RADIOACTIVE POLLUTION
Radiations and Radioactivity decay
Radiation is energy travelling through space. Energy can be transported either in form of
electromagnetic waves (radiations) or a stream of energetic particles, which can be
electrically charged or neutral.
These radiations are of two types:
(1) Non-ionizing radiations
Non-ionizing radiations are the electromagnetic waves of longer wavelength from near
ultraviolet rays to radio waves. These waves have energies enough to excite the atoms and
molecules of the medium through which they are moving, causing them to vibrate faster.
These do not have enough energy to ionize them.
Ionizing radiations are the electromagnetic radiations having high energy, such as short
wavelength ultra violet radiations, x-rays and gamma rays. The energetic rays like (α, β and γ
etc.) produced in radioactive decay can cause ionization of atoms and molecules of the
medium through which they pass and convert them into charged ions.
For example in water molecule, it can induce reaction that can break bonds in proteins, DNA
and or other important molecules. Alpha (α), beta (β) and gamma (γ) radiations are produced
by the process called radioactive decay. The unstable nuclei decay spontaneously and emit
these radiations. These rays (radiations) can affect some other non-radioactive atoms to
become radioactive (unstable) and give out radioactive radiations.
2 Radioactive Pollution and their Sources
Living organisms are continuously exposed to a variety of radiations called background
radiations. If the level of the radioactive radiations increases above a certain limit it causes
harmful effects to living beings. This harmful level of radiations emitted by radioactive
elements is called radioactive pollution.
There are two sources of radiation pollution, namely natural sources and arthropogenic
sources.
1. Natural Sources of Radiation
i. Atomic radioactive minerals are one of natural sources of radioactive pollution.
During mining of uranium, radon gas is constantly released into the air. The parent of
radon222 (t½ = 3.82 days) is radium 226 which has a half-life of 1602 years. Radium-
226 is widely distributed in rocks, sediments and soils along with isotopes of uranium.
Radioactive radiations from these natural sources are known as natural or background
radiation.
1
, ii. Cosmic rays are high energy ionizing electromagnetic radiation. The cosmic rays
originate from the stars in our galaxy by virtue of nuclear reactions primarily in their
cores. The cosmic rays are constantly reaching the earth from outer space.
iii. Naturally occurring radioisotopes such as radon-222 found in soil in small quantity is
another source of radioactive radiations.
iv. Radioactive elements which like uranium, thorium, radium, isotopes of potassium (K-
40) and carbon (C-40) occur in the lithosphere.Potassium-40 contributes radioactivity
to all potassium containing systems in the soil. Crops grown on such soil contain
radioactive elements like carbon-14 and potassium-40. Water gets contaminated with
various radionuclides when it runs through soils and rocks containing radioactive
minerals.
These are only rarely harmful as the radiation level is generally quite low. This small level of
radioactive radiation which is present everywhere is called the background radiation.
2. Anthropogenic Sources of Radiation
The following human activities add to the source of radioactive pollution:
(i) Diagnostic medical applications: Radiations are employed for diagnostic and therapeutic
applications. X-rays are used in general radiology and CT scan. Gamma rays are used in
treatment of cancer. In all these procedures we are exposed to varying doses of radiations.
(ii) Nuclear Tests: Nuclear explosion tests especially when carried out in the atmosphere are
a major cause of radiation pollution. It is responsible for increasing the background level of
radiation throughout the world. During atmospheric nuclear explosion tests, a number of
long-lived radionuclides are released into the atmosphere. This radioactive dust (also known
as radioactive fallout) gets suspended in air at a height of 6 to 7 km above the earth’s surface
and is dispersed over long distances by winds from the test site. These radionuclides often
settle down by rain and get mixed with soil and water. From there they can easily enter the
food chain and finally get deposited in the human body where they cause serious health
hazards. Some of the radioactive isotopes given off during nuclear test affect the human
body.
(iii) Nuclear Reactors: Radiations may leak from nuclear reactors and other nuclear facilities
even when they are operating normally. It is often feared that even with the best design,
proper handling and techniques, some radioactivity is routinely released into the air and
water.
However, dangers of radiation leakage are from possibility of accidents that could result in
the release of radioactive material which raises the level of radioactive (ionizing) radiations.
Such accidents took place at the ‘Chernobyl nuclear power plant’ in USSR in 1986 and at the
‘Three Mile Island Power Plant’ in USA in 1979. The accidents of ‘Three Mile Island’ plant
in Middletown (U.S.A.) in 1979 and at Chernobyl nuclear power plant (U.S.S.R.) in 1986
were the worst disasters in the history of nuclear power industry. In both incidents, a series of
mishaps and errors resulted in the overheating of the nuclear core. In both cases radiation was
2
Radiations and Radioactivity decay
Radiation is energy travelling through space. Energy can be transported either in form of
electromagnetic waves (radiations) or a stream of energetic particles, which can be
electrically charged or neutral.
These radiations are of two types:
(1) Non-ionizing radiations
Non-ionizing radiations are the electromagnetic waves of longer wavelength from near
ultraviolet rays to radio waves. These waves have energies enough to excite the atoms and
molecules of the medium through which they are moving, causing them to vibrate faster.
These do not have enough energy to ionize them.
Ionizing radiations are the electromagnetic radiations having high energy, such as short
wavelength ultra violet radiations, x-rays and gamma rays. The energetic rays like (α, β and γ
etc.) produced in radioactive decay can cause ionization of atoms and molecules of the
medium through which they pass and convert them into charged ions.
For example in water molecule, it can induce reaction that can break bonds in proteins, DNA
and or other important molecules. Alpha (α), beta (β) and gamma (γ) radiations are produced
by the process called radioactive decay. The unstable nuclei decay spontaneously and emit
these radiations. These rays (radiations) can affect some other non-radioactive atoms to
become radioactive (unstable) and give out radioactive radiations.
2 Radioactive Pollution and their Sources
Living organisms are continuously exposed to a variety of radiations called background
radiations. If the level of the radioactive radiations increases above a certain limit it causes
harmful effects to living beings. This harmful level of radiations emitted by radioactive
elements is called radioactive pollution.
There are two sources of radiation pollution, namely natural sources and arthropogenic
sources.
1. Natural Sources of Radiation
i. Atomic radioactive minerals are one of natural sources of radioactive pollution.
During mining of uranium, radon gas is constantly released into the air. The parent of
radon222 (t½ = 3.82 days) is radium 226 which has a half-life of 1602 years. Radium-
226 is widely distributed in rocks, sediments and soils along with isotopes of uranium.
Radioactive radiations from these natural sources are known as natural or background
radiation.
1
, ii. Cosmic rays are high energy ionizing electromagnetic radiation. The cosmic rays
originate from the stars in our galaxy by virtue of nuclear reactions primarily in their
cores. The cosmic rays are constantly reaching the earth from outer space.
iii. Naturally occurring radioisotopes such as radon-222 found in soil in small quantity is
another source of radioactive radiations.
iv. Radioactive elements which like uranium, thorium, radium, isotopes of potassium (K-
40) and carbon (C-40) occur in the lithosphere.Potassium-40 contributes radioactivity
to all potassium containing systems in the soil. Crops grown on such soil contain
radioactive elements like carbon-14 and potassium-40. Water gets contaminated with
various radionuclides when it runs through soils and rocks containing radioactive
minerals.
These are only rarely harmful as the radiation level is generally quite low. This small level of
radioactive radiation which is present everywhere is called the background radiation.
2. Anthropogenic Sources of Radiation
The following human activities add to the source of radioactive pollution:
(i) Diagnostic medical applications: Radiations are employed for diagnostic and therapeutic
applications. X-rays are used in general radiology and CT scan. Gamma rays are used in
treatment of cancer. In all these procedures we are exposed to varying doses of radiations.
(ii) Nuclear Tests: Nuclear explosion tests especially when carried out in the atmosphere are
a major cause of radiation pollution. It is responsible for increasing the background level of
radiation throughout the world. During atmospheric nuclear explosion tests, a number of
long-lived radionuclides are released into the atmosphere. This radioactive dust (also known
as radioactive fallout) gets suspended in air at a height of 6 to 7 km above the earth’s surface
and is dispersed over long distances by winds from the test site. These radionuclides often
settle down by rain and get mixed with soil and water. From there they can easily enter the
food chain and finally get deposited in the human body where they cause serious health
hazards. Some of the radioactive isotopes given off during nuclear test affect the human
body.
(iii) Nuclear Reactors: Radiations may leak from nuclear reactors and other nuclear facilities
even when they are operating normally. It is often feared that even with the best design,
proper handling and techniques, some radioactivity is routinely released into the air and
water.
However, dangers of radiation leakage are from possibility of accidents that could result in
the release of radioactive material which raises the level of radioactive (ionizing) radiations.
Such accidents took place at the ‘Chernobyl nuclear power plant’ in USSR in 1986 and at the
‘Three Mile Island Power Plant’ in USA in 1979. The accidents of ‘Three Mile Island’ plant
in Middletown (U.S.A.) in 1979 and at Chernobyl nuclear power plant (U.S.S.R.) in 1986
were the worst disasters in the history of nuclear power industry. In both incidents, a series of
mishaps and errors resulted in the overheating of the nuclear core. In both cases radiation was
2
