Transferts rivière-nappe et effet filtre des berges. Application aux transferts de l'azote

Abstract

The authors present results of a study designed to investigate hydrodynamical and geochemical environment of bank filtration, along the Seine river, downstream of Paris. Nitrogen species behaviour during bank filtration was examined. Water issues from bank filtration shows drastic changes when compared to river water, denoting a reductive trend. This geochemical evolution of the water in the aquifer is the reflect of intensive bacterial mineralization. As a consequence for nitrogen species, denitrification is very effective and no nitrate is found below a few centimeters depth in the sediments. On the contrary, ammonium concentration drastically increased at the same time. The problem of ammonium transfer to the well is addressed and key parameters, as percolation velocity and organic carbon content of sediments, are discussed in conjunction with drinking water production using bank filtration. -from English summary