2. Radioactive pollution
■ Radioactive pollution refers to the release of ionizing radiation into the environment.
While ionizing radiation is the form of radiation that has short wavelength and high
frequency and is the most dangerous kind.
■ Radioactive isotopes are unstable atomic nuclei. They decompose in the form of
alpha or beta particles or gamma rays.
■ Radium-226, Uranium-235 or 238, potassium-40 or carbon-14 are naturally
occurring radioactive isotopes.
■ Few radioactive isotopes are of environmental concern like cobalt-60, argon-41,
strontium-90 and iodine-131.
3. ■ Accumulation of different radioactive isotopes in Ecosystem
■ Strontium-90 normally occurs in radioactive fallout and has half life of 28 years.
■ Strontium-90 can concentrate in natural biological system as:
■ Water bottom sediments aquatic plants freshwater
clams minnows and small fish musk rats.
■ Grazing animals ingested it through grass and forage and passed on to human
through milk
■ These readily accumulate in plants and animals through food chain.
■ In food chain, radioactive isotopes of potassium, sodium and phosphorous
accumulate.
■ Isotopes of strontium and cobalt do not accumulate.
4. Causes of radioactive pollution
1. Nuclear Accidents From Nuclear Power Plants
■ An accident at nuclear power plant could release dangerous level of radiation
over an area (sometimes known as plume).
■ Radioactive materials in plume from nuclear power plant can settle and
contaminate people who are outdoors, buildings, food, water and livestock.
■ e.g. a nuclear power plant uses uranium fuel to produce steam for generating
electricity. This process changes uranium into other radioactive materials. If a
nuclear power plant accident occur, heat and pressure is generated and steam
with radioactive material may released.
5. 2. Usage of Radioisotope
For the development of detectors such as smoke detectors uses Americium-241
(produced by decay of plutonium in nuclear reactors).
In other manufacturing operations, radioisotopes are used. Like in industrial
radiography (Cobalt-60) & (Iradium-204).
In mineral analysis isotope of Iron (Fe-55 & Fe-59) and (Ca-45 & Ca-47) are used.
In scientific research for example in medical diagnostic procedures (mainly) gamma
rays are used.
3. Atomic Bomb
Nuclear weapons can produce enormous explosives energy for example the atomic
bomb dropped on Hiroshima, Japan containing 64 kg (140 ponds) of Uranium.
When blast it immediately produced strong shock wave, enormous amount of heat
and lethal ionizing radiations.
6. ■ 4. Mining
Mining involves excavation of mineral ores of radium, uranium, potassium, carbon and
phosphorus.
Mining increases natural, geological processes as weathering and deposition by moving
these materials from subsurface to surface of earth.
The radioactive mineral ores cause contamination in soil, react together with various
nutrients and causes them to be lost from the soil, making soil highly toxic and infertile.
5. Uses of Radioactive Isotopes in Experimental Studies
Radioactive isotopes are used in medical diagnostic procedures to study the dynamic
processes taking place in various parts of the body, e.g. cobalt-60 is used to treat
cancer.
Radioactive isotops are used as tags in experimental studies of plants to monitor to
monitor nutrient uptake. For this nitrogen-15 and phosphorus-32 to check and trace the
uptake and metabolic pathway of nutrient in plants.
7. Effects of radioactive elements on
Human
Radiation exposure from artificial source can cause serious diseases in man.
These include:
■ Leukemia
■ Bone tumors
■ Genetic damage
■ Infant mortality
The responses to radiation varies according to age, growth stage and high or low
dose of radiation.
8. Affects on Plant cell
Direct Effect
Indirect Effect
H2
H2O2
H2O
H2
OH
Free Radicals
Ionization of Cellular
membranes
9. Effects on plants
Experimental studies demonstrated that radiation is a
serious problem for seed and plants.
As high doses of radiation can inhibit seed germination,
slow seedling growth, and develop genetic mutations
that can change characteristics of the plant.
10. Affects on Seed Germination
No Seed
Germination
Χ
Trnscription
Inhibition
Inhibited
translation
Blocked
Protein
Synthesis
Restricted
Enzymes
and
hormones
Expression
Ionizing radiations damage the DNA and ultimately there is no
transcription and translation. Protein and enzyme production
also disturbed.
11. Effects on plant growth
■ If plant in its embryonic state is exposed to radiation, mutational changes like
increased disease susceptibility, reduced germination frequency, flowering, pod
maturity and decreased grain / straw yield can be very harmful.
■ Dwarfism, abnormal growth, underdeveloped root system or curly and misshaped
leaves are some of the changes showed by the growing plants after exposure to low
doses of radiations.
■ Foliage can get readily contaminated with radioactive substances and if ingested by
herbivores they are automatically exposed to radiation and suffer from its possible
effects.
■ In particular food chain, even small dose of radiation from contaminated producers
can reach up to tertiary consumers via primary and secondary consumers.
12. Preventive measures from
radiation
Following preventive measures should be adopted:
■ Nuclear devices should never be exploded in the air. If necessary, then they should be
exploded underground.
■ Containments may also be employed to decrease the radioactive emissions by using
tightly sealed boxes.
■ Production of radioisotopes should be minimized.
■ Carefully dispose industrial wastes contaminated with radionuclide.
■ Nuclear medicines and radiotherapy should be applied only when necessary and in
minimum doses.
13. ■ Radioactive operations may be carried out by keeping a sufficient
distance from the source.
■ For person working with radioactive material in the nuclear industry it is
difficult to reduce the radiation hazard. So by performing the operations
quickly, duration of exposure may be shortened.
■ Shielding can reduce the radiation dosage while working with
radionuclide.
■ Ingestion or inhalation of radioactive isotopes may be prevented by
proper working habits and clean hygienic conditions.
■ To lessen the risk of internal contamination and skin damage hoods,
boots, caps, gloves and overalls can be safely used.
