Metadata Report for BODC Series Reference Number 1362059

• 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

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

Non-toxic (underway) sea water supply

A source of uncontaminated near-surface (commonly 3 to 7 m) seawater pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the non-toxic supply. The system is also referred to as the underway supply.

Nutrients as part of the North Sea Project

Document History

Converted from CDROM documentation.

Sampling strategy and methodology

Survey cruises

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.

Process cruises

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.

References

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.

Project Information

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.

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.

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.

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.

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

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