Metadata Report for BODC Series Reference Number 2288575

• 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

Ocean Optics HR4000 Spectrometer

The High-Resolution (HR) 4000 spectrometer is a microcontroller-based Miniature Fiber Optic instrument created by Ocean Optics UK. It is a versatile high-resolution instrument which enables flexibility and customisation via the attachment of necessary components. The HR4000 spectrometer has a 3648-element CCD-array detector from Toshiba (product number: TCD1304AP) that enables optical resolution as precise as 0.02 nm Full Width Half Maximum(FWHM). It is responsive from 200-1100 nm, but as this instrument allows custom analysis to be carried out, the specific range and resolution depend on the grating and entrance slit choices.

The electronics have been designed for considerable flexibility in connecting to various modules as well as external interfaces to PC's, PLC's and other embedded controllers through USB 2.0 or RS-232 communications. The HR4000 supports four triggering operational modes which include Normal, Shutter, Normal (Shutter), External hardware level/edge modes with details on these found in the manufacturers specifications manual below.

The specifications and features of the HR4000 spectrometer can be found in the table below:

Additional information on the spectrometer used can be found in the manufacturer's specificationsand product sheet.

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.

pH measurements from CTD bottles: Cruise JR20120601 (JR271)

Originators protocol for data acquisition and analysis

As part of the UK Ocean Acidification project (UKOA) a total of 45 CTD casts were obtained on board the JR20120601 (JR271) cruise. Sampling took place as part of the Sea Surface Research Consortium of the UKOA Research Programme. The cruise passage took place from June to July 2012 departing from Immingham, United Kingdom traveling to Reykjavik, Iceland covering areas such as the Barents Sea, North Sea, Greenland Sea, Norwegian Sea, Arctic Ocean and the North East Atlantic Ocean.

Two CTD rigs were deployed on the cruise with the pH samples obtained from the stainless steel CTD. Samples for pH analysis were collected from the CTD niskin bottles via the use of silicone tubing and collected in 20 mL borosilicate vials. The bottles were filled with water allowing overflow by two or three bottle volumes. Water for pH measurement was sampled after oxygen and before DIC and alkalinity. The vials were closed with a plastic screw cap with a hole and silicon septum and were left in a water bath at 25 degrees Celsius for 10 minutes minimum to allow equilibrium before analysis.

The pH samples were analysed on board at 25 degrees Celsius using a custom made colorimetric pH analyser which was developed by the Sensor group at NOC Southampton. This instrumentation was custom made using a HR4000 Fiber Optic spectrometer (Ocean Optics) as the detector with a grating of 300 Line Composite Blaze and Slit width 5 m. The custom made analyser uses a simple micro-fluidic design consisting of syringe pumps (Nanomite, Harvard Apparatus, UK) which propelled the samples and indicator through the analyser with the distributed controlled by four micro-inert valves (LFNA1250125H, Lee Products Ltd., UK) (Rerolle et al 2013). The light source used in the pH system was a tri-coloured LED (Roithner Laser, Austria) with wavelengths of 435 nm (25 nm Full Width Half Maximum FWHM), 596 nm (15 nm FWHM) and 750 nm (30 nm FWHM). Custom made electronics boards were developed to interface the valves, light sources and thermistors. The sample was pumped through the system at a rate of 60 L min ^-1.

Instrument calibration was completed at 25 degrees Celsius and salinity 35 using unpurified mCP. 2 mM unpurified meta-Cresol Purple indicators were added to the samples for colorimetric analysis. Samples were analysed four times in a row, taking 20 minutes per sample and attaining standard deviation of the last three measurements. Only data with a standard deviation lower or equal to 0.010 pH units were kept.

During the cruise, performance of the system was evaluated by running certified reference material, Tris buffer and DIC/TA, provided by the Scripps Institution of Oceanography. An average offset of 0.018±0.007 pH units was observed between the certified and measured pH values. A correction was therefore applied to all samples by subtracting 0.018 pH units. The data were also corrected to in situ temperature and pressure by applying the following corrections: pH(Tinsitu)=pH(25)-0.0155(Tinsitu-25)-0.005 and pH(Pinsitu)=pH(P0)-4e-5*Pinsitu+0.0002.

BODC Processing

The data were submitted to BODC in excel format representing data collection from 45 CTD stations and were archived under accession SOC150207. The data were loaded into the BODC database using established BODC data banking procedures. Data were reformatted and the variables provided by the originator can be found in the table below. Sample metadata of Cruise ID, Site name/Station, Sampling gear, Lat (+veN), Lon (-veE), Unique project/Cruise sample ID and Sample depth were provided but not loaded to the database. Metadata were checked against information already held in the BODC database and matched against the database using site name/station, cruise and rosette position. There were no discrepancies.

The data were checked for any possible inconsistencies. It was observed that a pH value was below that of the pH scale/range with a measurement of -0.004. This value has been flagged using a BODC quality control flag for improbable data.

The table below illustrates how the variables reformatted within the excel files were mapped to the appropriate BODC parameter codes:

No parameters required unit conversions and no derived parameters were created during reformatting.

References

Rérolle, V. M. C., Floquet, C. F. A., Harris, A. J. K., Mowlem, M. C., Bellerby, R. R. G. J., and Achterberg, E. P.: Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements, Anal. Chim. Acta, 786, 124-131, doi:10.1016/j.aca.2013.05.008, 2013.

Project Information

UKOARP Theme B: Ocean acidification impacts on sea surface biology, biogeochemistry and climate

The overall aim of this theme is to obtain a quantitative understanding of the impact of ocean acidification (OA) on the surface ocean biology and ecosystem and on the role of the surface ocean within the overall Earth System.

The aims of the theme are:

• To ascertain the impact of OA on planktonic organisms (in terms of physiological impacts, morphology, population abundances and community composition).
• To quantify the impacts of OA on biogeochemical processes affecting the ocean carbon cycle (both directly and indirectly, such as via availability of bio-limiting nutrients).
• To quantify the impacts of OA on the air-sea flux of climate active gases (DMS and N₂O in particular).

The main consortium activities will consist of in-situ measurements on three dedicated cruises, as well as on-deck bioassay experiments probing the response of the in-situ community to elevated CO₂. Most of the planned work will be carried out on the three cruises to locations with strong gradients in seawater carbon chemistry and pH; the Arctic Ocean, around the British Isles and the Southern Ocean.

Weblink: http://www.oceanacidification.org.uk/research_programme/surface_ocean.aspx

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JR20120601_CTD_CTD017s

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: JR20120601_CTD_CTD017s

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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