Metadata Report for BODC Series Reference Number 1336090

• 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 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.

JC025 Dissolved Inorganic Nutrients Sampling Document

Originator's protocol for data acquisition and analysis

Water samples were drawn from the CTD rosette bottles deployed during the JC025 cruise with the majority of the sampling effort concentrated in the top 140 m of the water column.

Samples were analysed within 24 hours of collection and refridgerated prior to analysis. Measurements were made using standard colorimetric methods with a Lachat Autoanalyser.

Primary standards were prepared as follows:

• Ammonium 10013.27 µM
• Phosphate 10028.95 µM
• Nitrate 10072.30 µM
• Silicate 10511.86 µM

A mixed nutrient stock was prepared from adding 1 ml NH₄, 0.5 ml PO₄, 2 ml SiO₂ and 3 ml NO₃ of the primary standards, as listed above, and diluting to 100 ml. Five working stocks were subsequently prepared by diluting down the mixed nutrient stock, giving the highest concentration of 5 µM NH₄, 2.5 µM PO₄, 10.5 µM SiO₂ and 15.1 µM NO₃. Analyses of triplicate samples showed that results were reproducible to within 5% at concentrations >1 µM, with errors increasing at lower concentrations.

References

Sharples, J., et al. (2009) JC025 Cruise Report, Celtic Sea, 2 July - 27 July 2008. Proudman Oceanographic Laboratory, UK.

Available - JC025 Cruise Report

BODC data processing procedures

The nutrient data were supplied to BODC in Microsoft Excel format and values were extracted from these and saved in ASCII format prior to being loaded into the project database under the ORACLE Relational Database Management System without modification. Data that were considered unrealistic and lay outside of the permitted range for the parameter code were flagged suspect.

SAMS nitrate data quality warning

SAMS have notified BODC of a problem in the analytical procedure adopted for nitrate analysis on this cruise. The problem relates to the technique used to prepare the analytical standards, which results in nitrate (and consequently nitrite) values which are typically 10-15 % higher than they should be. Absolute data values should therefore be used with extreme caution.

Content of data series

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JC025_CTD_JC025_CTD033

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: