Application form InterRidge Student and Postdoctoral Fellowship ...

More documents

Recommendations

Info

e derived from biological processes. Second, previous experiments investigating hydrocarbonproduction at thermal decomposition of organic matter have been carried out at atmosphericconditions (under vacuum, argon, and so on) using artificial chemical substrates, but not underhigh hydraulic pressure using environmental samples. Obvisouly, water and co-existing mineralsin the sediment are important factors for thermal reaction of organic matter via controlling fO 2 .Threfore, the thermal experiments carried out previously [e.g., Galimov, 1988] might mislead thethermogenic area on the map.The objective of the proposed research project is to determine (refine) thermogeniccharacteristics of methane and relative molecules (H 2 , CO 2 , and hydrocarbons) by hydrothermalexperiments using seafloor sediment. Moreover, based on the thermogenic characteristicsdetermined by this project, novel and/or refined tracers for interpretations of the origin ofsediment-derived methane will be proposed.(c) Outline the approach (e.g., experimental design, observations, and/or modeling) andmethod(s):For the objectives mentioned above, an experiment handling thermal decomposition ofsedimentary organic matter under hydrothermal conditions (pressure, temperature, and naturalwater-sediment ratio) will be performed. The hydrothermal experiment is a direct way to figureout the characteristics of products through thermal reaction of sedimentary organic matter.A flexible-cell hydrothermal apparatus (Seewald et a., 1994) will be used for hydrothermalexperiment. Prior to heating the cell, sediment will be poisoned to avoid any biological activityand disturbed with helium bubbling to desorb physically attached gases on sediment surface.Stepwise heating (~50oC intervals by each 3days) up to 350oC (comparable with maximum fluidtemperature in the Okinawa Trough) and fluid sampling at each temperature phase will becarried out. Dissolved gases in sampled fluid will be extracted by fluid introduction into preevacuatedvials. Gas compositional (concentrations of CH 4 , H 2 , CO 2 , and hydrocarbons) andisotopic (δ 13 C-CH 4 , δ 13 C-C 2 H 6 , and δD-CH 4 ) properties will be determined using GC-FID andGC-IRMS.(d) Specify the duration and location of the research project, and the nature of thescientific cooperation (i.e., demonstrate the international dimension of the project):Proposed research projects will be done in WHOI, where the flexible-cell hydrothermalapparatus has been well established. The hydrothermal experiment (heating the sediment) willtake 20 days (~500 hours: Seewald et al. 1994) while gas analyses can be done along with theheating. In addition to the experiment, sample and apparatus preparation (~3 days) andinterpretation about observation datasets from sediment-covered hydrothermal systems (mydataset for Okinawa Trough sites while Dr. Seewald’s dataset for Middle Valley and Guaymassites) using the experimental result (~3 days) are also considered necessary. Together, thisproject will take approximately 1 month. There are two international dimensions in this project:international laboratory use and international data synthesis between US and Japan.
(e) Expected significance and impact of the results:The experimental results will reveal typical geochemical characteristics of the thermogeniccomposition, which contributes to divide the sediment-derived geochemical signatures intothermal and biological processes. These results will be of great importance in subsurfacemicrobiology as well as hydrogeology associated with hydrothermalism. For example, thepresence of sediment-derived biogenic methane in the high temperature hydrothermal fluid couldbe disclosed by distinguishing thermogenic methane from the sediment-derived methane. It alsoindicates a sediment-trophic methanogenic microbial ecosystem occurring at low-temperaturefluid recharge zone in addition to a vent-fluid-trophic ecosystem occurring at around fluid ventorifice. Furthermore, to elucidate the subsurface methane production rate at hydrothermalrecharge zones (by coring/drilling sample analyses) will enable to analyze the quantitativecomparison between the efflux of biogenic methane and the methane production rate, whichcould narrow down the spatial distribution of hydrothermal recharge zones that have not beenidentified thus far.(f) References:Cruse, A. M., and J. S. Seewald (2006), Geochemistry of low-molecular weight hydrocarbons in hydrothermal fluids fromMiddle Valley, northern Juan de Fuca Ridge, Geochimica Et Cosmochimica Acta, 70(8), 2073-2092.Galimov, E. M. (1988), Sources and Mechanisms of Formation of Gaseous Hydrocarbons in Sedimentary-Rocks, ChemicalGeology, 71(1-3), 77-95.Ishibashi, J., et al. (1995), Helium and Carbon Geochemistry of Hydrothermal Fluids from the Mid-Okinawa Trough Back-ArcBasin, Southwest of Japan, Chemical Geology, 123(1-4), 1-15.Kawagucci, S. H. Chiba, J. Ishibashi, T. Yamanaka, T. Toki, Y. Muramatsu, Y. Ueno, A. Makabe, K. Inoue, N. Yoshida, S.Nakagawa, T. Nunoura, K. Takai, N. Takahata, Y. Sano, T. Narita, G. Teranishi, H. Obata, and T. Gamo, Hydrothermalfluid geochemistry at the Iheya North field in the mid-Okinawa Trough, submitted to Geochemical Journal.Parkes, R. J., et al. (2007), Temperature activation of organic matter and minerals during burial has the potential to sustain thedeep biosphere over geological timescales, Organic Geochemistry, 38(6), 845-852.Pearson, A., et al. (2005), Bacterial incorporation of relict carbon in the hydrothermal environment of Guaymas Basin,Geochimica Et Cosmochimica Acta, 69(23), 5477-5486.Sakai, H., et al. (1990), Venting of Carbon-Dioxide Rich Fluid and Hydrate Formation in Mid-Okinawa Trough Backarc Basin,Science, 248(4959), 1093-1096.Schoell, M. (1988), Origins of Methane in the Earth - a Selection of Lectures from the Annual-Meeting of the Geological-Society-of-America, Phoeniz, Arizona, 26-29 October 1987 - Preface, Chemical Geology, 71(1-3), R7-R7.Seewald, J. S., et al. (1994), Variations in the Chemical and Stable-Isotope Composition of Carbon and Sulfur Species duringOrganic-Rich Sediment Alteration - an Experimental and Theoretical-Study of Hydrothermal Activity at Guaymas Basin,Gulf of California, Geochimica Et Cosmochimica Acta, 58(22), 5065-5082.Takai, K., et al. (2008), Cell proliferation at 122 degrees C and isotopically heavy CH4 production by a hyperthermophilicmethanogen under high-pressure cultivation, Proceedings of the National Academy of Sciences of the United States ofAmerica, 105(31), 10949-10954.VonDamm, K. L., et al. (1985), Chemistry of Submarine Hydrothermal Solutions at Guaymas Basin, Gulf of California,Geochimica Et Cosmochimica Acta, 49(11), 2221-2237.Whiticar, M. J. (1999), Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane, ChemicalGeology, 161(1-3), 291-314.
Page 1 and 2: Application formInterRidge Student
Page 3: II. PROPOSALPlease describe your pr
Page 7 and 8: III. CURRICULUM VITAEPlease attach
Page 9 and 10: Travel Grant, Japan Marine Science
Page 11 and 12: Independent Administrative Institut
Page 13 and 14: Dr. Jeffrey S. Seewald, Senior Scie
Page 15: Review of InterRidge Student Pr

Application form InterRidge Student and Postdoctoral Fellowship ...

Create successful ePaper yourself

Delete template?

Save as template?