Reference no: EM132385854

1. Let's continue with our radioactive rabbit example. Our 4-kg rabbit drank 0.7 liters of a lake that contains an activity of 550 Bq/liter of tritium. Tritium has a physical half-life of 12.3 years, and we will assume instantaneous mixing in all our compartments. So, using STELLA or by hand answer the following questions:

• What is the initial activity concentration in our rabbit?

• What is the activity concentration in the rabbit after one week? What is it after one year?

• If the background level of tritium in the rabbit is 1.5 Bq/kg, how long would it take for the activity to return to background?

2. Up to this, we have only considered the physical half-life of tritium. Now we will consider the biological half-life as well. Tritium has a biological half-life of 10 days.

• Using the biological and physical half-lives, what is the activity concentration in the rabbit after one week?

• How long would it take for tritium to return to background levels in the rabbit?

3. Now let's consider the time between when the effluent was put into the pond and when the rabbit drank it. Let's say the tritium effluent started out at 550 Bq/liter, but has been sitting in the pond for 1.5 years before the rabbit drank it

• What is the initial activity concentration in the rabbit?

• What would the activity concentration be after four days? (Include biological and physical half-life)

• How long would it take the activity concentration to return to background levels?

4. One of the most common nutrient cycles is the nitrogen cycle. Online, you will find many images that depict the nitrogen cycle. From one of these images create a STELLA compartment model which you could use to model the movement of nitrogen in the environment. You do not need to use actual numbers in any of your compartments or converters.