RADIOACTIVE WASTES

It is physical pollution of air, water and soil with radioactive materials.

Radioactivity is the property of certain elements (radium, thorium, uranium etc.) to spontaneously emit protons (alpha particles), electrons (beta particles) and gamma rays (electromagnetic waves of very short wavelength) by disintegration of their atomic nuclei.

The elements that give radiation are called radioactive elements.

The use of nuclear energy has two very serious inherent problems.

The first is accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second is safe disposal of radioactive wastes.

It causes mutations to occur at a very high rate.

At high doses, nuclear radiation is lethal and at lower doses, it creates various disorders, the most frequent of all being cancer.

It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks, about 500 m deep below the earth's surface.

Production of nuclear weapons involves the tests of nuclear arms.

These tests produce large amount radioactive elements into the environment and make other materials also radioactive. They include strontium-90, cesium-137, iodine-131 and some others.

The radioactive materials are transformed into gases and fine particles which are carried to distant places by wind.

When rain drops, the radioactive particles fall on the ground, it is called fall out.

Strontium-90 accumulates in the bones, replaces calcium and may cause bone cancer and tissue degeneration in most animals and man.

The operation of a nuclear power plant releases large amounts of energy.

This energy is used in large turbines, which produce electricity.

Wastes from atomic reactors also contain radioactive materials.

The biggest problem is the disposal of these radioactive wastes.

If these wastes are not properly disposed off, can harm the living organisms wherever they may be dumped.

NOISE POLLUTION

The quality of our environment is judged, apart from other factors, by the amount of noise present.

Noise has been defined as "unwanted sounds" which is being "dumped" into the atmosphere to disturb the unwilling ears.

It adversely affects our physiological and mental health.

Noise is measured by a sound meter and is expressed in a unit called decibel (dB).

Any value more than 80 dB causes noise pollution.

Noise becomes unbearable at 140 dB.

The quietest sound that man's ear can detect is known as threshold of hearing.

A noise that hurts one's ears and gives headache is called threshold of pain.

The role of sound vibrations is measured in cycles per second (cps) or hertz (Hz).

The ear is potentially liable to damage, if it receives high intensity noise.

Noise in general is a physical form of pollution.

It has no persistent adverse effects on the life supporting systems but, has direct effects on the recipients.

Moderate conversation = 60 dB

Loud conversation = 70 dB

Scooter = 80 dB

Truck / Bus = 90 dB

Jet aeroplane = 150 dB

Rocket = 180 dB

Zone-wise permissible ambient noise levels (acoustic zoning) are given below. (According to central pollution control board)

I. Sources of Noise Pollution

Noise can either be natural like thundering sound or man made. The main sources of man made noise pollution are:

(i) Annoying and damaging sounds of various industries.

(ii) Defence material like rockets, tanks etc.

(iii) Entertainment sources like record players, radios, cassette players, loud speakers etc.

(iv) Transport automobiles and other vehicles such as trucks, buses etc.

II. Effects of Noise Pollution

Noise causes some serious damaging effects which are briefed as follows :

(i) Diminish hearing. Noise damages the ears, causes temporary or permanent noise induced hearing loss, depending upon the intensity and duration of the noise level. It leads to auditory fatigue and may finally lead to deafness. A sudden loud noise of any explosion may damage the tympanic membrane permanently. Sudden noise is more harmful than the continuous one. Factory workers suffer chronic hearing loss after many years of occupational noise exposure.

(ii) It has adverse effects on thinking and coordination of limbs.

(iii) Noise affects verbal communication on which we depend in all kinds of environment.

(iv) Noise increases blood cholesterol level, causes high B.P., digestive spasm, decreased heart output, defective night and colour vision. It impairs the development of nervous system of unborn babies which leads to abnormal behaviour in later life.

Control of Noise Pollution

Noise pollution can be controlled by following measures :

(i) Green muflur scheme. Trees such as Neem and Ashoka absorb sound vibrations to a great extent. Plantation of these trees on both sides of the roads, around silent zones reduces the menace of noise pollution.

(ii) Sound absorbing material should be used for reducing industrial noise.

(iii) Noise producing agencies should be located far away from residential areas. Vehicular traffic should be directed away from the human dwellings, educational institutions and hospitals etc.

(iv) General awareness should be developed among the people to minimize noise pollution in the environment.