free booknotes online
PinkMonkey Online Study Guide-World History

20.1 Types of Pollution

A pollutant is any solid, liquid or gaseous substance present in such a concentration, so as to be injurious to the environment. Some of the common pollutants in developed as well as developing countries are : gaseous pollutants such as oxides of nitrogen, fluoride compounds, metals like mercury and lead, complex organic pollutants like benzene, petrochemical oxidants like ethylene, deposited matter like smoke and soot, solid waste, poisons like herbicides and fungicides, fertilizers, radioactive waste, noise and heat.

From the point of view of the ecosystem, pollutants may be classified as nondegradable pollutants like aluminum cans and DDT which do not degrade or degrade only very slowly in the environment, and biodegradable pollutants like domestic sewage which gets decomposed rapidly. Pollution may also occur naturally in the environment.

Adverse effects are noticed on plants since agriculture and horticulture are both affected by pollution. Air pollutants produce eye and respiratory irritation in animals and also in humans. Water pollutants can endanger aquatic life thus millions of fish are reported killed by municipal and industrial wastes. Sewage, toxic chemicals, and diseases causing germs can also make water unfit for farm animals. Thermal pollution, namely excessive heating of water in rivers or lakes can kill fish. Many diseases are water borne. Water pollutants like suspended particles can also adversely affect industrial equipment.

Air pollution is regarded as the most dangerous and common kind of environment pollution in recent times. The Bhopal Gas Tragedy in 1984 is regarded as the worst industrial accident, related to air pollution. Around two lakh Bhopal residents were affected by the leak of poisonous MIC gas from the Union Carbide Pesticide plant in Bhopal (India).

20.1a Air Pollution

(i) The Green House Effect

Large amounts of carbon dioxide are introduced in the atmosphere from fossil fuel burning, furnaces, and respiration of animals. Some of it is absorbed by water or is utilized by plant life. Much of the carbon dioxide is confined to the troposphere. The heated earth tries to reradiate the energy it has absorbed from the heat of the sun. However much of this cannot pass through the carbon dioxide layer into outer space. Thus the earth’s atmosphere heats up. This is known as the Green House Effect.

Exhibit 20.1
The Green House Effect

Some of the major causes of the Green House effect are the cutting down of forests. As more and more trees are being cut down there are fewer trees left to absorb the harmful Carbon Dioxide from the atmosphere. Secondly, the smoke given out by the factories is also an important cause and finally the fumes from cars and trucks, also contributes to the Green House effect. An increased heating of the earth would cause a rise in ocean levels, owing to the melting of ice caps and the receding of glaciers. Low-lying coastal cities like Bangkok and Venice are in a danger of getting flooded. Some of the small islands in the Caribbean might even vanish. On the other hand, deserts might spread further than they are now.

(ii) Ozone

Ozone protects us from harmful solar radiation. Any large-scale depletion of ozone content can exert catastrophic influence on biotic systems. However, during the past few years, it is evident that the ozone concentration of the earth’s atmosphere is decreasing largely due to the increasing use of CFMs or chloro fluoromethanes, that are used as propellants in pressurized aerosol cans, for example. Many ecologists also feel that the jet engines of supersonic aircrafts flying at high altitudes release nitrogen oxide, which endangers the protective ozone layer of the stratosphere. If efforts are not made to slow ozone depleting air pollutants, temperatures around the world may rise, endangering the human species besides other animals.

Exhibit 20.2

The ill-effects of Air Pollution are beginning to show

20.1b Water Pollution

The major sources of water pollution may be classified as domestic, industrial, agricultural and shipping wastewaters.

Domestic wastewater may arise from homes and commercial establishments. Many rivers and fresh-water streams are seriously polluted by industrial wastes or affluent. The chemicals of industrial wastes are highly toxic to animals. A steep rise in fish mortality was reported in the river Sone, in Bihar (India) owing to the chlorine content chemical wastes discharged by factories near the site. In Japan, in the 1950’s illness and even death occurred among the fishermen who consumed fish, contaminated with methyl mercury from Japanese coastal industries.

One of the major sources of water pollution is Acid Rain. This is a term used to describe rain or snow that has been polluted by Nitric and Sulphuric acid. Acid rain is formed when there is a combination or a reaction of the water vapor in the air with the gas emitted by vehicles, factories and other sources. These acidic gases and particles can even reach the Earth when there is no rain. Scientists use the term Acid Deposition to refer to wet and dry Acid Pollution that reaches the Earth. Scientists believe that Acid Rain is responsible for the destruction of trees, crops, soil and even buildings and statues. The phenomenon of Acid rain is common in Eastern North America and Central Europe.

One way of reducing the Acid pollutants is by removing Sulphur and Nitrogen compounds from the air. Devices have been developed to remove these compounds from the emissions of factories. In some of the areas, lime is added to the lakes and rivers, in order to neutralize the acidity. This is a temporary solution and can have harmful side effects.

Rainwater, running through farms, carries pesticides and chemical fertilizers and dumps them into the rivers and lakes. Farm animal wastes also enter waterways and pollute the water.

Shipping water pollutants include both human sewage and other wastes, such as oil. Oil pollution is of concern owing to the sensational major spills from ships and offshore drilling rigs, and also from small spills and cleaning operations.

Several waterborne infectious diseases are directly related to polluted water. The aquatic water chain concentrates several toxic substances in fish eaten by seals, certain birds or by people. Beaches are also closed when solid waste is washed up, or because of oil spills.

Oil pollution from accidents involving large tankers and offshore drilling rigs has attracted international attention. For example the Torrey Canyon carrying over 100,000 metric tons of Kuwaiti oil for the Union Oil Company ran aground off Cornwall, England on March 18, 1967. It released most of its cargo in the water, causing large-scale destruction of sea birds, not to mention detrimental effects on other ocean life, such as plankton. Several dozen large tanker accidents are reported every year. Efforts are made to contain the oil spills such as surrounding the oil slick with a mechanical barrier, or collecting it with suction pumps. However, these methods are slow and expensive.

Marine pollution occurs as sewage, garbage, pesticides, and discharge of oil and petroleum products. Solid wastes like mercury, which may be dumped into the rivers, ultimately goes into the sea. The large amount of plastic bags dumped into the oceans has threatened marine life. Ingested by sea birds, it causes gastro-intestinal diseases and ulcers since plastic contains PCB, a chemical known to cause eggshell thinning and tissue damage.

20.1c Radiation Pollution

The environmental problems of the Nuclear Age are concerned with radioactive fallout, both local as well as global and the consequent threat of environmental pollution.

Radioactive fallout means the deposition of air-borne radioactive contamination on the earth. Radioactive substances can enter the body through inhalation, through contaminated food and drinks, and through wounds and abrasions on the skin. When people are exposed to radiation there is bodily damage to them as well as impairment of the health of even their descendants. Apart from fallout, radiation sickness may be caused by x-ray machines.

Exhibit 20.3
Pollution results from radiation as well; hence warning labels are attached.

During World War II, the U.S. dropped the first atomic bombs on the Japanese cities of Hiroshima and Nagasaki injuring and killing thousands of people. When a radioactive substance gets deposited in the body, it causes delayed effects, which may include skin cancer, leukemia and stunted growth.

Exhibit 20.4
The Chernobyl Disaster had gruesome aftereffects

The Chernobyl Explosion in 1986 in Soviet Russia destroyed every living thing in the vicinity. Therefore it demonstrated the hazards inherent even in the peaceful uses of nuclear energy.

[next page]


20.0 - Introduction
20.1 - Types of Pollution
20.2 - Methods to check Pollution


All Contents Copyright ©
All rights reserved. Further Distribution Is Strictly Prohibited.

About Us
 | Advertising | Contact Us | Privacy Policy | Home Page
This page was last updated: 5/9/2017 9:56:17 AM