3.1. Box Model for Contaminated Water

Try these first

1. 1.

   What is a box model in environmental science?

   Hint

   Think about how we treat the space being studied.

2. 2.

   Define diffusion coefficient.

   Hint

   Consider its role in flux calculations.

3. 3.

   What does the box model assume about the concentration of contaminants?

   • It varies sharply
   • It is uniform
   • It only decreases

   Hint

   Consider the description of a homogeneous mixture.

4. 4.

   True or False: The diffusion coefficient increases with larger molecular weights.

   • True
   • False

   Hint

   Think about the relationship between size and movement through a medium.

5. 5.

   Given a river segment with an inflow contaminant concentration of 100 mg/L and an outflow concentration of 80 mg/L, along with a constant sediment transfer rate, develop a mass balance equation using the box model.

   Hint

   Balance the input and output considering sediment transfer.

6. 6.

   Analyze how introducing a chemical with a higher molecular weight than water into a river will affect the rate of diffusion and overall water quality.

   Hint

   Reflect on how size affects movement through water.