Metadata Report for BODC Series Reference Number 1748440
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
Data Description |
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Data Identifiers |
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Time Co-ordinates(UT) |
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Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||||||||||
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Parameters |
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Definition of BOTTFLAG | |||||||||||||||||||||||||||||||||||||||||||||
| BOTTFLAG | Definition |
|---|---|
| 0 | The sampling event occurred without any incident being reported to BODC. |
| 1 | The filter in an in-situ sampling pump physically ruptured during sample resulting in an unquantifiable loss of sampled material. |
| 2 | Analytical 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. |
| 3 | The 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. |
| 4 | During 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. |
| 5 | Water was reported to be escaping from the bottle as the rosette was being recovered. |
| 6 | The bottle seals were observed to be incorrectly seated and the bottle was only part full of water on recovery. |
| 7 | Either 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). |
| 8 | There is reason to doubt the accuracy of the sampling depth associated with the sample. |
| 9 | The bottle air vent had not been closed prior to deployment giving rise to a risk of sample contamination through leakage. |
Definition of Rank |
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Problem Reports
No Problem Report Found in the Database
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
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 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.
Discrete dissolved nutrient (ammonium, phosphate, silicate, nitrate and nitrite) samples from CTD bottles during cruise CD151
Originator's Protocol for Data Acquisition and Analysis
The RRS Charles Darwin CD151 cruise departed on the 17 September 2003 from Oman, Muscat traveling to the North East Arabia Sea. The cruise was a continuation of work carried out on cruise CD150 and set out to complete biological and geochemical surveys commenced on CD150 and in situ and shipboard incubation studies. The cruise returned to Oman, Muscat on the 20 October 2003.
Sample collection
Samples were collected from a Seabird CTD containing 24 10-litre niskin bottles. These samples were taken from stations A140, A300 and A940. The samples were initially collected in 5-litre polythene bottles and then transferred to polycarbonate bottles for use on the SAMS vacuum water filtration rig.
Sample analysis
Samples were filtered through 25 mm diameter Whatman GF/F filters and the filtrate initially collected in 250 ml polythene bottles. The dissolved nutrients were analysed on a Lachat QuikChem 8000 flow injection autoanalyser. The instrument uses flow injection modifications of classic colourimetric methods. Ammonium, phosphate, silicate and nitrate were analysed on all samples collected. By removal of the cadmium-copper reduction column in the nitrate line samples, nitrite were also analysed
Following cruise CD150 the method of salt correction for all nutrients was changed. For more information please see pages 31/32 of the CD150 cruise report.
BODC Data Processing Procedures
BODC received discrete dissolved nutrients in an Excel spreadsheet. BODC extracted this data and merged with information from the associated Sea-Bird .btl files (also provided). These data were loaded to BODC's ocean database under the ORACLE Relational Database Management System. Data that were considered unrealistic were flagged suspect.
BODC have not loaded nitrate values. This can be calculated by taking the nitrite value away from the nitrate+nitrite value.
BODC have also not loaded the ratio between nitrate and phosphate as these values can be calculated.
SAMS nitrate data quality warning
SAMS have notified BODC of a problem in the analytical procedure adopted for nitrate analysis on this cruise. The problem relates to the technique used to prepare the analytical standards, which results in nitrate (and consequently nitrite) values which are typically 10-15 % higher than they should be. Absolute data values should therefore be used with extreme caution.
Content of data series
The Originator's variables were mapped to appropriate BODC parameter codes as follows:
| Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|---|
| Ammonium | µmol L-1 | Concentration of ammonium {NH4} per unit volume of the water body [dissolved plus reactive particulate <GF/F phase] by filtration and colorimetric autoanalysis | AMONAAD1 | µmol L-1 | - |
| Phosphate | µmol L-1 | Concentration of phosphate {PO4} per unit volume of the water body [dissolved plus reactive particulate <GF/F phase] by filtration and colorimetric autoanalysis | PHOSAAD1 | µmol L-1 | - |
| Silicate | µmol L-1 | Concentration of silicate {SiO4} per unit volume of the water body [dissolved plus reactive particulate <GF/F phase] by filtration and colorimetric autoanalysis | SLCAAAD1 | µmol L-1 | - |
| NO3 + NO2 | µmol L-1 | Concentration of nitrate+nitrite {NO3+NO2} per unit volume of the water body [dissolved plus reactive particulate <GF/F phase] by filtration and colorimetric autoanalysis | NTRZAAD1 | µmol L-1 | - |
| Nitrite | µmol L-1 | Concentration of nitrite {NO2} per unit volume of the water body [dissolved plus reactive particulate <GF/F phase] by filtration and colorimetric autoanalysis | NTRIAAD1 | µmol L-1 | - |
Quality Report
Negative data values were flagged as below the detection limit by the Originator. BODC have changed these values to the detection limit value with the corresponding below detection BODC flag. BODC have applied flags to the nitrate/nitrite data in light of the quality issue documented above.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Data Activity
| Start Date (yyyy-mm-dd) | 2003-09-20 |
| End Date (yyyy-mm-dd) | 2003-09-20 |
| Organization Undertaking Activity | University of Edinburgh School of GeoSciences |
| Country of Organization | United Kingdom |
| Originator's Data Activity Identifier | CD151_CTD_56101#9 |
| Platform Category | lowered unmanned submersible |
No Document Information Held for the Series
Cruise
| Cruise Name | CD151 |
| Departure Date | 2003-09-17 |
| Arrival Date | 2003-10-20 |
| Principal Scientist(s) | Gregory L Cowie (University of Edinburgh School of GeoSciences) |
| Ship | RRS Charles Darwin |
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 |
