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: 53
Anaerobic methane oxidation in low-organic content methane seep sediments
Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sedime
Authors
John W. Pohlman, Michael Riedel, James E. Bauer, Elizabeth A. Canuel, Charles K. Paull, Laura Lapham, Kenneth S. Grabowski, Richard B. Coffin, George D. Spence
Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hy
Authors
Andrew G. Hunt, Laura Stern, John W. Pohlman, Carolyn Ruppel, Richard J. Moscati, Gary P. Landis
Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments
Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to d
Authors
Ruo He, Matthew J. Wooller, John W. Pohlman, John Quensen, James M. Tiedje, Mary Beth Leigh
Identification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing
Arctic lakes are a significant source of the greenhouse gas methane (CH4), but the role that methane oxidizing bacteria (methanotrophs) play in limiting the overall CH4 flux is poorly understood. Here, we used stable isotope probing (SIP) techniques to identify the metabolically active aerobic methanotrophs in upper sediments (0–1 cm) from an arctic lake in northern Alaska sampled during ice-free
Authors
Ruo He, Matthew J. Wooller, John W. Pohlman, Catharine Catranis, John Quensen, James M. Tiedje, Mary Beth Leigh
Reconstruction of past methane availability in an Arctic Alaska wetland indicates climate influenced methane release during the past ~12,000 years
Atmospheric contributions of methane from Arctic wetlands during the Holocene are dynamic and linked to climate oscillations. However, long-term records linking climate variability to methane availability in Arctic wetlands are lacking. We present a multi-proxy ~12,000 year paleoecological reconstruction of intermittent methane availability from a radiocarbon-dated sediment core (LQ-West) taken fr
Authors
Matthew J. Wooller, John W. Pohlman, Benjamin V. Gaglioti, Peter Langdon, Miriam Jones, Katey M. Walter Anthony, Kevin W. Becker, Kai-Uwe Hinrichs, Marcus Elvert
Shifts in identity and activity of methanotrophs in arctic lake sediments in response to temperature changes
Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperaturesincrease, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is importantto predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), andpyrosequencing analyses to id
Authors
Ruo He, Matthew J. Wooller, John W. Pohlman, John Quensen, James M. Tiedje, Mary Beth Leigh
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 Program (
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
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 dioxide6, 7. Her
Authors
John W. Pohlman, William F. Waite, James E. Bauer, Christopher L. Osburn, N. Ross Chapman
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 and mud vo
Authors
John W. Pohlman
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 into diffe
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
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 bottom simulat
Authors
Patrick E. Hart, John W. Pohlman, T.D. Lorenson, Brian D. Edwards
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 methane e
Authors
Andrew G. Hunt, John W. Pohlman, Laura A. Stern, Carolyn D. Ruppel, Richard J. Moscati, Gary P. Landis, John C. Pinkston
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Filter Total Items: 53
Anaerobic methane oxidation in low-organic content methane seep sediments
Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sedimeAuthorsJohn W. Pohlman, Michael Riedel, James E. Bauer, Elizabeth A. Canuel, Charles K. Paull, Laura Lapham, Kenneth S. Grabowski, Richard B. Coffin, George D. SpenceMass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hyAuthorsAndrew G. Hunt, Laura Stern, John W. Pohlman, Carolyn Ruppel, Richard J. Moscati, Gary P. LandisDiversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments
Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to dAuthorsRuo He, Matthew J. Wooller, John W. Pohlman, John Quensen, James M. Tiedje, Mary Beth LeighIdentification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing
Arctic lakes are a significant source of the greenhouse gas methane (CH4), but the role that methane oxidizing bacteria (methanotrophs) play in limiting the overall CH4 flux is poorly understood. Here, we used stable isotope probing (SIP) techniques to identify the metabolically active aerobic methanotrophs in upper sediments (0–1 cm) from an arctic lake in northern Alaska sampled during ice-freeAuthorsRuo He, Matthew J. Wooller, John W. Pohlman, Catharine Catranis, John Quensen, James M. Tiedje, Mary Beth LeighReconstruction of past methane availability in an Arctic Alaska wetland indicates climate influenced methane release during the past ~12,000 years
Atmospheric contributions of methane from Arctic wetlands during the Holocene are dynamic and linked to climate oscillations. However, long-term records linking climate variability to methane availability in Arctic wetlands are lacking. We present a multi-proxy ~12,000 year paleoecological reconstruction of intermittent methane availability from a radiocarbon-dated sediment core (LQ-West) taken frAuthorsMatthew J. Wooller, John W. Pohlman, Benjamin V. Gaglioti, Peter Langdon, Miriam Jones, Katey M. Walter Anthony, Kevin W. Becker, Kai-Uwe Hinrichs, Marcus ElvertShifts in identity and activity of methanotrophs in arctic lake sediments in response to temperature changes
Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperaturesincrease, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is importantto predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), andpyrosequencing analyses to idAuthorsRuo He, Matthew J. Wooller, John W. Pohlman, John Quensen, James M. Tiedje, Mary Beth LeighThe 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 Program (AuthorsJi-Hoon Kim, Marta E. Torres, Brian A. Haley, Miriam Kastner, John W. Pohlman, Michael Riedel, Young-Joo LeeMethane 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 dioxide6, 7. HerAuthorsJohn W. Pohlman, William F. Waite, James E. Bauer, Christopher L. Osburn, N. Ross ChapmanThe 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 and mud voAuthorsJohn W. PohlmanEvidence 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 into diffeAuthorsJohn 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. SpenceBeaufort 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 bottom simulatAuthorsPatrick E. Hart, John W. Pohlman, T.D. Lorenson, Brian D. EdwardsObservations 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 methane eAuthorsAndrew G. Hunt, John W. Pohlman, Laura A. Stern, Carolyn D. Ruppel, Richard J. Moscati, Gary P. Landis, John C. Pinkston - News