Any undesirable change in the earth’s environment (physical, chemical or biological) that is harmful to humans and other biological species, is called pollution. The accumulation and improper disposal of waste is one of the most important causes of pollution (air, water and soil).
1. Air Pollution:
The major sources of air pollution are the industrial wastes which include smoke and gases from chimneys and furnaces of industries and thermal power plants, exhausts from automobiles, gases produced on burning of wastes and dead bodies, gases and suspended particulate matter (SPM) from industries and agricultural practices and toxic waste.
Air pollution makes people sick (it causes breathing problems and promotes cancer), and it harms plants, animals and the ecosystem in which they live. Some air pollutants return to earth in the form of acid rain and snow. They can corrode statues and buildings, damage crops and forests, and make lakes and streams unsuitable for fish and other plants and animal life.
The acid from the air can combine with other chemicals to form urban smog, which affects the lungs and can cause premature deaths.
Excessive production of chlorine-containing compounds such as chlorofluorocarbons (CFCs) has depleted the stratospheric ozone layer, creating a hole above Antarctica.
The exposure to sun’s harmful rays can damage aquatic and terrestrial life and threaten human health in high latitude regions in both hemispheres.
2. Water Pollution:
Water is essential riot only for human beings but also for all living organisms on the earth. When water gets polluted in the waterbodies like rivers, lakes, ponds, seas and oceans, it adversely affects the living organisms. One of the important causes of water pollution is the waste from chemical and industrial processes. These wastes have toxic substances.
Animal remains from slaughter houses, fish and meat canning factories, leather tanning factories, pesticides and a variety of organic wastes pollute the water. Water is also polluted by animal manures and chemical fertilizers which are used to enhance plant growth. Garbage from our houses also pollutes water.
Nuclear power plants also generate radioactive waste, which also pollute water. Water is used in large quantities for househoid, agricultural and industrial purposes. Consumption of polluted water is the cause of various diseases of humans and animals throughout the world. The polluted water can kill large number of fishes, birds and other animals.
Water is drawn from rivers, lakes or the oceans for use as a coolant in factories and power plants. The water is generally returned warmer than when it was taken. The result may be migration or death of aquatic life. The drinking water supply especially from wells is contaminated with pesticides from widespread agricultural use.
3. Soil Pollution:
In the last 50 years, the quality of soil and its capacity to produce crops has degraded due to various pollutants present in it. The main sources of soil pollutants are waste from industries and agricultural practices. Municipal wastes are another important source of soil pollution. Other pollutants include acid rain, dumping of human excreta, animal dung and waste generated in slaughter houses.
About 25 per cent of the agrochemicals such as fertilizers, pesticides, insecticides, etc. are not used by crops and are retained either in the soil or are leached down and accumulates into the groundwater. The clearing of land for the purpose of farming, construction of buildings for housing and commercial use, destroys the soil. Wastes from industries are also responsible for soil pollution. Mining activities also pollute the soil.
The soil pollution reduces the fertility of soil, thus reducing the growth of plants and trees. Many diseases, such as cholera, and dysentery are caused due to soil pollution. Radioactive materials are discarded from the nuclear power plants. These waste materials get accumulated on land, and decrease the fertility of soil. Municipal solid wastes are often dumped as solid rubbish in heaps at nearby places.