The Chernobyl nuclear disaster of 1986 in Ukraine caused widespread radioactive contamination over much of western Europe, affecting humans, soil, plants, and animals. In response, firefighters extinguished external fires and received large radiation doses, a concrete shell was built around the reactor which continues to leak radiation, and Pripyat was evacuated. Satellite imaging and radiation detectors tracked the plume and dykes, dams, and walls were constructed to prevent contamination of soil and water. Environmental impact assessments, which predict project impacts and inform decision making, always include a baseline study of the pre-project environment.

1. Topic 2.7
Measuring changes in a system
http://www.youtube.com/watch?v=
xMQ0Ryy01yE

2. Ecological Gradients
• These occur where ecosystems meet or where an
ecosystem ends
• They occur due to gradual changes in biotic and
abiotic factors close to such boundaries
• They are usually measured using transect quadrat
sampling (random quadrat sampling alone is not
sufficient).
– A belt transect is a transect with width (1-2 m)
throughout which quadrat sampling is carried out.
– The belt can also be spilt into squares. Sampling
locations can then be chosen using a random number
generator

3. Measuring Abiotic and Biotic Changes
Due To A Specific Human Activity
• On 26th April 1986 there were two explosions at the
Chernobyl Nuclear Plant in Ukraine which blew a hole in
the top of the reactor
• Radioactive particles escaped into the atmosphere over a
10 day period
• There was widespread contamination over much of
western Europe – affecting humans, soil, plants and
animals
http://edroness.blogspot.mx/2014/
01/point-source-pollution-
incidents.html

4. The International Nuclear Event Scale
Chernobyl, Ukraine, 1986
Kyshtym, Russia, 1957
Three Mile Island, USA, 1979
Windscale, UK, 1973

5. Responses to the Chernobyl Accident
• Local firefighters from the nearby town of
Pripyat arrived and over 3 hours
extinguished the external fires, receiving
large radiation doses. Sand, lead and clay
were dumped into the reactor by
helicopter
• A concrete shell was build around the
reactor. Radiation is still leaking from it
and it requires repairs
• Pripyat was evacuated and is now a ghost
town
• Dykes, dams and concrete walls were
constructed to try to prevent radioactive
contamination of soil and water
• Satellite imaging and radiation detectors
were used to track the plume of
airbourne radiation that was released

6. Environmental Impact Assessments (EIAs)
• These became law in the US in 1969 and are
being increasingly used around the world
• They are a method of predicting possible impacts
on the environment prior to any major project,
and helps to decide if it should go ahead
• In some countries they have legal status, in
others they just supply information for decision-
making (in some they may be ignored in favour of
economic benefits)

7. Environmental Impact Assessments (EIAs)
• The first stage is always a baseline study to assess the status of the
environment prior to the project
– Habitat types and area
– Species present
– Biodiversity
– List of endangered species
– Hydrology
– Human population and requirements
– Soil types and quality
• The quality of an EIA depends to a large extent on the quality of the
baseline study
• All EIAs are speculative to some extent due to the inherent
complexities of ecosystems
http://edroness.blogspot.mx/
2014/02/environmental-
impact-assessment.html

8. The Three Gorges Dam Project
http://edroness.blogspot.mx/2014/0
2/the-three-gorges-dam-project-
china.html

9. Questions
1. Briefly describe the stages of primary
succession
2. What is P/R ration and how does it change as
succession proceeds
3. List the characteristics of a typical climax
community
4. What is plagioclimax. Give examples of how
humans may cause it