Orit Sivan | Ben Gurion University of the Negev (original) (raw)

Papers by Orit Sivan

Research paper thumbnail of Metagenomic insights into the metabolism of microbial communities that mediate iron and methane cycling in Lake Kinneret iron-rich methanic sediments

Biogeosciences, Mar 23, 2021

Research paper thumbnail of Fire and Brimstone: The Microbially Mediated Formation of Elemental Sulfur Nodules from an Isotope and Major Element Study in the Paleo-Dead Sea

Research paper thumbnail of Oxygen isotopic composition of sulfate in deep sea pore fluid: evidence for rapid sulfur cycling

Research paper thumbnail of Rates of methanogenesis and methanotrophy in deep-sea sediments

Geobiology, Jun 1, 2007

We use the carbon isotopic composition (δ 13 C) of the dissolved inorganic carbon (DIC) of pore f... more We use the carbon isotopic composition (δ 13 C) of the dissolved inorganic carbon (DIC) of pore fluids from Leg 175 of the Ocean Drilling Program (ODP) along the West African Margin to quantify rates of methane production (methanogenesis) and destruction via oxidation (methanotrophy) in deep-sea sediments. Results from a model of diffusion and reaction in the sedimentary column show that anaerobic methane oxidation (AOM) occurs in the transition zone between the presence of sulfate and methane, and methanogenesis occurs below these depths in a narrow confined zone that ends at about 250 m below the sea-sediments surface in all sediment profiles. Our model suggests that the rates of methanogenesis and AOM range between 6 • 10 − 8 and 1 • 10 − 10 mol cm − 3 year − 1 at all sites, with higher rates at sites where sulfate is depleted in shallower depths. Our AOM rates agree with those based solely on sulfate concentration profiles, but are much lower than those calculated from experiments of sulfate reduction through AOM done under laboratory conditions. At sites where the total organic carbon (TOC) is less than 5% of the total sediment, we calculate that AOM is the main pathway for sulfate reduction. We calculate that higher rates of AOM are associated with increased recrystallization rates of carbonate minerals. We do not find a correlation between methanogenesis rates and the content of carbonate or TOC in the sediments, porosity, sedimentation rate, or the C:N ratio, and the cause of lack of methanogenesis below a certain depth is not clear. There does, however, appear to be an association between the rates of methanogenesis and the location of the site in the upwelling system, suggesting that some variable such as the type of the organic matter or the nature of the microbiological community may be important.

Research paper thumbnail of Aerobic methanotrophic activity in anoxic lake sediments

Goldschmidt2022 abstracts, 2022

Research paper thumbnail of Quantifying rates of methanogenesis and methanotrophy in Lake Kinneret sediments (Israel) using pore-water profiles

Limnology and Oceanography, Jul 1, 2011

Research paper thumbnail of Correction: Challenges and approaches for management of seawater intrusion in coastal aquifers

Hydrogeology Journal, Jan 21, 2023

Research paper thumbnail of The distribution of saline groundwater and its relation to the hydraulic conditions of aquifers and aquitards: examples from Israel

Hydrogeology Journal, Oct 2, 2010

Research paper thumbnail of Aerobic methanotrophic activity stimulates iron reduction in lake sediments&#160

Research paper thumbnail of The effect of pumping saline groundwater for desalination on the fresh–saline water interface dynamics

Water Research, Jun 1, 2019

Research paper thumbnail of Isotopic evidence for the origin of dimethylsulfide and dimethylsulfoniopropionate-like compounds in a warm, monomictic freshwater lake

Environmental Chemistry, 2016

Research paper thumbnail of Redox condition of saline groundwater from coastal aquifers influences reverse osmosis desalination process

Research paper thumbnail of Challenges and approaches for management of seawater intrusion in coastal aquifers

Hydrogeology Journal, Nov 30, 2022

Coastal aquifers provide water for over one billion people worldwide; however, they face seawater... more Coastal aquifers provide water for over one billion people worldwide; however, they face seawater intrusion due to overpumping. The current and future challenges of coastal aquifer management involve issues such as climate change and the control of abstraction and recharge. Different management approaches are being used globally to prevent aquifer salinization. This essay presents the challenges and possible solutions while also discussing the different approaches and their needs for improvement.

Research paper thumbnail of Potential electron acceptors for anaerobic methane oxidation during long-term incubations of lake sediments

Goldschmidt2021 abstracts, 2021

Research paper thumbnail of The formation of elemental sulfur nodules ; A modified ‘ thiosulfate shunt ’ in unique environments

It is widely accepted that the generation of arc magmas is triggered by fluids released from the ... more It is widely accepted that the generation of arc magmas is triggered by fluids released from the subducting slab and by their interaction with the overlying mantle wedge [1]. The major lithologies involved in devolatilization are pelites, hydrothermally altered basalts, and serpentinized harzburgites. Thermodynamic calculations and experiments predict that HP fluids are dominated by H2O. Nevertheless, the importance of carbon species has been highlighted in the last years because of the relevant CO2 content of arc magmas and the observation of carbon-bearing phases in mantle-wedge peridotites. Experiments have shown that the release of volatiles extends over several tens of km depths and result from a succession of continuous and discontinuous reactions involving hydrous phases in the subducted lithosphere, such as antigorite and chlorite in ultramafics; amphibole, lawsonite, zoisite, and chloritoid in mafic rocks. Phengite and biotite are involved in melting reactions of a variety ...

Research paper thumbnail of Aerobic methanotrophy increases the net iron reduction in methanogenic lake sediments

Frontiers in Microbiology, Jul 27, 2023

Research paper thumbnail of Geochemical evidence for iron-mediated anaerobic oxidation of methane

Limnology and Oceanography, Jul 1, 2011

Anaerobic oxidation of methane (AOM) by sulfate has been recognized as a critical process to main... more Anaerobic oxidation of methane (AOM) by sulfate has been recognized as a critical process to maintain this greenhouse gas stability by limiting methane flux to the atmosphere. We show geochemical evidence for AOM in deep lake sediments and demonstrate that AOM is likely driven by iron (Fe) reduction. Pore-water profiles from Lake Kinneret (Sea of Galilee, Israel) show that this sink for methane is located below the 20-cm depth in the sediment, which is well below the depths at which nitrate and sulfate are completely exhausted, as well as below the zone of methanogenesis. Iron-dependant AOM was verified by Fe(III)-amended mesocosm studies using intact sediment cores, and native iron oxides were detectable throughout the sediments. Because anaerobic Fe(III) respiration is thermodynamically more favorable than both sulfate-dependent methanotrophy and methanogenesis, its occurrence below the zone of methane production supports the idea that reduction of sedimentary iron oxides is kinetically or biologically limited. Similar conditions are likely to prevail in other incompletely pyritized aquatic sediments, indicating that AOM with Fe(III) is an important global sink for methane.

Research paper thumbnail of Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments

Frontiers in Marine Science, Sep 15, 2022

Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine se... more Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments.

Research paper thumbnail of Authigenic Iron Minerals Associated with Iron and Methane Coupling in Marine Sediments

Goldschmidt Abstracts, 2020

Research paper thumbnail of Evidence for microbial iron reduction in the methanic sediments of the oligotrophic southeastern Mediterranean continental shelf

Biogeosciences, Aug 23, 2019

Research paper thumbnail of Metagenomic insights into the metabolism of microbial communities that mediate iron and methane cycling in Lake Kinneret iron-rich methanic sediments

Biogeosciences, Mar 23, 2021

Research paper thumbnail of Fire and Brimstone: The Microbially Mediated Formation of Elemental Sulfur Nodules from an Isotope and Major Element Study in the Paleo-Dead Sea

Research paper thumbnail of Oxygen isotopic composition of sulfate in deep sea pore fluid: evidence for rapid sulfur cycling

Research paper thumbnail of Rates of methanogenesis and methanotrophy in deep-sea sediments

Geobiology, Jun 1, 2007

We use the carbon isotopic composition (δ 13 C) of the dissolved inorganic carbon (DIC) of pore f... more We use the carbon isotopic composition (δ 13 C) of the dissolved inorganic carbon (DIC) of pore fluids from Leg 175 of the Ocean Drilling Program (ODP) along the West African Margin to quantify rates of methane production (methanogenesis) and destruction via oxidation (methanotrophy) in deep-sea sediments. Results from a model of diffusion and reaction in the sedimentary column show that anaerobic methane oxidation (AOM) occurs in the transition zone between the presence of sulfate and methane, and methanogenesis occurs below these depths in a narrow confined zone that ends at about 250 m below the sea-sediments surface in all sediment profiles. Our model suggests that the rates of methanogenesis and AOM range between 6 • 10 − 8 and 1 • 10 − 10 mol cm − 3 year − 1 at all sites, with higher rates at sites where sulfate is depleted in shallower depths. Our AOM rates agree with those based solely on sulfate concentration profiles, but are much lower than those calculated from experiments of sulfate reduction through AOM done under laboratory conditions. At sites where the total organic carbon (TOC) is less than 5% of the total sediment, we calculate that AOM is the main pathway for sulfate reduction. We calculate that higher rates of AOM are associated with increased recrystallization rates of carbonate minerals. We do not find a correlation between methanogenesis rates and the content of carbonate or TOC in the sediments, porosity, sedimentation rate, or the C:N ratio, and the cause of lack of methanogenesis below a certain depth is not clear. There does, however, appear to be an association between the rates of methanogenesis and the location of the site in the upwelling system, suggesting that some variable such as the type of the organic matter or the nature of the microbiological community may be important.

Research paper thumbnail of Aerobic methanotrophic activity in anoxic lake sediments

Goldschmidt2022 abstracts, 2022

Research paper thumbnail of Quantifying rates of methanogenesis and methanotrophy in Lake Kinneret sediments (Israel) using pore-water profiles

Limnology and Oceanography, Jul 1, 2011

Research paper thumbnail of Correction: Challenges and approaches for management of seawater intrusion in coastal aquifers

Hydrogeology Journal, Jan 21, 2023

Research paper thumbnail of The distribution of saline groundwater and its relation to the hydraulic conditions of aquifers and aquitards: examples from Israel

Hydrogeology Journal, Oct 2, 2010

Research paper thumbnail of Aerobic methanotrophic activity stimulates iron reduction in lake sediments&#160

Research paper thumbnail of The effect of pumping saline groundwater for desalination on the fresh–saline water interface dynamics

Water Research, Jun 1, 2019

Research paper thumbnail of Isotopic evidence for the origin of dimethylsulfide and dimethylsulfoniopropionate-like compounds in a warm, monomictic freshwater lake

Environmental Chemistry, 2016

Research paper thumbnail of Redox condition of saline groundwater from coastal aquifers influences reverse osmosis desalination process

Research paper thumbnail of Challenges and approaches for management of seawater intrusion in coastal aquifers

Hydrogeology Journal, Nov 30, 2022

Coastal aquifers provide water for over one billion people worldwide; however, they face seawater... more Coastal aquifers provide water for over one billion people worldwide; however, they face seawater intrusion due to overpumping. The current and future challenges of coastal aquifer management involve issues such as climate change and the control of abstraction and recharge. Different management approaches are being used globally to prevent aquifer salinization. This essay presents the challenges and possible solutions while also discussing the different approaches and their needs for improvement.

Research paper thumbnail of Potential electron acceptors for anaerobic methane oxidation during long-term incubations of lake sediments

Goldschmidt2021 abstracts, 2021

Research paper thumbnail of The formation of elemental sulfur nodules ; A modified ‘ thiosulfate shunt ’ in unique environments

It is widely accepted that the generation of arc magmas is triggered by fluids released from the ... more It is widely accepted that the generation of arc magmas is triggered by fluids released from the subducting slab and by their interaction with the overlying mantle wedge [1]. The major lithologies involved in devolatilization are pelites, hydrothermally altered basalts, and serpentinized harzburgites. Thermodynamic calculations and experiments predict that HP fluids are dominated by H2O. Nevertheless, the importance of carbon species has been highlighted in the last years because of the relevant CO2 content of arc magmas and the observation of carbon-bearing phases in mantle-wedge peridotites. Experiments have shown that the release of volatiles extends over several tens of km depths and result from a succession of continuous and discontinuous reactions involving hydrous phases in the subducted lithosphere, such as antigorite and chlorite in ultramafics; amphibole, lawsonite, zoisite, and chloritoid in mafic rocks. Phengite and biotite are involved in melting reactions of a variety ...

Research paper thumbnail of Aerobic methanotrophy increases the net iron reduction in methanogenic lake sediments

Frontiers in Microbiology, Jul 27, 2023

Research paper thumbnail of Geochemical evidence for iron-mediated anaerobic oxidation of methane

Limnology and Oceanography, Jul 1, 2011

Anaerobic oxidation of methane (AOM) by sulfate has been recognized as a critical process to main... more Anaerobic oxidation of methane (AOM) by sulfate has been recognized as a critical process to maintain this greenhouse gas stability by limiting methane flux to the atmosphere. We show geochemical evidence for AOM in deep lake sediments and demonstrate that AOM is likely driven by iron (Fe) reduction. Pore-water profiles from Lake Kinneret (Sea of Galilee, Israel) show that this sink for methane is located below the 20-cm depth in the sediment, which is well below the depths at which nitrate and sulfate are completely exhausted, as well as below the zone of methanogenesis. Iron-dependant AOM was verified by Fe(III)-amended mesocosm studies using intact sediment cores, and native iron oxides were detectable throughout the sediments. Because anaerobic Fe(III) respiration is thermodynamically more favorable than both sulfate-dependent methanotrophy and methanogenesis, its occurrence below the zone of methane production supports the idea that reduction of sedimentary iron oxides is kinetically or biologically limited. Similar conditions are likely to prevail in other incompletely pyritized aquatic sediments, indicating that AOM with Fe(III) is an important global sink for methane.

Research paper thumbnail of Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments

Frontiers in Marine Science, Sep 15, 2022

Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine se... more Iron oxides impact sulfate-driven anaerobic oxidation of methane in diffusion-dominated marine sediments.

Research paper thumbnail of Authigenic Iron Minerals Associated with Iron and Methane Coupling in Marine Sediments

Goldschmidt Abstracts, 2020

Research paper thumbnail of Evidence for microbial iron reduction in the methanic sediments of the oligotrophic southeastern Mediterranean continental shelf

Biogeosciences, Aug 23, 2019