Improving noble gas based paleoclimate reconstruction and groundwater dating using 20Ne/22Ne ratios

Peeters, Frank; Beyerle, Urs; Aeschbach–Hertig, Werner; Holocher, Johannes; Brennwald, Matthias S.; Kipfer, Rolf

doi:10.1016/s0016-7037(02)00969-9

Cited by 80 publications

(87 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Measured concentrations of dissolved noble gases (Ne, Ar, Kr and Xe) were interpreted using NOBLE90 (AeschbachHertig et al 2000;Peeters et al 2003) in terms of noble gas temperatures (NGTs) and excess air (see Table 1). Comparing NGTs and excess air concentrations to hydrochemical and stable isotope data, it is possible to identify two groundwater types in terms of the long-term recharge history.…”

Section: Resultsmentioning

confidence: 99%

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

et al. 2015

View full text Add to dashboard Cite

Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ 2 H and δ 18O values in comparison to regional modern groundwater recharge, and 4 He concentrations up to 1.7×10 −4 cm 3 (STP) g -1 ±2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ∼10 7 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study's geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduitbarrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.

show abstract

Section: Resultsmentioning

confidence: 99%

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Most previous studies in groundwater hydrology assumed that isotope fractionation of dissolved ions and noble gases during diffusion in the aqueous phase follows either the hydrodynamic theory (Berkowitz and Wan, 1987;Biswas and Bagchi, 1997;Chong and Hirata, 1998;McManus et al, 2002;Chernyavsky and Wortmann, 2007) or alternatively the kinetic theory, which was developed for gaseous mixtures (Senftle and Bracken, 1954;Desaulniers et al, 1985;Clark and Fritz, 1997;Peeters et al, 2003;Appelo and Postma, 2005;Donahue et al, 2008;LaBolle et al, 2008). The hydrodynamic theory assumes that a solute molecule moves through a continuum solvent with a specified viscosity and the diffusion coefficient is commonly described by the well-known Stokes-Einstein relation (Cussler, 2009):…”

Section: Introductionmentioning

confidence: 99%

“…In contrary, in the framework of the kinetic theory, the diffusion coefficient of a dissolved species is mass dependent and the ratio between two diffusion coefficients of two isotopically distinct species is proportional to the inverse square root of their reduced masses: For diffusing gases Eq. (2) can be simplified by assuming that the mass of the molecules of the medium (M i ) is infinitively large in comparison to the diffusing molecules (M i ) m i ) (Ballentine et al, 2002;Lippmann et al, 2003;Peeters et al, 2003;Strassmann et al, 2005;Zhou et al, 2005;Richter et al, 2006;Klump et al, 2007;Bourg and Sposito, 2008). Therefore, the reduced mass in Eq.…”

Section: Introductionmentioning

confidence: 99%

Carbon and chlorine isotopologue fractionation of chlorinated hydrocarbons during diffusion in water and low permeability sediments

Wanner

Hunkeler

2015

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

To identify reactive processes in diffusion dominated water-saturated systems using compound-specific isotope analysis (CSIA), the effect of the diffusive transport process on isotope ratios needs to be known. This study aims to quantify the magnitude of carbon and chlorine isotopologue fractionation of two chlorinated hydrocarbons (trichloroethene (TCE) and 1,2-dichloroethane (1,2-DCA)) during diffusion in the aqueous phase and to relate for the first time laboratory with field results. Diffusion coefficient ratios in the aqueous phase were experimentally quantified with a modified Stokes diffusion cell. The experiment revealed a significant shift of carbon and chlorine isotopologue ratios of TCE and 1,2-DCA during diffusion. For both TCE and 1,2-DCA, the magnitude of the shift of chlorine isotopologue ratios was larger , which is consistent with the larger mass difference between stable chlorine compared to carbon isotopes. Determined diffusion coefficients for carbon and chlorine isotopologues of TCE and 1,2-DCA follow an inverse power law form (D / m Àb ) with b < 0.5 revealing that the magnitude of isotopologue fractionation of TCE and 1,2-DCA is lower than in the previously postulated kinetic theory (D / m À0:5 ). To relate laboratory with field results, a water-saturated clay core from a VOC contaminated site was retrieved and subsampled as a function of depth to assess possible shifts in isotopologue ratios during downward diffusion of VOCs into the low permeable clay. Observed small shifts of TCE carbon and chlorine isotopologue ratio profiles were consistent with laboratory determined diffusion coefficient ratios, demonstrated by a 1D-diffusion model. Further 1D-simulations for shorter diffusion periods (5-10 years) than observed in the retrieved clay core (45 years), revealed a larger effect on TCE chlorine and carbon isotopologue ratio profiles. Thus, the diffusive transport process in water-saturated low permeability sediments only impairs the identification of reactive processes using compound-specific isotope analysis (CSIA) during short diffusion periods and for reactive processes with small enrichment factors.

show abstract

“…The term "excess air" is retained, although noble gas data of numerous field studies indicate that the composition of the excess gas does not correspond to atmospheric air (8). Excess air and its fractionation affects the interpretation of gas concentrations in groundwater [e.g., in noble gas based paleoclimate reconstruction (9)(10)(11)(12), in groundwater dating with the 3 H- 3 He method (12)(13)(14), or with SF6 (15)]. Simplified models describing the dissolved gas concentrations in the final state after interaction with entrapped air have been employed to estimate excess air and its composition (9,11).…”

Section: Introductionmentioning

confidence: 99%

Kinetic Model of Gas Bubble Dissolution in Groundwater and Its Implications for the Dissolved Gas Composition

Holocher

Peeters

Aeschbach–Hertig

et al. 2003

Environ. Sci. Technol.

129

116

View full text Add to dashboard Cite

Bubble-mediated mass transfer is of major importance for the gas exchange between soil air and groundwater. The presence of entrapped air bubbles in the upper, quasisaturated aquifer zone can crucially affect the interpretation of atmospheric trace gas concentrations in groundwater and associated fluids as well as intrinsic and enhanced bioremediation procedures that rely on the actual dissolved gas content of gases such as oxygen or nitrogen. To describe the bubble-mediated gas exchange in detail, a kinetic multi-species model for dissolved gas transport in a porous medium including inter-phase mass transfer with entrapped gas bubbles was developed. It takes into account changes in the entrapped gas bubble sizes resulting from the mass exchange and therefore allows the quantification of mass transfer between bubbles of any gas composition and flowing or stagnating water in a substrate column. Considering the dissolution of entrapped air bubbles, the resulting concentrations of dissolved atmospheric gases significantly exceed their solubility equilibrium concentrations. The temporal evolution of the composition of this excess gas is controlled by the solubility and the molecular diffusivity of the gases considered, by the flow conditions, and by the physical properties of the aquifer such as the ratio of entrapped air to water in the pore space. In the case of noble gases in a through-flow system, solubility differences appear to be more important for the composition of the gas excess than the differences between molecular diffusivities.

show abstract

Improving noble gas based paleoclimate reconstruction and groundwater dating using 20Ne/22Ne ratios

Cited by 80 publications

References 29 publications

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

Carbon and chlorine isotopologue fractionation of chlorinated hydrocarbons during diffusion in water and low permeability sediments

Kinetic Model of Gas Bubble Dissolution in Groundwater and Its Implications for the Dissolved Gas Composition

Contact Info

Product

Resources

About