Présentations Colloques

Session 7.03: Agricultural and sanitation contaminants and implications for water services and health
Jaunat (orateur)
Perchlorates in the chalk aquifer of Northeastern France (Marne, 51) – Preliminary results and perspectives
Noticeable concentrations of perchlorate ions have been measured since 2011 in numerous drinking water supplies of Northeast of France. Because the consumption of food and water containing ClO4- is suspected to result in thyroid tumors and mental retardations, authorities issued health recommendations for tap water beyond 4Ig L.**Perchlorates have both natural (associated with nitrate in caliche formation, e.g. Atacama Desert, Chile) and anthropogenic (numerous industrial processes use synthetic ClO4-) origins. Chilean caliche has been intensively imported in France before WWI since it was the unique nitrate supply for agriculture and nitrogen industry. The increased production of synthetic ClO4- dates back to WWI because of the widespread uses of trench artillery weapons (mortar bombs, grenades) loaded with chlorated perchlorated explosives, and the production of explosives for shells (TNT...).**ClO4- concentrations largely higher than 15Ig L are observed in groundwater from the chalk aquifer in the Marne French department. A geographical approach allowed to link perchlorate concentrations with WWI and post-WWI activities- shelling and fighting along the former front line, dumping breaking down of ammunition during the war and for several decades after, free and labile explosives still be buried in soil. But this area is also characterized by intensive agriculture. Past use of Chilean nitrate and intensive fertilization during the reconstruction of devastated soils after the Armistice could have resulted into widespread groundwater contamination. **Management of this issue requires better constraints on the sources of contamination thanks to the combination of historical archives and measurements of inorganic traces, organic warfare agents, explosives, and isotopic signatures of ClO4- from groundwater. Perchlorates mobility in the aquifer will be specified by a multi-tracer geochemical survey (major ions, stable isotopes of water molecule, trace elements) and groundwater residence time determination. The links between ClO4- and other molecules of military origin (NO3- and other organics) will also be clarified.