Page 26 - e-Modul

Radioactive pollution

The Earth's environment is naturally radioactive intensely ionising in the matter they pass
due to cosmic radiation emitted from space, and through and can cause more damage to living
terrestrial radiation emitted from the Earth's tissue than particles with a longer path. Like
crust. However, this background level of alpha particles, beta particles lose their energy
radiation is exceeded in many parts of the world within a short distance and their biological
by contamination from human-made sources of significance is greatest if a beta emitter is taken
radioactivity. into the body. Gamma radiation particles are
‘Radiation’ here means ionising radiation (as similar to X-rays - they are deeply penetrating
opposed to other non-ionising radiation, e.g. UV, and strongly ionising; gamma rays can only be
infra-red, microwave). Radiation is emitted from stopped by thick layers of concrete, lead or steel.
radioactive substances as they spontaneously The decay of radioactive wastes takes a very long
decay and takes several forms. The types of time. Some radioactive substances have a half-
most concern are: life of more than 10000 years, which means they
alpha particles are dangerous for a very long time. (The half-life
beta particles is the 'period of time required for the

gamma rays disintegration of half of the atoms in a sample of
Each type of radiation has different properties a radioactive substance'.)
and different penetrating power; e.g. alpha There are two major ways in which the
particles can be stopped by a few centimetres of atmosphere can become polluted by radiation:
air or a sheet of paper, however they are

Nuclear power plants
Nuclear power plant accidents can endanger life and the
surrounding environment if the radioactive core is exposed and

meltdown occurs and releases large amounts of radioactivity.
This happened at Chernobyl, a nuclear power station in the
Ukraine: an accident here destroyed the Chernobyl-4 reactor
and killed 30 people, including 28 from radiation exposure.
Large areas of Belarus, Ukraine, Russia and beyond were
contaminated in varying degrees, and an increased number of
birth defects was noted in the years following the disaster.
In 2011 a tsunami severely damaged the nuclear power station
at Fukushima, Japan. There are fears that marine life will be
contaminated, and a large area near the reactors has very
restricted access.

17 Learning Module Organisms and Their Environment | Class 11