EXERCISE #5: GEOLOGY AND RADON
To complete this assignment, you should read pages 490-491 in your text. A good source of information about radon (for those interested) is a U.S.G.S. web site (The Geology of Radon).
PART 1: The Geology of Radon
Read geology and radon (from the web site referenced above) and answer the following:
1. What is the typical uranium content of rocks and soil in parts per million (ppm)?
2. What is the typical radon level in soil air in picocuries per liter (pCi/L)?
3. Why do typical radon levels in soil air vary more than the typical uranium content of soil?
4. What might the soil air radon level be (in pCi/L) in a soil containing 100 ppm uranium?
5. What three factors influence the movement of radon through the soil?
6. Why does radon enter a house and accumulate during the winter time?
7. If the soil air near a house contains 200 pCi/L
radon, what percentage of the indoor air would
need to be composed of the soil air to reach the EPA
recommended limit of 4 pCi/L?
PART 2: The Relationship Between Geology and Indoor Radon Levels
1. Based on the uranium contents of some common rocks
given in your text (p. 490), which
areas of the
Upper
Midwest would you expect to have high radon levels? Note:
volcanic
rocks in this region are
mostly basalt, and the metamorphic rocks typically include schist.
2. How well do average
indoor radon levels correlate to the type of underlying bedrock in the
Upper Midwest (i.e., do indoor radon levels match
what you predicted in Question 1)?
3. How might the glacial
history of the Upper Midwest help to explain the distribution of indoor
radon levels? Refer to Figure 11.7 (on p.
355) and Figure 3 (on p. 357) of your textbook to
understand the effects that glaciers have on landscapes (both
eroding bedrock and depositing
sediments).
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