Metadata Report for BODC Series Reference Number 2046171

• 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 916 Ti-Touch compact potentiometric titrator

The Metrohm 916 Ti-Touch is a stand-alone potentiometric titrator for dynamic (DET), monotonic (MET), set endpoint (SET) and manual titrations (MAT). The instrument consists of an intergrated buret, rod stirrer (or magnetic stirrer) and dosing system with a live touch control display.

Specifications

More information can be found in the manufacturer's product description.

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 Samples for Cruise DY130

Originator's Protocol for Data Acquisition and Analysis

DY130 had a total of 14 CTD stations with nutrient bottle samples obtained from these casts using 20L niskin bottles.

Dissolved Oxygen samples were the first to be collected from the CTD rosette. Seawater was collected using a tube into pre-calibrated oxygen bottles. The bottles were rinsed out, flushed with seawater for approximately 3 times bottle volume and then filled from the Niskin bottle. Throughout the sampling process, care was taken to avoid bubble formation inside the sampling tube and sampling bottle. The fixing reagents (manganous chloride and alkalised sodium iodide solutions) were then immediately added, and the bottle sealed with a glass stopper, taking care not to introduce any air bubbles. Sample bottles were thoroughly mixed by shaking in order to homogenise the contents and then stored in a dark plastic crate for 30 to 40 minutes to allow the precipitate to settle. After settling the samples were thoroughly mixed for a second time in order to ensure that the reaction was complete. Analyses were carried out within four to six hours of sample collection. Temperature of the Niskin bottles was taken separately with a Fisher Scientific temperature probe.

The chemical reagents were all prepared in advance at NOCS following the procedures described by Dickson (1994). When ready to titrate, the stopper of the flask was carefully removed, a clean magnetic stirrer was added and the flask was placed on the stir plate. Once the precipitate was well mixed 1 ml of 5M sulphuric acid was dispensed into the flask and the electrode and burette were carefully inserted to place the tips in the lower-middle depth of the sample flask. The initial volume of sodium thiosulfate (Na2S-2O3) for each sample was 0.3 ml before continuing to be titrated at 0.0005 ml intervals using an electrode with amperometic end-point detection (Culberson and Huang, 1987) with an end current of 0.1 x 10-6 A. The resultant volume of titrant was recorded both by manual logging and on the Titrino (Metrohm). Following this the value was converted to a DO concentration. Thiosulfate calibrations and reagent blank checks were carried out for each sampling station following the GO-SHIP protocols (Langdon, 2010). At least 3 blank checks of the reagents and 3 standardisations of the sodium thiosulfate were completed using a 1.667 mol l-1 certified iodate standard (OSIL) every cast.

Duplicate samples were taken on each cast (usually from the two deepest depths).

References

Culberson, C.H. and Huang, S. (1987). Automated amperometric oxygen titration. Deep-Sea Res. Pt A 34(5-6), 875-880. doi:10.1016/0198-0149(87)90042-2

Dickson, A.G. (1994). Determination of dissolved oxygen in seawater by Winkler titration. Technical report, WOCE operations manual, WOCE report 68/91 Revision 1 November 1994.

Langdon, C. (2010). Determination of dissolved oxygen in seawater by Winkler titration using the amperometric technique. IOCCP Report No. 14, ICPO Publication Series No. 134, Version 1, 2010.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. Any replicates were averaged and standard deviation calculated. Details of mapping between originator's channels and BODC's parameter codes are given below:

Project Information

Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)

Introduction

CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.

Scientific Rationale

The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for DY130_CTD_DY130-019

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: DY130_CTD_DY130-019

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

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