4.2. Concentration Gradient and Diffusion

Try these first

1. 1.

   What is a concentration gradient?

   Hint

   Think about how substances move from areas of high to low concentration.

2. 2.

   Define D-NAPL.

   Hint

   Consider how it behaves in water.

3. 3.

   What drives diffusion?

   • Temperature difference
   • Concentration gradient
   • Air pressure

   Hint

   Think about where the molecules are coming from and going.

4. 4.

   True or False: D-NAPL floats on the surface of water.

   • True
   • False

   Hint

   Consider the definitions of D-NAPL and L-NAPL.

5. 5.

   A spill of D-NAPL occurs in a river. Discuss the potential long-term environmental impacts and the challenges involved in remediation.

   Hint

   Consider both ecological and legal perspectives.

6. 6.

   Create a model to describe how a contaminant will spread through sediment following a spill. What factors will influence the diffusion rate?

   Hint

   Think about the physical dimensions and properties of the materials.