Metadata Report for BODC Series Reference Number 1244328
Definition of BOTTFLAG
|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
No Problem Report Found in the Database
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."
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.
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.
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 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.
Nutrients as part of the North Sea Project
Converted from CDROM documentation.
Sampling strategy and methodology
Duplicate samples were collected in 30 ml 'Elkay Dilu-Vials' from each CTD bottle. Samples were stored in a refrigerator at 4°C between collection and analysis and usually analysed within four hours of collection. Initially, two aliquots from one the samples were analysed. If a problem was considered to have occurred, the second sample was analysed. The samples were unfiltered and no preservative was added.
The samples were analysed using a ChemLab AA-II segmented continuous flow autoanalyser. The chemistries used were similar to those described in Grasshof et al (1983). Peak heights were interpreted using a ChemLab PHA interface and software running on an IBM PS2/50. Each run was calibrated by measurement of a set of 4 standards run in duplicate at the start of the run to which a third order polynomial, forced to pass through the origin, was fitted.
Analyses were made for nitrate+nitrite, nitrate, phosphate, silicon and (for Challenger 39 and subsequent cruises), ammonia.
The replicate analyses were supplied to BODC. Values were subjected to a simple range check with seasonally varying tolerances and a check was made to identify samples with excessive differences between replicates. Any problems identified were resolved by interaction with the Principal Investigator and erroneous values corrected or deleted from the data set. All remaining replicates were then averaged.
In general, the autoanalyser worked well. The only problems reported were random variations in Cu/Cd reduction coil efficiency (between 70 and 90%) on two cruises (Challenger 33 and Challenger 72A) and occasional baseline drift and spiking, mostly on phosphate and nitrite.
During Challenger 33, problems were encountered with the PS2 processing software and the nutrient concentrations were obtained by manual determination of peak heights from chart recorder output.
The survey data set is believed to be of good quality and has borne up well to intercomparison with data from other sources during the compilation of synthesised data sets by the ICES hydrographer.
Analyses for the major nutrients (nitrate+nitrite, phosphate, nitrite and silicate) were undertaken on CTD water bottle samples for the following process cruises: Challenger 44, Challenger 48, Challenger 50, Challenger 52, Challenger 60, Challenger 62 and Challenger 72C.
For Challenger 50 and Challenger 72C the survey protocols, including the determination of ammonia, were followed exactly by an analyst who had also participated in survey cruises. Quality control was undertaken by the analyst prior to submission to BODC and the data are believed to be of the same good quality as the survey data.
For the resuspension cruises, Challenger 44, Challenger 52 and Challenger 60, the survey protocols were generally followed except the concentrations were computed manually and all quality control was done prior to submission to BODC. The analyst had participated in survey cruises.
On two of these cruises, Challenger 52 and Challenger 60 ammonia was determined by flow injection analysis. The method is based upon the conversion of the ammonium ion into gaseous ammonia across a hydrophobic membrane and is fully described in Willason and Johnson (1986) and Howland et al.
There are no reasons to suspect the quality of the data from these cruises.
For Challenger 48 and 62 the analyses were done using the same equipment but details of the protocols followed, including quality control procedures, are unknown.
Feedback to BODC indicates that the nitrate data from Challenger 48 appear to be high by up to a factor of 10 and that the phosphate data do not exhibit the expected relationships with other parameters. However, it is not possible to categorically state that the data are in error because the cruises were working in waters strongly influenced by the Rhine plume.
WARNING. It is strongly recommended that the nutrient data from Challenger 48 and Challenger 62 be used with caution.
Grasshof, K., Erhardt, M. and Kremling, K. (1983). Methods of sea water analysis, 2nd edition. Verlag Chemie, Weinheim, 419pp..
Howland, R.J.M., A.J. Bale and P.G. Watson. Plymouth Marine Laboratory Estuarine Processes Group Analytical Methods Handbook.
Willason, S.W. and K.S. Johnson (1986). A rapid, highly sensitive technique for the determination of ammonia in sea water. Mar. Biol. 91, 285-290.
North Sea Project
The North Sea Project (NSP) was the first Marine Sciences Community Research project of the Natural Environment Research Council (NERC). It evolved from a NERC review of shelf sea research, which identified the need for a concerted multidisciplinary study of circulation, transport and production.
The ultimate aim of the NERC North Sea Project was the development of a suite of prognostic water quality models to aid management of the North Sea. To progress towards water quality models, three intermediate objectives were pursued in parallel:
- Production of a 3-D transport model for any conservative passive constituent, incorporating improved representations of the necessary physics - hydrodynamics and dispersion;
- Identifying and quantifying non-conservative processes - sources and sinks determining the cycling and fate of individual constituents;
- Defining a complete seasonal cycle as a database for all the observational studies needed to formulate, drive and test models.
Proudman Oceanographic Laboratory hosted the project, which involved over 200 scientists and support staff from NERC and other Government funded laboratories, as well as seven universities and polytechnics.
The project ran from 1987 to 1992, with marine field data collection between April 1988 and October 1989. One shakedown (CH28) and fifteen survey cruises (Table 1), each lasting 12 days and following the same track, were repeated monthly. The track selected covered the summer-stratified waters of the north and the homogeneous waters in the Southern Bight in about equal lengths together with their separating frontal band from Flamborough head to Dogger Bank, the Friesian Islands and the German Bight. Mooring stations were maintained at six sites for the duration of the project.
|Table 1: Details of NSP Survey Cruises on RRS Challenger|
|CH28||29/04/88 - 15/05/88|
|CH33||04/08/88 - 16/08/88|
|CH35||03/09/88 - 15/09/88|
|CH37||02/10/88 - 14/10/88|
|CH39||01/11/88 - 13/11/88|
|CH41||01/12/88 - 13/12/88|
|CH43||30/12/88 - 12/01/89|
|CH45||28/01/89 - 10/02/89|
|CH47||27/02/89 - 12/03/89|
|CH49||29/03/89 - 10/04/89|
|CH51||27/04/89 - 09/05/89|
|CH53||26/05/89 - 07/06/89|
|CH55||24/06/89 - 07/07/89|
|CH57||24/07/89 - 06/08/89|
|CH59||23/08/89 - 04/09/89|
|CH61||21/09/89 - 03/10/89|
Alternating with the survey cruises were process study cruises (Table 2), which investigated some particular aspect of the science of the North Sea. These included fronts (nearshore, circulation and mixing), sandwaves and sandbanks, plumes (Humber, Wash, Thames and Rhine), resuspension, air-sea exchange, primary productivity and blooms/chemistry.
|Table 2: Details of NSP Process cruises on RRS Challenger|
|CH34||18/08/88 - 01/09/88||Fronts - nearshore|
|CH36||16/09/88 - 30/09/88||Fronts - mixing|
|CH56||08/07/89 - 22/07/89||Fronts - circulation|
|CH58||07/08/89 - 21/08/89||Fronts - mixing|
|CH38||24/10/88 - 31/10/88||Sandwaves|
|CH40||15/11/88 - 29/11/88||Sandbanks|
|CH42||15/12/88 - 29/12/88||Plumes/Sandbanks|
|CH46||12/02/89 - 26/02/89||Plumes/Sandwaves|
|CH44||13/01/89 - 27/01/89||Resuspension|
|CH52||11/05/89 - 24/05/89||Resuspension|
|CH60||06/09/89 - 19/09/89||Resuspension|
|CH48||13/03/89 - 27/03/89||Air/sea exchanges|
|CH62||05/10/89 - 19/10/89||Air/sea exchanges|
|CH50||12/04/89 - 25/04/89||Blooms/chemistry|
|CH54||09/06/89 - 22/06/89||Production|
In addition to the main data collection period, a series of cruises took place between October 1989 and October 1990 that followed up work done on previous cruises (Table 3). Process studies relating to blooms, plumes (Humber, Wash and Rhine), sandwaves and the flux of contaminants through the Dover Strait were carried out as well as two `survey' cruises.
|Table 3: Details of NSP `Follow up' cruises on RRS Challenger|
|CH62A||23/10/89 - 03/11/89||Blooms|
|CH64||03/04/90 - 03/05/90||Blooms|
|CH65||06/05/90 - 17/05/90||Humber plume|
|CH66A||20/05/90 - 31/05/90||Survey|
|CH66B||03/06/90 - 18/06/90||Contaminants through Dover Strait|
|CH69||26/07/90 - 07/08/90||Resuspension/Plumes|
|CH72A||20/09/90 - 02/10/90||Survey|
|CH72B||04/10/90 - 06/10/90||Sandwaves/STABLE|
|CH72C||06/10/90 - 19/10/90||Rhine plume|
The data collected during the observational phase of the North Sea Project comprised one of the most detailed sets of observations ever undertaken in any shallow shelf sea at that time.
|Start Date (yyyy-mm-dd)||1989-04-28|
|End Date (yyyy-mm-dd)||1989-04-28|
|Organization Undertaking Activity||Plymouth Marine Laboratory|
|Country of Organization||United Kingdom|
|Originator's Data Activity Identifier||CH51_CTD_1761|
|Platform Category||lowered unmanned submersible|
BODC Sample Metadata Report for CH51_CTD_1761
|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|
|284935||10.00||45.80||46.40||42.70||Niskin bottle||No problem reported|
|284952||10.00||25.00||25.20||21.90||Niskin bottle||No problem reported|
|284966||10.00||11.90||12.20||9.00||General Oceanics GO-FLO water sampler||No problem reported|
|284983||10.00||2.10||3.60||.50||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
|Principal Scientist(s)||Alan W Morris (Plymouth Marine Laboratory)|
Complete Cruise Metadata Report is available here
No Fixed Station Information held for the Series
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|<||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.)|
|E||End of CTD Down/Up Cast|
|G||Non-taxonomic biological characteristic uncertainty|
|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|
|O||Improbable value - user quality control|
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|0||no quality control|
|2||probably good value|
|3||probably bad value|
|6||value below detection|
|7||value in excess|
|A||value phenomenon uncertain|
|Q||value below limit of quantification|
Appendix 1: CH51_CTD_1761
Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.
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|Series Identifier||Data Category||Start date/time||Start position||Cruise|
|1705323||Water sample data||1989-04-28 01:16:00||52.67822 N, 2.41604 E||RRS Challenger CH51|