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
Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation
Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter...
Authors
W.K. Oestreich, Neil K. Ganju, John W. Pohlman, Steven E. Suttles
Slipstream: an early Holocene slump and turbidite record from the frontal ridge of the Cascadia accretionary wedge off western Canada and paleoseismic implications Slipstream: an early Holocene slump and turbidite record from the frontal ridge of the Cascadia accretionary wedge off western Canada and paleoseismic implications
Slipstream Slump, a well-preserved 3 km wide sedimentary failure from the frontal ridge of the Cascadia accretionary wedge 85 km off Vancouver Island, Canada, was sampled during Canadian Coast Guard Ship (CCGS) John P. Tully cruise 2008007PGC along a transect of five piston cores. Shipboard sediment analysis and physical property logging revealed 12 turbidites interbedded with thick...
Authors
T.S. Hamilton, Randolph J. Enkin, Michael Riedel, Gary C. Rogers, John W. Pohlman, Heather M. Benway
Nonequilibrium clumped isotope signals in microbial methane Nonequilibrium clumped isotope signals in microbial methane
Methane is a key component in the global carbon cycle with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply-substituted “clumped” isotopologues, e.g., 13CH3D, has recently emerged as a proxy for determining methane-formation temperatures; however, the impact of...
Authors
David T. Wang, Danielle S. Gruen, Barbara Sherwood Lollar, Kai-Uwe Hinrichs, Lucy C. Stewart, James F. Holden, Alexander N. Hristov, John W. Pohlman, Penny L. Morrill, Martin Konneke, Kyle B. Delwiche, Eoghan P. Reeves, Chelsea N. Sutcliffe, Daniel J. Ritter, Jeffrey S. Seewald, Jennifer C. McIntosh, Harold F. Hemond, Michael D. Kubo, Dawn Cardace, Tori M. Hoehler, Shuhei Ono
Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change
Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of...
Authors
Benjamin V. Gaglioti, Daniel H. Mann, Benjamin M. Jones, John W. Pohlman, Michael L. Kunz, Matthew J. Wooller
A simple headspace equilibration method for measuring dissolved methane A simple headspace equilibration method for measuring dissolved methane
Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the...
Authors
C Magen, L. L. Lapham, John W. Pohlman, Kristin N. Marshall, S. Bosman, Michael Casso, J. P. Chanton
Anaerobic methane oxidation in low-organic content methane seep sediments 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...
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
Science and Products
Filter Total Items: 62
Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation
Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter...
Authors
W.K. Oestreich, Neil K. Ganju, John W. Pohlman, Steven E. Suttles
Slipstream: an early Holocene slump and turbidite record from the frontal ridge of the Cascadia accretionary wedge off western Canada and paleoseismic implications Slipstream: an early Holocene slump and turbidite record from the frontal ridge of the Cascadia accretionary wedge off western Canada and paleoseismic implications
Slipstream Slump, a well-preserved 3 km wide sedimentary failure from the frontal ridge of the Cascadia accretionary wedge 85 km off Vancouver Island, Canada, was sampled during Canadian Coast Guard Ship (CCGS) John P. Tully cruise 2008007PGC along a transect of five piston cores. Shipboard sediment analysis and physical property logging revealed 12 turbidites interbedded with thick...
Authors
T.S. Hamilton, Randolph J. Enkin, Michael Riedel, Gary C. Rogers, John W. Pohlman, Heather M. Benway
Nonequilibrium clumped isotope signals in microbial methane Nonequilibrium clumped isotope signals in microbial methane
Methane is a key component in the global carbon cycle with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply-substituted “clumped” isotopologues, e.g., 13CH3D, has recently emerged as a proxy for determining methane-formation temperatures; however, the impact of...
Authors
David T. Wang, Danielle S. Gruen, Barbara Sherwood Lollar, Kai-Uwe Hinrichs, Lucy C. Stewart, James F. Holden, Alexander N. Hristov, John W. Pohlman, Penny L. Morrill, Martin Konneke, Kyle B. Delwiche, Eoghan P. Reeves, Chelsea N. Sutcliffe, Daniel J. Ritter, Jeffrey S. Seewald, Jennifer C. McIntosh, Harold F. Hemond, Michael D. Kubo, Dawn Cardace, Tori M. Hoehler, Shuhei Ono
Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change
Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of...
Authors
Benjamin V. Gaglioti, Daniel H. Mann, Benjamin M. Jones, John W. Pohlman, Michael L. Kunz, Matthew J. Wooller
A simple headspace equilibration method for measuring dissolved methane A simple headspace equilibration method for measuring dissolved methane
Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the...
Authors
C Magen, L. L. Lapham, John W. Pohlman, Kristin N. Marshall, S. Bosman, Michael Casso, J. P. Chanton
Anaerobic methane oxidation in low-organic content methane seep sediments 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...
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