Metadata Report for BODC Series Reference Number 2115763

• 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

SPX Bran+Luebbe Autoanalyser 3

The instrument uses continuous flow analysis (CFA) with a continuous stream of material divided by air bubbles into discrete segments in which chemical reactions occur. The continuous stream of liquid samples and reagents are combined and transported in tubing and mixing coils. The tubing passes the samples from one apparatus to the other with each apparatus performing different functions, such as distillation, dialysis, extraction, ion exchange, heating, incubation, and subsequent recording of a signal.

An essential principle of the system is the introduction of air bubbles. The air bubbles segment each sample into discrete packets and act as a barrier between packets to prevent cross contamination as they travel down the length of the tubing. The air bubbles also assist mixing by creating turbulent flow (bolus flow), and provide operators with a quick and easy check of the flow characteristics of the liquid.

Samples and standards are treated in an exactly identical manner as they travel the length of the tubing, eliminating the necessity of a steady state signal, however, since the presence of bubbles create an almost square wave profile, bringing the system to steady state does not significantly decrease throughput and is desirable in that steady state signals (chemical equilibrium) are more accurate and reproducible.

The autoanalyzer can consist of different modules including a sampler, pump, mixing coils, optional sample treatments (dialysis, distillation, heating, etc), a detector, and data generator. Most continuous flow analyzers depend on color reactions using a flow through colorimeter, however other methods have been developed that use ISE, flame photometry, ICAP, fluorometry, and so forth.

More details can be found in the manufacturer's introduction to autoanalysers andinstrument description.

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.

Stand Alone Pump (SAP)

A submersible battery powered water pump that sucks water through various filters leaving the materials of interest on the filter for analysis. SAPs are deployed clamped to a hydrographic wire and may be used to sample at depths of up to 6000 m. A SAP can pump thousands of litres of water over a few hours.

Dissolved inorganic carbon, total alkalinity, inorganic nutrients and associated calculated carbonate system parameters from Niskin bottle samples collected during UKOA cruise JC073

Originator's Protocol for Data Acquisition and Analysis

Seawater was collected from Niskin bottles in 50 mL Borosilicate glass bottles with ground glass stoppers. The bottles were rinsed and filled according to Standard Operating Procedure 1 in Dickson et al. 2007. Duplicate samples were taken from the same Niskin bottle. Samples were then poisoned with 10 µL mercuric chloride and taken to the chemical laboratory where the samples were brought to room temperature (approximately 23°C). Samples were collected from depths throughout the water column at the following sites: Mingulay reef area 1 (and Banana reef), Logachev reef area, PICES site, and the Hebrides Terrace Seamount site. A total of 343 water column samples were collected and analysed for dissolved inorganic carbon and total alkalinity. All samples were analysed within 24 hours of collection.

Directly after collecting samples for DIC and total alkalinity, duplicate samples were collected from the Niskin bottles for nutrient analysis. From these samples, 50 mL was filtered into acid-cleaned, aged, 60 mL Nalgene bottles. The Nalgene bottles were then frozen and shipped back to land where analysis took place at Plymouth Marine Laboratory.

Inorganic Carbon
An Apollo SciTech AS-C3 Dissolved Inorganic Carbon (DIC) analyser was used to measure inorganic carbon. The analyser adds a strong acid to the sample causing all carbon species to be converted to CO₂. This CO₂ gas is purged from the water by pure nitrogen (N₂) carrier gas which carries the CO₂ through a drying system that includes a cooling system, reducing water vapour. The concentration of the dried CO₂ gas is then measured using a LI-7000 CO₂ analyser. CO₂ was converted to DIC using a standard curve created from analysing known volumes of the Certified Reference Materials (Dickson, Batch 113 and Batch 109).

Total Alkalinity
Total alkalinity was measured by open-cell potentiometric titration (Dickson et al., 2007) using an Apollo SciTech AS-ALK2 total alkalinity titrator with replicate measurements made per sample. A calibration was conducted using Certified Reference Materials (Dickson, Batch 113 and Batch 109). The total alkalinity was then corrected with a calibration factor and also for the addition of mercuric chloride.

Inorganic Nutrients
A SPX Bran and Luebbe colorimetric Autoanalyser 3 was used to determine the concentration of the following inorganic nutrients: combined nitrate and nitrite, nitrite, phosphate and silicate. Nitrate concentrations were then calculated by subtracting the nitrite from the combined nitrate+nitrite concentration.

The remaining carbonate system parameters - including pHT, pCO₂, Ωaragonite - were then calculated using DIC, total alkalinity, depth, temperature, salinity, silicate and phosphate according to Pierrot et al. (2006).

References

Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.), 2007. Guide to Best Practices for Ocean CO₂ Measurements. PICES Special Publication 3, 191 pp.

Findlay, H. S., Artioli, Y., Moreno Navas, J., Hennige, S. J., Wicks, L. C., Huvenne, V. A. I., Woodward, E. M. S. and Roberts, J. M., 2013. Tidal downwelling and implications for the carbon biogeochemistry of cold-water corals in relation to future ocean acidification and warming. Global Change Biology, 19: 2708-2719.

Pierrot D., Lewis E. and Wallace D.W.R., 2006. CO₂sys DOS 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.

Instrumentation

The instrumentation used are as follows:

BODC Data Processing Procedures

Data were submitted to BODC as a text file accompanied by a PDF document containing metadata which were subsequently archived by BODC. The data file contained water column profiles of dissolved inorganic carbon, total alkalinity, inorganic nutrients and the associated calculated carbonate system parameters from Niksin bottle and ROV samples. The Niskin bottle data are processed here with the ROV data available on request. The data also includes CTD parameters including salinity, oxygen, fluorescence and temperature but like the ROV data, have not been processed here. The data file included the following metadata: cruise, station number, date and time, latitude, longitude, depth and QC flag.

The data were reformatted and assigned BODC parameter codes which were in equivalent units to the original data so no unit conversions were applied. Measurement data were duplicated at each depth and so the two measurements were averaged and the standard deviation calculated. Data were loaded in BODC's samples database under Oracle Relational Database Management System using established BODC data banking procedures. Sample metadata were checked against information held in the database were no discrepancies were found.

The originator's parameters were mapped to BODC parameter codes as follows:

Data Quality Report

The originator applied flags to all submitted data according to the following key: 1 = Good Quality; 4 = Questionable Quality; 8 = Bad Quality. During BODC processing the flags were removed if the flag was 1 and the flag was changed to L if the flag was 4. There were no instances were the flag 8 was applied.

If a value was flagged then this value was omitted when calculating the average at each depth and so the measurement would be the unflagged value within the pair. In these cases standard deviations were not calculated. In cases where both values at a depth were flagged L the average and standard deviation were calculated with the average flagged L. In a departure from standard practice, the means and standard deviations were calculated after the values had been rounded to the number of decimal places appropriate to the parameter, instead of before. This has resulted in a slight loss of precision.

The originator has no concerns over the quality of the data as the data is consistent with similar data in the wider literature and so no further flagging has been applied by BODC.

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 JC073_CTD_CTD45

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: JC073_CTD_CTD45

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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