Metadata Report for BODC Series Reference Number 1921491

• 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

BODC Data Quality Report

BODC improbable value 'M' flags were applied to the pH channel where it appeared the instrument had been calibrated, and pH values were markedly different. BODC 'M' flags were also applied to latitude and longitude data where positional data spikes were deemed to have deviated substantially from the track, along with the pH data associated with these points.

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

Colorimetric Microfluidic pH sensor

This sensor was specifically developed for autonomous seawater pH measurements by the National Oceaography Centre, Southampton in collaboration with the University of Southampton.

The seawater sample and thymol blue indicator solution are pumped by two syringe pumps and mixed in the flow cell in a static mixer before entering the absorption cell. The fluid distribution is controlled by four micro-inert valves. A three-wavelength LED light source transmits light through the absorption cell which is detected by a HR4000 spectrometer. The measurements are made close to in situ temperature (plus 0.2 degrees celsius) by placement of the microfluidic flow cell in the sampling chamber which has continuous access to the ship's underway seawater supply.

Measurements are made by first rinsing the flow cell with 300 µl of the sample before injecting 12 µl of indicator and determination of the absorption spectra. The remaining sample is then pumped through the system at a rate of 60 µl min^-1. The LED's wavelengths are 435 nm (25 nm full width half maximum (FWHM)), 596 nm (15 nm FWHM) and 750 nm (30 nm FWHM).

Further information can be found in the following publication.

BODC Data Processing

Data were provided by the originator via email in .xlsx format alongside the nutrients, oxygen, DIC, and TA data of the same cruise. The data were archived and then converted into BODC internal netCDF (QXF) format. Date/time channels were not monotonic and so were sorted prior to BODC processing. Two duplicate cycles were deleted (cycles 3324-3325 and 4053-4054) leaving one of the duplicate measurements in each instance. A further four cycles were deleted where metadata were identical but pH data were unique, and it could not be determined which data were accurate (cycles 1266 - 1267 and 3564 - 3565). The deleted six cycles are available on request.

The following table shows how the variables within the file were mapped to appropriate BODC parameter codes:

Note salinity and temperature channels were dropped after transfer but are available on request. Data were visualised using the in-house Edserplo software. Suspect and missing data were marked by adding an appropriate quality control flag.

Originator's Data Processing

Methodology

The automated pH system was running continuously on the non-toxic water supply onboard D366 from 06/06/2011 to 07/07/2011. Measurements were only interrupted for system performance checking and maintenance.

pH was measured by adding a coloured indicator to the seawater sample and measuring the colour of the mix. The indicator used was Thymol Blue. The pH sensor has been developed at the NOCS (Sensor group).

The performance of the system was evaluated by running certified Tris buffer provided by the Scripps Institution of Oceanography.

For more information on the originator's sampling methodology please see Rérolle et al., (2012).

References

Rérolle V.M.C, Floquet C.F.A., Mowlem M.C., Connelly D.P., Achterberg E.P. and Bellerby R.G.J., 2012. Seawater-pH measurements for ocean-acidification observations. TrAC Trends in Analytical Chemistry, 40, 146-157.

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

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: