Isotope evidence of hexavalent chromium stability in ground water samples

Čadková, Eva; Chrastný, Vladislav

doi:10.1016/j.chemosphere.2015.05.057

Cited by 15 publications

(2 citation statements)

References 21 publications

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“…All runoff samples were adjusted to pH ≥9 by adding ultrapure NH 4 OH in order to maintain Cr(VI) stability (Cadkova & Chrastny, 2015). Thereafter, filtered (0.45 μm) water samples containing ~1-2 μg Cr were loaded on 10-ml polyethylene columns filled with 2 ml of the anion exchange resin AG1-X8 (100-200 mesh, Bio-Rad).…”

Section: Chromium Isotope Analysesmentioning

confidence: 99%

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

Andronikov

Novák

Krám

et al. 2021

Hydrological Processes

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One pre-requisite for the construction of a global chromium isotope mass balance is detailed understanding of Cr isotope systematics in the critical zone where redoxprocesses can modify the isotope signature of geogenic Cr input into the hydrosphere. A Cr isotope inventory of bedrock, soil, and runoff was performed in a Central European headwater catchment underlain by amphibolite, situated in the vicinity of two previously studied catchments underlain by different bedrock types (serpentinite and leucogranite). Fresh bedrock in the amphibolite catchment NAZ contained ~300 mg/kg Cr, serpentinite at PLB contained ~800 mg/kg Cr, and leucogranite at LYS contained ~2 mg/kg Cr. Monthly hydrochemical monitoring at all three sites revealed higher Cr(VI) export fluxes in winter than in summer. NAZ was characterized by a distinct seasonality in the δ 53 Cr values, with minima during winter/spring snowmelts (À0.35‰) and maxima during dry summers (0.40‰). Similar seasonality in δ 53 Cr values had been reported from PLB and LYS. Bedrock at all three sites had similar Cr isotope composition close to À0.10‰, a value indistinguishable from the δ 53 Cr value of bulk silicate Earth (BSE). Positive mean δ 53 Cr value of NAZ runoff indicated Cr-isotope fractionations during weathering of geogenic Cr(III), combined with adsorption of the resulting Cr(VI) on soil particles during pedogenesis. However, the mass-weighted mean δ 53 Cr of NAZ runoff was lower (À0.08‰), indistinguishable from the Cr isotope signature of bedrock. The same pattern of lower mass-weighted mean δ 53 Cr values of runoff, compared to arithmetic mean δ 53 Cr values of runoff, were observed also at PLB and LYS. We suggest that elevated Cr runoff fluxes in winter remove some of the residual isotopically light Cr that accumulated in the soil during summer. Seasonality in runoff δ 53 Cr values appears to be a relatively widespread phenomenon, de-coupled from Cr availability for chemical weathering.

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Section: Chromium Isotope Analysesmentioning

confidence: 99%

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

Andronikov

Novák

Krám

et al. 2021

Hydrological Processes

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“…Sample volume containing 1-2 μg Cr was loaded on a PolyPrep (Biorad) chromatography column filled with 2 mL of pre-conditioned (2x10 mL of 6 N HCl) anion exchange resin (AG-1-X8, 100-200 mesh) (Cadkova and Chrastny, 2015). Matrix cations were eluted with 20 mL of 0.1 N HCl, and the purified Cr fraction was collected in 6 mL of 6 N HCl.…”

Section: Chemical Purification and Cr Isotope Analysismentioning

confidence: 99%

Chromium isotope fractionations resulting from electroplating, chromating and anodizing: Implications for groundwater pollution studies

Novák

Chrastný

Šebek

et al. 2017

Applied Geochemistry

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A number of shallow aquifers in industrial regions have been polluted by toxic Cr(VI). At some sites, spontaneous reduction of dissolved Cr(VI) to insoluble Cr(III) has been observed. Precipitation of non-toxic Cr(III) is accompanied by a Cr isotope fractionation, with the residual Cr(VI) becoming enriched in the heavier isotope 53 Cr, and depleted in the lighter isotope 52 Cr. Thus far, δ 53 Cr values of the contamination source have been poorly constrained. These values are needed to quantify the extent of Cr(VI) reduction in the aquifers. We present δ 53 Cr values of solutions generated during Cr-electroplating, chromating and anodizing at nine industrial sites. The source chemical, CrO 3 , had a mean δ 53 Cr of 0.0 ‰. A small-tonegligible Cr isotope fractionation was observed between the solutions of the plating baths and the source chemical. Across all sample types, the mean δ 53 Cr(VI) value was 0.2 ‰. The mean δ 53 Cr(VI) value of contaminated groundwater in the same region, studied previously, was significantly higher (2.9 ‰), indicating Cr(VI) reduction. Based on low δ 53 Cr(VI) values of plating baths and rinsewaters as potential contamination sources, and their low variability, we suggest that most aquifer δ 53 Cr(VI) values higher than 1.0 ‰ are a result of in-situ Cr(VI) reduction.

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Combustion Emissions

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Isotope evidence of hexavalent chromium stability in ground water samples

Cited by 15 publications

References 21 publications

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

Chromium isotope fractionations resulting from electroplating, chromating and anodizing: Implications for groundwater pollution studies

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Isotope evidence of hexavalent chromium stability in ground water samples

Cited by 15 publications

References 21 publications

δ53Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

δ53Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

Chromium isotope fractionations resulting from electroplating, chromating and anodizing: Implications for groundwater pollution studies

Bibliography

Contact Info

Product

Resources

About

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes

δ⁵³Cr values of catchment runoff exhibit seasonality regardless of bedrock Cr concentrations: Role of periodically changing chromium export fluxes