Cruise inventory

RRS Discovery D361 (GA06)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74E3)
Cruise identifierD361 (GA06)
Cruise period2011-02-07 — 2011-03-19
StatusCompleted
Port of departureSanta Cruz de Tenerife, Spain
Port of returnSanta Cruz de Tenerife, Spain
PurposeResearch
ObjectivesThe cruise D361 forms part of a study entitled 'Physical and chemical forcing of diazotrophy in the (sub)-tropical Atlantic Ocean'. The study is investigating the potential influence of iron and phosphorus availability on nitrogen fixation in regions of the tropical Atlantic Ocean. The cruise also undertakes deep trace metal clean CTD casts as part of the International GEOTRACES programme. The purpose of the cruise therefore is to undertake measurements of dissolved and particulate iron and phosporpus availability, their spatial and temporal variations, and their impact on diazotrophy in the surface ocean.

Aim: To quantify the supply and determine the biogeochemical cycling of Fe and other nutrients, and relate this to N2 fixation, diazotroph species distribution and N* fields.
1. Quantify the distribution of nutrients and trace metals: Quantify surface water and water column distributions of dissolved inorganic/organic N, P, Fe, and DAl, DMn and particulate P, N, Fe, Al, Mn.
2. Quantify the rate of Fe, Al, Mn, P and N supply to surface waters: Assess the source fluxes of the key elements for diazotrophs and source tracers to the surface ocean from atmospheric deposition and internal transport via diapycnal mixing and lateral advection.
3. Identify the source of subsurface Fe enrichment: Identify whether Fe-rich subsurface waters of the tropical North Atlantic thermocline originate from the atmosphere or the shelf using Fe distributions and Al, Mn, and O2 source tracers.
4. Quantify the diazotrophic response to Fe, phosphate, DOP supply: Relate the spatial distributions of inorganic Fe and organically complexed Fe, and phosphate and DOP to diazotrophy. The specific uptake of Fe, phosphate and DOP by the whole microbial community and Trichodesmium will be assessed by shipboard incubations, radiotracer techniques and enzyme bioassays. In addition, we will identify the connection between N2 fixation rates and diazotroph community structure, by comparing size fractionated 15N2-derived rates of N2 fixation (Fig. 1) with abundance and diversity of diazotrophs using nifH phylogeny.
Objective 5: Investigate how the large scale transport pathways of Fe and P influence the N* distribution: Use fine-scale isopycnic model to reveal the large-scale transport pathways of Fe and P in the (S)-T Atlantic, and their effect on the N* distribution.
Chief scientistEric Pieter Achterberg (University of Southampton School of Ocean and Earth Science)
ProjectGEOTRACES
Cruise reportRRS Discovery D361 (GA06) cruise report d361.pdf — access key 'C' (8.25 MB) 
Ocean/sea areas 
GeneralNorth East Atlantic Ocean (limit 40W)
South Atlantic Ocean
SpecificTropical North and South Atlantic Ocean
Measurements 
Physical oceanography 
CTD stationsQuantity: number of profiles = 8
Description: 7 + 1test CTD stations for Th-234 measurements. 6 Shallow (500 m) and two deep CTD profiles (1000m) were sampled
CTD stationsQuantity: number of profiles = 40
Description: 21 Stainless steel; 19 titanium CTD profiles. Shallow (500 m) and full depth.
Subsurface temperature and salinity measurementsQuantity: track kilometres = 8000
Description: Ship fitted underway data (surface temperature, salinity, fluorescence and transmissivity, bathymetry). Ship fitted meterological instruments (wind speed/direction incident light, PAR etc)
Current profiler (eg ADCP)Quantity: track kilometres = 8000
Description: Vessel mounted ADCP (75kHz)
Other physical oceanographic measurementsQuantity: number of profiles = 15
Description: Turbulence profiler
Chemical oceanography 
OxygenQuantity: number of stations = 21
Description: Dissolved oxygen (µmol l-1) discrete samples from vertical profiles - stainless steel (10depths) and titanium rosettes (4-16 depths). Analysed onboard using PC-controlled potentiometric system and modified Winkler method.
Carbon dioxideQuantity: number of stations = 37
Description: CTD Vertical profiles: Dissolved Inorganic Carbon, Dissolved Organic Carbon, Alkalinity
Carbon dioxideQuantity: activity duration in days = 25
Description: Dissolved Inorganic Carbon Automated underway samples
PhosphateQuantity: number of samples = 224
Description: Surface sampling Fish underway samples
PhosphateQuantity: number of stations = 42
Description: Micromolar Nutrients CTD Vertical profiles
NitrateQuantity: number of stations = 42
Description: Micromolar Nutrients CTD Vertical profiles
NitriteQuantity: number of stations = 42
Description: Micromolar Nutrients CTD Vertical profiles
SilicateQuantity: number of stations = 42
Description: Micromolar Nutrients CTD Vertical profiles
AlkalinityQuantity: number of stations = 37
Description: CTD Vertical profiles: Dissolved Inorganic Carbon, Dissolved Organic Carbon, Alkalinity
AlkalinityQuantity: number of samples = 128
Description: Alkalinity Underway samples
pHQuantity: number of samples = 360
Description: pH Underway samples
Trace elementsQuantity: number of samples = 50
Description: 0.4 µm filtered seawater for iron ligands was collected from the Titanium Rosette. Samples were stored frozen (-20C) for analysis at the National Oceanography Centre, Southampton by Competitive Ligand Exchange-Cathodic Stripping Voltammetry.
Trace elementsQuantity: number of samples = 180
Description: Unfiltered seawater for total dissolvable trace metal measurements was collected from the Titanium Rosette. Samples will be analysed after a minimum of 4 months at the National Oceanography Centre, Southampton by Isotope Dilution-ICPMS
Trace elementsQuantity: number of samples = 115
Description: Unfiltered seawater for total dissolvable trace metal measurements was collected from the underway fish along the cruise track. Samples will be analysed after a minimum of 4 months at the National Oceanography Centre, Southampton by Isotope Dilution-ICPMS
Trace elementsQuantity: number of samples = 213
Description: Filtered seawater samples for the detemination of dAl (H), dFe (G) and dissolved trace metals (I) were collected from the underway fish along the cruise track. Samples for dAl and dFe were analysed on board using Flow Injection Analysis. Dissolved trace metals will be analysed at the National Oceanography Centre, Southampton by Isotope Dilution-ICPMS
Trace elementsQuantity: number of samples = 50
Description: Filtered seawater samples for iron isotopes collected from the trace metal OTE bottles deployed on the Titanium Rosette. Samples will be analysed using ICP-MS at the University of Southampton.
Trace elementsQuantity: number of samples = 369
Description: Filtered seawater samples for determination of dissolved aluminium and iron (dAl (H) and dFe (G)) collected from the Titanium Rosette. Samples have been analysed on board using Flow Injection Analysis.
Trace elementsQuantity: number of samples = 200
Description: Filtered seawater samples for the detemination of total dissolved cobalt were collected from the underway fish along the cruise track. Samples will be determined using Flow Injection Analysis at the University of Plymouth
Trace elementsQuantity: number of samples = 371
Description: Particulate samples collected on PES filters from the trace metal OTE bottles deployed on the Titanium Rosette. Samples will be analysed using ICP-MS at the university of Plymouth.
Trace elementsQuantity: number of samples = 368
Description: Filtered seawater samples for determination of total dissolved cobalt collected from the Titanium Rosette. Samples will be determined using Flow Injection Analysis at the University of Plymouth
Trace elementsQuantity: number of samples = 57
Description: Unfiltered seawater samples were collected and analysed on board for dissolved Fe(II) using Flow Injection with Chemiluminescence detection.
Other chemical oceanographic measurementsQuantity: number of samples = 18
Description: Trichodesmium colonies were collected from plankton nets deployed in the upper 30m of the water column. 10-20 Trichodesmium colonies were placed in filtered or unfiltered seawater and rates of 33P-phosphate and alkaline phosphatase activity.
Other chemical oceanographic measurementsQuantity: number of samples = 114
Description: Rates of alkaline phosphatase activity were determined from water samples taken from 6 depths from the stainless steel CTD (114 rate measurements). Rates were determined by the change in fluoresence of the substrate MUFP and calibrated using the standard MUF. Fluoresence was determined using a Turner 10Au field fluorometer. Rates were determined onboard by Claire Mahaffey
Other chemical oceanographic measurementsQuantity: number of samples = 114
Description: Samples collected from the stainless steel rosette and FISH for 33phosphate uptake rates of the bulk community. Incubations conducted on board by Sarah Reynolds
Other chemical oceanographic measurementsQuantity: number of samples = 111
Description: Unfiltered seawater samples were collected and analysed on board for the determination of hydrogen peroxide using Flow Injection with Chemiluminescence detection.
Biology and fisheries 
Primary productivityQuantity: number of samples = 311
Description: Incubations with 15N2 and H13CO3 to measure uptake of inorganic carbon and dinitrogen by the phytoplankton and bacterial community
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 147
Description: Seawater samples from the stainless CTD were filtered onto GF/Fs to measure chlorophyll a concentration. Filters were submerged in 90% acetone for 24 hours and analysed onboard using a fluorometer. Samples were also collected from the continuous towed FISH supply (200 more samples).
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: activity duration in days = 27
Description: Continuous fluorescence data collected using a Chelsea Scientific instruments FASTtrackTM Fast Repetition Rate fluorometer (FRRf) that was attached to the ships non-toxic underway system.
Particulate organic matter (inc POC, PON)Quantity: number of samples = 137
Description: Seawater samples from the stainless CTD were filtered onto pre-ashed GF/Fs to measure POC/PON/15N tzero. Filters will be analysed using mass spectrometry. Samples were also collected from the continuous FISH supply (78 more samples).
Particulate organic matter (inc POC, PON)Quantity: number of samples = 114
Description: Filter samples for the determination of particulate phosphorus were collected from the stainless steel rosette. Concentrations will be determined by high temperature combustion and acid hydrolysis and subsequent phosphate analysis by Sarah Reynolds and Claire Mahaffey at the University of Liverpool.
Particulate organic matter (inc POC, PON)Quantity: number of deployments = 8
Description: 7 + 1test SAPS deployments, 53 and 1 micron mesh sizes x 3 depths (up to 500m) for POC, PON, BSi and PIC analyses.
Particulate organic matter (inc POC, PON)Quantity: number of samples = 311
Description: Incubations with 15N2 and H13CO3 to measure uptake of inorganic carbon and dinitrogen by the phytoplankton and bacterial community
Dissolved organic matter (inc DOC)Quantity: number of samples = 167
Description: Filtered seawater samples for the determination of enzyme hydrolysable phosphorus collected from the stainless steel rosette (0-500m, 183 samples). Samples will be determined by enzyme assays by Sarah Reynolds and Claire Mahaffey at the University of Liverpool. Samples were also collected from the FISH (37 samples).
Dissolved organic matter (inc DOC)Quantity: number of samples = 343
Description: Filtered seawater samples for the determination of dissolved organic phosphorus collected from the stainless steel (0-500m, 183 samples) and titanium rosette (below 500m, 133 samples). Samples will be determined by UV digestion and subsequent phosphate analysis by Sarah Reynolds and Claire Mahaffey at the University of Liverpool. Samples were also collected from the FISH (37 samples).
Dissolved organic matter (inc DOC)Quantity: number of stations = 37
Description: CTD Vertical profiles: Dissolved Inorganic Carbon, Dissolved Organic Carbon, Alkalinity
Biochemical measurements (eg lipids, amino acids)Quantity: number of samples = 116
Description: Filtered seawater samples for proteomic analyses were collected from the stainless steel CTD (0-1000m, 81 samples), and the SAPS deployments (60-500m, 35 samples). Samples will be analysed by Elizabeth Sargent at the National Oceanography Centre, Southampton
Biochemical measurements (eg lipids, amino acids)Quantity: number of samples = 127
Description: Seawater samples from the stainless CTD were filtered onto GF/Fs to measure heme b concentration. Filters will be analysed using high performance liquid chromatography with diode array spectrophotometry. Samples were also collected from the continuous FISH supply (79 more samples).
PhytoplanktonQuantity: number of samples = 106
Description: Whole water samples that were collected from the stainless steel CTD (0-500m, 63 samples) and the marine snow catcher (35-100m, 13 samples), and concentrated samples that were collected from the nets (30 samples) were preserved in lugol's iodine for phytoplankton community assessments. Assessments will be carried out by Elizabeth Sargent at the National Oceanography Centre, Southampton.
Pelagic bacteria/micro-organismsQuantity: number of hauls = 37
Description: Collected Trichodesmium colonies from plankton net hauls, each haul included 2 or 3 nets on the same line and were either 20 µm or 100 µm mesh nets. Picked Trichodesmium colonies were filtered onto suitable filters and frozen for analysis back at NOCS. Analysis will aim to relate the mRNA expression with the stoichiometric elemental composition.
Pelagic bacteria/micro-organismsQuantity: number of samples = 352
Description: Filters of 0.2µm filtered seawater to assess the community diversity and abundance of the nifH gene (a marker gene for nitrogen fixation).
Other biological/fisheries measurementQuantity: number of stations = 20
Description: Water samples were collected for the estimation of whole microbial community iron uptake using a 55Fe tracer technique. Water was collected from the underway trace clean metal fish. Incubations were performed over 10-12 hours.
Other biological/fisheries measurementQuantity: number of stations = 12
Description: Samples of trichodesimum were collected using net hauls for the estimation of colony specific iron uptake using a 55Fe tracer technique. Colonies were picked and rinsed 3 times in filtered trace clean seawater collected from the underway trace clean metal fish. Incubations were then performed over 10-12 hours in seawater collected in the same manner.
Other biological/fisheries measurementQuantity: number of samples = 91
Description: Seawater samples from the stainless CTD were used to measure in situ nitrogen fixation rates. Samples were 'spiked' with 15N2 gas and incubated for 24 hours. Samples were then filtered onto pre-ashed GF/Fs and dried for a further 24 hours. Samples will be analysed using mass spectrometry.
Meteorology 
Routine standard measurementsQuantity: track kilometres = 8000
Description: Ship fitted underway data (surface temperature, salinity, fluorescence and transmissivity, bathymetry). Ship fitted meterological instruments (wind speed/direction incident light, PAR etc)
Atmospheric chemistryQuantity: number of samples = 7
Description: Rainwater samples for determination of trace metal and major ion concentrations upon return to the UK.
Atmospheric chemistryQuantity: number of samples = 78
Description: High volume aerosol samples (1 m3 min-1) for determination of trace metals (TM), major ions (MI) and metal isotopes (ISO) upon return to the UK. TM and MI samples were size segregated using a cascade impactor, ISO samples were bulk only. To avoid contamination from the ships funnel, a wind sector controller was used to ensure samples were only collected when the relative wind direction was from the bows.
Data held at BODC 
Series/Profiles 
47  CTD/STD cast
Density of the water column
Transmittance and attenuance of the water column
Electrical conductivity of the water column
Chlorophyll pigment concentrations in water bodies
Vertical spatial coordinates
Salinity of the water column
Temperature of the water column
Reference numbers
Dissolved oxygen parameters in the water column
Density of the water column
Transmittance and attenuance of the water column
Electrical conductivity of the water column
Chlorophyll pigment concentrations in water bodies
Vertical spatial coordinates
Salinity of the water column
Temperature of the water column
Reference numbers
Dissolved oxygen parameters in the water column

BODC idDate/TimeLocationDoc.
10576192011-02-15 09:58:12  — 2011-02-15 10:14:39 28° 18' 45" N  16° 7' 18" W  View metadata report for BODC series reference number 1057619
10576202011-02-16 09:52:04  — 2011-02-16 10:51:07 28° 18' 59" N  16° 7' 32" W  View metadata report for BODC series reference number 1057620
10576322011-02-17 14:16:12  — 2011-02-17 14:30:16 28° 14' 7" N  16° 12' 52" W  View metadata report for BODC series reference number 1057632
10576442011-02-18 09:54:21  — 2011-02-18 10:11:17 27° 46' 37" N  16° 13' 40" W  View metadata report for BODC series reference number 1057644
10576562011-02-22 00:46:05  — 2011-02-22 01:04:26 12° 35' 13" N  17° 54' 47" W  View metadata report for BODC series reference number 1057656
10576682011-02-22 02:18:55  — 2011-02-22 03:21:50 12° 35' 39" N  17° 55' 11" W  View metadata report for BODC series reference number 1057668
10576812011-02-22 07:02:28  — 2011-02-22 07:17:42 12° 35' 27" N  17° 42' 48" W  View metadata report for BODC series reference number 1057681
10576932011-02-22 11:51:42  — 2011-02-22 12:16:01 12° 36' 35" N  17° 42' 56" W  View metadata report for BODC series reference number 1057693
10577002011-02-22 16:50:27  — 2011-02-22 17:00:59 12° 35' 13" N  17° 34' 6" W  View metadata report for BODC series reference number 1057700
10577122011-02-22 19:50:41  — 2011-02-22 19:55:12 12° 36' 35" N  17° 34' 21" W  View metadata report for BODC series reference number 1057712
10577242011-02-22 20:32:48  — 2011-02-22 20:35:50 12° 36' 43" N  17° 34' 22" W  View metadata report for BODC series reference number 1057724
10577362011-02-22 21:24:39  — 2011-02-22 21:28:52 12° 35' 17" N  17° 34' 20" W  View metadata report for BODC series reference number 1057736
10577482011-02-23 05:34:26  — 2011-02-23 05:48:57 12° 34' 1" N  18° 49' 24" W  View metadata report for BODC series reference number 1057748
10577612011-02-23 07:05:14  — 2011-02-23 08:36:37 12° 32' 54" N  18° 49' 47" W  View metadata report for BODC series reference number 1057761
10577732011-02-24 06:42:50  — 2011-02-24 06:58:10 12° 34' 37" N  21° 49' 4" W  View metadata report for BODC series reference number 1057773
10577852011-02-24 12:49:28  — 2011-02-24 14:13:07 12° 34' 25" N  21° 49' 1" W  View metadata report for BODC series reference number 1057785
10577972011-02-25 06:38:45  — 2011-02-25 06:54:24 12° 35' 5" N  23° 33' 25" W  View metadata report for BODC series reference number 1057797
10578042011-02-25 08:09:01  — 2011-02-25 09:50:43 12° 35' 7" N  23° 33' 46" W  View metadata report for BODC series reference number 1057804
10578162011-02-25 16:14:34  — 2011-02-25 16:42:44 12° 35' 16" N  23° 34' 44" W  View metadata report for BODC series reference number 1057816
10578282011-02-26 06:35:55  — 2011-02-26 06:51:58 12° 18' 0" N  25° 7' 40" W  View metadata report for BODC series reference number 1057828
10578412011-02-26 08:09:18  — 2011-02-26 09:56:12 12° 18' 4" N  25° 9' 12" W  View metadata report for BODC series reference number 1057841
10578532011-03-03 15:00:43  — 2011-03-03 15:20:39 7° 13' 19" S  24° 59' 37" W  View metadata report for BODC series reference number 1057853
10578652011-03-03 16:41:25  — 2011-03-03 18:38:57 7° 12' 55" S  24° 59' 54" W  View metadata report for BODC series reference number 1057865
10578772011-03-04 03:39:27  — 2011-03-04 03:57:05 7° 13' 6" S  24° 59' 34" W  View metadata report for BODC series reference number 1057877
10578892011-03-05 06:36:24  — 2011-03-05 06:50:20 3° 15' 40" S  25° 31' 13" W  View metadata report for BODC series reference number 1057889
10578902011-03-05 07:51:38  — 2011-03-05 09:40:09 3° 14' 54" S  25° 32' 29" W  View metadata report for BODC series reference number 1057890
10579082011-03-05 16:44:12  — 2011-03-05 17:25:03 2° 57' 44" S  25° 36' 53" W  View metadata report for BODC series reference number 1057908
10579212011-03-06 06:41:43  — 2011-03-06 06:53:16 1° 10' 23" S  25° 47' 38" W  View metadata report for BODC series reference number 1057921
10579332011-03-06 08:02:36  — 2011-03-06 09:58:07 1° 9' 47" S  25° 48' 11" W  View metadata report for BODC series reference number 1057933
10579452011-03-07 06:37:54  — 2011-03-07 06:51:19 1° 9' 24" N  26° 2' 45" W  View metadata report for BODC series reference number 1057945
10579572011-03-07 07:50:04  — 2011-03-07 09:04:39 1° 9' 39" N  26° 3' 13" W  View metadata report for BODC series reference number 1057957
10579692011-03-08 06:35:46  — 2011-03-08 06:51:44 3° 19' 48" N  26° 48' 37" W  View metadata report for BODC series reference number 1057969
10579702011-03-08 07:51:25  — 2011-03-08 09:26:38 3° 20' 58" N  26° 49' 32" W  View metadata report for BODC series reference number 1057970
10579822011-03-09 06:35:42  — 2011-03-09 06:54:02 5° 39' 42" N  27° 29' 56" W  View metadata report for BODC series reference number 1057982
10579942011-03-09 07:56:36  — 2011-03-09 09:11:59 5° 40' 8" N  27° 30' 44" W  View metadata report for BODC series reference number 1057994
10580082011-03-10 06:35:11  — 2011-03-10 06:48:08 8° 20' 21" N  28° 19' 55" W  View metadata report for BODC series reference number 1058008
10580212011-03-10 07:52:19  — 2011-03-10 09:31:26 8° 21' 0" N  28° 20' 32" W  View metadata report for BODC series reference number 1058021
10580332011-03-11 06:33:37  — 2011-03-11 06:48:17 10° 37' 36" N  28° 43' 52" W  View metadata report for BODC series reference number 1058033
10580452011-03-11 07:53:22  — 2011-03-11 09:44:12 10° 37' 28" N  28° 44' 5" W  View metadata report for BODC series reference number 1058045
10580572011-03-12 02:07:55  — 2011-03-12 04:00:57 12° 1' 57" N  28° 58' 49" W  View metadata report for BODC series reference number 1058057
10580692011-03-12 07:15:31  — 2011-03-12 07:30:48 12° 3' 15" N  28° 58' 48" W  View metadata report for BODC series reference number 1058069
10580702011-03-13 06:35:25  — 2011-03-13 06:49:40 15° 30' 30" N  28° 47' 11" W  View metadata report for BODC series reference number 1058070
10580822011-03-13 07:47:58  — 2011-03-13 09:19:36 15° 30' 20" N  28° 47' 39" W  View metadata report for BODC series reference number 1058082
10580942011-03-14 07:03:44  — 2011-03-14 07:14:56 17° 23' 56" N  28° 23' 41" W  View metadata report for BODC series reference number 1058094
10581012011-03-14 13:44:56  — 2011-03-14 15:39:06 17° 25' 56" N  28° 23' 6" W  View metadata report for BODC series reference number 1058101
10581132011-03-15 06:39:22  — 2011-03-15 07:03:17 19° 6' 54" N  28° 7' 51" W  View metadata report for BODC series reference number 1058113
10581252011-03-15 10:11:11  — 2011-03-15 10:34:27 19° 10' 12" N  28° 6' 55" W  View metadata report for BODC series reference number 1058125
Discrete samples 
210  All plastic clean surface pumped supplyDissolved metal concentrations in the water column
Radioactivity in the water column
Silicate concentration parameters in the water column
Nitrate concentration parameters in the water column
Nitrite concentration parameters in the water column
Phosphate concentration parameters in the water column
22  CTD frame plus rosette samplerDissolved total and organic nitrogen concentrations in the water column
Radioactivity in the water column
Silicate concentration parameters in the water column
Alkalinity, acidity and pH of the water column
Dissolved organic carbon concentration in the water column
Total dissolved inorganic carbon (TCO2) concentration in the water column
Nitrate concentration parameters in the water column
Dissolved oxygen parameters in the water column
Nitrite concentration parameters in the water column
Phosphate concentration parameters in the water column
20  Dissolved metal concentrations in the water column
Particulate metal concentrations in the water column
Dissolved total and organic nitrogen concentrations in the water column
Radioactivity in the water column
Silicate concentration parameters in the water column
Alkalinity, acidity and pH of the water column
Dissolved organic carbon concentration in the water column
Total dissolved inorganic carbon (TCO2) concentration in the water column
Nitrate concentration parameters in the water column
Dissolved oxygen parameters in the water column
Nitrite concentration parameters in the water column
Phosphate concentration parameters in the water column