2.6. Box Model Assumptions and Application

Try these first

1. 1.

   What is the basic assumption of a box model?

   Hint

   Think about how mixing affects concentration.

2. 2.

   What does steady-state mean in environmental systems?

   Hint

   Consider balance in flows.

3. 3.

   What is a primary assumption of the box model?

   • A. It's perfect for all systems.
   • B. Contents are well mixed.
   • C. It includes complex reactions.

   Hint

   Consider what simplifications the model offers.

4. 4.

   Steady-state implies:

   • True
   • False

   Hint

   Relate this to balance concepts.

5. 5.

   Consider a river system with three pollutants entering from different sources. Source A introduces 50 kg/day, Source B introduces 30 kg/day, and Source C introduces 10 kg/day. If the river flows at a steady rate, how much pollution will be present downstream if all pollutants are uniformly mixed and the total daily outflow is 80 kg?

   Hint

   Combine inputs and compare with outflows to determine equilibrium.

6. 6.

   A scientist is studying the oxygen balance within a lake modeled as a box. If 100 kg/day of oxygen enters the lake while 60 kg/day is consumed by biological processes and evaporation loses 20 kg/day, calculate the total change in oxygen concentration over a day in a lake with a volume of 500 m³.

   Hint

   Use the net balance approach to compute the concentration change.