Management of Aquifers - Hydrogeology: Objectives, Methods, Applications - page 219

groundwater
Figure 113 Restriction of a surface water intrusion into an aquifer with a hydraulic barrier.
environment. Action can be directed towards preserving an existing quality,
or the improvement of a degraded aquifer, but the natural properties of the
environment can also ensure the treatment of surface water. Indeed, the
aquifer includes several physical, chemical, and biological reactants that
interact with the fl uids passing through it. For example, the ammonium
present in the Seine's waters, downstream of Paris, is oxidized into nitrates
in the Croissy-sur-Seine site, thanks to an aeration waterfall placed upstream
of the basins, as well as the aerobic soil atmosphere of the unsaturated
zone that exists between the bottom of the basins and the surface of the
water table.