Metadata Report for BODC Series Reference Number 1131974


Metadata Summary

Data Description

Data Category Water sample data
Instrument Type
NameCategories
Niskin bottle  discrete water samplers
SPX Bran+Luebbe colorimetric Autoanalyser 3  colorimeters; autoanalysers
World Precision Instruments Liquid Waveguide Capillary Cell  spectrophotometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr Malcolm Woodward
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) Atlantic Meridional Transect Phase2(AMT)
 

Data Identifiers

Originator's Identifier AMT16_CTD_CTD046s_Woodward_nuts
BODC Series Reference 1131974
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-06-17 05:20
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 29.15196 N ( 29° 9.1' N )
Longitude 39.54014 W ( 39° 32.4' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 3.2 m
Maximum Sensor Depth 990.1 m
Minimum Sensor Height 3187.7 m
Maximum Sensor Height 4174.6 m
Sea Floor Depth 4177.8 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
ADEPZZ01 1 Metres DepBelowSurf Depth below surface of the water body
BOTTFLAG 1 Dimensionless C22_flag Sampling process quality flag (BODC C22)
FIRSEQID 1 Dimensionless FireSeqNo Bottle firing sequence number
NTRIAATX 1 Micromoles per litre NO2_Unfilt_ColAA Concentration of nitrite {NO2- CAS 14797-65-0} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
NTRILWTX 1 Micromoles per litre NO2_Lwnano Concentration (nM sensitivity) of nitrite {NO2- CAS 14797-65-0} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis with liquid waveguide capilliary cell
NTRZAATX 1 Micromoles per litre NO3+NO2_Unfilt_ColAA Concentration of nitrate+nitrite {NO3+NO2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
PHOSAATX 1 Micromoles per litre PO4_Unfilt_ColAA Concentration of phosphate {PO43- CAS 14265-44-2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
PHOSLWTX 1 Micromoles per litre PO4_Lwnano Concentration (nM sensitivity) of phosphate {PO43- CAS 14265-44-2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis with liquid waveguide capilliary cell
ROSPOSID 1 Dimensionless RosPos Bottle rosette position identifier
SAMPRFNM 1 Dimensionless SampRef Sample reference number
SLCAAATX 1 Micromoles per litre SiOx_Unfilt_ColAA Concentration of silicate {SiO44- CAS 17181-37-2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

No Problem Report Found in the Database

Data Quality Report - see processing documentation

Data quality information is included in the general documentation for this series. Please read.


Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


Narrative Documents

SPX Bran+Luebbe Autoanalyser 3

The instrument uses continuous flow analysis (CFA) with a continuous stream of material divided by air bubbles into discrete segments in which chemical reactions occur. The continuous stream of liquid samples and reagents are combined and transported in tubing and mixing coils. The tubing passes the samples from one apparatus to the other with each apparatus performing different functions, such as distillation, dialysis, extraction, ion exchange, heating, incubation, and subsequent recording of a signal.

An essential principle of the system is the introduction of air bubbles. The air bubbles segment each sample into discrete packets and act as a barrier between packets to prevent cross contamination as they travel down the length of the tubing. The air bubbles also assist mixing by creating turbulent flow (bolus flow), and provide operators with a quick and easy check of the flow characteristics of the liquid.

Samples and standards are treated in an exactly identical manner as they travel the length of the tubing, eliminating the necessity of a steady state signal, however, since the presence of bubbles create an almost square wave profile, bringing the system to steady state does not significantly decrease throughput and is desirable in that steady state signals (chemical equilibrium) are more accurate and reproducible.

The autoanalyzer can consist of different modules including a sampler, pump, mixing coils, optional sample treatments (dialysis, distillation, heating, etc), a detector, and data generator. Most continuous flow analyzers depend on color reactions using a flow through colorimeter, however other methods have been developed that use ISE, flame photometry, ICAP, fluorometry, and so forth.

More details can be found in the manufacturer's introduction to autoanalysers and instrument description .

World Precision Instruments Liquid Waveguide Capillary Cell

Liquid Waveguide Capillary Cell (LWCC) is a flow cell for absorbance measurements in the ultraviolet, visible and near infra-red ranges. Pathlengths range from 50-500cm, with increasing measurement sensitivity from 50 to 500-fold. The flow cells are fiber coupled and have a very small sample volume ranging from 125µL (50cm pathlength) to 1,250µL (500cm pathlength).

The sample solution is introduced into the LWCC at the liquid input. Light is coupled into the LWCC from a light source via a fiber optic cable. After passing through the LWCC, light is collected with an optical fiber and guided to a detector. The concentration of the sample is determined by measuring its absorbance in the LWCC, similar to a standard UV/VIS spectrometer.

Specifications

Model LWCC-3050 LWCC-3100 LWCC-3250 LWCC-3500
Optical Pathlength 50cm 100cm 250cm 500cm
Internal Volume 125µL 250µL 625µL 1250µL
Fiber Connection 500um SMA
Transmission @254nm* 20 10 5 -
Transmission @540nm* 35 30 25 20
Noise [mAU]** <0.1 <0.2 <0.5 <1.0

Maximum Pressure 100 PSI

Wetted Material PEEK, Fused Silica, PTFE

Liquid Input Standard 10-32 Coned Port Fitting

* Referenced using coupled 500µm fibers

** Measured using ASTM E685-93

*** A one-meter waveguide of 550µm internal diameter requires approximately 1.5 psi for water flow of 1.0 mL/min.

Further details can be found in the manufacturer's specification sheet .

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles have a capacity between 1.7 and 30 L, while Lever Action bottles have a capacity between 1.7 and 12 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

AMT16 Nutrient (micro- and nano-molar) measurements from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

Water samples were taken from the Sea-Bird CTD rosette system. The micro-molar samples were collected into acid-clean 60 ml HDPE (nalgene) sample bottles and the nano-molar samples into 120 ml HDPE (nalgene) sample bottles. Analysis for nutrients was completed within 2 hours for micro-molar and 3 hours for nano-molar measurements in all cases. Clean handling techniques were employed to avoid contamination of the samples. No underway samples were processed for this cruise.

The main nutrient analyser was a 5-channel Bran and Luebbe AAIII segmented flow autoanalyser. The analytical chemical methodologies used were according to Brewer and Riley (1965) for nitrate, Grasshoff (1976) for nitrite, Kirkwood (1989) for phosphate and silicate, and Mantoura and Woodward (1983) for ammonium.

Nanomolar ammonium concentrations were obtained using an adapted method from Jones (1991); this uses a fluorescent analysis technique following ammonia gas diffusion out of the samples, passing across a hydrophobic Teflon membrane due to differential pH chemistry. The ammonia analyser had several days of downtime and the recorder trace was intermittently too noisy to accurately determine nano-molar ammonia and the data were not supplied to BODC.

Nanomolar nitrate+nitrite, nitrate and phosphate concentrations were obtained on some samples using a 3-channel nanomolar analyser. This method combines sensitive segmented flow colorimetric analytical techniques with a Liquid Waveguide Capillary Cell (LWCC). The nitrate and nitrate systems worked throughout the cruise but due to time constraints the phosphate system was only used in the Southern Gyre region and beyond.

References Cited

Brewer P.G. and Riley J.P., 1965. The automatic determination of nitrate in sea water. Deep-Sea Research, 12, 765-772.

Grasshoff K., 1976. Methods of seawater analysis. Verlag Chemie, Weiheim: 317 pp.

Jones R.D., 1991. An improved fluorescence method for the determination of nanomolar concentrations of ammonium in natural waters. Limnology and Oceanography, 36, 814-819.

Kirkwood D.S., 1989. Simultaneous determination of selected nutrients in seawater. ICES CM1989/C:29, 12pp.

Mantoura R.F.C. and Woodward E.M.S., 1983. Optimisation of the indophenol blue method for the automated determination of ammonia in estuarine waters. Estuarine, Coastal and Shelf Science, 17, 219-224.

BODC Data Processing Procedures

The micro- and nano-molar nutrient data were submitted to BODC in a Microsoft Excel file. Sample metadata were checked against each dataset and the information held in the database. There were micro-molar ammonium but no nano-molar ammonium data provided to BODC. One set of micro- and nano-molar data was provided for a bottle that reportedly did not fire. These data were not loaded into the database.

There were a few discrepancies between information from the Sea-bird log files (used by BODC as a main reference for CTD rosette bottle metadata information) and the data originator records regarding the depth of the bottle firing for micro and nano-molar nutrient data (see table in the Problem Report section below). In particular for cast 43 a number of bottles had an offset of ~11 m between the actual depths sampled and the depths provided in the originator's data files.

Data from the LWCC systems were submitted in units of nmol l -1 . Nano-molar data were divided by 1000 to convert the units to µmol l -1 for storage in the database. Users should be aware that these LWCC measurements are valid to the fourth decimal place. The data were assigned parameter codes defined in BODC parameter dictionary. Data loaded into BODC's database using established BODC data banking procedures.

A parameter mapping table is provided below;

Originator's Parameter Units Description BODC Parameter Code Units Comments
Ammonium (AAIII) µmol l -1 Concentration of ammonium {NH 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis AMONAATX µmol l -1 -
Nitrate+Nitrite (AAIII) µmol l -1 Concentration of nitrate+nitrite {NO 3 +NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis NTRZAATX µmol l -1 -
Nitrate+Nitrite (LWCC nano-molar system) nmol l -1 Concentration (nM sensitivity) of nitrate+nitrite {NO 3 +NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis with liquid waveguide capilliary cell NTRZLWTX µmol l -1 nmol l -1 converted to µmol l -1 (conversion used * 1/1000)
Nitrite (AAIII) µmol l -1 Concentration of nitrite {NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis NTRIAATX µmol l -1 -
Nitrite (LWCC nano-molar system) nmol l -1 Concentration (nM sensitivity) of nitrite {NO 2 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis with liquid waveguide capilliary cell NTRILWTX µmol l -1 nmol l -1 converted to µmol l -1 (conversion used * 1/1000)
Phosphate (AAIII) µmol l -1 Concentration of phosphate {PO 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis PHOSAATX µmol l -1 -
Phosphate (LWCC nano-molar system) nmol l -1 Concentration (nM sensitivity) of phosphate {PO 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis with liquid waveguide capilliary cell PHOSLWTX µmol l -1 nmol l -1 converted to µmol l -1 (conversion used * 1/1000)
Silicate (AAIII) µmol l -1 Concentration of silicate {SiO 4 } per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis SLCAAATX µmol l -1 -

Data Quality Report

The dataset has been checked by the data originator - any suspect data values were removed from the data set before submission to BODC.

Measurement precision information from data originators

The detection limits for measurements from the AAIII Bran and Luebbe autoanalyser have are 0.02 µmol l -1 , except the colorimetric ammonium which has a detection limit of 0.03 µmol l -1 . Samples in the database with a flag of "<" had concentrations below the specified detection limits.

At low concentrations, the values obtained by the LWCC are likely to be more accurate than those from the AAIII analyser.

Problem Report

Because of a few remaining uncertainties in matching sample measurements with SeaBird bottle firing depths, users should exert caution when using data from the following CTD cast and depth (differecnes marked by asterisk are believed to have been caused by a typographical error):

CTD Cast ID Originator Bottle No. Originator Sample Depth BODC Bottle No. BODC Depth BODC Bottle ID
35 3 300 3 350 515692
43 20 31 20 42.6 516501
43 18 57 18 68.6 516500
43 6* 75 16 88.2 516498
43 15 100 15 112.1 516497
43 14 120 14 131.7 516496
43 12 130 12 141.9 516494
43 5 140 5 151.5 516493
43 10 180 10 191.1 516492
43 9 225 9 236.7 516491
43 8 300 8 311.7 516490

Project Information

The Atlantic Meridional Transect - Phase 2 (2002-2006)

Who was involved in the project?

The Atlantic Meridional Transect Phase 2 was designed by and implemented by a number of UK research centres and universities. The programme was hosted by Plymouth Marine Laboratory in collaboration with the National Oceanography Centre, Southampton. The universities involved were:

What was the project about?

AMT began in 1995, with scientific aims to assess mesoscale to basin scale phytoplankton processes, the functional interpretation of bio-optical signatures and the seasonal, regional and latitudinal variations in mesozooplankton dynamics. In 2002, when the programme restarted, the scientific aims were broadened to address a suite of cross-disciplinary questions concerning ocean plankton ecology and biogeochemistry and the links to atmospheric processes.

The objectives included the determination of:

The data were collected with the aim of being distributed for use in the development of models to describe the interactions between the global climate system and ocean biogeochemistry.

When was the project active?

The second phase of funding allowed the project to continue for the period 2002 to 2006 and consisted of six research cruises. The first phase of the AMT programme ran from 1995 to 2000.

Brief summary of the project fieldwork/data

The fieldwork on the first three cruises was carried out along transects from the UK to the Falkland Islands in September and from the Falkland Islands to the UK in April. The last three cruises followed a cruise track between the UK and South Africa, only deviating from the traditional transect in the southern hemisphere. During this phase the research cruises sampled further into the centre of the North and South Atlantic Ocean and also along the north-west coast of Africa where upwelled nutrient rich water is known to provide a significant source of climatically important gases.

Who funded the project?

Natural Environment Research Council (NERC)


Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 2005-06-17
End Date (yyyy-mm-dd) 2005-06-17
Organization Undertaking ActivityPlymouth Marine Laboratory
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierAMT16_CTD_CTD046s
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for AMT16_CTD_CTD046s

Sample reference number Nominal collection volume(l) Bottle rosette position Bottle firing sequence number Minimum pressure sampled (dbar) Maximum pressure sampled (dbar) Depth of sampling point (m) Bottle type Sample quality flag Bottle reference Comments
515786 20.0 2 1   999.90 1000.10   990.10 Niskin bottle No problem reported    
515787 20.0 3 2   600.30   600.50   594.80 Niskin bottle No problem reported    
515788 20.0 4 3   402.40   402.90   398.80 Niskin bottle Partial sample loss    
515789 20.0 5 4   284.70   285.50   282.30 Niskin bottle No problem reported    
515790 20.0 6 5   204.20   205.10   202.40 Niskin bottle No problem reported    
515791 20.0 7 6   205.00   205.10   202.80 Niskin bottle No problem reported    
515792 20.0 8 7   148.30   149.00   146.90 Niskin bottle No problem reported    
515793 20.0 9 8   135.20   136.00   133.90 Niskin bottle No problem reported    
515794 20.0 10 9   137.40   138.30   136.10 Niskin bottle No problem reported    
515795 20.0 11 10   136.90   137.70   135.60 Niskin bottle No problem reported    
515796 20.0 12 11   112.10   112.40   110.70 Niskin bottle No problem reported    
515797 20.0 13 12     82.10     82.60     81.00 Niskin bottle No problem reported    
515798 20.0 14 13     60.70     61.60     60.00 Niskin bottle No problem reported    
515799 20.0 15 14     61.30     61.40     60.20 Niskin bottle No problem reported    
515800 20.0 16 15     34.00     34.10     33.10 Niskin bottle No problem reported    
515801 20.0 17 16     33.90     34.30     33.10 Niskin bottle No problem reported    
515802 20.0 18 17     18.80     19.40     18.20 Niskin bottle No problem reported    
515803 20.0 19 18     19.80     20.20     19.10 Niskin bottle No problem reported    
515804 20.0 20 19     19.40     19.60     18.60 Niskin bottle No problem reported    
515805 20.0 21 20     19.90     20.30     19.20 Niskin bottle No problem reported    
515806 20.0 22 21       6.30       6.50       5.60 Niskin bottle No problem reported    
515807 20.0 23 22       3.60       4.40       3.20 Niskin bottle No problem reported    
515808 20.0 24 23       4.20       4.30       3.50 Niskin bottle No problem reported    
515809 20.0 1 24       4.10       4.70       3.60 Niskin bottle No problem reported    

Please note: the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.

Cruise

Cruise Name D294 (AMT16)
Departure Date 2005-05-20
Arrival Date 2005-06-29
Principal Scientist(s)Tony Bale (Plymouth Marine Laboratory)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information


No Fixed Station Information held for the Series


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain