Contaminants can enter the groundwater by seeping in from the surface or by flowing in from another part of the aquifer. Once in the aquifer they move with the groundwater flow.

As contamination moves it disperses. This means that the concentration decreases as it moves farther away from the source of the pollution. For that reason there are different concentrations of contaminants at different points in the aquifer.

The visual representation of these different concentrations is called a contamination plume. How the plume looks depends on the type of contamination source, the specific contaminant(s), where the aquifers are located, and different soils in that area. Below you can see two main categories of plumes based upon their source. Notice the differences between the two.

Alt | Win

Alt | Win