Metadata Report for BODC Series Reference Number 1974240

• 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

Skalar San+ Autoanalyzer

The San+ Autoanalyzer is an Automated Wet Chemistry Analyzer (Continuous Flow Analyzer) which has been designed as a modular system to measure a variety of water chemistry characteristics, such as nutrient concentrations in seawater. Individual modules are tailored to specific needs. It uses Continuous Flow Analysis (CFA), allowing up to 16 analytical measurements to be made on a single sample simultaneously. The system comprises a sampler, chemistry section, detector and specialist software.

Chemistry section
The San+ includes a chemistry section which has hundreds of applications. It houses up to five chemistry cartridges with built-in dosing pump and air injection systems, up to five interchangeable cartridges with build-in photometric detectors and five separate waste receptacles. The throughput of the analyser depends upon application and can vary from 25 to 120 analyses per hour. It has a double diameter pump deck for accurate dosing with 32 pump tubes, two separated pump decks for 2 x 2 channel concept, and controlled synchronised eight channel air injection with separate built-in compressor for increased flow stability and fast start-up. It has easy access to chemistry cartridges with flexible ultra low carry-over connections between dialysers, reactors, coils, flow cells and other components, leak detection, 3-cuffs long life pump tubes, and has manually operated and automatic rinsing valves for easy automatic start up and overnight operation.

Detectors
The San+ range of detectors comprises dual channel colorimetric detectors, the unique matrix correction detector with automatic background correction for difficult sample matrixes, but also covers a range of detectors for I.R., U.V., fluorimetry, ISE, flame photometry, refractometers, density meters, etc.

Software
The San+ 'Flow Access' windows software package controls the complete analyser, with auto start-up, function control, and auto-scaling, pre-and post run sample dilutions, result calculation and statistics. Up to 16 channels can be handled simultaneously, with multiple samplers, and chemistries can be grouped for analysis.

The San+ is also known as San++.

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.

RRS Discovery Cruise D354 inorganic nutrient sample analysis

Originator's protocol for data acquisition and analysis

Sampling protocol

846 inorganic nutrient samples were collected from 56 CTD casts during RRS Discovery cruise D354 and measured for total oxidised nitrogen(TON), phophate and silicate using a segemented flow analysis method. The cruise, which sailed from Avonmouth (UK) on 04 July 2010 and docked at Birkenhead (UK) on 11 August 2010 was undertaken as part of the 'Iron Biogeochemistry in the High Latitude north Atlantic' project.

Samples were drawn from Niskin bottles on the titanium and stainless steel-framed CTD units into 25ml Sterilin coulter counter vials and kept rerigerated at approx 4°C until analysis. The majority of the samples were analysed on board within 12 hours of collection, however all samples collected from Station 24 (CTDS029) onwards were frozen for analysis back at the NOC.

Sampling analysis

Analysis was performed using a Skalar SAN+ segmented flow autoanlyser (also known as the Skalar SAN__) following methods described by Kirkwood (1996). an artificial seawater matrix of 40g/ l^-1 sodium chloride was used as the inter-sample wash and standard matrix. The nutrient free status of theis solution was checked by running Ocean Scientific Inernational low nutrient seawater on every run.

A single set of mixed standards were made up by diluting 5nM solutions, made from weighed dried salts in 1litre of artificial seawater, into plastic 1litre volumetric flasks that had been cleaned by soaking in MilliQ water. The concentration of the standards were tested on every run by analysing diluted Ocean Scientific International certified standards, one high concentration standard (29.25µM for TON, 19.50µM for silicate and 1.95µM) and one low concentration standard (0.98µM for TON and silicate and 0.1µM for phosphate). These standards were only used during analysis on ship and not at the NOC. Data processing was undertaken using the Skalar proprietary software and was performed within 24 hours of the run being finished. The wash time and sample times were 90 seconds; the lines were washed daily with 10% Decon and MilliQ water.

For more information on the sampling protocol and analysis please consult the cruise report for D354.

References:

• " Kirkwood D., 1996. Nutrients: Practical Notes on Their Determination in Seawater. Technical Report 17, 1-25. International Council for the Exploration of the Seas.

BODC data processing procedures

Data received were loaded into the BODC database using established BODC databanking procedures. Data were supplied to BODC in the form of an Excel spreadsheet which was subsequently converted into individual .csv files. Data channels included in the Excel file were:

• Botsal (pss-78) - bottle salinity (salinometry results)
• Botoxy (umol/l) - bottle oxygen (Winkler titration results)
• No2+3 (umol/l) - measured nitrate
• No3_flag (flag) - QA flag on measured nitrate
• Sio3 (umol/l) - measured silicate
• Sio3flag (flag) - QA flag on measured silicate
• Po4 (umol/l) - measured phosphate
• Po4_flag (flag) - QA flag on measured phosphate
• CTD bottle data

The parameters ingested in this instance were no2+3 (total oxidised nitrogen: TON), sio3 (silicate) and po4 (phosphate), i.e. inorganic nutrient data. No conversions were required as data were supplied in units equivalent to those used in the BODC vocabulary dictionary. Bottle firing data were loaded to the database following BODC protocols.

Mapping of originator's parameters to BODC parameters was as follows:

Limits of detection for the Nitrate/Nitrite and Phosphate sensors were found in Kirkwood (1996). Values that fell below this limit value were flagged '<' (value below detection limit). No detection limit could be found for the silicate sensor. As such, values that fell below 0 were flagged 'M' (Improbably value, BODC quality control). Instances where the originator had flagged data during their processing were flagged with the BODC flag 'L' (Originator's flag).

Data Quality Report

During the cruise, the analyser software froze and had to be reinstalled, thought the issue was dealt with quickly and no samples were lost. In the first few runs of the analyser, the phosphate line appeared to have an area of noise at the beginning and end of each sample. This was traced back to an inter-sample bubble. Due to the large volume of sample that the phosphate line requires, this line pulls in the majority of this inter?sample bubble. Although the bubble itself does not go through the flow cell, the large bubble influences the amount of reagents that are in the segment in front and behind it. It's this digression from the usual sample to reagent ratio that creates the noisy baseline at these points. To combat this a debubbler was placed on the phosphate line in front of the pump decks.Cruise report p.206.

The final issues concerned the TON channel. Firstly the calibration was not linear, even over a relatively small range. However, during a check back at the NOC when both analysers were running, it was found that the curved calibration gave just as good results as the linear calibration as long as all samples were within the range of the standards. Finally there was a slight cross over issue from one sample to the next. This occurred because the sample was debubbled before it passed through the cadmium column. Not much can be done about this. The effect was minimised by never running two samples of largely differing concentrations next to each other, i.e. high concentration deep water samples before low concentration surface water samples.

Project Information

Iron Biogeochemistry in the high latitude North Atlantic - Irminger Basin Iron Study (IBIS)

Funding

Funding was provided by NERC, in the form of four standard (full Economic Cost - fEC) grants with a total value of £528,607. The project was a study of the iron (Fe) biogeochemistry in the high latitude North Atlantic, with the results providing a better understanding of the role that nutrients like iron play in the growth of phytoplankton cells in the ocean. The gathered data were intended to help computer modellers to design improved climate models that would allow for better predictions of the extent of climate change over the next hundreds of years.

Project dates - 21 June 2007 to 08 November 2013.

Background

With the rise in carbon dioxide concentrations throughout the world, the importance of carbon-ingesting marine plants, such as phytoplankton is becoming more important. As phytoplankton take up atmospheric carbon dioxide, they are helping to reduce the atmospheric concentration. Recently it has been discovered that the phytoplankton in many of the world's oceans are lacking in iron. For example, in the Southern Ocean, phytoplankton cell growth is limited by very low iron concentrations. Thus, they do not remove as much carbon dioxide as they could. Recent studies have suggested that iron may even play a role in the phytoplankton growth in the high latitude North Atlantic, which was thought to be iron replete.

Objectives

The main objective of this project was to study the iron biogeochemistry of the high latitude North Atlantic, assess whether community productivity in parts of the high latitude North Atlantic was iron limited following the annual spring bloom, and to determine the factors which lead to this situation. This project studied whether iron was limiting phytoplankton growth in the study area, by undertaking two cruises and taking samples of water, sedimenting material, and atmospheric dust and rain. The project also directly investigated whether iron is limiting the growth of phytoplankton in water samples from the study area.

Participants

• University of Southampton, School of Ocean and Earth Science.
• University of Liverpool, Earth Surface Dynamics.
• University of Essex, Biological Sciences.
• University of East Anglia, Environmental Sciences.

• Prof. Eric Achterberg, University of Southampton, School of Ocean and Earth Science (Principal Investigator)
• Dr. Gary Fones, University of Portsmouth, School of Earth and Environmental Sciences
• Dr. Richard Sanders, National Oceanography Centre, Science and Technology
• Dr. Christopher Mark Moore, University of Southampton, School of Ocean and Earth Science
• Prof. Richard Geider University of Essex, Biological Sciences
• Prof. Tim Jickells, University of East Anglia, Environmental Sciences
• Prof. Ric Williams, University of Liverpool, Earth, Ocean and Ecological Sciences

Methodology

• Took samples of water, sediments, atmospheric dust and rain.
• Calculated the supply ratios of iron (Fe) to nitrogen (N), phosphorus (P) and carbon (C) to the surface oceans and in sedimenting material.
• Calculated the oceanic transfers of these elements using models.
• Assessed whether iron was limiting phytoplankton growth using both models and water samples analysis.

More information can be found within the Gateway to Research website.

Fieldwork

Two research cruises

• RRS Discovery D350 - 26 April 2010 to 09 May 2010. Departed from Govan, UK and arrived in Reykjavík, Iceland. Study area: North Atlantic Ocean - Irminger and Iceland Basins. Principal Scientist: Dr. Mark Moore, University of Southampton.
• RRS Discovery D354 - 10 July 2010 to 11 August 2010. Departed from Avonmouth, UK and arrived in Birkenhead, UK. Study area: North Atlantic Ocean - Iceland and Irminger Basins. Principal Scientist: Prof. Eric Achterberg, University of Southampton.

Instrumentation

• Stainless Steel CTD rosette
• Titanium CTD rosette
• VM ADCP 75 kHz
• VM ADCP 150 kHz
• Stand Alone Pump Systems (SAPS)
• PELAGRA - Neutrally Buoyant Sediment Traps
• Trace metal clean tow fish
• Seasoar with CTD, fluorometer and Laser Optical Plankton Counter (LOPC)
• Zooplankton nets
• Underway - Navigation, surface and meteorology

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for D354_CTD_CTD_S_031

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: D354_CTD_CTD_S_031

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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