Chromium speciation in sea water
TL;DR: In this article, it was shown that theoretically unstable Cr (III) species are often dominant in water in solubility equilibrium with the atmosphere and CrO42− is the major form of trivalent and hexavalent chromium in sea water.
About: This article is published in Earth and Planetary Science Letters.The article was published on 1970-08-01. It has received 186 citations till now. The article focuses on the topics: Hexavalent chromium & Chromium.
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TL;DR: In this article, the authors examined the distribution of minor and trace elements in marine sediments and provided forensic tools for determining the redox conditions of the bottom waters at the time of deposition.
1,391 citations
TL;DR: In this paper, the authors developed a multiproxy technique for assessing redox facies in black shale samples: euxinic conditions were considered to have existed if at least two of four trace-indicator trace elements (Mo, U, V, Zn, and Pb), and nonsulfidic anoxic conditions were inferred otherwise.
1,209 citations
Cites background from "Chromium speciation in sea water"
...Under anoxic conditions, Cr(VI) is reduced to Cr(III), forming aquahydroxyl or hydroxyl cations (e.g., Cr(OH)2 +) that can be precipitated as insoluble Cr(OH)3 or Cr2O3 at high pH (Elderfield, 1970; Emerson et al., 1979; Drever, 1997)....
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..., Cr(OH)2 ) that can be precipitated as insoluble Cr(OH)3 or Cr2O3 at high pH (Elderfield, 1970; Emerson et al., 1979; Drever, 1997)....
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TL;DR: In this paper, the authors reviewed the aqueous geochemistry of chromium, especially with reference to the recent work of Rai et al. (report EPRI EA-4544, 1986, Report EPRi EA-5741, 1988), and showed that the chromium content of natural waters is generally low whereas rocks exhibit a wide range of Cr concentrations.
834 citations
TL;DR: In this article, a suite of Proterozoic sediments from China, Australia, and North America, interpreted in the context of data from similar depositional environments from Phanerozoic time, were used to find evidence for inhibited oxidation of chromium at Earth's surface in the mid-Proteozoic (1.8 to 0.8 billion years ago).
Abstract: The oxygenation of Earth’s surface fundamentally altered global biogeochemical cycles and ultimately paved the way for the rise of metazoans at the end of the Proterozoic. However, current estimates for atmospheric oxygen (O₂) levels during the billion years leading up to this time vary widely. On the basis of chromium (Cr) isotope data from a suite of Proterozoic sediments from China, Australia, and North America, interpreted in the context of data from similar depositional environments from Phanerozoic time, we find evidence for inhibited oxidation of Cr at Earth’s surface in the mid-Proterozoic (1.8 to 0.8 billion years ago). These data suggest that atmospheric O₂ levels were at most 0.1% of present atmospheric levels. Direct evidence for such low O₂ concentrations in the Proterozoic helps explain the late emergence and diversification of metazoans.
568 citations
01 Jan 2014
TL;DR: Evidence for inhibited oxidation of Cr at Earth’s surface in the mid-Proterozoic is found, suggesting that atmospheric O2 levels were at most 0.1% of present atmospheric levels.
501 citations
Cites background from "Chromium speciation in sea water"
...Under the conditions that typically pertain to oxygenated surface waters Cr(III) is thermodynamically unstable and the speciation of Cr should be dominated by Cr(VI) (53, 54)....
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Book•
01 Jun 1974
TL;DR: The Atlas of Electrochemical Equilibria in Aqueous solutions as discussed by the authors is the most complete and complete work on aqueous solvents, which includes a detailed description of the properties of the solvers.
Abstract: Environmental ChemistryAtlas D'équilibres Électrochimiques. Atlas of Electrochemical Equilibria in Aqueous Solutions. By Marcel Pourbaix. Translated by James A. Franklin, EtcElectrochemical ImpedanceAtlas of Electrochemical Equilibria in Aqueous SolutionsElectrochemical Techniques in Corrosion Science and EngineeringEffect of Mineral-OrganicMicroorganism Interactions on Soil and Freshwater EnvironmentsCorrosion EngineeringAtlas of Electrochemical Equilibria in Aqueous SolutionsHandbook of Corrosion DataSolved Problems in Electrochemistry for Universities and IndustryEquilibrium DiagramsCorrosionThe Aqueous Chemistry of Polonium and the Practical Application of its ThermochemistryElectrochemistry in TransitionCorrosion Tests and StandardsFundamentals of Electrochemical CorrosionAtlas of Electrochemical Equilibria in Aqueous SolutionsLectures on Electrochemical CorrosionAtlas of Electrochemical Equilibria in Aqueous SolutionElectrochemical and Optical Techniques for the Study and Monitoring of Metallic CorrosionAtlas of Electrochemical Equilibria in Aqueous SolutionsElectronics Packaging 3Atlas of Chemical and Electrochemical Equilibria in the Presence of a Gaseous PhaseElectrochemistry in Mineral and Metal Processing VATLAS OF ELECTROCHEMICAL EQUILIBRIA.Thermodynamics of Dilute Aqueous SolutionsAtlas of Chemical and Electrochemical Equilibria in the Presence of a Gaseous PhaseBiomaterialsCorrosion Mechanisms in Theory and PracticeAtlas d'équilibres électrochimiques. Atlas of electrochemical equilibria in aqueous solutions. By Marcel Pourbaix. Translated by James A. Franklin, etcAtlas of Electrochemical Equilibria in Aqueous SolutionsSilicon Nitride and Silicon Dioxide Thin Insulating FilmsElectrochemical Energy SystemsInorganic ChemistryThe DaguerreotypeStandard Potentials in Aqueous SolutionCorrosion Engineering and Cathodic Protection HandbookMicroelectronic Applications of Chemical Mechanical PlanarizationAtlas of Electrochemical Equilibria in Aqueous SolutionsAtlas of Electrochemical Equilibria in Aqueous Solutions
7,701 citations
TL;DR: In this article, a diagnostic principle is suggested, permitting a qualitative or semiquantitative discrimination between marine authigenic minerals crystallized from dissolved species, which have spent a long time in solution, and the same minerals generated from solutions, near their source on the other.
98 citations
85 citations
TL;DR: The rate of exchange of water between the hydrated forms of Al+++, Cr+++, Fe+++, Ga+++, and Th+4 and the solvent water has been measured in solutions of varying acidity.
Abstract: The rate of exchange of water between the hydrated forms of Al+++, Cr+++, Fe+++, Ga+++, and Th+4 and the solvent water has been measured in solutions of varying acidity. With the exception of chromic ion, and of ferric ion at low acidity, the exchange is complete in ca 3 min at 25°. For chromic ion, the half‐time for exchange is independent of acidity over a wide range and is ca 40 hr at 1 M salt concentration. The coordination number of chromic ion for water over the entire acidity range is 6.0. The initial hold‐back of oxygen by ferric ion at low acid is slight and is attributed to the presence of polynuclear hydrolyzed species. For all the cations, the distribution of oxygen isotopes in the final solution is noticeably different from random, the cations showing a greater affinity for H2O18 over H2O16.The rates of exchange are correlated with the electronic structure, which influences the energy required to form the transition state.
77 citations
TL;DR: In this article, it was reported that the major part of chromium-51 stayed in the original hexavalent state in seawater even at several hundred kilometres from the river mouth.
Abstract: THE valency state in which chromium occurs in seawater not only provides important information concerning the geochemical behaviour of this element in marine environment but has also in recent years become significant in connexion with the problem of disposal of radioactive waste. For example, Osterberg et al.1 investigated the variation of the spread of the Columbia River water along the Oregon coast of the Pacific by using chromium-51 which was originally released from the Hanford reactor as a radioactive tracer. In this case, it was reported by Cutshall et al.2 that the major part of chromium-51 stayed in the original hexavalent state in seawater even at several hundred kilometres from the river mouth. In order to understand the cycle of radioactive chromium in the sea-water, therefore, it seems indispensable to know the valency state in which chromium in seawater is stable. Unfortunately, the present day knowledge of this is very limited. In his recent compilation Riley3 gave six references for the chromium content of seawater but these data are not sufficient to indicate general trends in the behaviour of chromium in seawater. In these investigations, except for the two investigations by emission spectrography, chromium was separated with hydroxides of aluminium, iron or chromium itself. These separations are only effective when chromium in seawater is present in a trivalent form.
76 citations