# Master Student Internship in Development of a conceptual and mathematical framework integrating compound specific isotope analysis signals of pesticides and transit time distributions in the subsurface (M/F)

## Référence : ERIN-2018-INTERN_026

Type: Stagiaire
Type de contrat: CDD
Durée: 3 months
Lieu de travail: Belvaux

## Contexte

Compound-specific isotope analysis (CSIA) is a technique that measures the isotopic composition of specific isotopes (carbon, oxygen, nitrogen) in organic compounds. CSIA can be a powerful tool to differentiate between degradation and dilution as the former leads to a systematic shift in the isotopic composition (fractionation) while the latter does not, and can even in favourable cases quantify degradation losses.

Up to now, CSIA has been mostly used to study groundwater contamination by petroleum compounds, but the technique could also be applied to micropollutants such as pesticides. CSIA typically relates fractionation to reacted mass, but the dimension of time can be easily introduced. Furthermore, the effect of the distribution of transit times in the aquifer on the (measured) bulk isotopic composition of the samples can be calculated using a lumped-parameter approach.

The trainee will work in the group Agro-environmental Systems on the development of a theoretical framework to describe the evolution of the isotopic composition of pesticide transformation products (TPs) as a function of transit time in the subsurface.

## Description

The tasks of the trainee will be to develop a mathematical framework for the use of CSIA for pesticide transformation products in groundwater. Specific tasks will be to :

• integrate TPs in the equations describing changes in isotopic composition with increasing formation and further degradation
• couple these modified equations with weighing functions describing the transit time distribution of solutes in aquifers
• explore, using the obtained equations, the relationship between fractionation factors and transit time parameters

Time allowing, preliminary measurements might be undertaken on a few groundwater samples.

## Profil

Education

• Master

Competencies

• Good mathematical abilities

Language

• English, German or French
• All relevant literature is in English

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### ERIN-2018-INTERN_026

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