Metadata Report for BODC Series Reference Number 1261006

• 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

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.

AMT12 Ammonium and Urea nanomolar measurements

Data Acquisition and Analysis

This data originates from analyses on CTD rosette bottles from 27 casts. Water samples were collected from 6 depths during the pre-dawn CTD cast using the Sea-Bird CTD rosette system. Samples were collected into acid clean 60 mls HDPE (nalgene) sample bottles. Clean handling techniques were employed to avoid any contamination of the samples.

Ammonium determinations were made on frozen seawater samples due to technical complications prohibiting such measurements during the cruise. This is recognised as a suspect practice so the data should be viewed/used with caution. The manual method of Holmes et al (1999) was used, modified for 10ml sample volumes (after Johnson, UEA) and samples were measured on a Turner Designs TD700 fluorometer fitted with the CDOM filter kit. This is the first time (to the PI's knowledge) that this technique was used for AMT.

Urea concentrations were again determined on frozen samples using the room temperature manual method of Goeyens et al. (1998) adapted from Mulvenna and Savidge (1992). All samples were read on a Hitachi 810 Spectrophotometer.

References Cited

Goeyens L., Kindermans N., Abu Yusuf M. and Elskens M. 1998. A room temperature procedure for the manual determination of urea in seawater. Est. Coast. Shelf Science, 47, 415-418.

Holmes R.M., Aminot A., Kerouel R., Hooker B.A. and Peterson B.J. 1999. A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Can. J. Fish. Aquat. Sci. 56, 1801-1808.

Johnson M.T. 2004. The air-sea flux of ammonia, PhD Thesis, University of East Anglia, Norwich.

Mulvenna P.F. and Savidge G., 1992. A modified manual method for the determination of urea in seawater using diacetylmonoxime reagent. Est. Coast. Shelf Science, 34, 429-438.

Instrumentation Description

Not relevant to this dataset.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format. Sample metadata (Station, Light (%), Bottle Depth (m)) were checked against information held in the database - there were no discrepancies. Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were provided nano-mole per litre units which were converted to micro-mole per litre by dividing by 1000. The units were then consistent with those used for the relevant parameters in the BODC database. NB: the data are from nanomolar analysis and the 4th decimal place can be considered to be significant.

In the file two samples (CTD51 depth 61m and CTD58 depth 20m) referred to data that was not present and were not loaded.

Data loaded into BODC's database with only a unit conversion change applied.

A parameter mapping table is provided below;

Data Quality Report

BODC were not advised of any specific QC checks carried out by the data orginator.

Problem Report

The data originator advises that since the ammonium determinations were made on frozen seawater samples, which is recognised as a suspect practice, the data should be viewed/used with caution.

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

BODC Sample Metadata Report for AMT12_CTD_AMT12_47

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

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:

Appendix 1: AMT12_CTD_AMT12_47

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.