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Université de Neuchâtel

C and Cl Isotope Fractionation of 1,2-Dichloroethane Displays Unique δ13C/δ37Cl Patterns for Pathway Identification and Reveals Surprising C–Cl Bond Involvement in Microbial Oxidation

Palau, J ; Cretnik, S ; Shouakar-Stash, O ; Höche, M ; Elsner, M ; Hunkeler, Daniel

In: Environmental Science & Technology, 2014, vol. 48, no. 16, p. 9430-9437

This study investigates dual element isotope fractionation during aerobic biodegradation of 1,2-dichloroethane (1,2-DCA) via oxidative cleavage of a C−H bond (Pseudomonas sp. strain DCA1) versus C−Cl bond cleavage by SN2 reaction (Xanthobacter autotrophicus GJ10 and Ancylobacter aquaticus AD20). Compound-specific chlorine isotope analysis of 1,2-DCA was...

Université de Neuchâtel

Process based modeling of the karstification processes in the region of Tulum, Mexico

Maqueda, Axayacatl ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2017.

Caves are important since they are preferential paths for groundwater flow. Knowledge of caves or karst is essential for proper management of water resources, but the exploration of caves is a major challenge. An alternative to study caves and their structure is to simulate the processes related to cave growth. The motivation of this thesis is to study large karst networks in the region of...

Université de Neuchâtel

Chloroplast lipid droplet type II NAD(P)H oxidoreductase, NDC1, is essential for vitamin E and K1 metabolism

Eugeni Piller, Lucia ; Kessler, Felix (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2017.

Plant cells in different tissues contain specialized organelles belonging to the family of plastids. The chloroplast is the most prominent family member and responsible for photosynthesis in leaves. Most plastid types contain lipoprotein particles ("lipid droplets") termed plastoglobules. Little is known about plastoglobules that were long regarded as passive storage droplets. Indeed, the...

Université de Neuchâtel

Conjugacy growth series of groups

Mercier, Valentin ; Ciobanu, Laura I. (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2017.

In this thesis we study the conjugacy growth series of several group constructions in terms of the standard and the conjugacy growth series of the building groups, with a specific generating set. This includes (1) groups of the form $G\wr L$ when $L$ admits a Cayley graph that is a tree, (2) graph products, (3) a specific free product of $\mathbb{Z}*\mathbb{Z}$ with amalgamation over...

Université de Neuchâtel

Random sampling with repulsion

Wilhelm, Matthieu ; Tillé, Yves (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2017.

In this thesis, we explore the concept of repulsion and exploit it to develop new sampling designs. The first chapter is a review of the literature about sampling in finite population and consists of two distinct parts. In the first one, we suggest three principles as guidelines for designing a survey: randomization, overrepresentation and restriction. In the second part, we review the...

Université de Neuchâtel

The influence of model structure on groundwater recharge rates in climate-change impact studies

Moeck, Christian ; Brunner, Philip ; Hunkeler, Daniel

In: Hydrogeology journal, 2016, vol. 24, p. 1171-1184

Numerous modeling approaches are available to provide insight into the relationship between climate change and groundwater recharge. However, several aspects of how hydrological model choice and structure affect recharge predictions have not been fully explored, unlike the well-established variability of climate model chains—combination of global climate models (GCM) and regional climate models...

Université de Neuchâtel

Intrinsic biodegradation potential of aromatic hydrocarbons in an alluvial aquifer - Potentials and limits of signature metabolite analysis and two stable isotope-based techniques

Morasch, B ; Hunkeler, Daniel ; Zopfi, J ; Temime, B ; Höhener, P

In: Water Research, 2011, vol. 45, p. 4459-4469

Three independent techniques were used to assess the biodegradation of monoaromatic hydrocarbons and low-molecular weight polyaromatic hydrocarbons in the alluvial aquifer at the site of a former cokery (Flémalle, Belgium). Firstly, a stable carbon isotope-based field method allowed quantifying biodegradation of monoaromatic compounds in situ and confirmed the degradation of...

Université de Neuchâtel

Monitoring Microbial Dechlorination of Tetrachloroethene (PCE) in Groundwater Using Compound-Specific Stable Carbon Isotope Ratios : Microcosm and Field Studies

Hunkeler, Daniel ; Aravena, R ; Butler, B.J

In: Environmental Science & Technology, 1999, vol. 33, p. 2733-2738

The determination of compound-specific stable isotope ratios is a promising new tool to assess biodegradation of organic compounds in groundwater. In this study, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site. In the microcosm,...

Université de Neuchâtel

Petroleum hydrocarbon mineralization in anaerobic laboratory aquifer columns

Hunkeler, Daniel ; Jörger, D ; Häberli, K ; Höhener, P ; Zeyer, J

In: Journal of Contaminant Hydrology, 1998, vol. 32, no. 1-2, p. 41-61

The anaerobic biodegradation of hydrocarbons at mineral oil contaminated sites has gathered increasing interest as a naturally occurring remediation process. The aim of this study was to investigate biodegradation of hydrocarbons in laboratory aquifer columns in the absence of O2 and NOۙ, and to calculate a mass balance of the anaerobic biodegradation processes. The...

Université de Neuchâtel

Multiphase Transport of Tritium in Unsaturated Porous Media—Bare and Vegetated Soils

Jiménez-Martínez, J ; Tamoh, K ; Candela, L ; Elorza, F.J ; Hunkeler, Daniel

In: Mathematical Geosciences, 2012, vol. 44, no. 2, p. 187-208

Tritium is a short-lived radioactive isotope (T1/2 = 12.33 yr) produced naturally in the atmosphere by cosmic radiation but also released into the atmosphere and hydrosphere by nuclear activities (nuclear power stations, radioactive waste disposal). Tritium of natural or anthropogenic origin may end up in soils through tritiated rain, and may eventually appear in groundwater....