Hydrographic Parameters from Fram Strait and Denmark Strait, 1998

Summary

This data set is a compilation of hydrographic measurements made on bottle samples of seawater from CTD-rosette casts taken August-October, 1998, as part of the ARKTIS XIV/2 Polarstern Expedition.

The Polarstern cruise covered the Nordic Seas from Fram Strait to Denmark Strait. Physical and chemical oceanography investigations were carried out as part of a climate research programme. The mechanisms of heat exchange between ocean and atmosphere and the cycles of organic matter were investigated. Biogeochemical investigations concentrated on the composition, concentration and distribution of dissolved organic matter (DOM) and the production of methane in oceans.

During the cruise, measurements were carried out on 282 stations using a CTD (Conductivity, Temperature Depth) probe combined with a water sampler and a Lowered Acoustic Doppler Current Profiler (LADCP). The water samples were used to measure the concentrations of oxygen, nutrients (including nitrate, nitrite, phosphate and silicate), chloroflourocarbons (CFCs), tritium, helium, stable isotopes ¹⁶O and ¹⁸O, barium and sulfur hexafluoride (SF₆). During part of the cruise, samples were taken for the determination of methane and DOM. Ba was sampled in detail only on section 3 at Fram Strait and sections 7 and 8 in the vicinity of Denmark Strait. Note that section 3 is the only location for which a full set of oxygen isotope measurements is also available.

This cruise forms an important component of the Shelf-Basin Interaction (SBI) project, which is designed to examine the processes that control the transport of carbon from the biologically productive Arctic Ocean continental shelf to the deep basin. The results of this project will provide input for planning a large Phase 2 field program of the SBI project in 2002 in the same geographic area.

Note that this data set includes data only for the parameters listed in the Parameter Description section of this document and for areas where barium was sampled. For complete details of the Polarstern expedition, including the itinerary, participating institutions, and methods of collection, refer to the cruise report from the Alfred Wegener Institue for Polar and Marine Research.

Citing These Data:

Falkner, K. 2002. Hydrographic Parameters from Fram Strait and Denmark Strait, 1998. Boulder, CO: National Center for Atmospheric Research. Digital media.

Overview Table

Table of Contents

1. Contacts:

Investigator(s) Name and Title:

Technical Contact:

2. Detailed Data Description:

The primary hydrographic data are archived at the Alfred-Wegener-Institute in Bremerhaven, Germany.

Format:

Data are available as ASCII tab delimited text files.

Data are also available as Microsoft Excel 2000 files. Please note that older versions of Microsoft Excel may not be compatible with Microsoft Excel 2000 and the data files may not be compatible with future versions of Microsoft Excel.

File Size:

Microsoft Excel file - 229 Kb
ASCII text file - 81 Kb

Spatial Coverage:

Samples were taken from stations in several sections of the Norwegian Sea near Greenland and Iceland. The most complete coverage for dissolved barium concentrations occurred in one location in Fram Strait and in two locations between Greenland and Iceland near Denmark Strait.

The data were collected in areas between 80.222 N to 63.785 N, and 35.270 W to .015 E.

Temporal Coverage:

The data span ranges from August 1, 1998 to October 30, 1998.

See collection.html for specific dates and times that samples were collected.

Parameter or Variable:

Parameter Description:

The data set includes the following hydrographic parameters:

• dissolved barium
• bottom depth
• pressure
• temperature
• salinity
• dissolved oxygen
• phosphate
• siliceous acid
• nitrate
• nitrite
• oxygen isotopic composition of seawater (del notation with respect to Vienna Standard Mean Ocean Water [VSMOW])
• dissolved Ba concentration

Parameter Source:

The parameter source is seawater samples collected from the Research Vessel Polarstern.

Sample Data Record:

Definition of column headings:

1. Section#: Section number from which sample was collected
2. Stn#: Station number from which sample was collected
3. Lat dec deg: Latitude location of sample collection
4. Long dec deg: Longitude location of sample collection
5. Bottom depth m: Bottom depth in meters
6. PRES:R db: pressure in decibars
7. TEMP deg C: Temperature in degrees Celcius
8. SALT pss: Salinity in practical salinity scale
9. O2 ml/l: Dissolved oxygen in milliliters per liter
10. PO4 µM: Phosphate in micromoles
11. SI03 µM: Siliceous acid in micromoles
12. N03 µM: Nitrates in micromoles
13. N02 µM: Nitrites in micromoles
14. del018-VSMOW: Oxygen isotopic concentration of seawater expressed in del notation (with respect to Vienna Standard Mean Ocean Water)
15. Ba-Bottle#: Identification number of barium sample collection bottle
16. Ba nM: barium concentration in nanomoles

Quality Assessment:

The Ba data are precise to +/-2% and are referenced to the GEOSECS Ba data set.

3. Data Access and Tools:

Data Access:

Data are available for ordering from NCAR.

Related Data Collections:

• Arctic Ocean Barium Concentrations, 1993
• Arctic River Barium Concentrations, 1993-1996
• SCICEX Dissolved Barium Data, 1995-1997
• Seawater Chemistry from the North Pole Environmental Observatory

4. Data Acquisition and Processing:

Sensor or Instrument Description:

Water samples were obtained using a 24-position rosette comprised of 12-L Ocean-Test-Equipment bottles, a SBE911+ CTD and an RDI 150 kHz narrow band LADCP.

Data Acquisition Methods:

Water samples for barium analysis were collected into 20-ml polyethylene vials that had been precleaned by soaking in 0.2 N HCl overnight at 60°C, followed by copious rinsing with reverse osmosis deionized water and drying in a laminar flow bench. Samples were then stored at room temperature and shipped by air back to the Oregon State University laboratory for analysis within a year of collection.

Water samples for the analysis of dissolved oxygen and inorganic nutrients (silicate, nitrate, nitrite, and phosphate) were measured within a few hours after collection. Dissolved oxygen was determined according to Winkler method (Strickland and Parson, 1972) using potentiometric titration, and inorganic nutrients were determined with a Technicon Autoanalyzer system. The determination of nitrate and nitrite is based on the method described by Armstrong et al. (1967), silicate was measured according to Grasshoff et al. (1983), and phosphate according to Eberlein and Kattner (1987). During the cruise, 3100 samples were taken for the analysis of dissolved oxygen, and 3670 for nutrients. The following institutions supported the collection and analysis of samples:

• The Alfred Wegener Institute for Polar and Marine Research
• Instituto Sperimentale Talassografico
• Institut für Meereskunde

Processing Steps:

Isotope dilution Ba measurements were conducted on an Excel Plasmaquad inductively coupled plasma quadrupole mass spectrometer ICPMS). Briefly, aliquots (250 µl) of the sample were spiked with an equal volume of a 135Ba-enriched solution from Oak Ridge National Laboratories, diluted 20-fold with 0.2 N HCl and vortex mixed in a polypropylene test tube. Samples were introduced via a peristaltic pump (=1 ml/min) coupled to a Meinhard concentric nebulizer and a cyclone spray-chamber. The ICPMS was operated in a peak jump mode and data accumulated in three 20-s intervals for masses 135 and 138. A 4-minute washout with 0.2 N HCl was performed to diminish memory affects. A blank and a monitor (used to correct for mass bias), consisting of a spiked Ba standard solution, bracketed every five samples. Additionally, a consistency standard derived from a large volume of well-characterized seawater and random repeats of two samples were included with each tray (44 positions) of the autosampler. The consistency standard provides a run-to-run check on the spike solution.

Based on repeated runs of the consistency standard and sample repeats, the 2-sigma precision of the analysis ranges from 4% at 10 nM to 2% or better at 50 nM and above. To avoid uncertainties associated with the stoichiometry of BaCO3 salts that serve as starting materials for commercial standards, archived spiked GEOSECS standards serve as the absolute standard for data produced in the investigator's laboratory.

5. References and Related Publications:

Armstrong, F.A.J., Williams, P.M., and J.D.H. Strickland. 1966. Photooxidation of organic matter in seawater by ultraviolet radiation, analytical and other applications. Nature 211: 481-483.

Eberlein, K and G. Kattner. 1987. Automatic method for the determination of ortho-phosphate and total dissolved phosphorus in the marine environment. Fresenius Zeitschrift fur Analytische Chemie 326 (4): 354-357. Munich: J.F. Bergmann; Berlin: Springer-Verlag.

Fahrbach, E. 1999. The Expedition ARKTIS XIV/2 of the Research Vessel "Polarstern" in 1998. 1-114. Bremerhaven, Germany: Alfred Wegener Institute for Polar and Marine Research.

Fahrbach, E., J. Meincke, S. Østerhus, G. Rohardt, U. Schauer, V. Tverberg, and J. Verduin. 2001. Direct measurements of volume transports through Fram Strait. Polar Res. 20 (2): 217-224.

Grasshoff, K., Erhardt, M., and K. Kremling. 1983. Methods of seawater analysis. Verlag Chemie. Weinheim. 2nd revised and extended edition. 419 pp.

Meredith, M., K. Heywood, P. Dennis, L. Goldson, R. White, E. Farbach, U. Schauer, and S. Østerhus. 2001. Freshwater fluxes through the western Fram Strait. Geophy. Res. Lett. 28 (8):1615-1618.

Strickland, J.D.H. and T.R. Parson. 1972. A practical handbook of seawater analysis. Ottawa, Ontario: Fisheries Research Board of Canada Bulletin 167, 2nd Ed. 311 pp.

Taylor, J., K. Falkner, U. Schauer, and M. Meredith. Quantitative considerations of dissolved barium as a tracer in the Arctic Ocean. J. Geophys. Res. Accepted for publication.

6. Document Information:

Acronyms:

CTD

conductivity-temperature-depth sensor

ICPMS

inductively coupled plasma quadrupole mass spectrometer

LADCP

lowered narrow-band acoustic doppler current profiler

VSMOW

Vienna Standard Mean Ocean Water. VSMOW is the standard against which isotopic compositions of both hydrogen and oxygen are reported.

Document Creation Date:

2002-11-04

Document Revision Date:

Document Review Date:

Document URL:

http://data.eol.ucar.edu/codiac/dss/id=106.ARCSS105