

• Acid rain
• Ozone depletion
• Global warming

 Acid rain:

    Burning of fossil fuels produces nitrogen and sulfur. These dissolved in rain water and nitrogen oxides (NOx)  sulfur dioxide (SO₂) react with water vapor to form sulfuric acid (H₂SO₄), nitric acid (HN​O3) and nitrous acid (HNO2)​. The pH of rain is typically between 5.6 to 6, but it can drop to 4 due to these chemicals. This acidic rain is called acid rain.

 SO3​+H2​O→H2​SO4

SO2​+H2​O→H2​SO3

Causes:​

    Major cause of acid rain is oxides of nitrogen and sulfur. Burning of fossil fuels, combustion in automobiles and waste product of industries produce sulfur and nitrogen which is diffuse in air.

Effects of acid rain:

• It increases the acidity of soil, causing plant to get dry out and die.
• Damage leaves and trees and limit their growth.
• Acid rain attack on marble and causes dullness of buildings.

Ozone depletion:

    The region of earth in the lower portion of stratosphere where high concentration of ozone

molecule (O₃) is found is called ozone layer. The reduction of ozone layer due to air pollutant is called ozone depletion.

Causes:

      Ozone depletion is due to major compounds called chlorofluorocarbons (CFCs). These compounds are used in air conditioner, refrigerator and in printing machine. These compounds leak and diffuse in stratosphere.

 Effects:

     Due to ozone depletion, harmful radiations from the sun may have negative effects. Such as:

• The ultraviolet radiation can cause skin cancer in human beings and other animals.
•  It can change the life cycle of plant.
•  It increases the temperature, leading to increase in chemical reactions occur in atmosphere.
•  It also can change wind patterns causes climatic changes in the world.

Global Warming:

     Certain human activities increase the greenhouse effect, which is gradually raising

 temperatures, a phenomenon known as global warming.

Causes:

    The major cause of global warming are burning of fossil fuels, which produces greenhouse gases  and Oxides of nitrogen (NOx) that trap heat from the sun.

Effects:

   Global warming has bad impact on ecosystem. some are: 

• Melting of ice capes and glaciers lead to rising sea levels, increase bringing risks 
• Change the path of air and ocean currents 
• Loss of biodiversity
• Crop failures and food insecurity

2. Water Pollution:

    The contamination of water sources (lakes, rivers and sea) by pollutants is called water pollution.

Causes of water pollution:

    There are number of sources of water pollution. Major causes of water pollution are described below:

•  When acid rain fall on water bodies it carrying heavy metals (Al, Hg, Cr) which dissolved in water.
• Sometimes oil tanks are leaked and oil dissolved in water.
  
  
  
• The use of plastic bags made of polymers has a negative impact  if they are thrown into water.
• Industrial wastes contains heavy metal, chemicals and other toxic substances are diffuse in water bodies. 
• Uses of nonbiodegradable detergents had bad impact when they are discharge in rivers and lakes.
• Fertilizers and pesticides contain chemicals (which kills bacteria and algae) dissolve in ground water.

Effects of water pollution: 

    Water pollution has bad impact on marine ecosystem as well as human health. Some are:

• It damage aquatic life.
• Uses of polluted water causes dangerous disease  such as diarrhea, typhoid, cholera  and hepatitis A and E.
• When fishes respire in polluted water, metal ions can closed their gills and lead to death.
• Decomposition of organic matter in water produce methane which cause climate change.
• It causes rapid growth of algae. Algae trap sunlight to reach aquatic life.
• It break food chain lead to deficiency of food.

Land or soil pollution:

    Land or soil pollution refers to contaminants in the soil which damage both the Earth's surface and subsurface layers.

Causes of land pollution:

    Land pollution is caused by human beings. Some human activities are:

• 
  Construction of buildings use metal and chemicals sometimes dissolved in soil.
• Domestic waste contain non-biodegradable plastics that are not manage properly.
  
• Unlimited uses of fertilizers and pesticides damage earth due to containing ammonia.
• Industries and factories discharge their wastes on free land.

Effects of land pollution: 

    Land pollution has negative impact on ecosystem some are:

• It causes loss of biodiversity, due to contaminated soil plants reduces their growth and lead to their death.
• It converts fertile land into barren land, reduces crop yields.
• Some contaminated land produce poisonous food dangerous for human health.
• It contributes to climate change, particularly due to deforestation.