Dispersion in groundwater primarily causes what effect on a contaminant plume?

Dispersion in groundwater primarily causes what effect on a contaminant plume?

• A. Spreading of the plume
• B. Immediate dissolution
• C. Increase in plume concentration without spreading
• D. Spread of the contaminant plume

Answer: (D)

Dispersion in groundwater causes the contaminant plume to spread as it moves. As groundwater flows, different pathlines have slightly different velocities and molecular diffusion acts to mix neighboring water. This combination stretches the plume, widening its spatial extent and diluting concentrations over a larger area. It doesn’t trigger immediate dissolution and it isn’t about concentration increasing in place without spreading; the defining outcome of dispersion is the spreading and broadening of the plume as it advects through the subsurface.

Dispersion in groundwater causes the contaminant plume to spread as it moves. As groundwater flows, different pathlines have slightly different velocities and molecular diffusion acts to mix neighboring water. This combination stretches the plume, widening its spatial extent and diluting concentrations over a larger area. It doesn’t trigger immediate dissolution and it isn’t about concentration increasing in place without spreading; the defining outcome of dispersion is the spreading and broadening of the plume as it advects through the subsurface.