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Metadata Report for BODC Series Reference Number 1869389

Metadata Summary

Data Description

Data Category Water sample data
Instrument Type
Niskin bottle  discrete water samplers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Prof Rob Upstill-Goddard
Originating Organization Newcastle University School of Marine Science and Technology
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Atlantic Meridional Transect Phase2(AMT)

Data Identifiers

Originator's Identifier AMT12_CTD_CH4X_166:AMT12_56
BODC Series Reference 1869389

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2003-06-08 05:20
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -

Spatial Co-ordinates

Latitude 29.38868 N ( 29° 23.3' N )
Longitude 26.78529 W ( 26° 47.1' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 7.2 m
Maximum Sensor or Sampling Depth 300.3 m
Minimum Sensor or Sampling Height 4913.9 m
Maximum Sensor or Sampling Height 5207.0 m
Sea Floor Depth 5214.2 m
Sea Floor Depth Source PEVENT
Sensor or Sampling Distribution Unspecified -
Sensor or Sampling Depth Datum Unspecified -
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface


BODC CODERankUnitsTitle
ADEPZZ011MetresDepth (spatial coordinate) relative to water surface in the water body
BOTTFLAG1Not applicableSampling process quality flag (BODC C22)
CH4CGCXX1Nanomoles per litreConcentration of methane {CH4 CAS 74-82-8} per unit volume of the water body [dissolved plus reactive particulate phase] by gas chromatography
CH4SGCX11PercentSaturation of methane {CH4 CAS 74-82-8} in the water body [dissolved plus reactive particulate phase] by gas chromatography and computation from concentration
SAMPRFNM1DimensionlessSample reference number

Definition of BOTTFLAG

0The sampling event occurred without any incident being reported to BODC.
1The filter in an in-situ sampling pump physically ruptured during sample resulting in an unquantifiable loss of sampled material.
2Analytical evidence (e.g. surface water salinity measured on a sample collected at depth) indicates that the water sample has been contaminated by water from depths other than the depths of sampling.
3The feedback indicator on the deck unit reported that the bottle closure command had failed. General Oceanics deck units used on NERC vessels in the 80s and 90s were renowned for reporting misfires when the bottle had been closed. This flag is also suitable for when a trigger command is mistakenly sent to a bottle that has previously been fired.
4During the sampling deployment the bottle was fired in an order other than incrementing rosette position. Indicative of the potential for errors in the assignment of bottle firing depth, especially with General Oceanics rosettes.
5Water was reported to be escaping from the bottle as the rosette was being recovered.
6The bottle seals were observed to be incorrectly seated and the bottle was only part full of water on recovery.
7Either the bottle was found to contain no sample on recovery or there was no bottle fitted to the rosette position fired (but SBE35 record may exist).
8There is reason to doubt the accuracy of the sampling depth associated with the sample.
9The bottle air vent had not been closed prior to deployment giving rise to a risk of sample contamination through leakage.

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 Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

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.


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

AMT12 dissolved methane and nitrous oxide concentration and saturation measurements from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

Water samples were collected using a Sea-Bird 911plus CTD system fitted with 24 x 20 litre "Ocean Test Equipment" (Niskin type) external spring water bottles. Casts were completed predawn to minimise diurnal effects. Subsamples from the CTD bottles were collected in 1 litre volumetric flasks (Fisher), allowing overflow of the sample, to preclude contamination by air bubbles. Each sample was poisoned using 200ml of 0.25M aqueous HgCl2 and sealed with a ground glass stopper. The sample flasks were stored at room temperature for 0-8 hours, which treatment should result in no significant change in N2O (Elkins, 1980).

N2O and CH4 partial pressures and concentrations were measured by single phase equilibration gas chromatography, using the analytical apparatus described by Upstill-Goddard et al. (1996). The system was flushed with equilibrator gas (compressed air) and sealed. The sample to be analysed was warmed, in its sealed flask, to a constant 25°C. The glass stopper was then replaced with the equilibrator manifold, and the joint sealed with PTFE tape and a joint clip.

A headspace was created in the sample flask by introduction of compressed air with ambient N2O and CH4 mixing ratios of 318 ppbv and 1.79 ppmv respectively. The headspace was circulated through a closed circuit to return to the sample flask through a solvent filter (Jones Chromatography) with a period of 12 minutes. Two sample loops (one each for N2O and CH4) were simultaneously flushed with ultra high purity nitrogen carrier gas. Each sample run was followed by a standard (made from secondary standards), and then by ambient air analysis. Shimadzu Class VP software was used for the analysis of N2O and CH4 hromatograms. Run time of the system was typically 35 minutes. The water phase of the sample was measured gravimetrically.

N2O analysis

CO2 and water vapour were removed from the gas stream using stainless steel tubing (internal diameter 3.8 cm) packed with 1.22 cm3 Carbosorb and 1.2 cm3magnesium perchlorate (Mg(ClO4)), respectively. The N2O in the headspace was detected with an Electron Capture Detector (ECD), utilizing a 15 m Ci63Ni source, and operated at 320°C and 1.0 nA. The flow rate of 24 ml min-1 resulted in a retention time of 7.43 minutes.

CH4 analysis

Water vapour was removed from the gas stream using stainless steel tubing (internal diameter 3.8 cm) packed with 1.2 cm3 magnesium perchlorate (Mg(ClO4)). The CH4 in the headspace was determined by Flame Ionisation Detection using CP grade hydrogen (BOC) and compressed air (BOC) to support combustion at 120°C. The flow rate of 20 ml min-1 resulted in a retention time of 0.97 minutes.

References Cited

Elkins J.W., 1980. Determination of dissolved nitrous oxide in aquatic systems by gas chromatography using electron-capture detection and multiple phase equilibration. Analytical Chemistry, 52, 262-267.

Upstill-Goddard R.C., Rees A.P. and Owens N.J.P., 1996. Simultaneous high-precision measurements of methane and nitrous oxide in water and seawater by single-phase equilibration gas chromatography. Deep-Sea Research Part I, 43(10), 1669-1682.

BODC Data Processing Procedures

Data were submitted via email in an Excel spreadsheet archived under BODC's accession number UEA050040. Sample metadata (Latitude, longitude, ctd cast, station number and depth) were checked against information held in the database. There were no discrepancies.

The concentration data were provided in nanomoles per litre and percent. These units for the concentration data were consistent with the BODC parameter code units and no conversions were applied.

The data were reformatted and loaded in BODC's samples database under Oracle Relational Database Management System. Data were marked up with BODC parameter codes and loaded into the database. Individual samples were matched through CTD cast and depth.

A parameter mapping table is provided below:

Originator's Parameter Units Description BODC Parameter Code Units Comments
Methane concentration nmol l-1 Concentration of methane {CH4} per unit volume of the water body [dissolved plus reactive particulate phase] by gas chromatography CH4CGCXX nmol l-1 n/a
Methane saturation Percent Saturation of methane {CH4} in the water body [dissolved plus reactive particulate phase] by gas chromatography and computation from concentration CH4SGCX1 Percent n/a
Nitrous oxide concentration nmol l-1 Concentration of nitrous oxide {N2O} per unit volume of the water body [dissolved plus reactive particulate phase] by gas chromatography DN2OGCTX nmol l-1 n/a
Nitrous oxide saturation Percent Saturation of nitrous oxide {N2O} in the water body [dissolved plus reactive particulate phase] by gas chromatography and computation from concentration SN2OGCX1 Percent n/a

Data Quality Report

BODC was not advised by the data originator of any quality issues with the data.

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:

  • University of Liverpool
  • University of Newcastle
  • University of Plymouth
  • University of Southampton
  • University of East Anglia

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:

  • how the structure, functional properties and trophic status of the major planktonic ecosystems vary in space and time
  • how physical processes control the rates of nutrient supply to the planktonic ecosystem
  • how atmosphere-ocean exchange and photo-degradation influence the formation and fate of organic matter

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) 2003-06-08
End Date (yyyy-mm-dd) 2003-06-08
Organization Undertaking ActivityPlymouth Marine Laboratory
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierAMT12_CTD_AMT12_56
Platform Categorylowered unmanned submersible

BODC Sample Metadata Report for AMT12_CTD_AMT12_56

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
507308 20.0           7.90       8.10       7.20 Niskin bottle No problem reported    
507309 20.0         17.70     18.70     17.30 Niskin bottle No problem reported    
507310 20.0         59.00     59.70     58.20 Niskin bottle No problem reported    
507311 20.0       121.20   121.50   119.80 Niskin bottle No problem reported    
507312 20.0       136.00   136.50   134.60 Niskin bottle No problem reported    
507313 20.0       162.20   162.50   160.50 Niskin bottle No problem reported    
507314 20.0       252.90   253.10   250.40 Niskin bottle No problem reported    
507315 20.0       303.20   303.40   300.30 Niskin bottle No problem reported    
507474 20.0       101.30   101.60   100.00 Niskin bottle No problem reported    
507475 20.0       202.00   202.40   200.00 Niskin bottle No problem reported    
507533 20.0         32.90     33.30     32.10 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.

Related Data Activity activities are detailed in Appendix 1


Cruise Name JR20030512 (AMT12, JR102, JR88, JR90)
Departure Date 2003-05-12
Arrival Date 2003-06-17
Principal Scientist(s)Tim Jickells (University of East Anglia School of Environmental Sciences)
Ship RRS James Clark Ross

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
B nominal value
Q value below limit of quantification

Appendix 1: AMT12_CTD_AMT12_56

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
1124904Water sample data2003-06-08 05:20:0029.38868 N, 26.78529 WRRS James Clark Ross JR20030512 (AMT12, JR102, JR88, JR90)
1787659Water sample data2003-06-08 05:20:0029.38868 N, 26.78529 WRRS James Clark Ross JR20030512 (AMT12, JR102, JR88, JR90)
1887962Water sample data2003-06-08 05:20:0029.38868 N, 26.78529 WRRS James Clark Ross JR20030512 (AMT12, JR102, JR88, JR90)