John Pohlman, PhD
John Pohlman is a Research Chemist with the Woods Hole Coastal and Marine Science Center Gas Hydrates Project.
Science and Products
Filter Total Items: 62
The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin
Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling...
Authors
Ji-Hoon Kim, Marta E. Torres, Brian A. Haley, Miriam Kastner, John W. Pohlman, Michael Riedel, Young-Joo Lee
Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans
Marine sediments contain about 500–10,000 Gt of methane carbon1, 2, 3, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined1, 4, but it releases relatively little methane to the ocean and atmosphere5. Sedimentary microbes convert most of the dissolved methane to carbon...
Authors
John W. Pohlman, William F. Waite, James E. Bauer, Christopher L. Osburn, N. Ross Chapman
The biogeochemistry of anchialine caves: Progress and possibilities The biogeochemistry of anchialine caves: Progress and possibilities
Recent investigations of anchialine caves and sinkholes have identified complex food webs dependent on detrital and, in some cases, chemosynthetically produced organic matter. Chemosynthetic microbes in anchialine systems obtain energy from reduced compounds produced during organic matter degradation (e.g., sulfide, ammonium, and methane), similar to what occurs in deep ocean cold seeps...
Authors
John W. Pohlman
Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep
Delineating sediment organic matter origins and sediment accumulation rates at gas hydratebearing and hydrocarbon seeps is complicated by the microbial transfer of 13C-depleted and 14Cdepleted methane carbon into sedimentary pools. Sediment 13C and 14C measurements from four cores recovered at Bullseye vent on the northern Cascadia margin are used to identify methane carbon assimilation...
Authors
John W. Pohlman, Michael Riedel, Ivana Novosel, James E. Bauer, Elizabeth A. Canuel, Charles K. Paull, Richard B. Coffin, Kenneth S. Grabowski, David L. Knies, Roy D. Hyndman, George D. Spence
Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence
Gas hydrate was recovered from the Alaskan Beaufort Sea slope north of Camden Bay in August 2010 during a U.S. Coast Guard Cutter Healy expedition (USCG cruise ID HLY1002) under the direction of the U.S. Geological Survey (USGS). Interpretation of multichannel seismic (MCS) reflection data collected in 1977 by the USGS across the Beaufort Sea continental margin identified a regional...
Authors
Patrick E. Hart, John W. Pohlman, T.D. Lorenson, Brian D. Edwards
Observations of mass fractionation of noble gases in synthetic methane hydrate Observations of mass fractionation of noble gases in synthetic methane hydrate
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings are presently dissociating and releasing methane and other gases to the oceanatmosphere system. A key challenge in assessing the susceptibility of gas hydrates to warming climate is the lack of a technique able to distinguish between methane recently released from gas hydrates and...
Authors
Andrew G. Hunt, John W. Pohlman, Laura A. Stern, Carolyn D. Ruppel, Richard J. Moscati, Gary P. Landis, John C. Pinkston
Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand
Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS...
Authors
L.J. Hamdan, P.M. Gillevet, J. W. Pohlman, M. Sikaroodi, J. Greinert, R.B. Coffin
Macroscopic biofilms in fracture-dominated sediment that anaerobically oxidize methane Macroscopic biofilms in fracture-dominated sediment that anaerobically oxidize methane
Methane release from seafloor sediments is moderated, in part, by the anaerobic oxidation of methane (AOM) performed by consortia of archaea and bacteria. These consortia occur as isolated cells and aggregates within the sulfate-methane transition (SMT) of diffusion and seep-dominant environments. Here we report on a new SMT setting where the AOM consortium occurs as macroscopic pink to...
Authors
B.R. Briggs, J. W. Pohlman, M. Torres, M. Riedel, E.L. Brodie, F.S. Colwell
Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane? Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane?
The sulfate‐methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1–30 mbsf) in methane‐bearing marine sediments. Two processes consume sulfate at and above the SMT, anaerobic oxidation of methane (AOM) and organoclastic sulfate reduction (OSR). Differentiating the relative contribution of each process is...
Authors
A. Malinverno, John W. Pohlman
Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans
Marine sediments contain about 500-10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined, but it releases relatively little methane to the ocean and atmosphere. Sedimentary microbes convert most of the dissolved methane to carbon dioxide. Here we...
Authors
J. W. Pohlman, J.E. Bauer, W.F. Waite, C.L. Osburn, N.R. Chapman
Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system
The chemical and isotopic compositions of sedimentary organic matter (SOM) from two mid-slope sites of the northern Cascadia margin were investigated during Integrated Ocean Drilling Program (IODP) Expedition 311 to elucidate the organic matter origins and identify potential microbial contributions to SOM. Gas hydrate is present at both locations (IODP Sites U1327 and U1328), with...
Authors
Masanori Kaneko, Hiroshi Shingai, John W. Pohlman, Hiroshi Naraoka
Methane sources and production in the northern Cascadia margin gas hydrate system Methane sources and production in the northern Cascadia margin gas hydrate system
The oceanographic and tectonic conditions of accretionary margins are well-suited for several potential processes governing methane generation, storage and release. To identify the relevant methane evolution pathways in the northern Cascadia accretionary margin, a four-site transect was drilled during Integrated Ocean Drilling Program Expedition 311. The δ13C values of methane range from...
Authors
John W. Pohlman, Masanori Kaneko, Verena B. Heuer, Richard B. Coffin, Michael Whiticar
Science and Products
Filter Total Items: 62
The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin
Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling...
Authors
Ji-Hoon Kim, Marta E. Torres, Brian A. Haley, Miriam Kastner, John W. Pohlman, Michael Riedel, Young-Joo Lee
Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans
Marine sediments contain about 500–10,000 Gt of methane carbon1, 2, 3, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined1, 4, but it releases relatively little methane to the ocean and atmosphere5. Sedimentary microbes convert most of the dissolved methane to carbon...
Authors
John W. Pohlman, William F. Waite, James E. Bauer, Christopher L. Osburn, N. Ross Chapman
The biogeochemistry of anchialine caves: Progress and possibilities The biogeochemistry of anchialine caves: Progress and possibilities
Recent investigations of anchialine caves and sinkholes have identified complex food webs dependent on detrital and, in some cases, chemosynthetically produced organic matter. Chemosynthetic microbes in anchialine systems obtain energy from reduced compounds produced during organic matter degradation (e.g., sulfide, ammonium, and methane), similar to what occurs in deep ocean cold seeps...
Authors
John W. Pohlman
Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep Evidence and biogeochemical implications for glacially-derived sediments in an active margin cold seep
Delineating sediment organic matter origins and sediment accumulation rates at gas hydratebearing and hydrocarbon seeps is complicated by the microbial transfer of 13C-depleted and 14Cdepleted methane carbon into sedimentary pools. Sediment 13C and 14C measurements from four cores recovered at Bullseye vent on the northern Cascadia margin are used to identify methane carbon assimilation...
Authors
John W. Pohlman, Michael Riedel, Ivana Novosel, James E. Bauer, Elizabeth A. Canuel, Charles K. Paull, Richard B. Coffin, Kenneth S. Grabowski, David L. Knies, Roy D. Hyndman, George D. Spence
Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence
Gas hydrate was recovered from the Alaskan Beaufort Sea slope north of Camden Bay in August 2010 during a U.S. Coast Guard Cutter Healy expedition (USCG cruise ID HLY1002) under the direction of the U.S. Geological Survey (USGS). Interpretation of multichannel seismic (MCS) reflection data collected in 1977 by the USGS across the Beaufort Sea continental margin identified a regional...
Authors
Patrick E. Hart, John W. Pohlman, T.D. Lorenson, Brian D. Edwards
Observations of mass fractionation of noble gases in synthetic methane hydrate Observations of mass fractionation of noble gases in synthetic methane hydrate
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings are presently dissociating and releasing methane and other gases to the oceanatmosphere system. A key challenge in assessing the susceptibility of gas hydrates to warming climate is the lack of a technique able to distinguish between methane recently released from gas hydrates and...
Authors
Andrew G. Hunt, John W. Pohlman, Laura A. Stern, Carolyn D. Ruppel, Richard J. Moscati, Gary P. Landis, John C. Pinkston
Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand
Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS...
Authors
L.J. Hamdan, P.M. Gillevet, J. W. Pohlman, M. Sikaroodi, J. Greinert, R.B. Coffin
Macroscopic biofilms in fracture-dominated sediment that anaerobically oxidize methane Macroscopic biofilms in fracture-dominated sediment that anaerobically oxidize methane
Methane release from seafloor sediments is moderated, in part, by the anaerobic oxidation of methane (AOM) performed by consortia of archaea and bacteria. These consortia occur as isolated cells and aggregates within the sulfate-methane transition (SMT) of diffusion and seep-dominant environments. Here we report on a new SMT setting where the AOM consortium occurs as macroscopic pink to...
Authors
B.R. Briggs, J. W. Pohlman, M. Torres, M. Riedel, E.L. Brodie, F.S. Colwell
Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane? Modeling sulfate reduction in methane hydrate-bearing continental margin sediments: Does a sulfate-methane transition require anaerobic oxidation of methane?
The sulfate‐methane transition (SMT), a biogeochemical zone where sulfate and methane are metabolized, is commonly observed at shallow depths (1–30 mbsf) in methane‐bearing marine sediments. Two processes consume sulfate at and above the SMT, anaerobic oxidation of methane (AOM) and organoclastic sulfate reduction (OSR). Differentiating the relative contribution of each process is...
Authors
A. Malinverno, John W. Pohlman
Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans
Marine sediments contain about 500-10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined, but it releases relatively little methane to the ocean and atmosphere. Sedimentary microbes convert most of the dissolved methane to carbon dioxide. Here we...
Authors
J. W. Pohlman, J.E. Bauer, W.F. Waite, C.L. Osburn, N.R. Chapman
Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system
The chemical and isotopic compositions of sedimentary organic matter (SOM) from two mid-slope sites of the northern Cascadia margin were investigated during Integrated Ocean Drilling Program (IODP) Expedition 311 to elucidate the organic matter origins and identify potential microbial contributions to SOM. Gas hydrate is present at both locations (IODP Sites U1327 and U1328), with...
Authors
Masanori Kaneko, Hiroshi Shingai, John W. Pohlman, Hiroshi Naraoka
Methane sources and production in the northern Cascadia margin gas hydrate system Methane sources and production in the northern Cascadia margin gas hydrate system
The oceanographic and tectonic conditions of accretionary margins are well-suited for several potential processes governing methane generation, storage and release. To identify the relevant methane evolution pathways in the northern Cascadia accretionary margin, a four-site transect was drilled during Integrated Ocean Drilling Program Expedition 311. The δ13C values of methane range from...
Authors
John W. Pohlman, Masanori Kaneko, Verena B. Heuer, Richard B. Coffin, Michael Whiticar