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Reference : UMR5151-CATMAR-002
Workplace : MONTPELLIER
Date of publication : Tuesday, April 06, 2021
Type of Contract : FTC Scientist
Contract Period : 7 months
Expected date of employment : 1 June 2021
Proportion of work : Full time
Remuneration : 2675,27
Desired level of education : PhD
Experience required : 1 to 4 years
The post-doctoral fellow will be part of the team « Hydrogéologie et Transferts dans les Aquifères Karstiques et hEtérogènes », which is responsable of the Geochemistry Task of the research project Dem'Eaux Thau (financed by the ERDF and the RMC Water Agency and led by BRGM). He/She will work under the supervision of Véronique de Montéty and Christelle Guilhe-Batiot.
The objective of the project is to better understand the functioning of the Thau hydrosystem (Hérault), place of convergence of groundwater from several reservoirs (karstic, thermal, marine) which interact according to complex and variable processes in time. In addition, occasional episodes of marine water intrusion (inversac) in the karstic and thermal aquifer through the submarine source of the Vise can temporarily modify the quality of groundwater in the Balaruc-les-Bains peninsula. In order to better understand this phenomenon and preserve the resource and its multiple uses, it is necessary to study the functioning of the hydrosystem and to better constrain the different types of flows, their residence time and their mixing. The Geochemistry Task of the Dem'Eaux Thau project aims to conduct geochemical and isotopic investigations using a multi-tracer approach to understand the organization of groundwater flows, their origin and residence time, and to quantify water mixing between the different reservoirs. These results should allow to bring new constraints on the conceptual model of this hydrosystem and to estimate the contribution of the current karstic water to the thermal system of Balaruc. The data will in turn be used to develop groundwater resource management tools to help decision makers to address the challenges of this region.
The objective of the expected work is:
1) to complete the first interpretations made from hydrogeochemical tracing tools (major and trace elements; Total Organic Carbon and Dissolved Organic Matter fluorescence), isotopic (stable isotopes of water and carbon, isotopes of Lithium, Boron and Strontium) and residence time (CFCs, SF6, H3, He, noble gases and Radon, 14C, 36Cl) implemented during 4 spatial campaigns carried out in 2018 and 2019 in low and high water conditions.
2) to specially focus on the evolution of the conceptual scheme during the hydrological cycle by interpreting the data of the monthly geochemical monitoring of representative points of the hydrosystem, realized during the year 2020.
3) to carry out the follow-up of the geochemical samplings on the 600 m deep bore-hole which will be finalized in September 2021 as well as the analyses and interpretation.
Particular attention will be paid to the multi-isotopic approach and dissolved gases, which are innovative and relevant tracers for characterizing the origin of water masses and highlighting natural processes (water-rock interactions, mixing) affecting the composition of waters in karstic and coastal thermal areas.
- PhD en Géochimie de l'Eau avec des connaissances en Hydrogéologie,
- Expérience en séparation isotopique et spectrométrie de masse,
- - PhD in water geochemistry with knowledges in Hydrogeology,
- Experience in isotopic separation and mass spectrometry,
- Statistical analyses of data,
- Database management,
- Knowledge of karst or thermal areas would be a plus,
- Aptitude to work in a team on a multidisciplinary project and to communicate with external socio-economic partners,
- Driving licence (B) to go regularly on the field for samplings
The post-doctoral fellow will be based at the Laboratoire HydroSciences Montpellier, a joint research unit of the University of Montpellier-CNRS-IRD. The workplace is located on the University of Montpellier campus. He/she will be a member of the HYTAKE team, specialized in the study of heterogeneous aquifers and involved in several research observatories (SNO Karst). The field monitoring will only concern the Thau hydrosystem, located 40 km west of Montpellier. The isotopic analyses will be performed on the multi-collector ICP-MS Neptune+ of the AETE-ISO platform of the University of Montpellier and the dissolved gas analysis will be performed by the CONDATEau platform of OSUR Rennes.
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