Dataset: Baltic GasEx 1 SF6 and Helium

Name: SF6 and helium data from a tracer release experiment conducted June 2018 in the coastal Baltic Sea during FS Alkor cruise AL510
Published: 2024-01-10
Keywords: helium-3, SF6, gas exchange, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.915772.1

Spatial Extent: N:54.7075 E:10.1787 S:54.5343 W:10.0724

Temporal Extent: 2018-06-06 - 2018-06-12

Project:

Collaborative Research: Influence of Surfactants on Air-Sea Gas Exchange: 3He/SF6 Experiments in the Baltic Sea (Baltic GasEx)

Program:

United States Surface Ocean Lower Atmosphere Study (U.S. SOLAS)

Ocean Carbon and Biogeochemistry (OCB)

Principal Investigator:

David T. Ho (University of Hawaiʻi at Mānoa, SOEST)

Co-Principal Investigator:

Peter Schlosser (Arizona State University, ASU)

Student:

Ryo Dobashi (University of Hawaiʻi at Mānoa, SOEST)

BCO-DMO Data Manager:

Dana Stuart Gerlach (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2024-01-10

Restricted:

Validated:

Yes

Current State:

Final no updates expected

SF6 and helium data from a tracer release experiment conducted June 2018 in the coastal Baltic Sea during FS Alkor cruise AL510

Abstract:

These data are 3He and SF6 from a tracer release experiment conducted in the coastal Baltic Sea. The experiment was conducted in June 2018 and the goal was to determine gas transfer velocities in the Baltic Sea, where it is thought that excess surfactants and limited wind fetch would affect the relationship between wind speed and gas transfer velocity.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2024-01-10	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.915772.1	2024-01-22

Methods & Sampling

A tracer release experiment was conducted in the coastal Baltic Sea during cruise AL510 aboard the research vessel FS Alkor. On June 4th, 2018, we injected 3He and SF6 into the surface ocean (~5 m depth). After the injection, near the center of the SF6 patch, depth profiles of temperature and salinity were measured using a conductivity, temperature, and depth (CTD) sonde and water samples were collected in Niskin bottles.

Discrete SF6 samples (and replicates) were drawn from the Niskin bottles using 550 ml glass bottles with ground-glass stoppers. For discrete 3He samples, ~40 milliliters of seawater were collected in copper tubes mounted in aluminum channels and sealed at the ends with stainless steel clamps.

SF6 samples were taken at the same stations and measured on board the FS Alkor. Concentration of SF6 was measured using a purge-and-trap SF6 analysis system designed following Law et al. (1994). In this system, SF6 was separated from other gases and measured with a gas chromatography electron capture detector (GC-ECD).

3He samples were measured at the Lamont-Doherty Earth Observatory (LDEO) Noble Gas Laboratory. In the laboratory, 3He samples were extracted from the copper tubes using a vacuum extraction system (Ludin et al., 1998) and measured on a VG-5400 He isotope mass spectrometer. Precision is about 0.5 to 1% in δ3He for samples with high δ3He values (100% < δ3He < 1000%), and 0.2 to 0.5% for samples with lower δ3He values (-1.7% < δ3He < 100%).

Data Processing Description

We calculated 3He excess from the measured 3He/4He ratio and 4He concentration.
3He excess is 3He in excess of solubility equilibrium calculated using the following equation:

[3He]exc = [4He]s (Rs − Ra) + [4He]eqRa(1 − a),

where:

[3He]exc is 3He in excess of solubility equilibrium
[4He]s is the measured 4He concentration of the sample;
[4He]eq is the atmospheric equilibrium concentration of 4He (Weiss, 1971);
Rs is the measured 3He/4He ratio (ratio of sample);
Ra is the 3He/4He ratio in the atmosphere (1.386 × 10^^-6 (Clarke et al. 1976));
From (1 - a), a is the solubility isotope effect (0.983 (Benson and Krause, 1980)).

BCO-DMO Processing

* Imported data from source file "Baltic_Gas_Ex_1_20231113_with_SF6.txt" into the BCO-DMO data system.
* Modified parameter (column) names to conform with BCO-DMO naming conventions.
* Converted datetime to ISO8601 format yyyy-mm-ddThh:mm:ssZ
* Added column for station based on latitudes and longitudes

Data Files

File
915772_v1_sf6_helium.csv (Comma Separated Values (.csv), 4.40 KB) MD5:8f68022b581d2d9cd5f33489250db945 Primary data file for dataset ID 915772, version 1

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1756807

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
AL510	Alkor 510	2018-06-03	FS Alkor	Dennis Booge (Chief Scientist)	data info

Instruments

CTD - profiler

Supplied Name: Hydro-Bios MWS-12 CTD sonde

Supplied Description:

CTD rosette was used for Niskin sampling

Instrument Type

Generic Name: CTD - profiler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/130/

Generic Description:

The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.

This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934.

Gas Chromatograph

Supplied Name: GC-ECD (Shimazu GC-14A gas chromatography-electron capture detector)

Supplied Description:

Gases stripped from seawater were sent to a molecular sieve column, where SF6 was separated from other gases and then measured with a gas chromatography-electron capture detector (Shimazu GC-14A GC-ECD).

Instrument Type

Generic Name: Gas Chromatograph

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB02/

Generic Description:

Instrument separating gases, volatile substances, or substances dissolved in a volatile solvent by transporting an inert gas through a column packed with a sorbent to a detector for assay. (from SeaDataNet, BODC)

Mass Spectrometer

Supplied Name: VG-5400 noble gas mass spectrometer

Supplied Description:

In the laboratory, 3He samples were extracted from the copper tubes and measured on a VG-5400 He isotope mass spectrometer.

Instrument Type

Generic Name: Mass Spectrometer

Acronym: Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.

Niskin bottle

Supplied Description:

Discrete SF6 samples were drawn from the Niskin bottles using 550 ml glass bottles with ground-glass stoppers.

Instrument Type

Generic Name: Niskin bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/

Generic Description:

A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
ISO_DateTime_UTC	Date and Time in ISO8601 format in UTC Format: %Y-%m-%dT%H:%M:%SZ	unitless	ISO_DateTime_UTC
Station	Station	unitless	station
Latitude	Latitude of sampling station	decimal degrees	lat
Longitude	Longitude of sampling station	decimal degrees	lon
Depth	Depth	meters (m)	depth
Temperature	Temperature from CTD sonde	degrees Celsius (°C)	temperature
Salinity	Salinity from CTD sonde	PSU	sal_ctd
He3_excess	3He excess concentrations calculated from the measured 3He/4He ratio and the 4He concentration	cubic centimeters at standard temperature and pressure per gram times 10^-16 (ccSTP/g*10-16)	diss_noble_gas_conc
SF6_rep1	Sulfur hexafluoride (SF6) concentration	picomoles per kilogram (pmol/kg)	SF6
SF6_rep2	Sulfur hexafluoride (SF6) concentration	picomoles per kilogram (pmol/kg)	SF6
SF6_rep3	Sulfur hexafluoride (SF6) concentration	picomoles per kilogram (pmol/kg)	SF6

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