Metadata Report for BODC Series Reference Number 1251976
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.
D242 CTD Discrete Nutrient Sampling Document
Originator's Protocol for Data Acquisition and Analysis
Sample collection
Discrete dissolved inorganic nutrient samples were provided from 109 CTD casts performed during the RSS Discovery cruise 242. Dissolved silicon (referred to as silicate and reported as SiO3), nitrate and nitrite (referred to as nitrate or NO2+NO3) and phosphate (PO4), were collected after oxygen samples had been drawn from the Niskin bottles. Samples were collected into 30 ml "diluvial" sample cups, and rinsed 3 times before filling. The samples were then stored in a refrigerator at 4°C until analysed, 1 to 12 hours after collection.
In addition, a deep water sample was collected from test station 13630 at ~ 1915 m for calibration purposes.
Sample analysis
The samples were analysed onboard using a ChemLab AAII type Auto-Analyser coupled to a Digital-Analysis Microstream data capture and reduction system. The primary calibration standards for dissolved silicon, nitrate and phosphate were prepared from sodium hexaflurosilicate, potassium nitrate and potassium dihydrogenn phosphate respectively.
A number of samples were analysed in duplicate. This was a limited due to the large volume of samples required to be analysed daily and the instability of the photometer which experienced sensitivity to vibrations in particular during use of the CTD winch system. Where duplicate samples were taken, a definitive data value was derived from the averaging of the two samples. There were instances were one of the duplicated samples were deemed of poor quality by the Originator and so in these cases only the good quality data values has been used.
Silicon
Dissolved silicon analysis followed the standard AAII molybdate-ascorbic acid method with the addition of a 37°C heating bath (Hydes, 1984).The colorimeter was fitted with a 50 mm flow cell and a 660 nm filter. The gain was adjusted to 2.9 for a maximum response at 40.
Nitrate
Nitrate (and nitrite) analysis followed the standard AAII method using the sulphanimamide and naphtylethylenediamine-dihydrochloride with a copperised-cadmium filled glass reduction column. A 15 mm flow cell and 540 nm filter was used. The gain was adjusted to 2.9 for a maximum response at 40 µmol l-1
Phosphate
Phosphate analysis followed the standard AAII method which adheres to the method of Murphy and Ripley (1954). A 50 mm flow cell and 880 nm filter were used. The gain was set to 9 for concentrations of up to 2 µmol l-1
Further details are provided in the cruise report for cruise D242.
BODC Data Processing Procedures
The nutrient data were supplied to BODC in Pstar format containing duplicate data and corrected nutrient data for silicon, nitrate and phosphate.The Originator supplied flagged channels for each of the corrected variables populated by quality flags as defined by WOCE Hyrographic Programme. These files were reformatted to ASCII format by BODC, and the corrected nutrient values and any associated flags were extracted and loaded into BODC's database under the ORACLE Relational Database Management System. Any further data that BODC considered unrealistic were flagged suspect.
Content of data series
| Originator's Parameter | Unit | Description | BODC Parameter code | BODC Unit | Comments |
|---|---|---|---|---|---|
| SiO3 | µmol l-1 | Concentration of silicate {SiO4} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis | SLCAAATX | µmol l-1 | No unit conversion necessary |
| NO2+NO3 | µmol l-1 | Concentration of nitrate+nitrite {NO3+NO2} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis | NTRZAATX | µmol l-1 | No unit conversion necessary |
| PO4 | µmol l-1 | Concentration of phosphate {PO4} per unit volume of the water body [dissolved plus reactive particulate phase] by colorimetric autoanalysis | PHOSAATX | µmol l-1 | No unit conversion necessary |
References
Cunningham, A., (2000). RSS Discovery Cruise 242, 07 SEP - 06 OCT 1999. Atlantic - Norwegian Exchanges. Cruise Report No. 28 Southampton Oceanography Centre.
Hydes, D. J., (1984). A manual of methods for the continuous flow determination of ammonia, nitrate-nitrite, phosphate and silicate in seawater . Wormley, UK, Institute of Oceanographic Sciences, 37pp. (Institute of Oceanographic Sciences Report 177).
Murphy, J. and Ripley, J. P., (1954). A modified single solution method for the determination of phosphate in natural waters. Anal. Chem. Acta., 27, 31-66.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Data Activity
| Start Date (yyyy-mm-dd) | 1999-09-11 |
| End Date (yyyy-mm-dd) | 1999-09-11 |
| Organization Undertaking Activity | Southampton Oceanography Centre (now National Oceanography Centre, Southampton) |
| Country of Organization | United Kingdom |
| Originator's Data Activity Identifier | DI242_CTD_CTD13637 |
| Platform Category | lowered unmanned submersible |
BODC Sample Metadata Report for DI242_CTD_CTD13637
| 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| 878432 | 20.00 | 1 | 764.80 | 765.80 | 755.70 | Niskin bottle | No problem reported | 63701 | ||
| 878435 | 20.00 | 2 | 608.40 | 609.40 | 601.30 | Niskin bottle | No problem reported | 63702 | ||
| 878438 | 20.00 | 3 | 405.90 | 406.90 | 401.10 | Niskin bottle | No problem reported | 63703 | ||
| 878441 | 20.00 | 4 | 213.80 | 214.80 | 211.10 | Niskin bottle | No problem reported | 63704 | ||
| 878444 | 20.00 | 5 | 203.40 | 204.40 | 200.80 | Niskin bottle | No problem reported | 63705 | ||
| 878447 | 20.00 | 6 | 101.60 | 102.60 | 100.00 | Niskin bottle | No problem reported | 63706 | ||
| 878450 | 20.00 | 7 | 51.60 | 52.60 | 50.50 | Niskin bottle | No problem reported | 63707 | ||
| 878453 | 20.00 | 8 | 25.60 | 26.60 | 24.70 | Niskin bottle | No problem reported | 63708 | ||
| 878456 | 20.00 | 9 | 11.60 | 12.60 | 10.80 | Niskin bottle | No problem reported | 63709 |
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 | D242 |
| Departure Date | 1999-09-07 |
| Arrival Date | 1999-10-06 |
| Principal Scientist(s) | Stuart A Cunningham (Southampton Oceanography Centre) |
| 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 |
| B | nominal value |
| Q | value below limit of quantification |
