Metadata Report for BODC Series Reference Number 2111922

• 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.

Dissolved organic phosphorous (DOP) from titanium CTD bottle samples for GEOTRACES Cruise JC150

Responsible investigator

Dr Claire Mahaffey
email: claire.mahaffey@liverpool.ac.uk
University of Liverpool Department of Earth, Ocean and Ecological Sciences
4 Brownlow Street
Liverpool, Merseyside
United Kingdom
L69 3GP

Acquisition description:

Sampling methodology

Seawater samples were collected during cruise JC150 in the subtropical North Atlantic. The cruise took place during summer (26th June to 12th August 2017) sampling between Guadeloupe and Tenerife on-board the R.R.S. James Cook. Seven stations were occupied for high resolution vertical profiling. Seawater samples were collected according to the GEOTRACES guidelines. A titanium rosette fitted with 24 x 10 L trace metal-clean Teflon-coated OTE (Ocean Test Equipment) bottles and a CTD profiler (Sea-bird Scientific) were deployed on a conducting Kevlar wire to collect samples from the water column. Unfiltered seawater samples were collected under trace metal clean conditions for determination of DOP concentrations from each bottle of experiment D and the shallow (<1000 m) titanium CTD casts. Samples were collected in 125 mL HDPE bottles (acid washed, Fisher Scientific) and stored at -20°C for later analysis in the laboratory.

Analytical methodology

Total dissolved phosphorus (TDP) was determined using the high temperature acid persulfate technique as described in Lomas et al (2010) with the following modifications. Standards were prepared in P-free artificial seawater using potassium monobasic phosphate (KHPO₄, Sigma Aldrich). Samples and standards were autoclaved (121°C, 40 min) in 40 mL aliquots in tightly sealed 50 mL glass Pyrex bottles with Teflon lined screw caps after addition of 5 mL potassium persulfate solution (64 g/L). Following oxidation samples were left to cool overnight and then precipitated using the MAGIC technique (Karl and Tien 1992) by addition of 5 mL 1M NaOH solution (Sigma Aldrich). Following centrifugation (1000 x g, 60 min), the supernatant was discarded and the sample/standard pellet were completely dissolved in 40 mL 0.1 M HCl (Trace metal grade, Sigma Aldrich). Analytical blanks were determined as described in Lomas et al (2010).

Total dissolved phosphorus were determined in triplicate as dissolved inorganic phosphorus (DIP) concentrations after persulfate oxidation of the samples by the molybdenum blue method (Murphy and Riley, 1962) using a Bran and Leubbe QuAAtro 5-channel autoanalyser (DIP detection limit 50 nM). Dissolved organic phosphorus (DOP) has been taken as the difference between TDP and DIP determined prior to persulfate oxidation (i.e. DOP = TDP - DIP; DOP detection limit 40 nM). In this case, DIP values were taken from the phosphate data of Malcolm Woodward, PML, obtained during the cruise.

References Cited

Karl, D. M., Tien, G. (1992) MAGIC: A sensitive and precise method for measuring dissolved phosphorus in aquatic environments, Limnology and Oceanography, 37, doi: 10.4319/lo.1992.37.1.0105.

Lomas, M. W., Burke, A. L., Lomas, D. A., Bell, D. W., Shen, C., Dyhrman, S. T., and Ammerman, J. W.(2010) Sargasso Sea phosphorus biogeochemistry: an important role for dissolved organic phosphorus (DOP), Biogeosciences, 7, 695-710, https://doi.org/10.5194/bg-7-695-2010

Murphy, J and Riley, J.P.. (1962) A Modified Single Solution Method for the Dermination of Phosphate in Natural Waters. Anal. Chim. Acta. 26. 678-681.

BODC Data Processing Procedures

Data received were loaded into the BODC database using established BODC data banking procedures. A parameter mapping table is provided below:

Project Information

Zinc, iron and phosphorous co-limitation in the Ocean: ZIPLOc

ZIPLOc is an 3 year project that aims to measure how zinc and phosphorous control biological activity in the North Atlantic subtropical gyre using novel measurement techniques. The observations made will be further explored using the latest modelling techniques over decadal timescales and in other basins.

The research aims to make an improvement in our overall understanding of how subtropical gyre ecosystems respond to ongoing climate change.

The project is led by the University of Liverpool, Earth, Ocean and Ecological Sciences and is a collaboration with the University of Southampton, School of Ocean and Earth Science. The project received funding from the Natural Environmental Research Council and runs between January 2017 and February 2020.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JC150_UCCTD_CTD017T

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: JC150_UCCTD_CTD017T

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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