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Helmuth Thomas

Professor
Canada Research Chair, Tier II: Marine Biogeochemistry

Email: helmuth.thomas@dal.ca

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Recent Submissions

  • Annual cycles of pCO (sub 2) in the southeastern Beaufort Sea; new understandings of air-sea CO (sub 2) exchange in Arctic polynya regions 

    Else, B. G. T., T. N. Papakyriakou, R. J. Galley, A. Mucci, et al. 2012. "Annual cycles of pCO (sub 2) in the southeastern Beaufort Sea; new understandings of air-sea CO (sub 2) exchange in Arctic polynya regions." Journal of Geophysical Research 117(C): 0013-Citation C00G13.
    From 23 October 2007 to 1 August 2008, we made continuous measurements of sea surface partial pressure of CO (sub 2) (pCO (sub 2sw) ) in three regions of the southeastern Beaufort Sea (Canada): the Amundsen Gulf, the Banks ...
  • Wintertime CO (sub 2) fluxes in an Arctic polynya using eddy covariance; evidence for enhanced air-sea gas transfer during ice formation 

    Else, B. G. T., T. N. Papakyriakou, R. J. Galley, W. M. Drennan, et al. 2011. "Wintertime CO (sub 2) fluxes in an Arctic polynya using eddy covariance; evidence for enhanced air-sea gas transfer during ice formation." Journal of Geophysical Research 116(C): 0003-Citation C00G03.
    Between Nov. 1 2007 and Jan. 31 2008, we calculated the air-sea flux of CO (sub 2) , sensible heat, and water vapor in an Arctic polynya system (Amundsen Gulf, Canada) using eddy covariance equipment deployed on the research ...
  • Pore-water diffusive fluxes of (super 224) Ra and CO (sub 2) in Bedford Basin, Nova Scotia 

    Burt, William, Helmuth Thomas, Katja Fennel, John N. Smith, et al. 2012. "Pore-water diffusive fluxes of (super 224) Ra and CO (sub 2) in Bedford Basin, Nova Scotia." Mineralogical Magazine 76(6): 1531.
    On the seafloor, chemical processes occurring within sediments create pore-waters highly enriched in various chemical constituents. Many of these processes are fuelled by particulate organic matter (POM), generated during ...
  • Impact of biogeochemical processes and environmental factors on the calcium carbonate saturation state in the Circumpolar Flaw Lead in the Amundsen Gulf, Arctic Ocean 

    Chierici, Melissa, Agneta Fransson, Bruno Lansard, Lisa A. Miller, et al. 2011. "Impact of biogeochemical processes and environmental factors on the calcium carbonate saturation state in the Circumpolar Flaw Lead in the Amundsen Gulf, Arctic Ocean." Journal of Geophysical Research-Oceans 116: 0009-C00G09.
    We report on measurements across an annual cycle of carbon dioxide system parameters in the polar mixed layer (PML) of the circumpolar flaw lead in the Amundsen Gulf, Arctic Ocean. From these and other properties (nitrate, ...
  • Preferential recycling of nutrients - the ocean's way to increase new production and to pass nutrient limitation? 

    Thomas, H., V. Ittekkot, C. Osterroht, and B. Schneider. 1999. "Preferential recycling of nutrients - the ocean's way to increase new production and to pass nutrient limitation?." Limnology and Oceanography 44(8): 1999-2004.
    Uptake of atmospheric CO2 by the oceans and the export of carbon into deeper waters via the biological CO2 pump is driven by the production of particulate organic matter (POM). The elemental ratios of carbon, nitrogen, and ...
  • Determination of anthropogenic CO2 in the North Atlantic Ocean using water mass ages and CO2 equilibrium chemistry 

    Thomas, H., and V. Ittekkot. 2001. "Determination of anthropogenic CO2 in the North Atlantic Ocean using water mass ages and CO2 equilibrium chemistry." Journal of Marine Systems 27(4): 325-336.
    A new method to calculate the anthropogenic CO2 (Delta DICant) within the water column of the North Atlantic Ocean is presented. The method exploits the equilibrium chemistry of the carbonate system with reference to ...
  • Autotrophy, nitrogen accumulation and nitrogen limitation in the Baltic Sea: A paradox or a buffer for eutrophication? 

    Thomas, H., J. Pempkowiak, F. Wulff, and K. Nagel. 2003. "Autotrophy, nitrogen accumulation and nitrogen limitation in the Baltic Sea: A paradox or a buffer for eutrophication?." Geophysical Research Letters 30(21): 2130-2130.
    [1] The autotrophic Baltic Sea acts as a sink for atmospheric CO2, however it is also characterised by nitrogen limitation and nitrogen accumulation, the latter indicating heterotrophy. Physical and biogeochemical processes ...
  • An off-line 3D model of anthropogenic CO2 uptake by the oceans 

    Thomas, H., MH England, and V. Ittekkot. 2001. "An off-line 3D model of anthropogenic CO2 uptake by the oceans." Geophysical Research Letters 28(3): 547-550.
    A key unanswered question in global climate research is the extent to which the oceans absorb and redistribute anthropogenic CO2 (Delta DICant). We apply an offline ocean carbon cycle model, one that uses atmospheric CO2 ...
  • Different oceanic features of anthropogenic CO2 and CFCs 

    Thomas, H., and MH England. 2002. "Different oceanic features of anthropogenic CO2 and CFCs." Naturwissenschaften 89(9): 399-403.
    The relationship between CFC-11 and anthropogenic CO2 (DeltaDIC(ant)) concentrations in the world ocean are evaluated based on a simple off-line tracer ventilation model. Since the different solubility characteristics of ...
  • Response to Comment on "Enhanced Open Ocean Storage of CO sub(2) from Shelf Sea Pumping" 

    Thomas, Helmuth, Khalid Elkalay, and HJW de Baar. 2004. "Response to Comment on "Enhanced Open Ocean Storage of CO sub(2) from Shelf Sea Pumping"." Science (Washington) 306(5701): 1477.
    The comment by Cai and Dai recognizes the good design of our high-resolution carbon cycle study in the North Sea but purports to caution against the common practice of extrapolating regional results to a global scale. We ...
  • Barium and carbon fluxes in the Canadian Arctic Archipelago 

    Thomas, Helmuth, Elizabeth Shadwick, Frank Dehairs, Bruno Lansard, et al. 2011. "Barium and carbon fluxes in the Canadian Arctic Archipelago." Journal of Geophysical Research-Oceans 116: 0008-C00G08.
    [1] The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type ...
  • Changes in the North Atlantic Oscillation influence CO2 uptake in the North Atlantic over the past 2 decades 

    Thomas, Helmuth, A. E. Friederike Prowe, Ivan D. Lima, Scott C. Doney, et al. 2009. "Changes in the North Atlantic Oscillation influence CO2 uptake in the North Atlantic over the past 2 decades." Global Biogeochemical Cycles 22(4).
    Observational studies report a rapid decline of ocean CO2 uptake in the temperate North Atlantic during the last decade. We analyze these findings using ocean physical-biological numerical simulations forced with interannually ...
  • Rapid decline of the CO2 buffering capacity in the North Sea and implications for the North Atlantic Ocean 

    Thomas, Helmuth, A. E. Friederike Prowe, Steven van Heuven, Yann Bozec, et al. 2007. "Rapid decline of the CO2 buffering capacity in the North Sea and implications for the North Atlantic Ocean." Global Biogeochemical Cycles 21(4): 4001-GB4001.
    New observations from the North Sea, a NW European shelf sea, show that between 2001 and 2005 the CO2 partial pressure (pCO(2)) in surface waters rose by 22 mu atm, thus faster than atmospheric pCO(2), which in the same ...
  • The seasonal cycle of carbon dioxide in Baltic Sea surface waters 

    Thomas, H., and B. Schneider. 1999. "The seasonal cycle of carbon dioxide in Baltic Sea surface waters." Journal of Marine Systems 22(1): 53-67.
    A detailed analysis of the seasonal cycle of carbon dioxide (CO(2)) within the surface waters of the Baltic Proper is presented. Based on the data sets of two cruises during winter and summer, a model has been developed ...
  • Biogeochemistry of coastal seas and continental shelves - Including biogeochemistry during the International Polar Year 

    Thomas, Helmuth, and Alberto V. Borges. 2012. "Biogeochemistry of coastal seas and continental shelves - Including biogeochemistry during the International Polar Year." Estuarine Coastal and Shelf Science 100: 1-2.
    No abstract available.
  • Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from Ra-224 measurements 

    Burt, W. J., H. Thomas, K. Fennel, and E. Horne. 2013. "Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from Ra-224 measurements." Biogeosciences 10(1): 53-66.
    Exchanges between sediment pore waters and the overlying water column play a significant role in the chemical budgets of many important chemical constituents. Direct quantification of such benthic fluxes requires explicit ...
  • Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments 

    Thomas, H., L-S Schiettecatte, K. Suykens, YJ M Kone, et al. 2008. "Enhanced ocean carbon storage from anaerobic alkalinity generation in coastal sediments." Biogeosciences Discussions 5(4): 3575-3591.
    The coastal ocean constitutes the crucial link between land, the open ocean and the atmosphere. Furthermore, its shallow water column permits close interactions between the sedimentary and atmospheric compartments, which ...
  • Planktic foraminiferal dissolution in the twilight zone 

    Schiebel, Ralf, Stephen Barker, Ralf Lendt, Helmuth Thomas, et al. 2007. "Planktic foraminiferal dissolution in the twilight zone." Deep-Sea Research.Part II: Topical Studies in Oceanography 54(5-7): 676-686.
    No abstract available.
  • Carbon cycling in the Arctic Archipelago: the export of Pacific carbon to the North Atlantic 

    Shadwick, E. H., T. Papakyriakou, AEF Prowe, D. Leong, et al. 2009. "Carbon cycling in the Arctic Archipelago: the export of Pacific carbon to the North Atlantic." Biogeosciences Discussions 6(1): 971-994.
    The Arctic Ocean is expected to be disproportionately sensitive to climatic changes, and is thought to be an area where such changes might be detected. The Arctic hydrological cycle is influenced by: runoff and precipitation, ...
  • Seasonal variability of dissolved inorganic carbon and surface water pCO2 in the Scotian Shelf region of the Northwestern Atlantic 

    Shadwick, E. H., H. Thomas, K. Azetsu-Scott, BJW Greenan, et al. 2011. "Seasonal variability of dissolved inorganic carbon and surface water pCO2 in the Scotian Shelf region of the Northwestern Atlantic." Marine Chemistry 124(1-4): 23-37.
    The seasonal variability of inorganic carbon in the surface waters of the Scotian Shelf region of the Canadian northwestern Atlantic Ocean was investigated. Seasonal variability was assessed using hourly measurements, ...

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