Metadata Report for BODC Series Reference Number 2135788

• 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

Agilent/HP 5972A Mass Selective Detector

The Agilent/HP 5972A Mass Selective Detector (MSD) is a stand-alone, capillary Gas Chromatography (GC) detector, designed for use with a HP 5890 Gas Chromatograph. The HP 5890 GC powers the heater in the GC interface of the 5972A MSD by 110 V ac electricity. The data system features Hewlett Packard MS ChemStation software, which includes programs to calibrate (tune) the MSD, acquire and analyse the data.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/agilent_5972A_msd_manual.pdf

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.

Nitrogen Cycling Rate Measurements from on-deck incubations on UKOA cruise D366

Originator's Protocol for Data Acquisition and Analysis

Water samples were collected at the 55% sPAR depth (approximately 5 m) using 20 L Niskin bottles during CTD casts 3, 15, 19, 24, 28, 34, 38, 47, 55, 67 and 71 for deck incubations. The incubations were to estimate nitrate, nitrite and ammonium assimilation over 24 hours (the full light dark cycle) as well as rates of ammonium regeneration, ammonium oxidation and nitrate oxidation. Short term incubations of approximately 6 hours to estimate the maximum rate of nitrate, nitrite, and ammonium assimilation were also conducted. These short term incubations were conducted to include solar noon. The N-assimilation and N-regeneration rates were derived using methods in Clark et al. (2014) described below.

For the determination of N-regeneration rates, isotope dilution approaches were used where the DIN pool was enriched with ¹⁵N and the dilution of this tracer due to NH₄ ⁺ regeneration, NH₄ ⁺ oxidation or NO₂ ^- oxidation was determined following a period of incubation. For these methods, indophenol and sudan-l were synthesised from the DIN pool. Indophenol is derived from NH₄ ⁺ and sudan-l is derived from NO₂ ^- or NO₃ ^- following quantitative reduction to NO₂ ^-.

To determine NH₄ ⁺ regeneration rates, 4 L of seawater were amended with ¹⁵NH₄ ⁺ at an average of 5.76 ± 2.38% of the ambient concentration. The volume was thoroughly mixed and placed in a constant temperature room for five minutes to achieve homogeneity. The amended volume was then used to fill a 2.2 L incubation bottle which was incubated for approximately 24 hours in simulated light and temperature conditions. The remaining amended seawater was filtered through GF/F glass fibre filters and triplicate samples taken for the determination of pre-incubation NH₄ ⁺ concentration and isotopic enrichment. After incubation, samples were similarly filtered through GF/F glass fibre filters and triplicate samples taken to determine post incubation NH₄ ⁺ concentration and isotopic enrichment. Triplicate samples for both the pre and post incubations were of volumes 100-300 mL depending on ambient concentration. To determine NH₄ ⁺ and NO₂ ^- oxidation rates, the same procedure was used as above. Two 4 L seawater samples were amended with ¹⁵NO₂ ^- and ¹⁵NO₃ ^- respectively. The average enrichments achieved for the samples were 10 ± 6.9% for the NH₄ ⁺ oxidation rate incubations and 12.7 ± 2.2% for the NO₂ ^- oxidation rate incubations. To determine the concentration and isotopic enrichment of NO₂ ^-, sudan-l was synthesised in samples of volumes 100-200 mL. The concentration and isotopic enrichment of NO₃ ^- were determined by reducing NO₃ ^- to NO₂ ^- using a high-capacity cadmium column, and then synthesising sudan-1 in volumes of 50-100 mL. Again, the varying volumes were due to varying ambient concentrations. Samples were then collected using solid phase extraction (C18-SPE) as detailed in Clark et al (2006, 2007). These cartridges were frozen and transported back to the laboratory. Here, the samples were eluted from C18-SPE columns and purified by high-performance liquid chromatography (HPLC) prior to analysis by gas chromatography mass spectrometry (GCMS). The N-regeneration rates were then determined using the Blackburn-Caperon model. (Blackburn, 1979; Caperon et al., 1979).

N-assimilation rates were determined alongside the N-regeneration incubations. Samples were separately amended with either ¹⁵NH₄ ⁺, ¹⁵NO₂ ^-, or ¹⁵NO₃ ^- and the assimilation rates were estimated by the ¹⁵N enrichment of particulate organic nitrogen (PON).¹⁵NH₄ ⁺, ¹⁵NO₂ ^-, or ¹⁵NO₃ ^- were each added to triplicate 660 mL samples which were then incubated in conditions of simulated in situ light and temperature for an average of 6 hours. A volume of unamended seawater was filtered through GF/F and used to derive the natural abundance of ¹⁵N in PON. After incubation, the samples were filtered onto GF/F filters which were frozen and transported back to the laboratory for isotope ratio mass spectrometry analysis (Clark et al. 2011). The rates of assimilation were determined using Dugdale and Goering's (1967) equations and corrected for nitrogen regeneration using Kanda et al. (1987) equations.

References Cited

Blackburn T.H., 1979. Method for measuring rates of NH+4 turnover in anoxic marine sediments, using a 15N-NH+4 dilution technique. Applied and Environmental Microbiology, 37, 760-765.

Caperon J., Schell D., Hirota J., and Laws E., 1979. Ammonium excretion rates in Kaneohe Bay, Hawaii, measured by a 15N isotope dilution technique. Marine Biology, 54, 33-40.

Clark D.R., Brown I.J., Rees A.P., Somerfield P.J., and Miller P.I., 2014. The influence of ocean acidification on nitrogen regeneration and nitrous oxide production in the northwest European shelf sea. Biogeosciences, 11, 4985-5005. doi:10.5194/bg-11-4985-2014.

Clark D.R., Fileman T.W. and Joint I., 2006. Determination of ammonium regeneration rates in the oligotrophic ocean by gas chromatography/mass spectrometry. Marine Chemistry, 98, 121-130. doi:10.1016/j.marchem.2005.08.006

Clark D.R., Miller P.I., Woodward E.M.S. and Rees A.P., 2011. Inorganic nitrogen assimilation and regeneration in the coastal upwelling region of the Iberian Peninsula. Limnology and Oceanography, 56, 1689-1702. doi:10.4319/lo.2011.56.5.1689.

Clark D.R., Rees A.P. and Joint I., 2007. A method for the determination of nitrification rates in oligotrophic marine seawater by gas chromatography/mass spectrometry. Marine Chemistry, 103, 84-96. doi:10.1016/j.marchem.2006.06.005

Kanda J., Laws E.A., Saino T. and Hattori A., 1987.An evaluation of isotope dilution effect from conventional data sets of 15N uptake experiments, Journal of Plankton Research, 19, 79-90.

Instrumentation

High-Performance Liquid Chromatograph

Hewlett Packard 5890 Series II Gas Chromatograph

PDZ Europa 20-20 Isotope Ratio Mass Spectrometer

BODC Data Processing Procedures

Data were submitted by email to BODC as an Excel spreadsheet containing ammonium, nitrite and nitrate concentrations and assimilation rates; ammonium regeneration rates and ammonium and nitrite oxidation rates. The data included standard deviations for each parameter. The file also contained the following metadata: cruise, Julian day, date, station and cast number, latitude, longitude, depth and Niskin bottle number. The spreadsheet was archived following BODC procedure.

The data were reformatted and assigned BODC parameter codes which were in equivalent units to the data and so no unit conversions were necessary. Data were loaded in BODC's samples database under Oracle Relational Database Management System using established 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 did not advise BODC of any data quality issues and during BODC quality control no data flags were applied.

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 D366_CTD_D366071

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: D366_CTD_D366071

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