Chapter 12. Simulating the Flow of DDT -- 4 Exercises

Page 134 of the book refers you to this website for the DDT models shown in Figure 12.10 and in Figure 12.14. It is more instructive to build these models yourself rather than down-loading them from the website.

1. Build and Verify the Original Model

Build the model shown in Figure 12.10.
You will need extra information on the equations and parameter values.
Click here to see a list of the Stella equations.
Run the model with DT set to 0.02 years to verify the results in Figure 12.13 and in Table 12.2.

2. Build and Verify the Revised Model

Build the model shown in Figure 12.14.
You will need extra information on the equations and parameter values.
Click here to see a list of Stella equations.
Run the model with DT set to 0.125 years to verify the results in Figure 12.15 and in Table 12.2.

3. DDT in Birds

Randers' model follows DDT up the chain, but he stops short of the top carnivores. Expand the model in Figure 12.10 to simulate DDT uptake in birds. Use the expanded model to learn whether the "return to 1962 results" are significantly different than shown in Figure 12.15. Add the concentration of DDT in birds to a bar chart (similar to the bar chart in the 4th exercise of chapter 12).

4. DDT in Farm Workers

Farm workers are exposed to DDT immediately after its application. Expand the model in Figure 12.10 to simulate DDT update in workers who are exposed to DDT use during its application and when it evaporates from the agricultural fields. Run the expanded model to study the time delays that are analogous to the "fifty year return interval" for fish shown in Figure 12.15