Redox Fronts in Aquifer Systems and Parameters Controlling their Dimensions

Schüring, J.; Schlieker, M.; Hencke, Jörg

doi:10.1007/978-3-662-04080-5_11

Cited by 13 publications

(15 citation statements)

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“…Thus, we propose that residual brackish water trapped in the clay-rich layer has undergone BSR resulting in very high δ 34 S sulfate values for the remaining sulfate. These δ 34 S sulfate values are comparable or higher compared to those reported for BSR in other groundwater environments (e.g., Schüring et al, 2000;Dogramaci et al, 2001). In general, the sulfur isotopic fractionation during BSR (Δ 34 S = δ 34 S sulfate − δ 34 S sulfide ) decreases as the cell-specific rate of sulfate reduction increases (Fritz et al, 1989;Canfield, 2001a;Stam et al, 2006).…”

Section: Calculation Of Sulfur Isotope Enrichment Factors For Bsrsupporting

confidence: 73%

“…Therefore, a detailed understanding of the development of redox zoning in aquifers is crucial for sustainable management of groundwater quality. Reduction processes in groundwater generally succeed one another in the order of decreasing free energy yield, beginning with the reduction of oxygen, followed by reduction of NO 3 − , Mn(IV), Fe(III), SO 4 2− and CO 2 (Froelich et al, 1979;Berner, 1981;Schüring et al, 2000). Among these processes, BSR and methanogenesis can occur only in a very reducing environment with sufficient organic carbon (Stumm and Morgan, 1981;Chapelle et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

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Assessing redox zones and seawater intrusion in a coastal aquifer in South Korea using hydrogeological, chemical and isotopic approaches

et al. 2014

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Section: Calculation Of Sulfur Isotope Enrichment Factors For Bsrsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Assessing redox zones and seawater intrusion in a coastal aquifer in South Korea using hydrogeological, chemical and isotopic approaches

et al. 2014

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“…In soil chemistry, for example, the redox potential value can estimate whether the soil is aerobic or anaerobic, and whether chemical compounds such as Fe oxides or nitrate have been chemically reduced or are present in their oxidised form. In natural waters, redox reactions include the oxidation of organic matter and various reduction reactions such as the reduction of oxygen to water, nitrate to elementary nitrogen dioxide, iron (III) to Fe (II), sulphate to sulphide, and carbon dioxide to methane [ 6 ]. In terms of nanomaterial toxicity, redox potential is a parameter that has been associated with inducing oxidative stress.…”

Section: Introductionmentioning

confidence: 99%

“…Redox potential is a measure of a system's affinity for electrons, and the measurement of redox potential will only have meaning when there are reduced and oxidised species, called the redox couple, in the liquid media. The redox couple undergoes a redox reaction, in which the reduction (gain of electrons) of one redox species is accompanied by the oxidation (loss of electrons) of another [ 6 ]. The movement of electrons, governed by kinetics (e.g., transport limitations of the redox species to the electrode), creates an electric potential.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Redox Potential in Nanoecotoxicological Investigations

Tantra

Cackett

Peck

et al. 2012

Journal of Toxicology

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Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO2)) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe.

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“…Furthermore, groundwater velocity, capillary fringes, and redox gradients might cause a vertical heterogeneity within an aquifer (Spalding and Exner, ). For example, in humid regions under natural conditions, the concentrations of redox‐sensitive substances, such as phosphate and iron, decrease with sediment depths (Schüring et al ., ), whereas more conservative substances increase because of leaching processes in the upper soil. In comparison to the often observed spatial heterogeneity, the temporal variance of the groundwater composition is usually small (e.g.…”

Section: Introductionmentioning

confidence: 99%

Impacts of alluvial structures on small‐scale nutrient heterogeneities in near‐surface groundwater

2014

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Spatially heterogeneous and temporally variable nutrient concentrations (P, N) in near‐surface aquifers are common and are driven by different factors such as climate, topography, vegetation, sediment compositions, and water level fluctuations. Nonetheless, the identification of discrete areas where similar concentrations patterns can be expected is still difficult, especially in patchy systems such as riparian zones of lowland rivers. To address this challenge, a floodplain aquifer of the river Spree (Germany) has been investigated by sampling groundwater with high vertical and horizontal resolutions. Vertical nutrient distributions measured by multi‐level samplers with a 10 cm resolution indicate a biogeochemical layering of the aquifer. High concentrations in the upper 2 m can be attributed to a local redox gradient, which is induced by water level fluctuations and biological turnover processes, while the layer below is mainly influenced by medium‐scale to large‐scale groundwater flow patterns. High concentration in the upper part of the aquifer enforces groundwater sampling with a high horizontal resolution of 3 m from the near‐surface groundwater. The results compared with highly resolved elevation and sediment data indicate that geomorphological features and water level fluctuations control the thickness of the unsaturated zone and the redox gradient. The strength of the gradient and the amount of degradable organic matter determine the intensity of nutrient release by chemical reactions and biological turnover. Copyright © 2014 John Wiley & Sons, Ltd.

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Redox Fronts in Aquifer Systems and Parameters Controlling their Dimensions

Cited by 13 publications

References 1 publication

Assessing redox zones and seawater intrusion in a coastal aquifer in South Korea using hydrogeological, chemical and isotopic approaches

Assessing redox zones and seawater intrusion in a coastal aquifer in South Korea using hydrogeological, chemical and isotopic approaches

Measurement of Redox Potential in Nanoecotoxicological Investigations

Impacts of alluvial structures on small‐scale nutrient heterogeneities in near‐surface groundwater

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