Many problems have been arisen on the earth due to human interference in the nature. Industrialization, increasing population, mining, transportation, indiscriminate use of pesticides and fertilizers are causing pollution on the earth. It is affecting human beings. Pollution : Contamination of natural environment that will be harmful to ecosystems is called as pollution.

Pollutants : Factors affecting natural functions of ecosystem and causing harmful effects on abiotic and biotic factors are called as pollutants. Pollutants make the environment poisonous and unhealthy. Pollutants may be natural or manmade. Natural pollutants are destroyed in due course of time by nature’s rule; however, manmade pollutants are not.

1. Air Pollution :
2. Plot a graph showing the proportion of various gases in earth’s atmosphere.
3. Why is it said that air is homogenous mixture of different gases?
4. Which different hazardous gases are released through fuel combustion? Contamination of air by harmful substances like poisonous gases, smoke, particulate matter, microbes, etc. is called as air pollution.

Reasons of air pollution

Effect of air pollution on plants and animals

Depletion in Ozone layer : Earlier, we have studied that ozone layer is present below the stratosphere, at the height of 48 kilometres from earth’s surface. It protects the living world of the earth from ultraviolet rays (UV-B) radiating from the Sun. However, nowadays, ozone layer is getting depleted due to following reasons.

Green house effect and Global warming : Though CO2 is present in very less quantity in atmosphere, it plays very important role of absorption of solar heat. Over the last 100 years, proportion of CO2 has been increased due to industrialization. Effect of this CO2 on the earth’s temperature is nothing but green house effect. Similar to CO2 , nitrous oxide, methane and CFC also trap the heat. Collectively, these are called as green house gases.

Global temperature is gradually increasing due to green house effect. Due to this, atmosphere is changing, causing disturbances in agricultural yield, distribution of wild animals. Icebergs and glaciers are melting causing increase in sea level.

Acid Rain : Oxides of sulphur and nitrogen are released into atmosphere through burning of coal, timber and fuel oils. Those oxides mix with rain water and form acids like sulphuric acid, nitric acid, nitrous acid, etc. These acids mix with rain drops and snowflakes and come down as rain, called as acid rain.

Effects of acid rain:

1. Acidity of soil and water bodies increases due to acid rain. It harms the aquatic organisms, plants and entire forest life. Total ecosystems are adversely affected.
2. Erosion of buildings, busts, historical monuments, bridges, metal idols, wire fences, etc. occurs due to acid rain.
3. Heavy metals like mercury and cadmium are absorbed up by plants and thereby enter the food chain indirectly due to acid rain.
4. Due to acidification of water in water bodies and pipes, leaching of metal and plastic material occurs in water and thereby serious health problems arise.

Preventive measures of air pollution

1. Smoke emerging from factories contains harmful particles. Hence, pollution controlling machinery should be used. Ex. Arresters, filters.
2. Proper disposal of stinking waste generated in cities.
3. Control on atomic tests, chemical weapons, etc.
4. Control / ban over CFC production.

   Water Pollution :

Water is said to be polluted when it becomes unclean and poisonous due to mixing of natural or artificial unwanted material, when it becomes harmful to living organisms due to decreased oxygen content, when epidemic diseases are spread through the water. Fresh water or marine water pollution includes physical, chemical and biological changes.

Water Pollutants

1. Biological pollutants : Water does not remain potable due to algae, bacteria, viruses, parasites, etc. Diseases are spread due to biological pollution.
2. Inorganic pollutants : Suspended particles like fine sand, dust, soil, precipitates of salt, compounds of arsenic, cadmium, lead, mercury, and traces of radioactive material.
3. Organic pollutants : Weedicides, insecticides, fertilizers, sewage, industrial effluents, etc.

   Soil Pollution :

Out of the total land area of the soil, some is covered by ice; some is desert, whereas some is occupied by mountains and hills. Very less area of land is available for human use. Soil is said to be polluted when there are changes in its physical biological and chemical properties and its fertility decreases due to either natural or manmade reasons.

1. Soil fertility decreases due to mixing of salty, acidic water from industry.
2. Radioactive and other pollutants enter and pass through food chain like the soil, crop, water and human body.
3. Problem of water pollution increases due to soil pollution. Toxic substances leach into water. Similarly, diseases spread through various pathogens.

Relationship of soil pollution with air and water pollution

If wet waste is dumped at wrong places instead of composting, pathogens grow upon it, which are then mixed with water causing water pollution. Insecticides, chemical fertilizers, weedicides are used in agriculture, which causes soil pollution. Excessively sprayed insecticides and weedicides are mixed with air causing air pollution. Similarly, excessive use of chemical fertilizers causes water pollution. Soil pollution occurs due to mixing of human wastes, birds and animals waste. This releases various stinking gases causing air pollution. Same waste may cause water pollution if mixed with water.

Pollution – Prevention and control : Government of India has enacted some laws for control, regulation and prevention of pollution. Following are laws regarding pollution control.

1. Water pollution and prevention act, 1974.
2. Air pollution and prevention act, 1981.
3. Environmental Protection Act, 1986.

Various laws and rules are in force in relation to biomedical waste, harmful effluents, solid waste and sound pollution. Government statutory bodies like Maharashtra Pollution Control Board and Central Pollution Control Board supervise about whether the industries, industrial areas, local governing bodies like municipalities, district councils, panchayat samiti, gram panchayat, etc. follow the laws about pollution control.