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Hunkeler, Daniel
Nom
Hunkeler, Daniel
Affiliation principale
Fonction
Professeur ordinaire
Email
daniel.hunkeler@unine.ch
Identifiants
Résultat de la recherche
Voici les éléments 1 - 9 sur 9
- PublicationAccès libreInfluence of surface water – groundwater interactions on the spatial distribution of pesticide metabolites in groundwater(2020-4)
; ; In groundwater, pesticidemetabolites tend to occurmore frequently and at higher concentrations than their parent pesticides, due to their highermobility and persistence. These properties might also favor their transfer across surface water – groundwater interfaces. However, the effect of surface water – groundwater interactions on the metabolite occurrence in groundwater and pumpingwells has so far received little attention.Weinvestigated the spatial distribution of metabolites in an unconsolidated aquifer, which interacts with two surface water bodies originating from catchments with contrasting land use. We focused onmetabolites of the herbicide chloridazon, namely desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) and characterized surface water – groundwater interactions with various environmental tracers (e.g. electrical conductivity, stable water isotopes,wastewater tracers). In zones influenced by a river fromamountainous area,metabolite concentrations were low(median values ≤0.50 μg L−1 for DPC, ≤0.19 μg L−1 forMDPC). In contrast, high concentrations occurred in areas dominated by recharge fromagricultural fields and/or influenced by a streamfroman adjacent intensely farmed catchment (median values up to 1.9 μg L−1 for DPC and up to 0.75 μg L−1 forMDPC). An endmember analysis using hydro-chemical data suggested that about 20% of the DPC mass in a pumping well originated from the neighboring catchment and on its own would cause a concentration above 0.1 μg L−1 for DPC. Our findings highlight that the mobile metabolites can be imported from zones with intense agriculture outside of the exploited aquifer via surface-water groundwater interactions influencing the metabolite concentration level and longterm dynamics in the aquifer. - PublicationAccès libreAdsorbing vs. Nonadsorbing tracers for assessing pesticide transport in arable soils(2017-9)
; ; ; - PublicationAccès libreReview: From multi-scale conceptualization to a classification system for inland groundwater-dependent ecosystems(2012)
; Aquifers provide water, nutrients and energy with various patterns for many aquatic and terrestrial ecosystems. Groundwater-dependent ecosystems (GDEs) are increasingly recognized for their ecological and socio-economic values. The current knowledge of the processes governing the ecohydrological functioning of inland GDEs is reviewed, in order to assess the key drivers constraining their viability. These processes occur both at the watershed and emergence scale. Recharge patterns, geomorphology, internal geometry and geochemistry of aquifers control water availability and nutritive status of groundwater. The interface structure between the groundwater system and the biocenoses may modify the groundwater features by physicochemical or biological processes, for which biocenoses need to adapt. Four major types of aquifer-GDE interface have been described: springs, surface waters, peatlands and terrestrial ecosystems. The ecological roles of groundwater are conditioned by morphological characteristics for spring GDEs, by the hyporheic zone structure for surface waters, by the organic soil structure and volume for peatland GDEs, and by water-table fluctuation and surface floods in terrestrial GDEs. Based on these considerations, an ecohydrological classification system for GDEs is proposed and applied to Central andWestern-Central Europe, as a basis for modeling approaches for GDEs and as a tool for groundwater and landscape management. - PublicationAccès libreDetermination of spatiotemporal variability of tree water uptake using stable isotopes (? 18O, ? 2H) in an alluvial system supplied by a high-altitude watershed, Pfyn forest, Switzerland(2012)
; - PublicationAccès libreIntrinsic biodegradation potential of aromatic hydrocarbons in an alluvial aquifer - Potentials and limits of signature metabolite analysis and two stable isotope-based techniques(2011)
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Firstly, a stable carbon isotope-based field method allowed quantifying biodegradation of monoaromatic compounds in situ and confirmed the degradation of naphthalene. No evidence could be deduced from stable isotope shifts for the intrinsic biodegradation of larger molecules such as methylnaphthalenes or acenaphthene. Secondly, using signature metabolite analysis, various intermediates of the anaerobic degradation of (poly-) aromatic and heterocyclic compounds were identified. The discovery of a novel metabolite of acenaphthene in groundwater samples permitted deeper insights into the anaerobic biodegradation of almost persistent environmental contaminants. A third method, microcosm incubations with 13C-labeled compounds under in situ-like conditions, complemented techniques one and two by providing quantitative information on contaminant biodegradation independent of molecule size and sorption properties. Thanks to stable isotope labels, the sensitivity of this method was much higher compared to classical microcosm studies. The 13C-microcosm approach allowed the determination of first-order rate constants for 13C-labeled benzene, naphthalene, or acenaphthene even in cases when degradation activities were only small. The plausibility of the third method was checked by comparing 13C-microcosm-derived rates to field-derived rates of the first approach. Further advantage of the use of 13C-labels in microcosms is that novel metabolites can be linked more easily to specific mother compounds even in complex systems. This was achieved using alluvial sediments where 13C-acenaphthyl methylsuccinate was identified as transformation product of the anaerobic degradation of acenaphthene. - PublicationAccès libreEvaluating the fate of chlorinated ethenes in streambed sediments by combining stable isotope, geochemical and microbial methods(2009)
; - PublicationAccès libreCarbon and chlorine isotope fractionation during aerobic oxidation and reductive dechlorination of vinyl chloride and cis-1,2-dichloroethene(2009)
; - PublicationAccès libreGeochemical influences on H40/1 bacteriophage inactivation in glaciofluvial sands(2004)
; - PublicationAccès libreEffect of molecule size on carbon isotope fractionation during biodegradation of chlorinated alkanes by Xanthobacter autotrophicus GJ10
; The effect of the number of carbon and chlorine atoms on carbon isotope fractionation during dechlorination of chlorinated alkanes by Xanthobacter autotrophicus GJ10 was studied using pure culture and cell-free extract experiments. The magnitude of carbon isotope fractionation decreased with increasing carbon number. The decrease can be explained by an increasing probability that the heavy isotope is located at a non-reacting position for increasing molecule size. The isotope data were corrected for the number of carbons as well as the number of reactive sites to obtain reacting-site-specific values denoted as apparent kinetic isotope effect (AKIE). Even after the correction, the obtained AKIE values varied (on average 1.0608, 1.0477, 1.0616, and 1.0555 for 1,2-dichloroethane, chloropentane, 1,3-dichloropentane and chlorobutane, respectively). Cell-free extract experiments were carried out to evaluate the effect of transport across the cell membrane on the observed variability in the AKIE values, which revealed that variability still persisted. The study demonstrates that even after differences related to the carbon number and structure of the molecule are taken into account, there still remain differences in AKIE values even for compounds that are degraded by the same pure culture and an identical reaction mechanism.