Metadata Report for BODC Series Reference Number 2049328

• 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

Metrohm 888 Titrando

A modular pentiometric titrator for dynamic, monotonic and set endpoint titrations. The instrument consists of an intergrated buret, rod or magnetic stirrer and dosing system. Operation is carried out by means of a touch-sensitive display or with high-performance PC software.

Specifications

The 888 Titrando has one galvanically isolated measuring interface. The measuring cycle is 100 ms for all measuring modes.

For more information about this model see the manufactures data sheet - Metrohm 888 Titrando.

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.

Dissolved Oxygen data for Cruise JR15007

Originator's Protocol for Data Acquisition and Analysis

Sampling Collection

Niskin bottles were deployed at 35 locations in the Mid Atlantic, to a range of depths. Oxygen samples were the first drawn from the Niskin bottles as soon as the rosette was secured on deck. 125 ml optically-clear glass oxygen bottles were calibrated for volume and prepared to store the samples. The glass bottles were triple-rinsed and stored full with Milli-Q. Tygon tubing was used to fill the bottles from the Niskin, the bottles were overflowed for 20 seconds to ensure the sample contained no bubbles. Temperature of each sample was taken immediately then the sample was fixed with 1 ml manganese sulphate (3 M) and 1 ml alkaline iodide and shaken vigorously for 20 seconds prior to storage, which occurred approximately 15 minutes later. Samples were stored upright under water in a dark 60 l container until the precipitate had settled.

Sample Analysis

Samples were analysed for dissolved oxygen concentration onboard using the modified Winkler method (Carpenter, 1965) and a PC-controlled potentiometric titration system (Metrohm Titrando 888). The samples were analysed between 4 hours and 4 days of collection. Prior to analysis 1 ml sulphuric acid (10 N) was added to each sample to dissolve the precipitate. Reagent blanks were run using 0.025 N potassium iodate (1 aliquot) and sodium thiosulphate titrant (~ 0.18 N). Each of these was performed in triplicate (at minimum) prior to sample analysis each day. Mean reagent blank was 0.00174 ± 0.016 mL over the course of the cruise and mean thiosulphate normality was 0.3070 ± 0.0002 N. Lab temperature was monitored throughout analysis. Calculation of dissolved oxygen concentration was according to HOT protocol (Karl et al., 1990) and Grasshoff (1983). Samples were analysed to produce a dissolved oxygen concentration in umol/l.

References Cited

Carpenter, J.H. (1965). The Chesapeake Bay Institute Technique for the Winkler oxygen method. Limnol. Oceanogr., 10, 141-143.

Karl, D.M., Winn, C. D., Hebel, D.V.W. and Letelier, R. 1990. Hawaii Ocean Time-series (HOT) program field and laboratory protocols.

Grasshoff, K. Ehrhardt, M, and K. Kremling. 1983. Methods of Seawater Analysis. Grasshoff, Ehrhardt and Kremling, eds. Verlag Chemie GmbH. 419 pp.

JR15007 Cruise report

Further information can be found in the JR15007 Cruise report.

BODC Data Processing Procedures

Data were received in an excel file and loaded into the BODC database using established BODC data banking procedures. A parameter mapping table is provided below:

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_030

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_030

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.