Metadata Report for BODC Series Reference Number 2003484

• 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

Thermo Scientific Accela High Performance Liquid Chromatograph

The Accela high performance liquid chromatography system provides fast separations at pressures of up to 18,130 psi and at flow rates of 1 to 5000 µL/min. The system consists of an analytical pump, an autosampler, an optional PDA detector or UV/Vis detector and a solvent platform.

There is a choice of three analytical pumps to use with the system (the Accela Pump, Accela 600 Pump and Accela 1250 Pump) with each pump having a built-in degassing unit which is remotely controlled from the data system computer via USB. The autosampler automates sample injections and sample preparation and includes a built-in column oven, with a temperature range of 5 to 95°C, and a sample temperature control (0 to 60°C). Within the autosampler there is the capacity for 200 samples across five sample trays. There is a choice to use a PDA detector which in combination with the 5 or 1 cm LightPipe flowcell, provides the highest level of sensitivity available in photodiode array detection for HPLC. The second detector that can be used is a UV/Vis detector which can monitor two wavelength channels. Both detectors have a dual-lamp optical bench that covers the UV-visible spectrum from 190 to 800 nm. The solvent platform is located on top of the system stack and holds four 1 L solvent reservoir bottles and one 1 L wash bottle.

Please see the manufacturer's user's guide and product sheet for further details.

Carboy

Rigid container with a capacity of 20 to 60 litres and used primarily for transporting or storing fluids (water or chemicals). These containers are usually made of plastic or glass.

AMT23 JR20131005 pigment composition by HPLC analysis from underway samples

Originator's Protocol for Data Acquisition and Analysis

Seawater samples were collected typically 2-3 times each day from the ships underway system. Seawater was sampled into 9.5 L polypropylene carboys covered in black plastic to keep out light.

The method was based on Zapata et al. (2000) Samples (1-4L) were vacuum filtered onto GF/F filters, flash frozen in liquid nitrogen and stored at -80°C. Pigments were extracted from the sample filters into 2 mL 90% acetone using an ultrasonic probe (35 s; 50W). Extracts were clarified and analysed by reversed phase HPLC using a Thermo Accela Series HPLC system with chilled autosampler (4°C) and photodiode array detector. The HPLC was calibrated using a suite of standards purchased from DHI (Denmark). The average precision and accuracy for chl a (standards) was 1.44 and 2.01%, respectively. Pigments were identified based on retention time and spectral match using photo-diode array.

Quality Assurance protocols

• The first run of the day was discarded. A sample of mixed pigments was run prior to any samples to check retention times and resolution of critical pairs.
• Three samples of chlorophyll standard were analysed with each sample set to check response factor is within 5% of calibration value.
• Up to 20 samples are analysed per day, so the maximum time of samples in autosampler is 24 h. The autosampler was maintained at 4°C.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format. The file was provided to BODC with cruise, underway sample number, sequential day of year, depth, time, latitude and longitude as metadata. Sample metadata were checked against information held in the database - there were no discrepancies.

The following parameters were provided in the file but only the parameters that were not derived from the summation of other parameters in the dataset were loaded into the database. The absent data value was recorded as the effective limit of detection (LOD). The effective limits of detection, calculated for a filter volume of 3L are given in the table below.

Data received were loaded into the BODC database using established BODC data banking procedures. Data were loaded into BODC's database without any changes.

Originators parameters were mapped to BODC parameter codes as follows:

Data Quality Report

Quality assurance procedures for pigment analysis at PML were put in place for samples collected after 1st May 2011. Values of precision are given where replicate samples were available. The whole dataset conforms to the quality assurance criteria set out in Aiken et al. (1999):

1. The difference of [TChl a] and [Tacc] should be less than 30% of [Tpig]
2. Regression between Tchla and Tacc should have a slope within the range 0.7-1.4 and must explain more than 90% of total variance (r2>0.9)
3. More than 85% of the total observations must pass the qualifying criteria for data to be accepted

The pigment profile of AMT23 underway surface samples frequently contained an unknown component with an absorption maximum at 418 nm, that coeluted with [Chl c3]. The unknown component, when present, affected the quantification of [Chl c3]. For [Chl c3], we have indicated whether the peak is mostly [Chl c3], a mixture of [Chl c3] + unknown component "418nm", or mostly the unknown component "418nm". Values that were indicated to be a mixture of [Chl c3] + unknown component "418nm", or mostly the unknown component "418nm" were assigned the BODC flag 'L'.

Values less than or equal to the limit of detection were assigned the BODC flag '<'.

References Cited

Aiken, J., Y. Pradhan, R. Barlow, S. Lavender, A. Poulton, P. Holligan and N.J. Hardman-Mountford (2009) Phytoplankton pigments and functional types in the Atlantic Ocean: a decadal assessment, 1995-2005. Deep-Sea Research II 56(15): 899-917.

Zapata M, Rodriguez F, Garrido JL. (2000) Separation of chlorophylls and carotenoids from marine phytoplankton: a new HPLC method using a reversed phase C8 column and pyridine-containing mobile phases. MEPS 195, 29-45.

Project Information

PML National Capability

The Plymouth Marine Laboratory National Capability focuses on long term science concerned with basin/decadal variability of the Ocean.

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: