Metadata Report for BODC Series Reference Number 2282647

• 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

Metrohm 794 Basic Titrino Titrator

The Metrohm 794 Basic Titrino is an all-purpose titrator used for dynamic and monotonic determination of solution concentrations. Titration modes of the instrument are constant or depending on the titration curve variable dosing of the titration reagent and Endpoint-Titration. The operation modes include; Dynamic Equivalence-point Titration (DET), Monotonic Equivalence-point Titration (MET), Set Endpoint Titration (SET), pH Calibration (CAL), Measuring (MEAS) and Titration Procedure (TIP) which links various commands and methods to a titration procedure. All operating modes of the Titrino can be combined to perform extensive analytical sequences.

Ready-to-start methods for the most common applications are stored in the internal method memory for example; the determination of the hardness of drinking water, diazotation of sulfonamides and primary amines, and determination of the peroxid number of edible oil sand fats. The operator is free to modify and overwrite the methods or to create and store new titration sequences.

The instrument consists of an exchange unit with a small display, which can be connected to either a magnetic stirrer (728), propeller rod stirrer (802) or Ti stand (703 or 727). Data exchange with a PC is possible with the Metrodata VESUV Software and with Metrodata TiNet Software complete keypad remote control, data acquisition and evaluation via PC is enabled.

Further details can be found in the manufacturer's user manual.

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.

UKOA JR20120601 dissolved oxygen concentrations from CTD bottle samples and underway samples

Originator's Protocol for Data Acquisition and Analysis

Water samples were collected from a selected number of CTD casts for calibration of the CTD oxygen sensor. Seventeen CTDs were sampled for dissolved oxygen (DO) which were the first samples to be drawn from the Niskin bottles. Duplicate samples were collected from on average 6 depths. Seawater was collected directly into pre-calibrated glass bottles using a Tygon tube. Before the sample was drawn, the bottles were flushed with seawater for several seconds (for about 3 times the volume of the bottle) and the temperature of the water was recorded simultaneously using a handheld thermometer. The fixing reagents (manganese chloride and sodium hydroxide/sodium iodide solutions) were then added. Care was taken to avoid bubbles inside the sampling tube and sampling bottle. Samples were thoroughly mixed following the addition of the fixing reagents and were then kept in a dark plastic crate for 30 to 40 minutes to allow the precipitate to settle to <50% the volume of the bottle. Once the precipitate had settled all samples were thoroughly mixed for a second time in order to maximize the efficiency of the reaction.

Dissolved oxygen determinations were made using a Winkler O-Metrohm titration unit (794 DMS Titrino) with an amperometric system to determine the end point of the titration (Culberson and Huang, 1987). Chemical reagents were previously prepared at NOCS following the procedures described by Dickson (1994). Recommendations given by Dickson (1994), and by Holley and Hydes (1994) were adopted. In general, thiosulphate calibrations were carried out twice a week using a 1.667 mmol L-1 certified OSIL iodate standard, with the aid of a O-Metrohm 776 Dosimat unit. The thiosulphate solution was prepared at the beginning of the cruise by dissolving 50 g of sodium thiosulphate in 1L of MilliQ water. This solution was left to stabilize for 24 hours before the initial calibration, with a subsequent calibration 12 hours later to ensure the thiosulphate had stabilized.

References Cited

Culberson, C.H. and Huang, S. 1987. Automated amperometric oxygen titration. Deep Sea Research, 34, 875-880.

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.

Holley, S.E. and Hydes, D.J. 1994. Procedures for the determination of dissolved oxygen in seawater. Technical report, James Rennell Centre for Ocean Circulation.

Instrumentation Description

Metrohm 794 Basic Titrino Titrator

BODC Data Processing Procedures

Data were submitted in individual Excel spreadsheets for each CTD cast and archived under BODC's accession number DML120164. Sample metadata (Station, CTD cast, bottle number and depth) were checked against information held in the database. There were several discrepancies in the cast dates between the files and the database, but the data were loaded with the dates already in the database. Underway samples were provided with the same metadata as the CTD casts.

The concentration data were provided in micro-moles per litre. These units match the BODC parameter code units and a unit conversion was not applied. Where replicate measurements were provided the mean and standard deviation were calculated and loaded to the database. The standard deviation of oxygen fixation temperature was not loaded to the database. These data are available on request.

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 from cast 10, depth 5 m and from cast 63, 30 m were flagged as suspect by the data originator. These samples have been marked as improbable in the database. No values were flagged by BODC.

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

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.

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.