Metadata Report for BODC Series Reference Number 2256966

• 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.

Discrete Chlorophyll-a samples from CTD bottles during cruise CD150

Originator's Protocol for Data Acquisition and Analysis

The RRS Charles Darwin CD150 cruise departed on the 22 August 2003 from Oman, Muscat traveling to the Arabian Sea and returned to Oman, Muscat on the 15 September 2003. RRS Charles Darwin Cruise 150 forms part of a larger programme of research ("Benthic processes in the Arabian Sea: mechanistic relationships between benthos, sediment, biogeochemistry and organic matter cycling"), focusing on the benthic biogeochemistry of the Pakistan Margin, that includes four cruises in total (CD145, 146, 150 and 151).

Sample collection

Samples were collected from the Seabird CTD 24 bottle rosette using the 10 litre Seabird bottles. The algal maxima depth was identified from the fluorescence trace from the Seabird software. The samples were initially collected in 5 litre polythene bottles and then transferred to approx 1.2 litre polycarbonate bottles for use on the SAMS vacuum water filtration rig. The rig uses the ship's compressed air via a pneumatically operated Seimens venturi pump to provide the vacuum. Samples were filtered through 25 mm diameter Whatman GF/F filters and the filters stored frozen in 15 ml polypropylene vials.

Sample analysis

The method used to analyse the samples is an isocratic high performance liquid chromatography (HPLC) method.

The HPLC method which uses a 90%:10% Methanol:Acetone eluent with a cycle time of 5 minutes pumped at 1 ml per minute through a reverse phase 2 cm C18 column. The extracted sample, which is in 95% buffered acetone, is mixed with a 0.5 M ammonium acetate solution buffer in a sample:buffer ratio of 3:1. The method only measures Chlorophyll-a and the fluorimeter is calibrated with a Chlorophyll-a standard obtained from DHI water and environment, based in Denmark.

BODC Data Processing Procedures

BODC received discrete Chlorophyll-a samples and extracted the data and merged with information from the associated Sea-Bird .btl files (also provided). These data were loaded to BODC's ocean database under the ORACLE Relational Database Management System. Data that were considered unrealistic were flagged suspect.

Content of data series

The Originator's variables were mapped to appropriate BODC parameter codes as follows:

Quality Report

Negative data values were flagged as below the detection limit by the Originator. BODC have changed these values to the detection limit value with the corresponding below detection BODC flag.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for CD150_CTD_56028#01

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: CD150_CTD_56028#01

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.