Metadata Report for BODC Series Reference Number 2134539

• 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

Apollo Sci Tech AS-C3 Dissolved Inorganic Carbon (DIC)

A Dissolved Inorganic Carbon (DIC) analyser, for use in aquatic carbon dioxide parameter analysis of coastal waters, sediment pore-waters, and time-series incubation samples. The analyser consists of a solid state infrared CO2 detector, a mass-flow controller, and a digital pump for transferring accurate amounts of reagent and sample. The analyser uses an electronic cooling system to keep the reactor temperature below 3°C, and a Nagion dry tube to reduce the water vapour and keep the analyser drift-free and maintenance-free for longer. It is designed for both land based and shipboard laboratory use.

Specifications

Marianda Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity (VINDTA) 3C

The VINDTA 3C (Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity) is a laboratory alkalinity titration system combined with an extraction unit for coulometric titration, which simultaneously determines the alkalinity and dissolved inorganic carbon content of a sample. The sample transport is performed with peristaltic pumps and acid is added to the sample using a membrane pump. No pressurizing system is required and only one gas supply (nitrogen or dry and CO2-free air) is necessary. The system uses a Metrohm Titrino 719S, an ORION-Ross pH electrode and a Metrohm reference electrode. The burette, the pipette and the analysis cell have a water jacket around them. Precision is typically ± 1 µmol kg^-1 for TA and/or DIC in open ocean water.

Further details can be found in the manufacturer's brochure.

Non-toxic (underway) sea water supply

A source of uncontaminated near-surface (commonly 3 to 7 m) seawater pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the non-toxic supply. The system is also referred to as the underway supply.

UKOA D366 dissolved inorganic carbon (DIC) and total alkalinity (TA) concentrations from CTD bottle and underway samples

Originator's Protocol for Data Acquisition and Analysis

Sampling from the CTD Rosette for DIC and TA - Water samples for the determination of DIC and alkalinity were drawn from the 20 l Niskin bottles on the CTD rosette and collected in 250 ml glass bottles with ample rinsing and overflowing to avoid gas exchange with the air. Two replicate 250 ml samples were collected per Niskin. Most CTD stations and most depths were sampled. Leaking Niskins were not sampled. About 60 CTD casts with typically 6 to 8 Niskins per cast were sampled and analysed on board, equivalent to about 420 samples. The samples were poisoned with a saturated mercuric chloride solution (50 µl per 250 ml sample).

Surface water sampling for DIC and TA - Two hourly water samples for the determination of DIC and alkalinity were drawn from the non-toxic surface water supply in the deck laboratory. Parallel sampling was undertaken for nutrients and salinity (4 times per day). The series was extended to also include samples for the microscopic determination of plankton species during the second half of the cruise. The DIC and alkalinity samples were collected in 250 ml glass bottles with ample rinsing and overflowing to avoid gas exchange with the air. Two replicate 250 ml samples were collected every two hours, equivalent to 323 samples throughout the cruise. The samples were poisoned with a saturated mercuric chloride solution (50 µl per 250 ml sample).

Dissolved Inorganic Carbon and Total Alkalinity measurements -

The DIC concentration was determined by coulometry after the method of Johnson et al. (1987). Generally all samples from two stations were run on one coulometer cell (#7). Two to three CRMs (Certified Reference Material, batch 107) were used per coulometric cell and station. The average of the two DIC replicates was used.

The alkalinity measurements were made by potentiometric titration. The acid consumption up to the second endpoint is equivalent to the titration alkalinity. The systems use a Metrohm Titrino 719S for adding acid, an ORION-Ross pH electrode and a Metrohm reference electrode. The burette, the pipette (volume approximately 100 ml), and the analysis cell have a water jacket around them. The titrant (0.1 M hydrochloric acid, HCl) was made at UEA. The average of the two alkalinity replicates was used.

The VINDTA instruments performed well during the cruise. Problems included a broken Peltier element (#4), failing level sensors for pipette full and cell full (#4, #7), a malfunctioning temperature sensor (#4) and rough sea state reduced the accuracy of TA and DIC analyses.

Instrumentation Description

Water samples were analysed for DIC and TA on two VINDTA instruments. The VINDTA combined DIC/alkalinity instruments (#4 and #7, version 3C) operate at 25°C (Mintrop, 2004). Most CTD samples were analysed on one instrument (#7) and most underway samples on the second instrument (#4).

BODC Data Processing Procedures

Data were submitted via email in an Excel spreadsheet archived under BODC's accession number SOC120231. Sample metadata (Cruise, Latitude, Longitude, Station, CTD cast, niskin bottle number and depth) were checked against information held in the database. There were no discrepancies.

The concentration data were provided in micro-moles per kilogram. These units match the BODC parameter code units and a unit conversion was not applied. Where only two replicates were analysed the means were supplied with the difference between the replicate values. Where more than two replicates were provided standard deviations were provided. Only the means and standard deviations were loaded to the database. The original submission file can be requested if required from BODC.

The data were reformatted and loaded in BODC's samples database under Oracle Relational Database Management System. Data were marked up with BODC parameter codes and loaded into the database.

A parameter mapping table is provided below;

Data Quality Report

The data originator provided a quality controlled data set. WOCE flags were converted to the appropriate BODC data quality flag.

Problem Report

Not relevant to this data set.

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: