Page 173 - Soil and water contamination, 2nd edition

160 Soil and Water Contamination

EXERCISES
1. Define the following terms:
a. Isotope
b. Alpha radiation
c. Beta radiation
d. Gamma radiation
e. Nuclear fission
f. Neutron activation
g. Absorbed dose
h. Cosmogenic radionuclides
i. Man-made radionuclides

2. a. What does background radiation consist of?
b. Explain why background radiation varies from location to location.

3. Name the three natural radioactive decay series of heavy radionuclides.
4. a. Name a terrestrial radionuclide that is not a member of these decay series.
b. Name a cosmogenic radionuclide.
c. Explain why the heads of the three decay series and other non-series terrestrial
radionuclides have very long half-lives in the order of the Earth’s age.
5. Radon-222 gas has a half-life of 3.825 days.
222
a. Given an initial amount of 1 g of Rn, how much will be left after one week?
b. Which decay product predominates then? (Hint: consider the half-lives of the
successive decay products (see Figure 8.2)).
6. Name the two major events that have caused global fallout of fission products.

7. On 26 April 1986 the Chernobyl accident happened in Ukraine. From a radioecological
137
90
131
perspective, the most important radionuclides released were I, Cs, and Sr. Which
of these radionuclides was of most concern for humans in the contaminated area in the
following situations?
a. Drinking water preparation from lake water in a peat area in 1995.
b. Potato cultivation on a sandy soil in 1990.
c. Milk production on 5 May 1986.
Give reasons for your answers
8. Does plutonium-239 occur naturally in the environment?

9. Describe the differences between the possible radioecological effects of the Chernobyl
nuclear accident and those of the Fukushima nuclear accident.

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