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Philip M Gschwend - One of the best experts on this subject based on the ideXlab platform.

  • Ferrous Iron Oxidation rates in the pycnocline of a permanently stratified lake
    Chemosphere, 2007
    Co-Authors: Sergi Diez, Gregory O Noonan, John K Macfarlane, Philip M Gschwend
    Abstract:

    Ferrous Iron was found year round at 2–4 mM in the anoxic hypolimnion of the Halls Brook Holding Area (HBHA), a small lake in eastern Massachusetts. Oxygenated epilimnion waters always had total Iron concentrations of <80 nanomolar, implying nearly complete Oxidation of Ferrous Iron as it mixed upward across the lake’s pycnocline. Assuming conductivity was a conservative parameter, and using data on the lake’s water balance, upward advection rates (0.02–0.05 m d � 1 ) and vertical eddy diffusion coefficients (0.007– 0.05 m 2 d � 1 ) were determined for the lake’s pycnocline on five dates. Using the same advection and diffusion parameters, corresponding pseudo first-order rate coefficients for Ferrous Iron Oxidation, kox (s � 1 ), on those dates were calculated (0.0004–0.007 s � 1 ). The values of kox (s � 1 ) were always too large to reflect only homogeneous solution reactions; and on at least four dates they appeared too fast to be due to heterogeneous catalysis on Iron oxyhydroxides. This suggested that Ferrous Iron Oxidation in this lake’s pycnocline was primarily due to catalysis by microorganisms, and this was supported by comparison of azide-poisoned vs. untreated batch tests. As a result of their continuous production, Iron oxyhydroxide precipitates and any associated sorbates/coprecipitates are most likely continuously settling back into the lake’s deep water and bed sediments, except when episodic storm events flush these solids out of the pycnocline and downstream via the Aberjona River. � 2006 Elsevier Ltd. All rights reserved.

  • Ferrous Iron Oxidation rates in the pycnocline of a permanently stratified lake
    Chemosphere, 2006
    Co-Authors: Sergi Diez, Gregory O Noonan, John K Macfarlane, Philip M Gschwend
    Abstract:

    Ferrous Iron was found year round at 2–4 mM in the anoxic hypolimnion of the Halls Brook Holding Area (HBHA), a small lake in eastern Massachusetts. Oxygenated epilimnion waters always had total Iron concentrations of

Matthias Reuss - One of the best experts on this subject based on the ideXlab platform.

Sergi Diez - One of the best experts on this subject based on the ideXlab platform.

  • Ferrous Iron Oxidation rates in the pycnocline of a permanently stratified lake
    Chemosphere, 2007
    Co-Authors: Sergi Diez, Gregory O Noonan, John K Macfarlane, Philip M Gschwend
    Abstract:

    Ferrous Iron was found year round at 2–4 mM in the anoxic hypolimnion of the Halls Brook Holding Area (HBHA), a small lake in eastern Massachusetts. Oxygenated epilimnion waters always had total Iron concentrations of <80 nanomolar, implying nearly complete Oxidation of Ferrous Iron as it mixed upward across the lake’s pycnocline. Assuming conductivity was a conservative parameter, and using data on the lake’s water balance, upward advection rates (0.02–0.05 m d � 1 ) and vertical eddy diffusion coefficients (0.007– 0.05 m 2 d � 1 ) were determined for the lake’s pycnocline on five dates. Using the same advection and diffusion parameters, corresponding pseudo first-order rate coefficients for Ferrous Iron Oxidation, kox (s � 1 ), on those dates were calculated (0.0004–0.007 s � 1 ). The values of kox (s � 1 ) were always too large to reflect only homogeneous solution reactions; and on at least four dates they appeared too fast to be due to heterogeneous catalysis on Iron oxyhydroxides. This suggested that Ferrous Iron Oxidation in this lake’s pycnocline was primarily due to catalysis by microorganisms, and this was supported by comparison of azide-poisoned vs. untreated batch tests. As a result of their continuous production, Iron oxyhydroxide precipitates and any associated sorbates/coprecipitates are most likely continuously settling back into the lake’s deep water and bed sediments, except when episodic storm events flush these solids out of the pycnocline and downstream via the Aberjona River. � 2006 Elsevier Ltd. All rights reserved.

  • Ferrous Iron Oxidation rates in the pycnocline of a permanently stratified lake
    Chemosphere, 2006
    Co-Authors: Sergi Diez, Gregory O Noonan, John K Macfarlane, Philip M Gschwend
    Abstract:

    Ferrous Iron was found year round at 2–4 mM in the anoxic hypolimnion of the Halls Brook Holding Area (HBHA), a small lake in eastern Massachusetts. Oxygenated epilimnion waters always had total Iron concentrations of

T. Vargas - One of the best experts on this subject based on the ideXlab platform.

Paul R Norris - One of the best experts on this subject based on the ideXlab platform.

  • ore column leaching with thermophiles i copper sulfide ore
    Hydrometallurgy, 2012
    Co-Authors: Paul R Norris, Leonides A Calvobado, Carly F Brown, Carol S Davisbelmar
    Abstract:

    Abstract The concentrations of Ferrous Iron in ore column effluents and the pH of the effluents during the leaching of a copper sulfide ore were followed as an indication of the activity of the microbial populations that were established in the ore columns. The impact of this activity and the release of copper were influenced by addition of ferric Iron to the irrigation solution, by imposed anoxic conditions and, particularly at higher temperatures, by precipitation of oxidised Iron compounds. Moderately thermophilic, acidophilic actinobacteria appeared to dominate the microbial population at 47–57 °C with a transition to Ferrous Iron Oxidation by thermophilic archaea as the temperature was increased above 60 °C.

  • Ferrous Iron Oxidation and rusticyanin in halotolerant, acidophilic 'Thiobacillus prosperus'.
    Microbiology, 2009
    Co-Authors: James Le C. Nicolle, Susan Simmons, Stephan Bathe, Paul R Norris
    Abstract:

    The halotolerant acidophile ‘Thiobacillus prosperus’ was shown to require chloride for growth. With Ferrous Iron as substrate, growth occurred at a rate similar to that of the well-studied acidophile Acidithiobacillus ferrooxidans. Previously, the salt (NaCl) requirement of ‘T. prosperus’ was not clear and its growth on Ferrous Iron was described as poor. A subtractive hybridization of cDNAs from Ferrous-Iron-grown and sulfur-grown ‘T. prosperus’ strain V6 led to identification of a cluster of genes similar to the rus operon reported to encode Ferrous Iron Oxidation in A. ferrooxidans. However, the ‘T. prosperus’ gene cluster did not contain a homologue of cyc1, which is thought to encode a key cytochrome c in the pathway of electron transport from Ferrous Iron in A. ferrooxidans. Rusticyanin, another key protein in Ferrous Iron Oxidation by A. ferrooxidans, was present in ‘T. prosperus’ at similar concentrations in cells grown on either Ferrous Iron or sulfur.

  • Ferrous Iron Oxidation and leaching of copper ore with halotolerant bacteria in ore columns
    Hydrometallurgy, 2008
    Co-Authors: Carol S. Davis-belmar, James Le C. Nicolle, Paul R Norris
    Abstract:

    Growth on Ferrous Iron of a new isolate of the acidophile Thiobacillus prosperus occurred with a substrate Oxidation rate similar to that of Acidithiobacillus ferrooxidans. As well as similar capacities for Iron Oxidation, these species were shown to possess similar, but not identical, clusters of genes (the rus operon) that encode proteins likely to be involved in transfer of electrons from Ferrous Iron. Abundant rusticyanin was present in acidified, cell-free extracts of T prosperus. In contrast to these similarities between the species, T prosperus grew at a salt (NaCl) concentration several times that which prevented growth of A. ferrooxidans. A mixed culture of halotolerant bacteria maintained continuous Ferrous Iron Oxidation in the presence of 5% w/v NaCl in solution percolating through ore in laboratory columns, and so enhanced ferric Iron-dependent solubilization of copper. (C) 2008 Elsevier B.V. All rights reserved.

  • Ferrous Iron Oxidation by Salt-Tolerant “Thiobacillus prosperus”
    Advanced Materials Research, 2007
    Co-Authors: Carol S. Davis-belmar, James Le C. Nicolle, Paul R Norris
    Abstract:

    Growth on Ferrous Iron of a new isolate of the halotolerant acidophile “Thiobacillus prosperus” occurred with a substrate Oxidation rate similar to that of Acidithiobacillus ferrooxidans, but with a requirement for salt (NaCl). These observations contrast with the previous description of “T. prosperus” in which a salt requirement was not noted and growth on Ferrous Iron was described as poor. As well as similar capacities for Iron Oxidation, these species were shown to possess similar clusters of genes (the rus operon) that encode proteins likely to be involved in transfer of electrons from Ferrous Iron. There were some differences in the organization of the genes and one of them that encodes a cytochrome c in At. ferrooxidans was absent from the “T. prosperus” cluster.

  • Acidimicrobium ferrooxidans gen. nov., sp. nov.: mixed-culture Ferrous Iron Oxidation with Sulfobacillus species
    Microbiology, 1996
    Co-Authors: Darren A Clark, Paul R Norris
    Abstract:

    A new species of Ferrous-Iron-oxidizing, moderately thermophilic, acidophilic bacteria, Acidimicrobium ferrooxidans, has been described. Two isolates of the species differed only in the tendency of one, previously known as strain TH3, to grow in filaments. The chromosomal DNA base composition is between 67 and 69 mol% G + C. The capacity of this species to fix CO2 from air was greater than that of Iron-oxidizing thermoacidophiles of the genus Sulfobacillus, which required an enhanced CO2 concentration for optimum autotrophic growth. Under air, Ferrous Iron Oxidation in mixed cultures of A. ferrooxidans with either Sulfobacillus thermosulfidooxidans or Sulfobacillus acidophilus was more extensive than in pure cultures of these three strains. The greater part of Ferrous Iron Oxidation in mixed cultures probably resulted from activity of the Sulfobacillus species, which possess a greater tolerance of ferric Iron, and which presumably grew mixotrophically utilizing organic compounds from A. ferrooxidans.