Université de Neuchâtel

Evidence of Substantial Carbon Isotope Fractionation among Substrate, Inorganic Carbon, and Biomass during Aerobic Mineralization of 1,2-Dichloroethane by Xanthobacter autotrophicus

Hunkeler, Daniel ; Aravena, R

In: Applied and Environmental Microbiology, 2000, vol. 66, no. 11, p. 4870-4876

Carbon isotope fractionation during aerobic mineralization of 1,2-dichloroethane (1,2-DCA) by Xanthobacter autotrophicus GJ10 was investigated. A strong enrichment of 13C in residual 1,2-DCA was observed, with a mean fractionation factor α ± standard deviation of 0.968 ± 0.0013 to 0.973 ± 0.0015. In addition, a large carbon isotope fractionation between biomass and inorganic...

Université de Neuchâtel

Carbon and Chlorine Isotope Ratios of Chlorinated Ethenes Migrating through a Thick Unsaturated Zone of a Sandy Aquifer

Hunkeler, Daniel ; Aravena, R ; Shouakar-Stash, O ; Weisbrod, N ; Nasser, A ; Netzer, L ; Ronen, D

In: Environmental Science & Technology, 2011, vol. 45, p. 8247-8253

Compound-specific isotope analysis (CSIA) can potentially be used to relate vapor phase contamination by volatile organic compounds (VOCs) to their subsurface sources. This field and modeling study investigated how isotope ratios evolve during migration of gaseous chlorinated ethenes across a 18 m thick unsaturated zone of a sandy coastal plain aquifer. At the site, high concentrations of...

Université de Neuchâtel

Assessing chlorinated ethene degradation in a large scale contaminant plume by dual carbon–chlorine isotope analysis and quantitative PCR

Hunkeler, Daniel ; Abe, Y ; Broholm, M.M ; Jeannottat, S ; Westergaard, C ; Jacobsen, C.S ; Aravena, R ; Bjerg, P.L

In: Journal of Contaminant Hydrology, 2011, vol. 119, p. 69-79

The fate of chlorinated ethenes in a large contaminant plume originating from a tetrachloroethene (PCE) source in a sandy aquifer in Denmark was investigated using novel methods including compound-specific carbon and chlorine isotope analysis and quantitative real-time polymerase chain reaction (qPCR) methods targeting Dehaloccocides sp. and vcrA genes. Redox conditions were...

Université de Neuchâtel

Snowmelt infiltration and storage within a karstic environment, Vers Chez le Brandt, Switzerland

Meeks, Jessica ; Hunkeler, Daniel

In: Journal of Hydrology, 2015, vol. 529, no. Part 1, p. 11-21

Even though karstic aquifers are important freshwater resources and frequently occur in mountainous areas, recharge processes related to snowmelt have received little attention thus far. Given the context of climate change, where alterations to seasonal snow patterns are anticipated, and the often-strong cou- pling between recharge and discharge in karst aquifers, this research area is of great...

Université de Neuchâtel

Radon and CO2 as natural tracers to investigate the recharge dynamics of karst aquifers

Savoy, L ; Surbeck, H ; Hunkeler, Daniel

In: Journal of Hydrology, 2011, vol. 406, no. 3-4, p. 148-157

This study investigated the use of radon (222Rn), a radioactive isotope with a half-life of 3.8 days, and CO2 as natural tracers to evaluate the recharge dynamics of karst aquifer under varying hydrological conditions. Dissolved 222Rn and carbon dioxide (CO2) were measured continuously in an underground stream of the Milandre test site, Switzerland....

Université de Neuchâtel

Can Soil Gas VOCs be Related to Groundwater Plumes Based on Their Isotope Signature?

Jeannottat, S ; Hunkeler, Daniel

In: Environmental Science & Technology, 2013, vol. 47, no. 21, p. 12115-12122

The isotope evolution of tetrachloroethene (PCE) during its transport from groundwater toward the soil surface was investigated using laboratory studies and numerical modeling. During air−water partitioning, carbon and chlorine isotope ratios evolved in opposite directions, with a normal isotope effect for chlorine (ε = −0.20‰) and an inverse effect for carbon (ε = +0.46‰). During the...

Université de Neuchâtel

Carbon and Chlorine Isotope Fractionation Patterns Associated with Different Engineered Chloroform Transformation Reactions

Torrentó, C ; Palau, J ; Rodríguez-Fernández, D ; Heckel, B ; Meyer, A ; Domènech, C ; Rosell, M ; Soler, A ; Elsner, M ; Hunkeler, Daniel

In: Environmental Science & Technology, 2017, vol. 51, no. 11, p. 6174-6184

To use compound-specific isotope analysis for confidently assessing organic contaminant attenuation in the environment, isotope fractionation patterns associated with different transformation mechanisms must first be explored in laboratory experiments. To deliver this information for the common groundwater contaminant chloroform (CF), this study investigated for the first time both carbon and...

Université de Neuchâtel

Documentation of time-scales for onset of natural attenuation in an aquifer treated by a crude-oil recovery system

Ponsin, V ; Maier, J ; Guelorget, Y ; Hunkeler, Daniel ; Bouchard, D ; Villavicencio, H ; Höhener, P

In: Science of the Total Environment, 2015, vol. 512-513, p. 62-73

A pipeline transporting crude-oil broke in a nature reserve in 2009 and spilled 5100 m3 of oil that partly reached the aquifer and formed progressively a floating oil lens. Groundwater monitoring started immediately after the spill and crude-oil recovery by dual pump-and-skim technology was operated after oil lens formation. This study aimed at documenting the implementation of...

Université de Neuchâtel

Carbon and Chlorine Isotope Analysis to Identify Abiotic Degradation Pathways of 1,1,1-Trichloroethane

Palau, J ; Shouakar-Stash, O ; Hunkeler, Daniel

In: Environmental Science & Technology, 2014, vol. 48, no. 24, p. 14400-14408

This study investigates dual C−Cl isotope fractionation during 1,1,1-TCA transformation by heat-activated persulfate (PS), hydrolysis/dehydrohalogenation (HY/DH) and Fe(0). Compound-specific chlorine isotope analysis of 1,1,1-TCA was performed for the first time, and transformation-associated isotope fractionation εCbulk and ε CIbulk...

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...