2.4. Application of Mass Balance in Lakes

Try these first

1. 1.

   What does mass balance measure?

   Hint

   Think about what happens when something is added or removed.

2. 2.

   Define a well-mixed lake.

   Hint

   How does mixing affect concentration?

3. 3.

   What is the main purpose of the mass balance equation?

   • To calculate temperature changes
   • To analyze pollutant concentration changes
   • To determine water flow rates

   Hint

   Think about what mass balance concerns in environmental science.

4. 4.

   True or False: A steady state means concentration levels fluctuate over time.

   • True
   • False

   Hint

   What does steady state imply regarding input and output?

5. 5.

   A lake receives runoff from a nearby agricultural field that contains pollutants. After a significant rain, the concentration of a specific pollutant increases by 25%. How would you set up the mass balance to estimate the new concentration?

   Hint

   Consider how the prior concentration plus the influx changes the overall balance.

6. 6.

   In a simplified box model of a lake, water flows in at a rate of 10 cubic meters per hour, and pollutants enter at a concentration of 5 mg/L. If the outflow is constant, and evaporation removes pollutants, how would you calculate the pollutant concentration after one hour?

   Hint

   Ensure you're considering both the inflow and outflow rates.