Metadata Report for BODC Series Reference Number 1970712

• 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

Seal Analytical AutoAnalyzer 3HR

The model AA3 is an upgrade from Seal Analytics AutoAnalyzer II and is specifically designed for colorimetric determination of dissolved nutrients in environmental smaples. This model fully automates repetitive and complex sample analysis and can perform solvent extractions, distillation, gas diffusion, on-line filtration and in-line UV digestion in a continuously flowing stream.

It has a modular design which can integrate a sampler, pump, chemistry test module and photometer. It also accepts Multitest Manifolds designed to extend any size analyzer to a multiple chemistry system capable of dual range of tests which, in turn, eliminate the need to change manifolds and filters when changing tests.

The AA3 uses segmented flow analysis principles to reduce inter-sample dispersion, it can analyse up to 100 samples per hour using stable LED light sources. It also contains glass coils, which allow for chemically inert and easy visual checks.

The available modules are:

• Digital colorimeter: bubble through the flow cell to increase sampling rate and true Dual beam operation with continuous real-time referencing
• High Precision Pump: multi-speed motor, electronic air injection, optional valves for auto reagent switching and a buil in leak detector
• Multitest Manifold: allows for up to 16 different analyses
• Chemistry Module: glass coils which are chemically inter and allow for clear view of the flow, gas difusion or dialysis options
• XY2/XY3: high capacity random access sampler, up to 180/270 samples in cups or tubes in 2/3 racks, separate rack for standards, optional integrated pump and auto-diluter
• Distillation Module: automatic in line distillation when required before colorimetric analysis

Further information can be found in the manufacturer's brochure.

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.

AMT28 (JR18001) Micro-molar nutrient measurements from CTD bottle samples

Originator's Protocol for Data Acquisition and Analysis

A total of 63 CTD casts and 925 samples were collected and analyzed for dissolved nutrients. Nutrient samples were drawn into 30 ml polypropylene screw-capped centrifuge tubes. The tubes and caps were cleaned with 10% HCl and rinsed 2-3 times with sample before filling. Samples were either analyzed within 1-3 hours after sample collection or stored overnight in the fridge, allowing sufficient time for all samples to reach room temperature. The centrifuge tubes fit directly onto the sampler.

Nutrient analyses (phosphate, silicate, nitrate+nitrite, and nitrite) were performed on a Seal Analytical continuous-flow AutoAnalyzer 3 (AA3). The methods used are described by Gordon et al (1992), Hager et al. (1972), and Atlas et al. (1971). Details of modification of analytical methods used in this cruise are also compatible with the methods described in the nutrient section of the GO-SHIP repeat hydrography manual (Hydes et al. 2010).

Nitrate/Nitrite Analysis

A modification of the Armstrong et al. (1967) procedure was used for the analysis of nitrate and nitrite. For nitrate analysis, a seawater sample was passed through a cadmium column where the nitrate was reduced to nitrite. This nitrite was then diazotized with sulfanilamide and coupled with N-(1-naphthyl)-ethylenediamine to form a red dye. The sample was then passed through a 10mm flowcell and absorbance measured at 540nm. The procedure was the same for the nitrite analysis but without the cadmium column.

Phosphate Analysis

Ortho-Phosphate was analyzed using a modification of the Bernhardt and Wilhelms (1967) method. Acidified ammonium molybdate was added to a seawater sample to produce phosphomolybdic acid, which was then reduced to phosphomolybdous acid (a blue compound) following the addition of dihydrazine sulfate. The sample was passed through a 10mm flowcell and absorbance measured at 820nm.

Silicate Analysis

Silicate was analyzed using the basic method of Armstrong et al. (1967). Acidified ammonium molybdate was added to a seawater sample to produce silicomolybdic acid which was then reduced to silicomolybdous acid (a blue compound) following the addition of stannous chloride. The sample was passed through a 10mm flowcell and measured at 660nm.

Data collection and processing was done with the software (ACCE ver 6.10) provided with the instrument from Seal Analytical. After each run, the charts were reviewed for any problems during the run, any blank was subtracted, and final concentrations (micro moles/liter) were calculated, based on a linear curve fit. Once the run was reviewed and concentrations calculated a text file was created. That text file was reviewed for possible problems and then converted to another text file with only sample identifiers and nutrient concentrations that was merged with other bottle data.

Standards and Glassware Calibration

Primary standards for silicate (Na2SiF6), nitrate (KNO3), nitrite (NaNO2), and phosphate (KH2PO4) were obtained from Johnson Matthey Chemical Co. and/or Fisher Scientific. The supplier reports purities of >98%, 99.999%, 97%, and 99.999 respectively. All glass volumetric flasks and pipettes were gravimetrically calibrated prior to the cruise. The primary standards were dried and weighed out to 0.1mg prior to the cruise. The exact weight was noted for future reference. When primary standards were made, the flask volume at 20C, the weight of the powder, and the temperature of the solution were used to buoyancy-correct the weight, calculate the exact concentration of the solution, and determine how much of the primary was needed for the desired concentrations of secondary standard. Primary and secondary standards were made up every 10-14 days. The new standards were compared to the old before use. All the reagent solutions, primary and secondary standards were made with fresh distilled deionized water (DIW). Standardizations were performed at the beginning of each group of analyses with working standards prepared every 10-12 hours from a secondary. Working standards were made up in low nutrient seawater (LNSW). One batch of LNSW was used on the cruise. It was collected and filtered prior to the cruise. The actual concentration of nutrients in this water was empirically determined during the standardization calculations.

References Cited

Armstrong, F.A.J., Stearns, C.A., and Strickland, J.D.H., 1967. The measurement of upwelling and subsequent biological processes by means of the Technicon Autoanalyzer and associated equipment. Deep-Sea Research, 14, pp.381-389.

Atlas, E.L., Hager, S.W., Gordon, L.I., and Park, P.K., 1971. A Practical Manual for Use of the Technicon AutoAnalyzer in Seawater Nutrient Analyses Revised. Technical Report 215, Reference 71-22, p.49, Oregon State University, Department of Oceanography.

Bernhardt, H., andWilhelms, A., 1967. The continuous determination of low level iron, soluble phosphate and total phosphate with the AutoAnalyzer. Technicon Symposia, I, pp.385-389.

Gordon, L.I., Jennings, J.C., Ross, A.A., Krest, J.M., 1992. A suggested Protocol for Continuous Flow Automated Analysis of Seawater Nutrients in the WOCE Hydrographic Program and the Joint Global Ocean Fluxes Study. Grp. Tech Rpt 92-1, OSU College of Oceanography Descr. Chem Oc.

Hager, S.W., Atlas, E.L., Gordon L.I., Mantyla, A.W., and Park, P.K., 1972. A comparison at sea of manual and autoanalyzer analyses of phosphate, nitrate, and silicate. Limnology and Oceanography, 17,pp.931-937.

Hydes, D.J., Aoyama, M., Aminot, A., Bakker, K., Becker, S., Coverly, S., Daniel,A.,Dickson,A.G., Grosso, O., Kerouel, R., Ooijen, J. van, Sato, K., Tanhua, T.,Woodward, E.M.S., Zhang, J.Z., 2010. Determination of Dissolved Nutrients (N, P, Si) in Seawater with High Precision and Inter-Comparability Using Gas-Segmented Continuous Flow Analysers, In: GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines. IOCCP Report No. 14, ICPO Publication Series No 134.

Instrumentation Description

Seal Analytical continuous-flow AutoAnalyzer 3 (AA3)

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format and saved to the BODC archive with reference SIO190036. Sample metadata provided (Site number, Cast number and niskin bottle number) were checked against information held in the database. There were no discrepancies.

No unit conversions were necessary as the units provided matched the units for the parameter codes in the BODC Parameter Dictionary. The dataset was loaded to the database following BODC protocols.

A parameter mapping table is provided below:

Data Quality Report

All final data is reported in micro-moles/kg. NO3, PO4, and NO2 are reported to two decimals places and SIL to one. Accuracy is based on the quality of the standards the levels are:

NO3 0.05 µM (micro moles/Liter)

PO4 0.004 µM

SIL 2-4 µM

NO2 0.05 µM

As is standard ODF practice, a deep calibration "check" sample was run with each set of samples to estimate precision within the cruise. This water was collected from station 6, niskin 1.

Reference materials for nutrients in seawater (RMNS) were also used as a check sample run once a day. The RMNS preparation, verification, and suggested protocol for use of the material are described by Aoyama (2006), Aoyama (2007), Aoyama (2008) and Sato (2010). RMNS batch CG-1733 was used on this cruise, with each bottle being used once or twice before being discarded and a new one opened.

The data were provided to BODC with WOCE flags applied. Leaking bottles identified by abnormal nutirent data profiles were flagged 3 (leaking). Nutrient values from analysis QC were flagged 2 (acceptable), 3 (questionable), or 4 (bad). These originator flags were converted to BODC flags during loading to the database.

Project Information

Marine LTSS: CLASS (Climate Linked Atlantic Sector Science)

Introduction

CLASS is a five year (2018 to 2023) programme, funded by the Natural Environment Research Council (NERC) and extended until March 2024.

Scientific Rationale

The ocean plays a vital role in sustaining life on planet Earth, providing us with both living resources and climate regulation. The trajectory of anthropogenically driven climate change will be substantially controlled by the ocean due to its absorption of excess heat and carbon from the atmosphere, with consequent impacts on ocean resources that remain poorly understood. In an era of rapid planetary change, expanding global population and intense resource exploitation, it is vital that there are internationally coordinated ocean observing and prediction systems so policy makers can make sound evidence-based decisions about how to manage our interaction with the ocean. CLASS will underpin the UK contribution to these systems, documenting and understanding change in the marine environment, evaluating the impact of climate change and effectiveness of conservation measures and predicting the future evolution of marine environments. Over the five-year period CLASS will enhance the cost-effectiveness of observing systems by migrating them towards cutting edge autonomous technologies and developing new sensors. Finally, CLASS will create effective engagement activities ensuring academic partners have transparent access to NERC marine science capability through graduate training partnerships and access to shipborne, lab based and autonomous facilities, and modelling capabilities.

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JR18001_CTD_CTD004

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: JR18001_CTD_CTD004

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.