Dataset: GP16 Tritium

Name: Tritium Concentrations from the 2013 Eastern Pacific Zonal Transect cruise on R/V Thomas G. Thompson (TN303) (US GEOTRACES EPZT project)
Published: 2016-11-15
Keywords: oceans

Cite This Dataset

Spatial Extent: N:-10.2499 E:-77.3761 S:-16.0006 W:-152.0006

Project:

Measurement of Helium Isotopes, Tritium, Noble Gases, and Radiocarbon (EPZT Noble Gases He Tritium)

U.S. GEOTRACES East Pacific Zonal Transect (GP16) (U.S. GEOTRACES EPZT)

Program:

U.S. GEOTRACES (U.S. GEOTRACES)

Principal Investigator:

William J. Jenkins (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

15 Nov 2016

Version Date:

2016-11-15

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Tritium Concentrations from the 2013 Eastern Pacific Zonal Transect cruise on R/V Thomas G. Thompson (TN303) (US GEOTRACES EPZT project)

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Description

Tritium Concentrations from GEOTRACES 2013 Eastern Pacific Zonal Transect cruise (TN303).

Methods & Sampling

Tritium samples were obtained by transfer from NISKIN bottles to cleaned and baked 1 liter flint glass bottles fitted with polyseal caps (Lott and Jenkins 1998). On shore, approximately 500 ml of the sample is transferred under an argon atmosphere to a pre-cleaned 1 liter aluminosilicate glass flask and degassed (quantitatively removing all dissolved helium) and stored for a minimum of 6 months in a cosmic-ray sheltered environment for 3-He regrowth (Clarke, Jenkins et al. 1976). The tritiugenic 3-He is harvested and analyzed with a mass spectrometer (Lott and Jenkins 1998). The overall uncertainty is estimated from a combination of measurement counting statistics, variation in cosmogenic production rates, and uncertainty in the running standard.

References:
Clarke, W. B., W. J. Jenkins and Z. Top (1976). "Determination of tritium by spectrometric measurement of 3He." International Journal of Applied Radiation and Isotopes 27: 515-525.

Lott, D. E. and W. J. Jenkins (1998). "Advances in the analysis and shipboard processing of tritium and helium samples." International WOCE Newsletter 30: 27-30.

Data Processing Description

Additional columns (pressure, temperature, salinity, latitude, longitude) provided in original data are included for reference only. All quality flags follow CCHDO/WOCE conventions.

BCO-DMO Processing Note: modified parameter names to conform with BCO-DMO and GEOTRACES naming conventions.

Additional GEOTRACES Processing:
As was done for the GEOTRACES-NAT data, BCO-DMO added standard US GEOTRACES information, such as the US GEOTRACES event number, to each submitted dataset lacking this information. To accomplish this, BCO-DMO compiled a 'master' dataset composed of the following parameters: cruise_id, EXPOCODE,SECT_ID, STNNBR, CASTNO, GEOTRC_EVENTNO, GEOTRC_SAMPNO, GEOTRC_INSTR, SAMPNO, GF_NO, BTLNBR, BTLNBR_FLAG_W, DATE_START_EVENT, TIME_START_EVENT, ISO_DATETIME_UTC_START_EVENT, EVENT_LAT, EVENT_LON, DEPTH_MIN, DEPTH_MAX, BTL_DATE, BTL_TIME, BTL_ISO_DATETIME_UTC, BTL_LAT, BTL_LON, ODF_CTDPRS, SMDEPTH, FMDEPTH, BTMDEPTH, CTDPRS, CTDDEPTH.

This added information will facilitate subsequent analysis and inter comparison of the datasets.

Bottle parameters in the master file were taken from the GT-C_Bottle and ODF_Bottle datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the TN303 Event Log (version 30 Oct 2014). Where applicable, pump information was taken from the PUMP_Nuts_Sals dataset.

A standardized BCO-DMO method (called "join") was then used to merge the missing parameters to each US GEOTRACES dataset, most often by matching on sample_GEOTRC or on some unique combination of other parameters.

If the master parameters were included in the original data file and the values did not differ from the master file, the original data columns were retained and the names of the parameters were changed from the PI-submitted names to the standardized master names. If there were differences between the PI-supplied parameter values and those in the master file, both columns were retained. If the original data submission included all of the master parameters, no additional columns were added, but parameter names were modified to match the naming conventions of the master file.

See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.

Data Files

File
tritium_joined.csv (Comma Separated Values (.csv), 65.35 KB) MD5:eb3990572adda8bea97af5e31ad54af6 Primary data file for dataset ID 664765

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1232991

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
TN303	GP16 GEOTRACES EPZT GEOTRACES East Pacific Zonal Transect (EPZT) GT13 325020131025	2013-10-25	R/V Thomas G. Thompson	James W. Moffett (Chief Scientist) Gregory A. Cutter (Co-Chief Scientist) Christopher R. German (Co-Chief Scientist)	data info

Instruments

Mass Spectrometer

Supplied Name: mass spectrometer

Supplied Description:

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 Name: NISKIN bottle

Supplied Description:

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
cruise_id	Cruise identification	unitless	cruise_id
STNNBR	Station number	unitless	station
CTDPRS	CTD pressure	decibars	press
CTDDEPTH	CTD bottle firing depth; joined from BCO-DMO GEOTRACES master file	meters	depth
CTDTMP	CTD temperature	degrees Celsius	temp
CTDSAL	CTD salinity	PSU	sal
GEOTRC_EVENTNO	GEOTRACES event number; joined from BCO-DMO GEOTRACES master file	unitless	event
CASTNO	Cast number	unitless	cast
SAMPNO	Sequential sample number within the cast (usually corresponds to bottle number).	unitless	bottle
GEOTRC_SAMPNO	Unique GEOTRACES sample number	unitless	sample
TRITIUM	Tritium concentration in Tritium Units	Tritium units	radioactive_isotope_conc
TRITIUM_ERR	Uncertainty in tritium concentration in Tritium Units	Tritium units	radioactive_isotope_err
TRITIUM_FLAG_W	Quality flag for tritium concentration	unitless	q_flag
GEOTRC_INSTR	Sampling instrument; joined from BCO-DMO GEOTRACES master file	unitless	instrument
BTLNBR	Bottle number; typically 1-24; joined from BCO-DMO GEOTRACES master file	unitless	bottle
BTLNBR_FLAG_W	Bottle number quality flag; follows WOCE conventions. 2 = good; 3 = questionable; 4 = bad; 9 = missing data; joined from BCO-DMO GEOTRACES master file	unitless	flag
BTL_ISO_DATETIME_UTC	Date and time, formatted to the ISO 8601 standard, at the time of bottle firing; joined from BCO-DMO GEOTRACES master file	YYYY-MM-DDTHH:MM:SS[.xx]Z	ISO_DateTime_UTC
BTL_LAT	Latitude of bottle firing; north is positive; joined from BCO-DMO GEOTRACES master file	decimal degrees	lat
BTL_LON	Lonitude of bottle firing; east is positive; joined from BCO-DMO GEOTRACES master file	decimal degrees	lon
BTMDEPTH	Bottom depth; joined from BCO-DMO GEOTRACES master file	meters	depth_bottom

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Database

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Dataset: GP16 Tritium