Dataset: GP16 Radiocarbon DelC14

Name: Radiocarbon DelC14 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:-10.5002 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

Radiocarbon DelC14 from the 2013 Eastern Pacific Zonal Transect cruise on R/V Thomas G. Thompson (TN303) (US GEOTRACES EPZT project)

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Description

Radiocarbon DelC14 from GEOTRACES 2013 Eastern Pacific Zonal Transect cruise (TN303).

Methods & Sampling

Radiocarbon measurements were performed on gas splits from gas extracted for d13C measurements by the University of Washington group (headed by Dr. Paul Quay). The measurements were done by AMS by NOSAMS (http://www.whoi.edu/nosams/home).

Radiocarbon Measurement Methodology:
Samples were drawn from 30 liter Niskin bottles to 500 ml gas tight bottles and treated with mercuric chloride. The CO2 was stripped from the water using acidification in high vacuum line, a small split was taken for 13C analysis by another laboratory, and the remainder flame sealed in a glass ampoule.

The gas samples were submitted for analysis to the U.S. National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility in Woods Hole, MA, USA (http:// http://www.whoi.edu/nosams/home). The CO2 was processed by iron-catalyzed hydrogen reduction to filamentous graphite. The graphite was packed into ~1 mg aluminum targets and analyzed by Cs-sputter accelerator mass spectrometry. Either or both of the following AMS systems were used for measurement (it is NOSAMS policy not to divulge which instrument is used for a particular analysis):

(1) A custom-built compact 500 KV National Electrostatics Corporation (NEC), Middleton, WI model 15SDH-1 accelerator with a 134 position NEC MC-SNICS source.
(2) A 2.5 MV US-AMS tandetron accelerator with a modified bouncer-injector and 40 position NEC MC-SNICS source.

In both instances, primary standardization of the AMS was done use NBS oxalic acid (OX-I) and blanks were assessed using IAEA C-1 standard material.

Radiocarbon data calculations are further described on the NOSAMS website: http://www.whoi.edu/nosams/radiocarbon-data-calculations

Data Processing Description

Additional column (pressure) provided in original data is 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
delC14_joined.csv (Comma Separated Values (.csv), 46.86 KB) MD5:9427418a8e32f5b65504e58504e41039 Primary data file for dataset ID 664845

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

Accelerator Mass Spectrometer

Supplied Name: Cs-sputter accelerator mass spectrometry

Supplied Description:

The CO2 was processed by iron-catalyzed hydrogen reduction to filamentous graphite. The graphite was packed into ~1 mg aluminum targets and analyzed by Cs-sputter accelerator mass spectrometry. Either or both of the following AMS systems were used for measurement: (1) A custom-built compact 500 KV National Electrostatics Corporation (NEC), Middleton, WI model 15SDH-1 accelerator with a 134 position NEC MC-SNICS source. (2) A 2.5 MV US-AMS tandetron accelerator with a modified bouncer-injector and 40 position NEC MC-SNICS source.

Instrument Type

Generic Name: Accelerator Mass Spectrometer

Acronym: AMS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB17/

Generic Description:

An AMS measures "long-lived radionuclides that occur naturally in our environment. AMS uses a particle accelerator in conjunction with ion sources, large magnets, and detectors to separate out interferences and count single atoms in the presence of 1x1015 (a thousand million million) stable atoms, measuring the mass-to-charge ratio of the products of sample molecule disassociation, atom ionization and ion acceleration." AMS permits ultra low-level measurement of compound concentrations and isotope ratios that traditional alpha-spectrometry cannot provide. More from Purdue University: http://www.physics.purdue.edu/primelab/introduction/ams.html

Niskin bottle

Supplied Name:

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
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
C_14_DELTA	Radiocarbon \ Delta^{14}C in per mil. d14C is the per mil deviation of 14C/12C ratio relative to a standard, normalized to a d13C of -25 per mil. For more details on radiocarbon calculation, see: http://www.whoi.edu/nosams/radiocarbon-data-calculations	per mil	radioactive_isotope_conc
C_14_DELTA_ERR	Uncertainty in radiocarbon \ Delta^{14}C in per mil	per mil	radioactive_isotope_err
C_14_DELTA_FLAG_W	Quality flag for radiocarbon \ Delta^{14}C	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 Radiocarbon DelC14