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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
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