CRUISE REPORT MD 166 BONUS-GOODHOPE Cape Town, 7 February 57° 33’S 0°E 17 March Durban 24 March 2008 CRUISE REPORT MD 166 BONUS-GOODHOPE Cape Town, 7 February 57° 33’S 0°E 17 March Durban 24 March 2008 Chief Scientist: Sabrina Speich Assisted by Marie Boye & Frank Dehairs May 30, 2008 – BONUS-GOODHOPE Cruise Report – CONTENTS AKNOWLEDGMENTS 5 FOREWORD 7 1 GEOGRAPHICAL REGION OF OPERATIONS 9 2 CRUISE PARTICIPANTS 11 3 COMPLETED RESEARCH 17 3.1 CRUISE OBJECTIVES REMINDER 17 3.1.1 OBJECTIVE 1: LARGE SCALE INTEROCEAN EXCHANGES 19 3.1.2 OBJECTIVE 2: DISTRIBUTION, SOURCE, SINK OF SELECTED TEIS AND CHARACTERISATION OF THE BIOGEOCHEMICAL PROCESSES INVOLVED IN THE INTERNAL CYCLING OF TEIS AND CARBON 22 3.2 SUMMARY OF OBSERVATIONS 29 3.2.1 SAMPLING STRATEGY 29 3.2.2 SAMPLING METHODOLOGIES 29 3.2.3 STATIONS DESCRIPTION: PLANNED AND EFFECTIVE WORK 31 GENERAL IMPRESSION ON THE RESULTS QUALITY 39 4 PRELIMINARY SCIENTIFIC CONCLUSIONS 41 4.1 PHYSICAL OBSERVATIONS 41 4.1.1 INVOLVED SCIENTIFIC STAFF AND TASKS DISTRIBUTION DURING THE CRUISE: 42 4.1.2 FULL DEPTH CTD ACQUISITION: PRELIMINARY VERTICAL DISTRIBUTIONS 44 4.1.2.1 OCeaniC fronts along the BONUS‐GOODHOPE transeCt 45 4.1.2.2 Water masses from north (the AfriCan Continental slope) to south (Weddell gyre). 46 4.1.2.3 Preliminary BGH vertiCal distribution of Temperature and Salinity from the CTD 48 4.1.2.4 Preliminary θ – S diagrams 52 4.1.2.5 Preliminary vertiCal distribution of Salinity and Oxygen from the 22‐ bottle rosette 53 4.1.3 ACOUSTIC DOPPLER CURRENT PROFILERS (ADCPS) DATA 54 4.1.3.1 Vessel Mounted ACoustiC Doppler Current Profiler (VM‐ADCP) 54 4.1.3.2 Lowered ACoustiC Doppler Current Profiler (LADCP) 57 4.1.4 EXPANDABLE BATHY‐THERMOGRAPH DATA 61 4.1.4.1 SurfaCe and SubsurfaCe Thermal struCture derived from XBTs 62 4.1.4.2 Sampling of an Agulhas Return Current antiCyClone 65 4.1.4.3 DynamiC Height and BaroCliniC Transports 66 4.1.4.4 BONUS‐GOODHOPE derived Gravest EmpiriCal Modes 68 4.1.5 THERMOSALINOGRAPH DATA 69 4.1.6 ARGO PROFILING FLOATS (PROVORS) 73 4.1.7 CURRENTMETER PRESSURE INVERTED ECHO SOUNDER (C‐PIES) MOORINGS 77 4.1.8 REMOTE SENSING AND OCEAN AND ATMOSPHERE MODELLING FORECASTS 81 4.1.8.1 Satellite Sea SurfaCe Temperature 83 4.1.8.2 Satellite derived absolute dynamiC topography 89 4.1.8.3 OCean Colour 91 4.1.8.4 IrradianCe, Winds and PreCipitation data 92 – 1 – – – BONUS-GOODHOPE Cruise Report – 4.1.8.5 Regional AtmospheriC ForeCasts 92 4.1.8.6 MERCATOR‐OCEAN foreCasts 93 4.1.9 ATMOSPHERE AND AIR‐SEA PHYSICAL ON‐BOARD OBSERVATIONS 95 4.2 BIOGEOCHEMICAL PROCESSES INVOLVED IN THE CARBON CYCLE 109 4.2.1 AIR‐SEA CO2 FLUXES AND INORGANIC CARBON VERTICAL DISTRIBUTION 111 4.2.2 UNDERWAY PCO2 111 4.2.3 CARBONATE SYSTEM VARIABLES : PH, TOTAL ALKALINITY, DIC 116 4.2.4 INTERCOMPARISON OF CARBON DIOXIDE VARIABLES WITH THE GERMAN R.V. POLARSTERN 121 4.3 TRACE ELEMEMENTS AND ISOTOPES (TEIS) 125 4.3.1 WORK AT SEA 127 4.3.2 ORIGIN, PATHWAYS AND VENTILATION OF WATER MASSES 129 4.3.2.1 Neodynium isotopiC Composition , 230Th and 231Pa ConCentrations, REE and Iron ISOTOPIC Composition and ConCentration 129 4.3.2.2 226Ra, 228Ra and 227AC sampling 131 4.3.2.3 Dissolved Barium 133 4.3.2.4 Carbon isotopes (14C and 13C) 135 4.3.2.5 Alkenons 139 4.3.3 EXPORT FLUXES, SCAVENGING RATES AND REMINERALISATION INVOLVED IN THE CARBON CYCLE 141 4.3.3.1 210Lead ‐ 210Pollonium disequilibrium in the 0‐1000 m water Column 141 4.3.3.2 BiogeoChemiCal proCesses involved in Carbon export and remineralization 143 4.3.3.3 Use of Carbon isotopes (14C and 13C) to traCe marine Carbon CyCle in the water Column 146 4.3.3.4 Distribution and internal CyCle of siliCon 147 4.3.3.5 New and Total ProduCtion in the AtlantiC SeCtor of the Southern OCean – BONUS‐GOODHOPE researCh Cruise; 150 4.3.3.6 SpeCifiC biogeniC Compounds 161 4.3.3.7 Boron isotopes in the Southern OCean 162 4.3.4 TRACE METALS AND INTERNAL CYCLE OF TRACE METALS 163 4.3.4.1 GO‐FLO’s samples and traCe metals on deCkinCubations 165 4.3.4.2 TraCe metals (zinC, Cobalt, Cadmium) CyCles 168 4.3.4.3 Fe(II) ConCentrations in the water Column 169 4.3.4.4 Dissolved, Total dissolvable and Soluble Iron ConCentrations in the water Column 171 4.3.4.5 On‐board Iron inCubations 173 4.3.4.6 Co‐impaCts of traCe metals (Fe, Zn, Co) on phytoplanktonassemblage, growth and biologiCal proCesses 175 4.3.4.7 VertiCal distributions of hydrogen peroxide 177 4.3.4.8 InterComparison of GEOTRACES variables with the German R.V. Polarstern 179 4.4 MACRO­NUTRIENTS AND BIOLOGICAL PARAMETERS 187 4.4.1 MACRO‐NUTRIENTS 189 4.4.2 CHLOROPHYLLE – A AND PHAEOPYGMANTS 194 4.4.3 PIGMENTS 196 4.4.4 PARTICULATE ORGANIC CARBON AND NITROGEN; PARTICULATE INORGANIC CARBON 199 4.4.5 BIOGENIC SILICA ‐ 30SI INCUBATIONS ‐ SI DILUTION EXPERIMENTS 201 4.4.6 DISSOLVED ORGANIC CARBON DISTRIBUTION 203 4.5 SURFICIAL SEDIMENTS AND PORE WATERS 205 4.5.1.1 Sediment biogeoChemistry evolution aCross frontal eCosystems: Southern OCean bottom boundary Conditions and proxy Calibration 207 4.5.2 ATMOSPHERIC BIOGEOCHEMISTRY 221 – 2 – – – BONUS-GOODHOPE Cruise Report – 4.5.2.1 AtmospheriC nutrients and traCe metals sampling: Aerosols and Rain 223 5 THE CRUISE LOG­BOOK 225 5.1 CHRONOLOGY OF ALL THE ONBOARD OPERATIONS: THE “BRIDGE JOURNAL” 225 5.1.1 OCEAN OPERATIONS 226 5.1.2 ATMOSPHERIC PHYSICS OPERATIONS ‐ RADIOSONDE LAUNCHES 241 5.2 INVENTORY OF THE SAMPLES COLLECTED FOR EACH INSTRUMENT 241 5.3 THE DATABASE DICTIONARY 241 5.3.1 CONCLUSION 263 6 IMPLEMENTED EQUIPMENT 264 6.1 THE VESSEL 264 6.2 RADIOCOMMUNICATION AND RADIONAVIGATION 265 6.3 SCIENTIFIC EQUIPMENT 266 6.3.1 METHODS AND SCIENTIFIC EQUIPMENT USED ON BOARD 266 6.3.2 LABORATORY AND EQUIPMENT CONTAINERS 267 7 COMMUNICATION 270 8 ASSESSMENT OF OPERATIONS AND CRUISE ISSUES 272 BIBLIOGRAPHY 274 – 3 – – – BONUS-GOODHOPE Cruise Report – – 4 – – – BONUS-GOODHOPE Cruise Report – AKNOWLEDGMENTS The BONUS-GOODHOPE project was initiated jointly by a group of scientists from the Laboratoire d’Environnement Marin (LEMAR; Laurent Mémery and Geraldine Sarthou), the Laboratoire d’Etudes en Géophysique et Océanographie Spatiale (LEGOS; Catherine Jeandel), and the Laboratoire de Physique des Océans (Sabrina Speich). Although not participating to the cruise, Catherine Jeandel and Laurent Mémery and many other French and foreigner scientists strongly supported the project. The scientific proposal, ship and funding applications were prepared jointly by Marie Boyé (LEMAR) and Sabrina Speich. Thanks to all scientific personnel who participated in the cruise. We wish to particularly thank Elodie Kestenare for her great help in following each observation made on board and variable measured to compile the cruise “Logbook”, very precious tool for all future BONUS-GOODHOPE data analyses. The scientific party extends warm thanks to the Master, Pierre Courtes, officers and crew of the R/V Marion Dufresne, for their help and co-operation during the cruise, and to IPEV all willingly given and making the scientific work possible. The work was primarily supported by the following French Institutions : Institut National des Sciences de l’Univers (INSU), Institut Français pour l’Exploitation de la Mer (IFREMER), Institut polaire français Paul Emile Victor (IPEV), the Agence Nationale pour la Recherche (ANR), the Institut pour la Recherche et le Développement (IRD) and the Institut Universitaire Européen de la Mer (IUEM) of the Université de Bretagne Occidentale (UBO). All the foreign teams have received support from their national programmes. – 5 – – – BONUS-GOODHOPE Cruise Report – – 6 – – – BONUS-GOODHOPE Cruise Report – FOREWORD This report is a compilation of the cruise narrative, observed variables, implemented equipment and preliminary results provided by the groups who participated to the cruise. Many operations were carried out and many variables were measured during the BONUS-GOODHOPE cruise. We tried to make this report as much exhaustive as possible. – 7 – – – BONUS-GOODHOPE Cruise Report – – 8 – – – BONUS-GOODHOPE Cruise Report – 1 GEOGRAPHICAL REGION OF OPERATIONS The BONUS-GOODHOPE cruise took place on board of the French R/V Marion Dufresne in the South-West Atlantic and in the Atlantic sector of the Southern Ocean (the cruise track and stations are showed in the Figures 1 and 2 below). More specifically, it started on February 13 2008. Oceanographic operations have been undertaken from the shelf region just out of Cape Town harbour (at the isobath 200m), following the GOODHOPE-A21 repeated hydrographic section, and reached 57° 33’S along the Greenwich Meridian on the evening of March 15, 2008. Full water depth operations ended on March 17, at 1:45 pm (Local Time). Figure 1 – Map of the BONUS-GOODHOPE transect. Each cross indicates the position of a station. Black crosses are for hydrological stations only. Blue crosses designate LARGE stations; Red crosses the SUPER stations. Pink crosses define the two C-PIES moorings deployed during the cruise The yellow cross indicates the position of the intercalibration station. – 9 – – – BONUS-GOODHOPE Cruise Report – Figure 2 – Map of the BONUS-GOODHOPE transect. Dates are reported along the track. – 10 – – – BONUS-GOODHOPE Cruise Report – 2 CRUISE PARTICIPANTS Picture of the BONUS-GOODHOPE cruise participants. – 11 – – – BONUS-GOODHOPE Cruise Report – – 12 – – – BONUS-GOODHOPE Cruise Report – SURNAME NAME NATIONALITY TASK ORGANISM EMAIL Pb-Po-Ac-Ra sampling & Amado José Luis Spanish UAB, Spain [email protected] Geo.