Citation:

PANGAEA.770678 (unpublished dataset)

Project(s):

Global marine biogeochemical cycles of trace elements and their isotopes (GEOTRACES)

Coverage:

Median Latitude: -58.054750 * Median Longitude: -59.739759 * South-bound Latitude: -60.705600 * West-bound Longitude: -65.193800 * North-bound Latitude: -55.339800 * East-bound Longitude: -53.608300

Date/Time Start: 2006-01-16T12:08:00 * Date/Time End: 2006-02-06T04:40:00

Minimum DEPTH, water: 7.8 m * Maximum DEPTH, water: 4461.9 m

Event(s):

PS69/134-1 * Latitude: -55.339800 * Longitude: -65.193800 * Date/Time: 2006-01-16T12:08:00 * Elevation: -1567.0 m * Campaign: (PS69) * Basis: * Method/Device: (CTD-RO)

PS69/135-1 * Latitude: -55.464400 * Longitude: -64.946300 * Date/Time: 2006-01-16T20:06:00 * Elevation: -2550.0 m * Campaign: (PS69) * Basis: * Method/Device: (CTD-RO)

PS69/136-1 * Latitude: -55.588400 * Longitude: -64.742900 * Date/Time: 2006-01-17T00:50:00 * Elevation: -3595.0 m * Campaign: (PS69) * Basis: * Method/Device: (CTD-RO)

Comment:

On the Drake Passage section we took samples for noble gases (helium isotopes 3He and 4He and neon 20Ne), distributed on 18 profiles, and samples for Chlorofluorocarbons (CFC-11 and CFC-12) distributed on 22 profiles. Most of the profiles were carried out on the first section southward and thus will provide a synoptic section of the variable current system. Two stations were on the repeated section northwards, one station to fill the gap in the southward section close to 55.9° S (PS69/232 with He/Ne and CFCs) and one repeat of station PS69/138 (PS69/230, CFCs only to check for synopticity in the gas tracers).

The water samples for helium isotopes and neon from the CTD-bottle-system are tapped in copper tubes, preventing air contamination and bubbles during the filling of the tubes and squeezed at both ends to keep them gas tight during transportation and storage.

In the IUP Bremen noble gas lab the samples are processed in a first step with a UHV (ultra high vacuum) gas extraction system. The required vacuum conditions are achieved by a rotary pump and an oil diffusion pump. To maintain contamination-free samples, the extraction system is checked for leaks on each sample separately. Sample gases are transferred via water vapour into a glass ampoule kept at liquid nitrogen temperature. Quality checks of this sample preparation line are done on a routine basis. This includes special vacuum checks and preparing accurately defined samples for internal control measurement.

For analysis of the noble gas isotopes the glass ampoules are connected to a fully automated UHV mass spectrometric system equipped with a two stage cryo system. Every 2 to 4 samples the system is calibrated with atmospheric air standards (reproducibility <0.2%). Also measurement of line blanks and linearity are done. The performance of the Bremen facility is described in Sultenfus et al. (2009, doi:10.1080/10256010902871929).

Error estimate for absolute noble gases concentrations:

- D(4He) < 1.0 %

- D(Ne) < 1.0 %

- D(d3He) < 0.5 %

The Chlorofluorocarbon (CFC-11 and CFC-12) water samples from the CTD-bottle-system are stored in glass ampoules without contact to the atmosphere during the tapping. Immediately after sampling the ampoules are flame sealed after a CFC free headspace of pure nitrogen had been applied.

The loss of CFCs into the headspace is considered by a careful equilibration between liquid and gas phase under controlled conditions before the sealed ampoules are opened and a precise measurement of the volume of the headspace. The determination of CFC concentrations in the IUP Bremen gas chromatography lab is accomplished by purge and trap sample pre-treatment followed by gas chromatographic (GC) separation on a capillary column and electron capture detection (ECD). The system is calibrated by analyzing several different volumes of a known standard gas. CFC concentrations are calibrated on SIO98 scale (Prinn et al., 2000, doi:10.1029/2000JD900141). A more detailed description of the measurement system is given by Bulsiewicz et at. (1998, doi:10.1029/98JC00140).

Accuracy (i.e. uncertainties of calibrated sample volume, calibration curve, extraction efficiency, standard and working gas, water blank, etc.):

- CFC-12 < 1.9 %

- CFC-11 < 3.3 %

Precision (i.e. mean error from 4 replicate samples):

- CFC-12 < 0.007 pmol/kg or < 1.3% (which ever is greater) (n=6)

We do not give a value for the precision of CFC-12. Offline sample chromatograms regularly show a negative peak in the vicinity of the CFC-11 peak, which decreases the accuracy of CFC-11 in comparison to CFC-12, and which does not allow giving an objective estimate of a precision for CFC-11.

Noble gas data were used in Sudre et al., 2011, doi:10.1016/j.dsr2.2011.01.005

Sampling on board and measurement of CFCs and noble gases at the IUP Bremen was funded by the Deutsche Forschungsgemeinschaft within the SPP 1158 "Antarktisforschung", grant RH 25/27. We thank Christine Provost, Nathalie Sennechael, Veronique Garcon and their teams to participate in the ANT-XXIII/3 expedition and the excellent assistance and cooperation on board. We thank also the master and crew of RV Polarstern.

Noble gas measurements: Jürgen Sültenfuß; CFC measurements: Klaus Bulsiewicz

Quality flags: ? = doubtful; / = bad; # = mean of replicates

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Event label	Event
2	Date/Time of event	Date/Time
3	Latitude of event	Latitude
4	Longitude of event	Longitude
5	Elevation of event	Elevation	m
6	DEPTH, water	Depth water	m			Geocode
7	Freon-11 (trichorofluoromethane)	CFC-11	pmol/kg	Huhn, Oliver	Gas chromatography
8	Freon-12 (dichlorodifluoromethane)	CFC-12	pmol/kg	Huhn, Oliver	Gas chromatography
9	Helium	HELIUM	nmol/kg	Huhn, Oliver	Ultra high vacuum (UHV) mass spectrometry
10	Helium, dHe-3	DELHE3	%	Huhn, Oliver	Ultra high vacuum (UHV) mass spectrometry	100 x ([3He/4He]obs/[3He/4He]atm.- 1)
11	Neon	NEON	nmol/kg	Huhn, Oliver	Ultra high vacuum (UHV) mass spectrometry
12	Bottle number	Bottle		Huhn, Oliver

Size:

1403 data points

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