Index Catalog // ScholarsArchive@OSU

Creator:: McManus, James
Abstract:: The exchange of waters between the Pacific and the Southern Oceans occurs along the eastern boundary of the South Pacific. Because water masses of the Antarctic provide a connection among the world's ocean basins, these water masses maintain the ability to influence changes in ocean circulation and climate (Lynch-Stieglitz et...
Resource Type:: Article

Creator:: Wheat, C. Geoffrey, McManus, James, Mottl, Michael J., and Giambalvo, Emily
Abstract:: We present a new estimate for the crustal phosphorous sink that results from reactions among seawater, basalt, and sediment blanketing low temperature mid-ocean ridge flank hydrothermal systems. New estimates for global hydrothermal power output, sediment thickness, and the dissolved phosphate concentrations in basement formation fluids indicate that fluid flow through...
Resource Type:: Article

Creator:: McManus, James, Nägler, Thomas F., Siebert, Christopher, Wheat, C. Geoffrey, and Hammond, Douglas E.
Abstract:: Isotopic analyses of dissolved molybdenum are presented for sediment pore waters from a reducing sedimentary basin and for fluids from a low-temperature ridge flank hydrothermal system. δ⁹⁸/⁹⁵Mo in these fluids range from 0.8 to 3.5%₀ (relative to a laboratory standard), demonstrating that marine sedimentary reactions significantly fractionate Mo isotopes. Within...
Resource Type:: Article

Creator:: Wheat, C. Geoffrey and McManus, James
Abstract:: We present concentrations of germanium and silicon in sediment pore waters, basaltic formation fluids, and bulk sediment from three ridge flank hydrothermal systems (RFHS). Basaltic formation fluids from warm (>30°C) RFHS have much higher Ge concentrations and Ge:Si molar ratios than overlying sediment pore waters, requiring seawater-basalt reactions to dominate...
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Creator:: Hammond, Douglas E., McManus, James, and Berelson, William M.
Abstract:: Diatom remains indicate the oceanic Ge/Si ratio (μmol/mol) has varied temporally, ranging from Miocene values of 0.9 to Last Glacial Maximum (LGM) values of 0.55, with the present value of 0.69. These ratios lie between those for the primary sources for these elements: continental weathering (Ge/Si = 0.5) and hydrothermal...
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Creator:: Poulson Brucker, Rebecca L., McManus, James, Severmann, Silke, and Berelson, William M.
Abstract:: We present molybdenum isotope and concentration data from 14 sites in the eastern Pacific from the central California to the Peru margin. The environments studied have been chosen to represent a broad range in oxidation-reduction (redox) potential, which provide a framework for the behavior of this redox-sensitive element. Manganese-rich hemipelagic...
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Creator:: Torres, Marta E., Mix, Alan C., Kinports, K., Haley, Brian A., Klinkhammer, Gary P., McManus, James, and de Angelis, M. A.
Abstract:: The isotopic composition of the dissolved inorganic carbon (DIC) collected at sites of active methane discharge on Hydrate Ridge, Oregon, reveals anaerobic methane oxidation mediated by bacteria, with δ13CDIC reaching values as low as –48‰ in the upper 4 cm of the sediment. In spite of the high sulfide levels...
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Creator:: Hulme, Samuel M., Wheat, C. Geoffrey, Coggon, Rosalind M., and McManus, James
Abstract:: The data presented in this report demonstrate significant improvements in the ability to constrain trace element and Sr isotopic concentrations in sediments overlying ridge-flank hydrothermal systems. Improved sampling methods orchestrated by the Integrated Ocean Drilling Program (i.e., advanced piston coring and anoxic sample processing) enabled the collection of reactive pore...
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Creator:: McManus, James, Heinen, Erik A., and Baehr, Matthew M.
Abstract:: On average, the water column of Lake Superior is undersaturated with respect to dissolved oxygen and supersaturated with respect to carbon dioxide during the summer-stratified period. On the basis of temporal changes in water column dissolved oxygen, we calculate rates of oxygen consumption that range from 0.19 to 0.75 mmol...
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Creator:: Hammond, Douglas E., Cummins, Kathleen M., McManus, James, Berelson, William M., Smith, Gerry, and Spagnoli, Federico
Abstract:: The objective of this study was to compare two techniques for estimating benthic fluxes of nutrients (nitrate, phosphate, and silicic acid) and Ge/Si flux ratios. In situ flux chambers were deployed, and cores were collected and incubated at 9 sites along the California margin in July 2001. Both techniques were...
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