Metadata Report for BODC Series Reference Number 1622221

• 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

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 nutrient data measured on the GEOTRACES cruises JC057 (GA02 leg 3)

Responsible investigator

Dr Micha J A Rijkenberg
email: Micha.Rijkenberg@nioz.nl
Royal Netherlands Institute for Sea Research (NIOZ)
P.O. Box 59 1790 AB Den Burg
The Netherlands

Data contributor

Evaline van Weerlee
email: Evaline.van.Weerlee@nioz.nl
Royal Netherlands Institute for Sea Research (NIOZ)
P.O. Box 59 1790 AB Den Burg
The Netherlands

Laboratory of analysis

NIOZ (Shipboard)

Originator's Protocol for Data Acquisition and Analysis

During JC057 more than 1000 samples were analyzed for phosphate, silicate, nitrate and nitrite (912 samples from CTD bottles and 112 samples from the 'underway fish samples') using a Bran en Luebbe trAAcs 800 Auto-analyzer. The different nutrients were determined colorimetrical as described by Grashoff et al. (1983).

Samples were obtained from both CTD's, the large volume CTD rosette sampler and the ultra clean CTD, as well as the tow FISH. All samples were collected directly after the DIC and DOC sampling in 125ml polypropylene bottles and stored in a fridge at 4°C (unfiltered). Fish samples were filtrated over a 0.2 µm filters and collected in 125ml polypropylene bottles and stored at 4 °C prior to analysis.

Calibration Standards were prepared fresh every day diluted from stock solutions of the different nutrients in 0.2 µm filtered low nutrient seawater (LNSW). Stock standards were made by weighing in primary nutrient salts in deionized water (DIW) at the home laboratory. The analytical grade nutrient salts used were: 1) KH2PO4, 2) Na2SiF6, 3) KNO3, 4) NaNO2. The LNSW is surface seawater depleted for most nutrients, and is also used as baseline water for the analysis inbetween the samples. The samples were measured from the lowest to the highest concentration in order to keep the carry over effects as small as possible, so from surface to deep waters. Prior to analysis, all samples and standards were brought to room temperature of 23 °C.

In every run a mixed nutrient standard containing silicate, phosphate and nitrate a so called nutrient-cocktail, was measured in triplicate. Secondly a natural sterilized Reference Nutrient Sample (RMNS Kanso, Japan) containing a known concentration of silicate, phosphate, nitrate and nitrite , was analyzed in triplicate every run. The cocktail and the RMNS were both used to monitor the performance of the analysis. Finally the RMNS was used to adjust all data by means of computing with a factor, to obtain the final data set, so all referred to the same RMNS values for each analysis. This made data international comparable and comparable to the first legs of GEOTRACES.

From every station the deepest sample is sub sampled for nutrients in duplicate, the duplicate sample-vials were all stored dark at 4 °C, and measured again with the next station, for statistics.

The baseline resulted of low nutrient seawater (LNSW) the same water was used as diluents for the nutrient working standards. The back ground level of nutrients within this LNSW was determined by omitting one of the crucial reagents for color forming being: 1) Phosphate; ascorbic acid, 2) Silicate; ascorbic acid, 3) Nitrate; naphtylethylene diamine , 4) Nitrite; naphtylethylene diamine, compared with the same procedure in de-ionised water (MQ-water, Millipore). Taking A = LNSW + all reagents, B = LNSW + reagents - crucial reagent, C = MQ + all reagents, and D = MQ + reagents - crucial reagent, than the concentration of the nutrients of the zero nutrient baseline was determined using equation 1,

[nutrients baseline] = (A-B)-(C-D) * 1/slope of the calibration (1)

To clarify the baseline procedure the below example is given. The 'Baseline Background' procedure determines the amount of nutrient background in the base water being used. This procedure was performed by running the TrAAcs on all reagents and using the LNSW to be determined as the base water. The gain was set on its most sensitive setting and a low PO4 standard solution (0.2 to 0.5uM) was added to set the scale and its concentration measured with the peak height being recorded. Once a steady baseline was observed, a colour reagent line is placed into a reagent which doesn't contain the essential colour reagent, Ascorbic Acid, and then was placed back into the normal colour reagent mix. The process with and without the Ascorbic Acid in the colour reagent is then repeated with fresh Ultra-Pure Water being used as the baseline, see Figure 9. It is important to note that the Ultra-Pure Water needs to be checked for water quality. Therefore, by using the peak height from the added PO4 standard in LNSW and the difference between the baselines with and without the colour chemistry during LNSW and Ultra-Pure Water base waters, the Phosphate concentration in the LNSW can be computed using the following calculation;

µM of PO4 in LNSW = ([PO4] peak/y)*(ΔLNSW- ΔUltra-Pure Water) (2)

where,

[PO4] peak -is the concentration in µM of the low PO4 peak

y -is the peak height of the low concentration PO4 peak to the baseline

Δ LNSW -is the difference in baseline height that is seen with and then without ascorbic acid during LNSW base water

Δ Ultra Pure Water -is the difference in baseline height that is seen with and without ascorbic acid during Ultra-Pure Water baseline

All working standards were prepared by diluting stock standards with the LNSW. The salinity matrix of the working standards were not kept constant. The highest dilution was 1050 µl stock standard added to 98.95 ml LNSW which means an offset in salinity of maximum 0.4. Typically, the concentrations used for the calibration ranged between 0 up till 120% from the highest environmental concentrations that we encountered. Calibrations for all nutrients were always linear and therefore fitted linearly. A calibration was executed for each run of up to 48 samples maximum.

Table 1. Results of Reference material of Nutrients. The reference material of nutrients is deep Pacific Ocean seawater that is filtered, processed and bottled by The General Environment Technos Co., Ltd. 3-1-1, higashikuraji, katano-shi, Osaka, 576-0061 Japan. URL: http://www.kanso.co.jp/. The manufacturer provides values for concentrations on the basis of their own analyses. This value is not an absolute value, instead it is equivalent in accuracy to the value obtained by another laboratory for the same reference material. Therefore in a recent 2012 intercomparison excercise between laboratories a consensus value was produced, this is the mean of reported values of the X laboratories including NIOZ (Aoyama et al., 2013).

During the 2010-2012 GEOTRACES cruises of the Netherlands the reproducibility of the Kanso reference standard was typically around 0.6 % of the average value for silicate, phosphate, nitrate. Day-to-day variability of the analyses was monitored and compensated for by 2 approaches. Firstly the Kanso standard was run along with the 24 samples of each station, and at the end of the cruise the mean of these Kanso values was calculated and used to correct the devation of every analytical run station by station. Secondly, the deepest sample analyzed of a station of 24 samples, was also kept and re-analyzed within the next run of the next station of 24 samples as another verification for ruling out variability between runs.

Chemistry:

Silicate reacts with ammoniummolybdate to a yellow complex, after reduction with ascorbic acid the obtained blue silica molybdenum complex was measured at 800 nm. Oxalic acid was used to prevent formation of the blue phosphate molybdenum.

Phosphate reacts with ammoniummolybdate at pH 1.0, and potassiumantimonyl tartrate was used as an inhibitor. The yellow phosphate molybdenum complex was reduced by ascorbic acid and measured at 880 nm.

Nitrate plus nitrite (NOx) was mixed with a buffer imidazol at pH 7.5 and reduced by a copperized cadmium column to nitrite. This was diazotated with sulphanylamide and naphtylethylenediamine to a pink coloured complex and measured at 550 nm. After subtracting the nitrite value of the nitrite channel the nitrate value was achieved.

Nitrite was diazotated with sulphanylamide and naphtylethylenediamine to a pink coloured complex and measured at 550 nm.

References Cited

Grasshoff K, Erhardt M, Kremling K., 1983. Methods of seawater analysis, 2nd revised and extended edition. Verlag Chemie, Weinheim

Aoyama, M., and 67 others, 2013. 2012 Interlaboratory Comparison Study of a Reference Material for Nutrients in Seawater. Technical Report of the Meteorological Research Institute No. 70. In press.

BODC Data Processing Procedures

Data were submitted to BODC in Excel spreadsheet format, sample metadata provided (Station, lat, lon, depth, bottle) were checked against information held in the database and the final event log, no discrepancies were found. The mapping between the originator's channels and BODC parameter codes is detailed in the table below, the originators quality control flags were changed to BODC quality control flags no other changes were made.

Data Quality Report

The nitrite channel has a sinus baseline signal during the cruise due to sensitive adjustment of the system. The detection limit was therefore increased to 0.04 umol/L.

Project Information

GEOTRACES

Introduction

GEOTRACES is an international programme sponsored by SCOR which aims to improve our understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes (TEIs) in the marine environment. The global field programme started in 2009 and will run for at least a decade. Before the official launch of GEOTRACES, fieldwork was carried out as part of the International Polar Year (IPY)(2007-2009) where 14 cruises were connected to GEOTRACES.

GEOTRACES is expected to become the largest programme to focus on the chemistry of the oceans and will improve our understanding of past, present and future distributions of TEIs and their relationships to important global processes.

This initiative was prompted by the increasing recognition that TEIs are playing a crucial role as regulators and recorders of important biogeochemical and physical processes that control the structure and productivity of marine ecosystems, the dispersion of contaminants in the marine environment, the level of greenhouse gases in the atmosphere, and global climate.

Scientific Objectives

GEOTRACES mission is: To identify processes and quantify fluxes that control the distribution of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.

Three overriding goals support the GEOTRACES mission

• Determine ocean distributions of selected TEIs at all major ocean basins
• Evaluate the sources, sinks, and internal cycling of these TEIs and thereby characterize more completely their global biogeochemical cycles
• Provide a baseline distribution in the Polar Regions as reference for assessing past and future changes.

These goals will be pursued through complementary research strategies, including observations, experiments and modelling.

Fieldwork

The central component of GEOTRACES fieldwork will be a series of cruises spanning all Ocean basins see map below.

Three types of cruise are required to meet the goals set out by GEOTRACES. These are

• Section cruises - These will measure all the key parameters (see below) over the full depth of the water column. The sections were discussed and approved by the International GEOTRACES Scientific Steering Committee at the basin workshops.
• Process Studies - These will investigate a particular process relevant to the cycling of trace metal and isotopes. They must follow the "Criteria for Establishing GEOTRACES Process Studies" and be approved by the International GEOTRACES Scientific Steering Committee.
• Cruises collecting GEOTRACES compliant data - These will collect some trace element or isotope data. They must follow the GEOTRACES Intercalibration and Data Management protocols

IPY-GEOTRACES

The IPY-GEOTRACES programme comprised of 14 research cruises on ships from 7 nations; Australia, Canada, France, Germany, New Zealand, Japan and Russia. The cruises will not be classified in the same way as the full GEOTRACES programme since the intercalibration protocols and data management protocols had not been established before the start of the IPY. But IPY-GEOTRACES data will still be quality controlled by GDAC and in the majority of cases verified versus Intercalibration standards or protocols.

Key parameters

The key parameters as set out by the GEOTRACES science plan are as follows: Fe, Al, Zn, Mn, Cd, Cu; 15N, 13C; 230Th, 231Pa; Pb isotopes, Nd isotopes; stored sample, particles, aerosols.

Weblink:

http://www.bodc.ac.uk/geotraces/
http://www.geotraces.org/

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for JC057_CTD_02_02_ROS

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.

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: