Présentations Colloques

Oral Presentation
LOPEZ Benjamin
Perchlorates in French groundwater- Former uses and emerging concerns
In 2010, perchlorate contaminations have been reported in groundwater used for supplying a large city in the Southwest of France in drinking water, at concentration exceeding threshold values for children (4 Ig L) and adults (15 Ig L). Recent investigations show that high concentrations have been also found in groundwater used for drinking water supplies in the North and North of France. Perchlorate is not routinely analyzed in groundwater. Consequently, the extent of perchlorate contamination is not well-known. The widespread occurrence of perchlorate in drinking water leads to concerns regarding perchlorate-induced health issues. Indeed, it could disrupt the thyroid gland’s use of iodine in the generation of metabolic hormones. Because of its extremely strong resistance to most treatment technologies, perchlorate has become one of the biggest challenges currently being faced by the drinking water industry.**The study of literature and historical archives shows that perchlorates may come from different sources and use patterns- former and actual intentional uses in industrial and military domains+ former non-intentional uses via Chilean nitrates (that contain perchlorates) imported from 1830 to 1950 for chemical industry, explosive powders and agriculture, etc... In our work, a GIS-Database method has been developed to assess groundwater vulnerability, at French national scale, to perchlorate originating from industrial and military activities. A map showing areas considered at “high-risk” for groundwater exposure has been edited and validated.**A case study has been also carried out at catchment scale in agricultural context to source perchlorates in groundwater and propose a conceptual scheme of its transfer through aquifers. Results show that perchlorate can generate diffuse pollutions when they source from former agricultural use of Chilean nitrates.**The overall results led French authorities to put perchlorates in the list of priority substances to be monitored in groundwater (national decree of 7 august 2015). First results from river basin monitoring networks show that perchlorate in groundwater should become of great concern to stakeholders creating new challenges in groundwater resources management.