DOCSLIB.ORG

Subseafloor Sedimentary Life in the South Pacific Gyre

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Subseafloor Sedimentary Life in the South Pacific Gyre Subseafloor sedimentary life in the South Pacific Gyre Steven D’Hondta,1, Arthur J. Spivacka, Robert Pockalnya, Timothy G. Ferdelmanb, Jan P. Fischerb, Jens Kallmeyerc, Lewis J. Abramsd, David C. Smitha, Dennis Grahama, Franciszek Hasiuke, Heather Schruma, and Andrea M. Stancine aGraduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, South Ferry Road, Narragansett, RI 02882; bMax Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany; cDepartment of Geosciences, University of Potsdam, Haus 27, Zi. 0.34, Karl-Liebknecht-Strasse 24, 14476 Golm, Germany; and dDepartment of Geography and Geology, University of North Carolina at Wilmington, DeLoach Hall, 601 South College Road, Wilmington, NC 28403; and eDepartment of Geological Sciences, University of Michigan, 2534 C.C. Little Building, 1100 North University Avenue, Ann Arbor, MI 48109 Edited by Edward F. DeLong, Massachusetts Institute of Technology, Cambridge, MA, and approved May 6, 2009 (received for review November 23, 2008) The low-productivity South Pacific Gyre (SPG) is Earth’s largest oce- anic province. Its sediment accumulates extraordinarily slowly (0.1–1 60˚ m per million years). This sediment contains a living community that is characterized by very low biomass and very low metabolic activity. 30˚ At every depth in cored SPG sediment, mean cell abundances are 3 to 4 orders of magnitude lower than at the same depths in all previously 0˚ explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is 1 to 3 orders -30˚ of magnitude lower than the rates at previously explored sites. Because of the low respiration rates and the thinness of the sediment, -60˚ interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the sedimentary community of the SPG Sea-surface Chlorophyll (mg/m3) is predominantly aerobic, unlike previously explored subseafloor communities. Generation of H2 by radiolysis of water is a significant 0.01 0.03 0.1 0.3 1 3 10 electron-donor source for this community. The per-cell respiration rates of this community are about 2 orders of magnitude higher (in Fig. 1. Site locations on a map of time-averaged sea-surface chl-a concen- trations [Global SeaWiFS Chlorophyll (mean of September 1997–December oxidation/reduction equivalents) than in previously explored anaer- 2004)]. White dots mark sites analyzed for this study. Black dots mark sites obic subseafloor communities. Respiration rates and cell concentra- previously analyzed for subseafloor biomass and/or activity (2, 3). Dashed tions in subseafloor sediment throughout almost half of the world white lines delimit the area in each gyre where the sea-surface chlorophyll-a ocean may approach those in SPG sediment. (chl-a) concentration is Յ0.14 mg/m3. aerobic ͉ biomass ͉ oxic ͉ radiolysis ͉ respiration 130 m (SPG-12) (determined from 3.5-kHz sonar and seismic ife is previously unknown in the subseafloor sediment of the vast reflection profiles). At the deepest water sites in the low- Llow-productivity regions that dominate the open ocean. Past chlorophyll region of the SPG (sites SPG-1 to SPG-4 and SPG-9 studies have focused on sites relatively close to shore and beneath to SPG-11), the cored sediment is homogeneous brown clay major upwelling zones (1–4) (Fig. 1), where biological productivity capped by a nearly continuous layer of manganese (Mn) nodules. and organic flux to the seafloor are generally high (5). Their Discrete horizons of Mn nodules or Mn crust also occur deeper subseafloor [greater than 1.5 m below seafloor (mbsf)] sedimentary in the cored sediment at SPG-1 and SPG-10. Silt and sand-sized communities contain abundant living microbes (6–9). These com- Mn nodules and cosmic debris commonly occur within the brown munities (10, 11) and their metabolic activities (3, 12) are diverse. clay, but fossils, except for scattered ichthyoliths, do not. The Their activities are dominated by fermentation, sulfate reduction, cored sediment at the shallowest sites (SPG-6 and SPG-7) is and methanogenesis (13). Their principal food source is buried calcareous nannofossil-bearing clay. The sediment at SPG-5 is organic matter from the surface world (3). The environmental transitional between these 2 lithologies. Site SPG-12 lies outside properties of these previously sampled sites differ greatly from the low-chlorophyll region, and its cored sediment is dominantly environmental properties throughout most of the open ocean, where siliceous ooze with abundant diatom debris and sponge spicules. oceanic productivity and organic flux to the seafloor are very low (5). Mean sedimentation rates are extremely low in the low- To understand the extent and nature of subseafloor life in the chlorophyll region of the SPG (17) (Table 1). In general, they are low-productivity heart of the ocean, expedition Knox-02RR lowest at sites where the seafloor is below the calcite compen- surveyed and cored the sediment at 10 sites throughout the sation depth [Ϸ4,500 m below sea level in this region (18)] and South Pacific Gyre (SPG) and at 1 site at its southern margin sea-surface chlorophyll concentrations are below 0.1 mg chl/m3. (Fig. 1). The central SPG has been described as Earth’s largest Mean sedimentation rate is higher at our eastern-most sites, oceanic desert (14). The middle of the gyre is farther from where water depth is shallowest (allowing carbonate sediment to continents and productive oceanic regions than any other site on accumulate), and at our western-most sites, where sea-surface Earth. It contains the clearest seawater in the world (15). Its chlorophyll content is above 0.1 mg chl/m3 and the sites were organic flux to the seafloor is extremely low (5). The area of its south of the central gyre many tens of millions of years ago. The rate low-chlorophyll [Յ0.14 mg of chlorophyll-a/m3 (chl-a/m3)] re- gion (5.2 ϫ 107 km2) is more than twice the area of North America (equal to Ϸ19,000 Rhode Islands) (Fig. 1). Its subsea- Author contributions: S.D., A.J.S., R.P., and T.G.F. designed research; S.D., A.J.S., R.P., T.G.F., floor ecosystem has never before been explored. J.P.F., J.K., L.J.A., D.C.S., D.G., F.H., H.S., and A.M.S. performed research; S.D., A.J.S., R.P., T.G.F., J.P.F., J.K., L.J.A., D.C.S., D.G., F.H., H.S., and A.M.S. analyzed data; and S.D. wrote the paper. Results The authors declare no conflict of interest. This article is a PNAS Direct Submission. Sedimentation and Organic Burial. The cored sediment ranged in SCIENCES Freely available online through the PNAS open access option. age from 0 to 70 Ma and in depth below seafloor from 0 to 9 m ENVIRONMENTAL (Table 1). Total sediment thickness ranges from 1 m (SPG-7) to 1To whom correspondence should be addressed. E-mail: [email protected]. www.pnas.org͞cgi͞doi͞10.1073͞pnas.0811793106 PNAS ͉ July 14, 2009 ͉ vol. 106 ͉ no. 28 ͉ 11651–11656 Downloaded by guest on September 27, 2021 Downloaded by guest on September 27, 2021 11652 Table. 1. Sediment properties and subseafloor (>1.5 mbsf) biogeochemical fluxes ͉ www.pnas.org Organic Organic Organic carbon carbon carbon burial burial Total content at rate at rate at Downward Upward Ϫ Basement water sediment Cored 0Ϫ5 cmbsf Ϸ0Ϫ5 cmbsf Ϸ150 cmbsf O2 flux at NO3 flux Radiolytic H2 ͞ cgi age (16) depth thickness sediment Sedimentation (dry weight (molC/ (molC/ 1.5 mbsf at 1.5 mbsf production ͞ 2 2 2 2 2 doi Site latitude longitude (Ma) (m) (m) (mbsf) rate (cm/kyr) %) cm /yr) cm /yr) (mol/cm /yr) (mol/cm /yr) (mol H2/cm /yr) ͞ 10.1073 SPG-1 Ϫ23°51ЈϪ165°39Ј 100 5697 71 7.79 0.031 0.33 3.6EϪ09 1.6EϪ09 Ϫ2.0EϪ08 6.9EϪ10 1.4EϪ08 SPG-2 Ϫ26°03ЈϪ156°54Ј 100 5127 17 8.20 0.017 0.53 3.2EϪ09 8.7EϪ10 Ϫ6.8EϪ09 3.5EϪ10 3.1EϪ09 ͞ SPG-3 Ϫ27°57ЈϪ148°35Ј 71 4852 5.49 5.49 0.008 0.42 1.2EϪ09 4.4EϪ10 Ϫ4.1EϪ09 5.4EϪ10 8.0EϪ10 pnas.0811793106 SPG-4 Ϫ26°29ЈϪ137°56Ј 33.5 4285 9 7.24 0.028 0.42 4.2EϪ09 1.6EϪ09 Ϫ5.4EϪ09 n.d. 1.6EϪ09 SPG-5 Ϫ28°27ЈϪ131°23Ј 24.1 4221 17 8.05 0.069 0.36 8.8EϪ09 3.8EϪ09 Ϫ7.6EϪ09 n.d. 3.0EϪ09 SPG-6 Ϫ27°55ЈϪ123°10Ј 13.5 3738 15 2.59 0.111 n.d. n.d. 7.0EϪ09 Ϫ2.2EϪ08 n.d. 2.7EϪ09 SPG-7 Ϫ27°44ЈϪ117°37Ј 6.1 3688 1.05 1.05 0.017 0.29 1.7EϪ09 n/a n/a n/a n/a SPG-9 Ϫ38°04ЈϪ133°06Ј 39 4925 20 7.05 0.051 0.38 9.5EϪ09 3.8EϪ09 Ϫ2.8EϪ09 3.0EϪ10 4.5EϪ09 SPG-10 Ϫ39°19ЈϪ139°48Ј 58 5283 21 5.63 0.037 0.56 1.0EϪ08 2.0EϪ09 Ϫ1.2EϪ08 6.0EϪ10 4.8EϪ09 SPG-11 Ϫ41°51ЈϪ153°06Ј 75 5076 67 2.98 0.089 0.51 2.2EϪ08 8.2EϪ09 Ϫ2.4EϪ09 1.6EϪ09 1.6EϪ08 SPG 12 Ϫ45°58ЈϪ163°11Ј 73 5306 130 4.98 0.178 0.34 3.0EϪ08 2.7EϪ08 n/a Ϫ3.1EϪ08 n.d n/a, not applicable; n.d., not determined. Program (ODP) Sites 1225 and 1226 and 3.1 through the near-surface zone in itsinaccessible initial few that million years almost after burial.
Load more

Recommended publications
  • Ganymede Science Questions and Future Exploration
    Planetary Science Decadal Survey Community White Paper Ganymede science questions and future exploration Geoffrey C. Collins, Wheaton College, Norton, Massachusetts [email protected] Claudia J. Alexander, Jet Propulsion Laboratory Edward B. Bierhaus, Lockheed Martin Michael T. Bland, Washington University in St. Louis Veronica J. Bray, University of Arizona John F. Cooper, NASA Goddard Space Flight Center Frank Crary, Southwest Research Institute Andrew J. Dombard, University of Illinois at Chicago Olivier Grasset, University of Nantes Gary B. Hansen, University of Washington Charles A. Hibbitts, Johns Hopkins University Applied Physics Laboratory Terry A. Hurford, NASA Goddard Space Flight Center Hauke Hussmann, DLR, Berlin Krishan K. Khurana, University of California, Los Angeles Michelle R. Kirchoff, Southwest Research Institute Jean-Pierre Lebreton, European Space Agency Melissa A. McGrath, NASA Marshall Space Flight Center William B. McKinnon, Washington University in St. Louis Jeffrey M. Moore, NASA Ames Research Center Robert T. Pappalardo, Jet Propulsion Laboratory G. Wesley Patterson, Johns Hopkins University Applied Physics Laboratory Louise M. Prockter, Johns Hopkins University Applied Physics Laboratory Kurt Retherford, Southwest Research Institute James H. Roberts, Johns Hopkins University Applied Physics Laboratory Paul M. Schenk, Lunar and Planetary Institute David A. Senske, Jet Propulsion Laboratory Adam P. Showman, University of Arizona Katrin Stephan, DLR, Berlin Federico Tosi, Istituto Nazionale di Astrofisica, Rome Roland J. Wagner, DLR, Berlin Introduction Ganymede is a planet-sized (larger than Mercury) moon of Jupiter with unique characteristics, such as being the largest satellite in the solar system, the most centrally condensed solid body in the solar system, and the only solid body in the outer solar system known to posses an internally generated magnetic field.
    [Show full text]
  • A Comparative View of Radiation, Xa9745787 Photo and Photocatalytically Induced Oxidation of Water Pollutants
    A COMPARATIVE VIEW OF RADIATION, XA9745787 PHOTO AND PHOTOCATALYTICALLY INDUCED OXIDATION OF WATER POLLUTANTS N. GETOFF Institute for Theoretical Chemistry and Radiation Chemistry, University of Vienna, Vienna, Austria Abstract Water resources are presently overloaded with biologically resistant (refractory) pollutants. Several oxidation methods have been developed for their degradation, the most efficient of which is iradiation treatment, particularly that based on e-beam processing in the presence of Q/O3. The next-best method is photoinduced pollutant oxidation with VUV- and/or UV-light, using HjO2 or H2O2/O3 as an additional source of OH radicals. The photocatalytic method, using e.g. TiQ as a catalyst in combination with oxidation agents such as If Oj or H2O2/O3, is also recommended. The suitability of these three methods is illustrated by examples and they are briefly discussed and compared on the basis of theirenergy consumption and efficiency. Other methods, such as ozone treatment, the photo-Fenton process, ultrasonic and elctrochemical treatments, as well as the well known biological process and thermal oxidation of refractory pollutants, are briefly mentioned. 1. INTRODUCTION Current water resources are strongly overloaded with biologically resistant pollutants, as a result of global population growth and the development of certain industries in the past few decades. The disposal of chemical waste in rivers, seas and oceans has contributed to possibly-irrepairable destruction of marine life. The application of fertilizers, pesticides etc. in modern agriculture has exacerbated the situation. Hence, urgent measures are necessary for remediation of water resources. For the degradation of water pollutants, a number of oxidation methods, based on processes initiated by ionizing radiation, UV- and visible light, photocatalytic induced reactions, as well as combinations of these, have been developed.
    [Show full text]
  • Productivity and Sustainable Management of the Humboldt Current Large Marine Ecosystem Under Climate Change
    Environmental Development 17 (2016) 126–144 Contents lists available at ScienceDirect Environmental Development journal homepage: www.elsevier.com/locate/envdev Productivity and Sustainable Management of the Humboldt Current Large Marine Ecosystem under climate change Dimitri Gutiérrez a,c,n, Michael Akester b,n, Laura Naranjo b a Dirección General de Investigaciones en Oceanografía y Cambio Climático, Instituto del Mar del Perú, IMARPE, Peru b Global Environment Facility (GEF)-UNDP Humboldt Current LME Project, Chile-Peru c Universidad Peruana Cayetano Heredia, Programa de Maestría en Ciencias del Mar, Lima, Peru article info abstract Article history: The Humboldt Current Large Marine Ecosystem (HCLME) covers 95% of the southeast Received 14 September 2015 Pacific seaboard of which the area of influence from the Humboldt Current and associated Received in revised form upwelling areas in the Humboldt Current System (HCS) stretches from around 4° to 40° 4 November 2015 south. Global warming will likely affect marine circulation and land-atmosphere-ocean Accepted 5 November 2015 exchanges at the regional level, affecting the productivity and biodiversity patterns along the HCLME. The expected decrease of upwelling productivity in the HCS could be am- Keywords: plified by worldwide trends of oxygen depletion and lower pH. In addition, higher fre- Humboldt-current quency of extreme climatic events, such as El Niño in a warmer ocean, might augment the Coastal-upwelling risks for the recruitment success of anchovy and other short-lived fish resources, espe- Productivity cially in the Northern HCLME. A range of non-climatic anthropogenic stressors also Fisheries Climate-change combines to reduce productivity and biomass yields.
    [Show full text]
  • Investigations of Moon-Magnetosphere Interactions by the Europa Clipper Mission
    EPSC Abstracts Vol. 13, EPSC-DPS2019-366-1, 2019 EPSC-DPS Joint Meeting 2019 c Author(s) 2019. CC Attribution 4.0 license. Investigations of Moon-Magnetosphere Interactions by the Europa Clipper Mission Haje Korth (1), Robert T. Pappalardo (2), David A. Senske (2), Sascha Kempf (3), Margaret G. Kivelson (4,5), Kurt Retherford (6), J. Hunter Waite (6), Joseph H. Westlake (1), and the Europa Clipper Science Team (1) Johns Hopkins University Applied Physics Laboratory, Maryland, USA, (2) Jet Propulsion Laboratory, California, USA, (3) University of Colorado, Colorado, USA, (4) University of Michigan, Michigan, USA, (5) University of California, California, USA, (6) Southwest Research Institute, Texas, USA. ([email protected]) 1. Introduction magnetic fields inducing eddy currents in the ocean. By measuring the induced field response at multiple The influence of the Jovian space environment on frequencies, the ice shell thickness and the ocean Europa is multifaceted, and observations of moon- layer thickness and conductivity can be uniquely magnetosphere interaction by the Europa Clipper will determined. The ECM consists of four fluxgate provide an understanding of the satellite’s interior sensors mounted on a 5-m-long boom and a control structure and compositional makeup among others. electronics hosted in a vault shielding it from The variability of Jupiter’s magnetic field at Europa radiation damage. The use of four sensors allows for induces electric currents within the moon’s dynamic removal of higher-order spacecraft- conducting ocean layer, the magnitude of which generated magnetic fields on a boom that is short depends on the ocean’s location, extent, and compared with the spacecraft dimensions.
    [Show full text]
  • Quantitative Estimation of Track Segment Yields of Water Radiolysis
    www.nature.com/scientificreports OPEN Quantitative estimation of track segment yields of water radiolysis species under heavy ions around Bragg peak energies using Geant4‑DNA Kentaro Baba1, Tamon Kusumoto2, Shogo Okada3, Ryo Ogawara4, Satoshi Kodaira2, Quentin Rafy5, Rémi Barillon5, Nicolas Ludwig5, Catherine Galindo5, Philippe Peaupardin5 & Masayori Ishikawa1,6* − · We evaluate the track segment yield G′ of typical water radiolysis products (eaq , OH and H2O2) under heavy ions (He, C and Fe ions) using a Monte Carlo simulation code in the Geant4‑DNA. Furthermore, we reproduce experimental results of ·OH of He and C ions around the Bragg peak energies (< 6 MeV/u). In the relatively high energy region (e.g., > 10 MeV/u), the simulation results using Geant4‑DNA have agreed with experimental results. However, the G‑values of water radiolysis species have not been properly evaluated around the Bragg peak energies, at which high ionizing density can be expected. Around the Bragg peak energy, dense continuous secondary products are generated, so that it is necessary to simulate the radical–radical reaction more accurately. To do so, we added the role of secondary products formed by irradiation. Consequently, our simulation results are in good agreement with experimental results and previous simulations not only in the high‑energy region but also around the Bragg peak. Several future issues are also discussed regarding the roles of fragmentation and multi‑ionization to realize more realistic simulations. Cancer patients can nowadays select several modalities in radiotherapy such as conventional X-ray therapy and particle therapies (e.g., proton therapy, heavy ion therapy and boron neutron capture therapy).
    [Show full text]
  • 6 Ocean Currents 5 Gyres Curriculum
    Lesson Six: Surface Ocean Currents Which factors in the earth system create gyres? Why does pollution collect in the gyres? Objective: Develop a model that shows how patterns in atmospheric and ocean currents create gyres, and explain why plastic pollution collects in them. Introduction: Gyres are circular, wind-driven ocean currents. Look at this map of the five main subtropical gyres, where the colors illustrate enormous areas of floating waste. These are places in the ocean that accumulate floating debris—in particular, plastic pollution. How do you think ocean gyres form? What patterns do you notice in terms of where the gyres are located in the ocean? The Earth is a system: a group of parts (or components) that all work together. The components of a system have different structures and functions, but if you take a component away, the system is affected. The system of the Earth is made up of four main subsystems: hydrosphere (water), atmosphere (air), geosphere (land), and biosphere (organisms). The ocean is part of our planet’s hydrosphere, but it is also its own system. Which components of the Earth system do you think create gyres, and why would pollution collect in them? Activity 1 Gyre Model: How do you think patterns in ocean currents create gyres and cause pollution to collect in the gyres? Use labels and arrows to answer this question. Keep your diagram very basic; we will explore this question more in depth as we go through each part of the lesson and you will be able to revise it. www.5gyres.org 2 Activity 2 How Do Gyres Form? A gyre is a circulating system of ocean boundary currents powered by the uneven heating of air masses and the shape of the Earth’s coastlines.
    [Show full text]
  • Interactive Comment on “Impacts of UV Radiation on Plankton Community Metabolism Along the Humboldt Current System” by N
    Biogeosciences Discuss., 8, C2596–C2611, 2011 Biogeosciences www.biogeosciences-discuss.net/8/C2596/2011/ Discussions © Author(s) 2011. This work is distributed under the Creative Commons Attribute 3.0 License. Interactive comment on “Impacts of UV radiation on plankton community metabolism along the Humboldt Current System” by N. Godoy et al. Anonymous Referee #3 Received and published: 23 August 2011 Review Impacts of UV radiation on plankton community metabolism along the Hum- boldt Current System by N. Godoy, A. Canepa, S. Lasternas, E. Mayol, S. RuÄsz-´ Halpern, S. AgustÄs,´ J. C. Castilla, and C. M. Duarte. Biogeosciences Discuss., 8, 5827–5848, 2011 General Comment This article reports experimental estimates of community metabolism assessed at 8 stations in the eastern south Pacific conducted during the Humboldt-2009 cruise on board RV Hesperides from 5 to 15 March 2009. An experimental evaluation of the ef- fect of UVB radiation on community metabolism is conducted. From few experiments the authors claim that UVB radiation suppressed net community production, result- ing in a dominance of heterotrophic communities in surface waters, compared to the C2596 prevalence of autotrophic communities inferred when materials, excluding UVB radia- tion, are used for incubation. They also claim that their results show that UVB radiation, which has increased greatly in the study area, may have suppressed net community production of the plankton communities, possibly driving plankton communities in the Southwest Pacific towards CO2 sources. The evidence provided in the manuscript is not sufficient to support the conclusions. The sampling is clearly too limited, both spatially and temporally, to extrapolate their results to the Humboldt Current System.
    [Show full text]
  • Radiolysis of H2O:CO2 Ices by Heavy Energetic Cosmic Ray Analogs
    A&A 523, A77 (2010) Astronomy DOI: 10.1051/0004-6361/201015123 & c ESO 2010 Astrophysics Radiolysis of H2O:CO2 ices by heavy energetic cosmic ray analogs S. Pilling1, E. Seperuelo Duarte2, A. Domaracka3,H.Rothard3, P. Boduch3, and E. F. da Silveira4 1 IP&D/UNIVAP, Av. Shishima Hifumi, 2911, São Jose dos Campos, SP, Brazil e-mail: [email protected] 2 Grupo de Física e Astronomia, CEFET/Química de Nilópolis, Rua Lúcio Tavares, 1052, CEP 2653-060, Nilópolis, Brazil 3 Centre de Recherche sur les Ions, les Matériaux et la Photonique (CEA/CNRS/ENSICAEN/Université de Caen-Basse Normandie), CIMAP – CIRIL – GANIL, Boulevard Henri Becquerel, BP 5133, 14070 Caen Cedex 05, France 4 Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Rua Marquês de São Vicente 225, CEP 22453-900, Rio de Janeiro, Brazil Received 1 June 2010 / Accepted 3 August 2010 ABSTRACT 58 13+ An experimental study of the interaction of heavy, highly charged, and energetic ions (52 MeV Ni ) with pure H2O, pure CO2 and mixed H2O:CO2 astrophysical ice analogs is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by heavy cosmic rays inside dense and cold astrophysical environments, such as molecular clouds or protostellar clouds. The measurements were performed at the heavy ion accelerator GANIL (Grand Accélérateur National d’Ions Lourds in Caen, France). The gas samples were deposited onto a CsI substrate at 13 K. In-situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified.
    [Show full text]
  • Nutrient Limitation of Primary Productivity in the Southeast Pacific (BIOSOPE Cruise) Sophie Bonnet, C
    Nutrient limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise) Sophie Bonnet, C. Guieu, F. Bruyant, O. Prášil, France van Wambeke, Patrick Raimbault, T. Moutin, C. Grob, M. Y. Gorbunov, J. P. Zehr, et al. To cite this version: Sophie Bonnet, C. Guieu, F. Bruyant, O. Prášil, France van Wambeke, et al.. Nutrient limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise). Biogeosciences, European Geo- sciences Union, 2008, 5 (1), pp.215-225. hal-00330343 HAL Id: hal-00330343 https://hal.archives-ouvertes.fr/hal-00330343 Submitted on 14 Oct 2008 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Biogeosciences, 5, 215–225, 2008 www.biogeosciences.net/5/215/2008/ Biogeosciences © Author(s) 2008. This work is licensed under a Creative Commons License. Nutrient limitation of primary productivity in the Southeast Pacific (BIOSOPE cruise) S. Bonnet1, C. Guieu1, F. Bruyant2, O. Pra´silˇ 3, F. Van Wambeke4, P. Raimbault4, T. Moutin4, C. Grob1, M. Y. Gorbunov5, J. P. Zehr6, S. M. Masquelier7, L. Garczarek7, and H. Claustre1
    [Show full text]
  • Origin and Temperature Dependence of Radiation Damage in Biological Samples at Cryogenic Temperatures
    Origin and temperature dependence of radiation damage in biological samples at cryogenic temperatures Alke Meentsa,b,1,2, Sascha Gutmanna,1,3, Armin Wagnerc, and Clemens Schulze-Briesea aPaul Scherrer Institut, Swiss Light Source, CH-5232 Villigen, Switzerland bHamburger Synchrotronstrahlungslabor, Deutsches Elektronen Synchrotron, D-22607 Hamburg, Germany cDiamond Light Source, Harwell Science and Innovations Campus, Didcot, OX11 0DE, United Kingdom Edited by Venkatraman Ramakrishnan, Medical Research Council, Cambridge, United Kingdom, and approved November 23, 2009 (received for review May 20, 2009) Radiation damage is the major impediment for obtaining structural electrons with energies of a few up to severals tens of eV (4, 5). information from biological samples by using ionizing radiation Subsequent radiolytic reactions caused by products of primary such as x-rays or electrons. The knowledge of underlying processes damage are classified as secondary damage. Possible consequences especially at cryogenic temperatures is still fragmentary, and a con- of primary and secondary radiation damage reactions include sistent mechanism has not been found yet. By using a combination breakage of chemical bonds, redox processes, and generation of of single-crystal x-ray diffraction, small-angle scattering, and qual- free radicals. Alterations of the sample at primary and secondary itative and quantitative radiolysis experiments, we show that hy- damage sites may eventually cause long-range rearrangements of drogen gas, formed inside the sample during irradiation, rather molecules in crystals or other assemblies. The loss of crystalline than intramolecular bond cleavage between non-hydrogen atoms, order has been referred to as tertiary or global damage (1). is mainly responsible for the loss of high-resolution information In crystallography, radiation damage results in the decrease of and contrast in diffraction experiments and microscopy.
    [Show full text]
  • Safety Analysis Report and Associated Documentation, TH
    This page intentionally left blank to facilitate duplex printing. RH-TRU Payload Appendices Rev. 1, February 2011 TABLE OF CONTENTS 1.0 INTRODUCTION 2.0 GAS GENERATION METHODOLOGY 2.1 Radiolytic G Values for Waste Materials 2.2 G Values for RH-TRU 72-B Waste 2.3 Shipping Period – General Case 2.4 Shipping Period – Controlled Shipments 2.5 Compliance Methodology for Gas Generation Requirements 3.0 ASSESSMENT METHODS 3.1 Gas Generation Test Plan for Remote-Handled Transuranic (RH-TRU) Waste Containers 3.2 Summary of the Flammability Assessment Methodology Program 4.0 SUPPORTING EVALUATIONS 4.1 Chemical Compatibility of Waste Forms 4.2 Free Halides in the RH-TRU 72-B Payload – Source Term and Release Rate Estimates 4.3 Payload Compatibility with Butyl Rubber O-Ring Seals 4.4 Volatile Organic Compounds (VOCs) in the RH-TRU 72-B Payload – Source Term and Release Rate Estimates 4.5 Biological Activity Assessment 4.6 Thermal Stability of Payload Materials at Transport Temperatures 5.0 PAYLOAD CONTAINER DESIGN BASIS EVALUATIONS 5.1 Description of Neutron Shielded Canister i RH-TRU Payload Appendices Rev. 1, February 2011 This page intentionally left blank. ii RH-TRU Payload Appendices Rev. 1, February 2011 1.0 INTRODUCTION This document, the RH-TRU Payload Appendices, accompanies the Remote-Handled Transuranic Waste Authorized Methods for Payload Control (RH-TRAMPAC) and is provided as supplemental information pertaining to issues related to the transportation of remote-handled transuranic (RH-TRU) waste in the RH-TRU 72-B packaging. The RH-TRAMPAC contains all information, including requirements and methods of compliance, required for the qualification of a payload for transport in the RH-TRU 72-B packaging.
    [Show full text]
  • Chemical Basis of Reactive Oxygen Species Reactivity and Involvement in Neurodegenerative Diseases
    International Journal of Molecular Sciences Review Chemical Basis of Reactive Oxygen Species Reactivity and Involvement in Neurodegenerative Diseases Fabrice Collin Laboratoire des IMRCP, Université de Toulouse, CNRS UMR 5623, Université Toulouse III-Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse CEDEX 09, France; [email protected] Received: 26 April 2019; Accepted: 13 May 2019; Published: 15 May 2019 Abstract: Increasing numbers of individuals suffer from neurodegenerative diseases, which are characterized by progressive loss of neurons. Oxidative stress, in particular, the overproduction of Reactive Oxygen Species (ROS), play an important role in the development of these diseases, as evidenced by the detection of products of lipid, protein and DNA oxidation in vivo. Even if they participate in cell signaling and metabolism regulation, ROS are also formidable weapons against most of the biological materials because of their intrinsic nature. By nature too, neurons are particularly sensitive to oxidation because of their high polyunsaturated fatty acid content, weak antioxidant defense and high oxygen consumption. Thus, the overproduction of ROS in neurons appears as particularly deleterious and the mechanisms involved in oxidative degradation of biomolecules are numerous and complexes. This review highlights the production and regulation of ROS, their chemical properties, both from kinetic and thermodynamic points of view, the links between them, and their implication in neurodegenerative diseases. Keywords: reactive oxygen species; superoxide anion; hydroxyl radical; hydrogen peroxide; hydroperoxides; neurodegenerative diseases; NADPH oxidase; superoxide dismutase 1. Introduction Reactive Oxygen Species (ROS) are radical or molecular species whose physical-chemical properties are well-known both on thermodynamic and kinetic points of view.
    [Show full text]