Metadata Report for BODC Series Reference Number 1094869

• 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 Quality Report - see processing documentation

Data quality information is included in the general documentation for this series. Please read.

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

Technicon AutoAnalyzer II (AAII)

The AAII is a segmented flow analyzer used for automated colorimetric analysis. The apparatus uses 2 mm diameter glass tubing and pumps reagents at flow rates of 2 to 3 ml s^-1, producing results at a typical rate of 30 to 60 samples per hour. The system comprises an autosampler, peristaltic pump, chemistry manifold a detector and a data acquisition software.

This instrument was replaced by the AA3 in 1997 which was upgraded to the AA3 HR systems in 2006.

Specifications

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.

AMT6 Nutrient (micromolar) measurements from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

This data originates from analyses of bottle samples taken from 38 CTD casts.

The nutrient analyser used during the AMT-6 cruise was a five-channel Technicon AAII, segmented flow autoanalyser. The chemical methodologies used were: nitrate (Brewer and Riley, 1965), nitrite (Grasshoff, 1976), phosphate (Kirkwood, 1989), silicate (Kirkwood, 1989) and ammonia (Mantoura and Woodward, 1983) the nanomolar nitrate and nitrite detection methodology was from Garside (1982) and the nanomolar ammonia system was adapted from Jones (1991). Water samples were taken from the 30 litre CTD/Rosette system (SeaBird) and sub-sampled into clean Nalgene bottles. The analysis of the samples was completed within 3 hours of sampling. Clean handling techniques were employed to avoid any contamination of the samples, particularly by ammonia. No samples were stored.

Underway continuous sampling of surface water used the non-toxic water system. The water was filtered in-line (Morris et al., 1978), by a 0.45 µm Millipore filter, before analysis of the macronutrients. For the underway nanomolar ammonia system the Millipore filter was removed and the water was only course filtered through a stainless steel mesh. The results for the CTD and underway samples from the same approximate depth of 7 m then agreed. Underway sampling was carried out where possible for the nanomolar ammonia system, and where necessary. Where values exceeded 1 microgram, the five channel Technicon analyser was deployed for the other nutrients.

The maximum sampling depth was 200 m for the CTD samples and was the bottom depth for all CTDs where possible. There was one deep CTD (to 1500 m) in the north of the Canigo region, off the Iberian Peninsula. All CTD samples were analysed successfully with a negligible sample loss rate. One CTD section was lost due to poisoning of the Copper/Cadmium Nitrate reducing column by anoxic bottom water samples on one day of the Benguela study. As usual, the Technicon system showed its reliability and reproducibility in the extreme environment of marine research. The nanomolar nitrate/nitrite chemiluminescent system worked as well as could be expected, although this system was at the limits of its detection for many mixed layer samples from the oligotrophic stations, and the present detector is of insufficient sensitivity to show fine scale changes and variations at less than 10 nanomoles. The ammonia system performed well following an extensive pre-cruise rebuild, and again it will have produced unique measurements of ammonia concentrations from these parts of the world's oceans.

References Cited

Brewer P.G. and Riley J.P., 1965. The automatic determination of nitrate in sea water. Deep-Sea Research, 12, 765-772.

Garside C., 1982. A chemiluminescent technique for the determination of nanomolar concentrations of nitrate and nitrite in seawater. Marine Chemistry, 11, 159-167.

Grasshoff K., 1976. Methods of seawater analysis. Verlag Chemie, Weiheim: 317 pp.

Jones R.D., 1991. An improved fluorescence method for the determination of nanomolar concentrations of ammonium in natural waters. Limnology and Oceanography, 36, 814-819.

Kirkwood D.S., 1989. Simultaneous determination of selected nutrients in seawater. ICES CM1989/C:29, 12pp.

Mantoura R.F.C. and Woodward E.M.S., 1983. Optimisation of the indophenol blue method for the automated determination of ammonia in estuarine waters. Estuarine, Coastal and Shelf Science, 17, 219-224.

Morris A.W., Bale A.J. and Howland R.J.M., 1978. A filtration unit for use with continuous autoanalytical systems applied to highly turbid waters. Estuarine and Coastal Marine Science, 6, 105-109.

Instrumentation Description

Not relevant to this data set.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format and saved to the BODC archive with reference PML020107. Sample metadata were checked against information held in the database. Originator's sample ID was matched based on CTD cast and bottle firing depth. OIDs were present in the database for the CTD events in the format CTDxx, where xx was the cast number for the cruise.

The CTD36 samples were matched to the cruise report depths as it appears there was a keying error and the 50 m sample should have read 80 m. A similar discrepancy was observed for CTD51 sample keyed as 10m by originator should have been keyed 100 m according to Cruise Report.

There were replicate samples provided for one depth on a number of casts. The mean of the replicates were taken for each depth and the values entered into the database for the following samples.

Although the cruise report indicates underway and nanomolar measurements were made, there were none supplied to BODC. The files also contained related data from incubations carried out during the cruise.

Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were assigned parameter codes defined in BODC parameter dictionary. Data loaded into BODC's database using established BODC data banking procedures.

A parameter mapping table is provided below;

Data Quality Report

BODC has not been advised of any quality checks carried out by the data originator.

Problem Report

Not relevant to this data set.

Project Information

The Atlantic Meridional Transect (AMT) - Phase 1 (1995-2000)

Who was involved in the project?

The Atlantic Meridional Transect (AMT) programme was designed by and implemented as a collaboration between Plymouth Marine Laboratory (PML) and Southampton Oceanography Centre (SOC). The programme was hosted by Plymouth Marine Laboratory and involved additional researchers from UK and international universities throughout its duration.

What was the project about?

When AMT began in 1995 the programme provided a platform for international scientific collaboration, including the calibration and validation of SeaWiFs measurements and products. The programme provided an exceptional opportunity for nationally and internationally driven collaborative research and provided a platform for excellent multi-disciplinary oceanographic research. As an in situ observation system, the data collected by the AMT consortium informed on changes in biodiversity and function of the Atlantic ecosystem during this period of rapid change to our climate and biosphere.

The scientific aims were to assess:

• mesoscale to basin scale phytoplankton processes
• the functional interpretation of bio-optical signatures
• the seasonal, regional and latitudinal variations in mesozooplankton dynamics

When was the project active?

The first phase of the AMT programme ran from 1995 to 2000 and consisted of a total of 12 cruises. A second phase of funding allowed the project to continue for the period 2002 to 2006 with a further 6 cruises.

Brief summary of the project fieldwork/data

The AMT programme undertook biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crossed a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. The transect route was covered north-south in September/October and south-north in April/May of each year.

The measurements of hydrographic and bio-optical properties, plankton community structure and primary production completed on the first 12 transects (1995-2000) represent the most coherent set of repeated biogeochemical observations over ocean basin scales. This unique dataset has led to several important discoveries concerning the identification of oceanic provinces, validation of ocean colour algorithms, distributions of picoplankton, identifying new regional sinks of pCO2 and variability in rates of primary production and respiration.

Who funded the project?

The programme was funded by the Natural Environment Research Council (NERC) and further support was received from the National Aeronautics and Space Administration (NASA) with equipment and funding from the Sea-viewing Wild Field-of-view Sensor (SeaWiFS) project.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for AMT6_CTD_CTD43

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

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: