Page 328 - Soil and water contamination, 2nd edition

Patterns in groundwater 315

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Figure 17.6 Potassium (K ) concentrations in European bottled water (source: Reimann and Birke, 2010).
In the case of point source pollution of groundwater, the contaminants come from
a discernible, spatially confined, and discrete source: usually spills from storage tanks
or containers, underground injection of waste, or effluents from factories or landfills.
Groundwater flow brings about the development of a contaminant plume in downgradient
direction. Several schematic examples of such plumes were given in Chapters 11 and 13 (e.g.
Figures 11.10, 13.2, and 13.4). If the contaminant is an NAPL, the plume of pure liquid
develops virtually independently from the groundwater flow. LNAPLs float on the water
table, whereas DNAPLs sink through the aquifer until they reach an impermeable layer (see
Figure 11.13). As NAPLs are sparingly soluble in water, the dissolved phase does migrate
with groundwater flow, also resulting in the formation of a plume. As noted above, the
dissolved compounds are subjected to a number of physico-chemical processes while being
transported along the groundwater flow lines in the plume.

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