9 Apr 2024
Job Information
- Organisation/Company
University of Strasbourg- Department
EOST (Earth Sciences School and Observatory)- Research Field
Geosciences » Other- Researcher Profile
First Stage Researcher (R1)- Country
France- Application Deadline
3 May 2024 - 23:59 (Europe/Paris)- Type of Contract
Temporary- Job Status
Full-time- Hours Per Week
35- Offer Starting Date
2 Sep 2024- Is the job funded through the EU Research Framework Programme?
Not funded by an EU programme- Is the Job related to staff position within a Research Infrastructure?
No
Offer Description
Impact of climate change on the mobility of radionuclides: Role of organic matter in the current and future mobility of radium.
Exposure to external and internal radiation caused by Naturally Occurring Radioactive Materials (NORM) accounts for approximately 50% of the annual dose of radionuclides for humans. Among these NORM, radium (Ra) is a critically important element to consider in radiation protection due to its chemical similarity to calcium (alkaline earth cations family), which is heavily taken up by vegetation, the very short radioactive periods of its descendants, its high mobility in the biosphere, and the numerous potential sources of this radionuclide in the environment (waste from historical or contemporary industrial activities such as phosphate industries, coal combustion, oil and gas production, uranium ore mining, or deep geothermal energy). Ra and its descendants thus constitute the second source of radioactivity in the human diet. Comparative studies of temperate and subtropical climates have shown that the behavior of radionuclides is influenced by many environmental characteristics such as temperature, precipitation, soil properties, and organic matter (OM) content. Therefore, climate change could potentially significantly alter the currently known interactions of radionuclides with compartments of the critical zone (hydrosphere, pedosphere, biosphere, atmosphere) through direct or indirect effects such as changes in soil properties, especially those related to OM. Indeed, a significant change in the quantity and reactivity of OM is predicted in response to temperature or precipitation changes. However, the influence of OM on the mobility of certain radionuclides such as radium remains poorly quantified, mainly due to the great heterogeneity of natural OM. The impact of changes in soil OM on the mobility of radionuclides is thus almost unpredictable to date.
The objective of the thesis is to quantify and model the dynamics of Ra associated with OM in soils and to propose a prediction of the impact of climate change on its mobility. Among the numerous effects of climate change, the increase in drought events will be particularly targeted as this increase is assumed to induce significant changes in soil OM. This work will involve two complementary aspects: the characterization of the Ra-OM interaction in ecosystem compartments of two study sites involving laboratory work in geochemistry and a coupled hydro-biogeochemical modeling.
i) Characterization of organic matter - Ra interaction in soils
The objective of this task is to identify a number of organic functional groups that may significantly affect the retention/mobility of Ra within a soil, information that is currently almost unknown but nevertheless crucial for predicting Ra mobility. Characterization of organic functional groups (carboxylic, phenolic, alcoholic, etc.) in soils, coupled with the quantification of Ra in the corresponding fraction, will provide an first approach to better understand Ra-OM interaction mechanisms. Identification of organic functional groups involved in Ra retention will allow for subsequent experiments on Ra complexation with relevant reference molecules (to be defined based on results obtained on the studied soils) in order to experimentally determine the corresponding complexation constants and then more accurately implement Ra adsorption/complexation models.
ii) Modeling Ra mobility and assessment of hydro-climatic influence
Predicting the impact of reduced water quantity on OM reactivity and thus on Ra mobility will be approached by hydro-biogeochemical modeling of the studied sites. Existing coupled biogeochemical numerical models take into account exchanges between vegetation and soil as well as cation exchanges with the clay-humic complex in watershed-scale or soil profile-scale simulations. This task will be carried out with the coupling of WITCH-LPJ models using available data chronicles from studied sites to simulate the monitoring of soil solution concentrations. The second step of this part will be to test several climate change scenarios of decreased rainfall and/or modification of soil exchange complex characteristics (involving OM).
Requirements
- Research Field
- Geosciences » Other
- Education Level
- Master Degree or equivalent
Skills/Qualifications
Affinity for laboratory work (isotopic chemistry) and modeling (basic coding skills)
- Languages
- FRENCH
- Level
- Good
- Languages
- ENGLISH
- Level
- Good
- Research Field
- Geosciences » OtherEnvironmental science » Earth scienceChemistry » Analytical chemistry
Additional Information
Work Location(s)
- Number of offers available
- 1
- Company/Institute
- Institut Terre et Environnement de Strasbourg
- Country
- France
- City
- Strasbourg
- Postal Code
- 67000
- Street
- 5 rue Descartes
- Geofield
Where to apply
[email protected]
Contact
- City
Strasbourg- Website
https://ites.unistra.fr/- Street
5 rue Descartes- Postal Code
67000
[email protected]
[email protected]
STATUS: EXPIRED