Metadata Report for BODC Series Reference Number 1982079

• 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.

Turner Designs Trilogy Fluorometer

The Trilogy Laboratory Fluorometer is a compact laboratory instrument for making fluorescence, absorbance and turbidity measurements using the appropriate snap-in Application Module.

The following snap-in application modules are available:

For extracted chlorophyll measurements using EPA 445, Trilogy automatically calculates the concentration using the filtered and solvent volumes. The turbidity modules use an IRLED with a wavelength of 860nm to meet ISO 7027 standards for turbidity water quality measurements.

Specifications

Further details can be found in the manufacturer's specification sheet.

Size fractionated chlorophyll-a concentrations from CTD bottle samples on RidgeMix cruise JR15007

Originator's Protocol for Data Acquisition and Analysis

Seawater samples were taken from 20 L Niskin bottles on a rosette sampler throughout the RidgeMix cruise JR15007.

8 to 14 samples were analysed for chlorophyll concentration to characterise the shape of the deep chlorophyll maximum. The deepest sample was at 300 m. Seawater samples for size-fractionated chlorophyll-a were collected by transferring 1L of seawater from the Niskin bottle into 1 L brown bottles, which were triple rinsed with milli-Q and seawater. Analysis was performed on-board by filtering between 0.25 and 1L through sequential filters of pore size 20 µm, 2 µm and 0.2 µm (45 mm polycarbonate filters) in a size-fractionated chlorophyll 'rig'. After filtration samples were folded and transferred into labelled glass tubes with screw-cap lids. 5 ml of 90% acetone was added in the fume cupboard and samples were stored at 4°C in the fridge for 24 hours. Sample raw fluorescence (RFU) was measured using a Turner Trilogy Fluorometer and chlorophyll-a concentrations calculated by calibrating fluorescence with chlorophyll-a standards of known concentration. Prior to sample fluorescence measurement, three blanks and two solid standards were measured to confirm instrument stability. The fluorometer cuvette was triple acetone rinsed between samples.

Instrumentation Description

Turner Designs Trilogy fluorometer

BODC Data Processing Procedures

Data were submitted by email to BODC as an Excel spreadsheet containing size fractionated chlorophyll-a concentrations along with the cruise number, CTD number, latitude, longitude, and depth. A pdf copy of the PhD thesis this data was collected for, which detailed the sampling protocol and analytical methods, was submitted alongside the data. The data and metadata were archived following standard BODC procedure.

The data were reformatted and assigned BODC parameter codes which were in equivalent units to the data and so no unit conversions were necessary. During reformatting, replicate measurements were averaged and standard deviation was calculated. Data were then loaded into BODC's samples database under Oracle Relational Database Management System using established data banking procedures.

The originator's parameters were mapped to BODC parameter codes as follows:

Data Quality Report

The originator did not provide any quality control comments and during BODC processing it was not deemed that any values required flagging.

Project Information

A nutrient and carbon pump over mid-ocean ridges (RidgeMix)

RidgeMix is a five year (August 2014 to February 2019) research programme which received funding from the Natural Environment Research Council (NERC). The aim of the programme was to address the problem of how deep nutrients are transported into the surface waters in mid-latitudes, by testing a new view: tides passing over the mid-Atlantic ridge generate enhanced turbulence and mixing, which in turn provides a nutrient supply to the upper thermocline waters. These nutrients are then transported horizontally along density surfaces over the western side of the basin, probably being swept along the Gulf Stream and eventually passing into the winter mixed surface layer. When this surface layer shallows and warms in spring, the nutrients are then available to the phytoplankton.

Fieldwork involved collecting measurements of the turbulence and nutrient concentrations over and adjacent to the Mid-Atlantic Ridge, using a novel long-term moored array of instruments along the ridge, deployed over a five-week research cruise. Sampling was done sufficiently quickly to resolve tidal changes in currents and mixing over the ridge. A second component of the fieldwork will use computer models of circulation in the Atlantic to explore the wider implications of the fieldwork observations, to determine whether or not mixing over the mid-Atlantic ridge really does provide enough nutrients to explain the phytoplankton production in the mid-latitude North Atlantic.

RidgeMix was a collaborative project involving five organisations, of which three were UK based and two were US based. The project was led by the Professor Jonathan Sharples, University of Liverpool, Earth, Ocean and Ecological Sciences. Collaborators were:

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JR15007_CTD_CTD_058

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: JR15007_CTD_CTD_058

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.