Metadata Report for BODC Series Reference Number 2111737

• 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-ALK2 Total Alkalinity titrator

An automated acid-base titrator for use in aquatic carbon dioxide parameter analysis. The titrator provides standardisation and sample analysis, using the Gran titration procedure for alkalinity determination of seawater and brackish waters. It is designed for both shipboard and land based laboratory use. The precision of the instrument is 0.1% or higher, and sample volumes may range from 10-25 ml. Titraton takes approximately 8 minutes per sample, and the repeatability is within plus or minus 1-2 micromoles per kg.

Specifications

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

Digitron 2000 series 2028T Thermometer

Digitron 2000 series are a range of hand-held digital thermometers. The 2028T model presents readings in seconds with an accuracy of 0.2%. Digitron provide a unique SpeedRead feature which supplies an answer in 14 seconds or if this measurement cannot be made the instrument automatically reverts back to a standard thermometer accuracy. Additional features of the Digitron 2000 series include logging mode for storage, retrieval and output of readings and a long battery life of approximately 500 hours. The 2028T thermometer provides Celsius or Fahrenheit function and has a temperature range of 200°C to +1350°C/ -328°F to +2462°F.

Common specifications of the instrument can be found in the table below:

Further information can be found in the manufacturers manual.

Additional information can also be found on the technical data 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.

Carbonate chemistry - DIC and total alkalinity from CTD bottles during AMT22(JC079)

Originator's Protocol for Data Acquisition and Analysis

Sampling

Seawater samples were collected from the Niskin bottles in 125 mL glass bottles with ground glass stoppers using Si-tubing. The end of the tubing was placed into the bottom of the sample bottle and the sample allowed to overflow with 3 time the volume of the sample bottle. The samples were immediately poisoned with 100 μL of saturated HgCl₂ and the stoppers inserted after coating with a thin layer of Si-free grease (Apiezon™). Samples were stored at room temperature until analysis (within 12 months).

Analysis

Analysis of the preserved seawater samples was performed in the laboratory.

For TA, samples were analysed by pH end-point titration against HCl, using an alkalinity titrator (Apollo SciTech, Model AS-ALK2) fitted with bench-top pH sensor (Thermo Scientific, model ORION 3STAR). HCl used in the titration (ca ~0.1 M) was calibrated against certified reference materials (CRM) from the Scripps Institution of Oceanography (Prof. Andrew Dickson; University of California - San Diego, USA).

For DIC, samples were analysed using a DIC analyser (Apollo SciTech, model AS-C3) fitted with a non-dispersive infrared gas analyser (LiCor, model LI7000). Zero grade Nitrogen gas was used as the carrier (BOC gases Ltd.). The system was calibrated with CRM as above.

References Cited

Dickson, A.G., Sabine, C.L., Christion, J.R., 2007. Guide to best practices for ocean CO₂ measurements. PICES Special Publication 3, PICES Special Publication 3, p. 191.

JC079 Cruise report

Further information can be found in the JC079 Cruise report.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. Data was loaded into BODC's database without any changes. The data were mapped to BODC parameter codes.

A parameter mapping table is provided below:

Data Quality Report

The data consists of the mean DIC and standard deviation as calculated by the originator. For the original values contact the data originator.

Carbonate chemistry - pH from CTD bottles during AMT22(JC079)

Originator's Protocol for Data Acquisition and Analysis

A 2 mmol/L solution of m-cresol purple (Sigma-Alrich, product number: 857890-5G) was prepared for spectrophotometric pH determination. A spectrophotometer (Perkin Elmer, model: Lamda 35) was used to measure absorbance at 434, 578 and 730 nm with a 10 cm quartz cuvette. The spectrophotometer was switched on at least one hour before measurements. Samples were collected in 250 mL amber glass bottles and placed in a water bath at 25 ^oC. Temperature equilibration was achieved within 15-20 minutes.

Temperature-equilibrated sample was transferred to the cuvette and the absorbance read at 434, 578 and 730 nm. The temperature of the sample was recorded and 100 μL of the dye solution added directly to the cuvette followed by another absorbance reading at 434, 578 and 730 nm. The sample pH at measurement temperature was calculated according to Dickson et al. (2007), taking into account the volume of dye added and the measurement temperature as well as the sample salinity. In situ pH (on the Total scale) was calculated using the CO2SYS software (Lewis and Wallace, 1998) with the measurement temperature as input and in situ temperature as output conditions.

Correction for the addition of dye

Addition of the dye changes the pH of the sample because the dye itself is another acid-base pair in solution. This ΔpHdye is related to the volume of dye added as well as the initial pH of the sample. These dependencies can be calculated and the procedure is described here. This procedure needs to be repeated a few times for samples with different pH. Each sample has a 434:578 absorbance ratio (A1/A2) which corresponds to its pH. Each addition of dye causes a change in this ratio (Δ(A1/A2). Δ(A1/A2) is proportional to the volume of dye added (V) for a given A1/A2. The procedure was repeated as above adding 50, 100, 150 and 200 μL of dye to the same sample. The regression of Δ(A1/A2) against V allows for a correction to be made (e.g. Δ(A1/A2)* for 100 μL of dye addition). By repeating the procedure for different samples regression of Δ(A1/A2)* against A1/A2 is obtained. A correction can thereby be applied to all samples. It was found that the pH correction for dye addition was the same as in Dickson et al. (2007) though it is good practice to verify this result for each batch of dye used.

References Cited

Dickson, A.G., Sabine, C.L., Christion, J.R., 2007. Guide to best practices for ocean CO₂ measurements. PICES Special Publication 3, PICES Special Publication 3, p. 191.

Lewis, E., Wallace, D.W.R., 1998. Program Developed for CO₂ System Calculations., ORNL/CDIAC-105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

JC079 Cruise report

Further information can be found in the JC079 Cruise report.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. Data was loaded into BODC's database without any changes. The data were mapped to BODC parameter codes.

A parameter mapping table is provided below:

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

• give early warning of any fundamental change in Atlantic ecosystem functionng
• improve forecasts of the future ocean state and associated socio-economic impacts
• provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.

The specific objectives are:

• To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
• To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
• To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JC079_CTD_CTD65

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: JC079_CTD_CTD65

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.