Metadata Report for BODC Series Reference Number 2121664

• 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

ThermoFinnigan Neptune inductively coupled plasma mass spectrometer

A laboratory high mass resolution inductively coupled plasma mass spectrometer (ICP-MS) designed for elemental and isotopic analysis. The instrument is based on a multicollector platform and combines the features of high mass resolution, variable multicollection, zoom optics and multiple ion counting (MIC). It has a large mass dispersion (812 mm) using an ion optical magnification of two.

The Neptune ICP-MS includes eight moveable collector supports and one fixed center channel which are installed on the optical bench of the multicollector module. The center channel is equipped with a Faraday cup and, optionally, an ion counter with or without a retardation lens. The eight detector supports are driven by motors and can be precisely positioned along the focal plane according to need. Beneath each variable detector platform there is a position sensor located inside the vacuum chamber, allowing precise in situ monitoring of the detector position.

Each moveable support can carry a Faraday cup, a miniature Secondary Electron Multiplier (SEM) or a combination of the two. The large Faraday cups have been laser machined from solid carbon and each is connected to a current amplifier whose signal is digitised by a high linearity voltage to frequency converter. The amplifiers are mounted in a doubly shielded, evacuated and thermostated housing with a temperature stability of ± 0.01°C. Amplifier dynamic range is restricted to 15 volts in negative ion detection mode and 50 volts in positive ion detection mode. The instrument eliminates gain calibration biases by using the Virtual Amplifier concept whereby all Faraday cups involved in a certain measurement are sequentially connected to all amplifiers and it can detect up to 17 ion beams simultaneously.

The instrument includes refined ion optics which are almost coincident angular, energy image planes and large focal depth due to large ion optical magnification. It has three resolution settings and a wide detector slit for each of these. In high resolution settings the resolving power can go as high as m/Δm = 10.000. The m/Δm is derived from the peak slope of the rising edge measured at 5% and 95% relative peak height.

The instrument has been discontinued and ThermoFinnigan has been incorporated into Thermo Scientific (part of Thermo Fisher Scientific).

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.

Cruise DY021 total dissolved chromium concentration, chromium(III) concentration and isotopic composition

This dataset contains total dissolved chromium concentration, chromium(III) concentration and isotopic composition data from samples collected during RRS Discovery cruise DY021 (sampling period 08/03/2015 to 22/03/2015), as part of the UK Shelf Sea Biogeochemistry research programme

Originator's Protocol for Data Acquisition and Analysis

Sampling protocol for total dissolved Cr and δ⁵³Cr: Ultra-clean CTD bottles containing seawater were transferred to class 100 clean laboratory aboard RRS Discovery and seawater was filtered through Sartorius Sartobran 0.45 µm capsule filters. Acid-washed 1 L LDPE bottles were rinsed 3 times with sample before the final seawater sample was collected (5 x 1 L per sample). These were stored double-bagged and tranferred to the National Oceanography Centre (Southampton, UK) on 26th March 2015, where they were acidified using 2 mL L^-1 sub-boiled hydrochloric acid.Samples were stored for ~10 months before analysis.

Sampling protocol for Cr(III): Ultra-clean CTD bottles containing seawater were transferred to class 100 clean laboratory aboard RRS Discovery and seawater was filtered through Sartorius Sartobran 0.45 µm capsule filters. Acid-washed 500 mL LDPE bottles were rinsed 3 times with sample before the final seawater sample was collected (1 x 500 mL per sample). The samples were treated with a⁵³Cr isotopic spike and Fe(III) hydroxide solution to capture Cr(III) (Cranston and Murray, 1978) within ~1 hour of collection. They were double-bagged and transported back to NOCS and stored for ~5 months before analysis.

Analytical protocol for total dissolved Cr and δ⁵³Cr: Samples were treated with an isotopic double spike (⁵⁰Cr-⁵⁴Cr). Approx. 24 hours later, sample pH was adjusted to 8-9 using ammonia, then Cr was removed from the seawater matrix using a Fe(II) co-precipitation technique (Bonnand et al. 2013; Cranston and Murray, 1978). The resulting Cr-Fe precipitates were filtered using vacuum filtration through pre-cleaned Millipore Omnipore filters (1 µm) and purified using a two stage ion chromatography procedure. Samples were then treated with hydrogen peroxide to oxidise any remaining organic material and analysed in 3% nitric acid using the Thermo Fisher Neptune MC-ICP-MS in medium resolution at NOCS. Blank 3% nitric acid solutions were measured between samples and resulting voltages subtracted from the sample voltages. Values of δ⁵³Cr were calculated using a Newton-Raphson deconvolution calculation and expressed relative to the NBS979 standard (δ⁵³Cr = 0‰ see Bonnand et al. 2013). NBS979 Cr standards were also repeatedly analysed during each anaytical session and initial sample δ⁵³Cr values were corrected for instrumental drift using these. Finally, a correction to account for the procedural blank (derived from the Fe(II) hydroxide precipitate) was applied. Total dissolved Cr values were calculated by applying isotope dilution calculations to MC-ICP-MS data (e.g. Ohata et al. 1998) and a blank subtraction (using the concentration of Cr in the Fe(II) solution) was applied.

Analytical protocol for Cr(III): Cr-Fe precipitates resulting from on-board sample treatment were filtered using vacuum filtration through pre-cleaned Millipore Omnipore filters (11 µm) and purified using a two stage ion chromatography procedure (Bonnand et al. 2013). Samples were then treated with hydrogen peroxide to oxidise any remaining organic material and analysed in 3% nitric acid using the Element 2 ICP-MS. Cr(III) values were calculated by applying isotope dilution calculations (e.g. Ohata et al. 1998) and a blank subtraction (using the total procedural blank for an equivalent volume of Milli-Q water) was applied.

References Cited

Bonnand, P., James, R.H., Parkinson, I.J., Connelly, D.P. and Fairchild, I.J., 2013. The chromium isotopic composition of seawater and marine carbonates. Earth. Planet. Sci. Lett. 382, 10-20.

Cranston, R.E., and Murray, J.W. 1978. The determination of chromium species in natural waters. Anal. Chem. Act., 99, 275-282.

Ohata, M., Ichinose, T. Furuta, N., Shinohara A. and Chiba M. 1998. Isotope dilution analysis of Se in human blood serum by using high power nitrogen microwave-induced plasma mass spectrometry coupled with a hydride generation technique", Anal. Chem., 70(13), 2726-2730

BODC Data Processing Procedures

Data were provided in an Excel spreadsheet and archived at BODC. The file contained the water sample data from an UltraClean CTD (UCCTD) bottles. Data received were loaded into the BODC database using established BODC data banking procedures. The data were loaded into BODC's database without any changes. The originator variables were mapped to appropriate BODC parameter codes as follows:

The originator variables were mapped to appropriate BODC parameter codes as follows:

Project Information

Shelf Sea Biogeochemistry (SSB) Programme Work Package 3: Supply of iron from shelf sediments to the ocean

Work Package 3 is a £0.78 million component of the Natural Environment Research Council (NERC) Shelf Sea Biogeochemistry (SSB) research programme, running from 2013 to 2017. It is jointly funded by NERC and the Department for Environment, Food and Rural Affairs (DEFRA). The goal of this project is to quantify iron (Fe) fluxes from the north-west European shelf seas to the adjacent North Atlantic Ocean.

Background

Low iron (Fe) concentrations control productivity, phytoplankton community structure and carbon cycling in 25 % of the open ocean. Iron concentrations are tightly coupled to Fe supply, and Fe fluxes from shelf seas to the open ocean are poorly constrained, although estimates indicate they could be 2-10 times higher than atmospheric inputs and thus potentially a major contributor to the oceanic Fe cycle.

The goal of Work Package 3 will be realised during cruises in the Celtic Sea as part of the Shelf Sea Biogeochemistry Research Programme (SSB), which will provide the physical and chemical context for our study. The data collection will utilise trace metal clean sampling techniques, with associated physical diffusion and advection measurements, to determine the supply of dissolved, colloidal and particulate forms of Fe from sediments and their subsequent fate in shelf sea waters and during export to the North Atlantic Ocean. Data analyses will use Fe isotopes, physical-chemical Fe species characterisation and geochemical tracers to quantify the Fe supply, attenuation and export processes.

Further details are available on the SSB website.

Participants

6 different organisations are directly involved in research for SSB Work Package 3. These institutions are

• Centre for Environment, Fisheries and Aquaculture Science (Cefas)
• National Oceanography Centre (NOC)
• Plymouth University
• University of Edinburgh
• University of Oxford
• University of Southampton

Objectives

This Work Package aims to:

• Study the processes whereby iron is released from shelf sediments into overlying waters, and how these mechanisms can be influenced by organic matter from decaying plant material

• Provide new information on processes influencing release of iron to shelf waters to allow improved modelling of the size of this source, and of the key processes involved. For example, organic carbon inputs are expected to be associated with iron releases from the sediments, and using models will help extrapolate into the future and how the system will respond to climate change.

• Link the processes impacting iron in shelf waters with physical models and radionuclide estimates of the movement of water off shelf to give new estimates of the size of this source to the ocean. This information will have implications for shelf break and ocean productivity.

• Help interpret existing collected data (sediment profile images) on organic carbon within sediments and the status of the seabed through specific studies of sediment iron geochemistry. Specific studies of sediment iron geochemistry will help better interpret presently collected data (sediment profile images) on organic carbon within sediments and status of the seabed.

Fieldwork and data collection

Data for Work Package 3 will be gathered on all process cruises. These are listed in the table below. The study area is the marine shelf (and shelf-edge) of the Celtic Sea. Work will be carried out on board the NERC research vessels RRS Discovery and RRS James Cook.

Activities will include iron and radium measurements, glider work, coring, CTDs, stand alone pumps (SAPS), incubations with sediments and sea water.

Data Activity or Cruise Information

Data Activity

No Document Information Held for the Series

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Shelf Seas Biogeochemistry Fixed Station Benthic G

This station is one of four benthic sites sampled on the Celtic Sea shelf as part of work package II of the Shelf Seas Biogeochemistry project. The station has a mean water depth 109 m at the following co-ordinates:

The position of this station relative to the other Shelf Seas Biogeochemistry sites can be seen from the figure below.

Sampling History

Mooring deployments

Related Fixed Station activities are detailed in Appendix 2

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: DY021_UCCTD_118

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.

Appendix 2: Shelf Seas Biogeochemistry Fixed Station Benthic G

Related series for this Fixed Station 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.