Dataset: GP16 Beryllium-7

Name: Beryllium-7 (Be-7) measurements from samples collected on R/V Thomas G. Thompson (TN303) in the Eastern Tropical Pacific from October to December 2013 (U.S. GEOTRACES EPZT project)
Published: 2016-11-18
Keywords: oceans

Cite This Dataset

Spatial Extent: N:-10.5003 E:-79.19517 S:-16.0006 W:-152.00059

Project:

GEOTRACES Peru-Tahiti section: Measurement of 7Be as a Tracer of Upper Ocean Processes (EPZT Be-7)

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

Program:

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

Principal Investigator:

David C. Kadko (Florida International University, FIU)

BCO-DMO Data Manager:

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

Version:

18 Nov 2016

Version Date:

2016-11-18

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Beryllium-7 (Be-7) measurements from samples collected on R/V Thomas G. Thompson (TN303) in the Eastern Tropical Pacific from October to December 2013 (U.S. GEOTRACES EPZT project)

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Methods & Sampling

A weighted sampling hose with a portable CTD was deployed over the side of the ship to collect seawater for Beryllium-7 (Be-7) analysis. The seawater was collected in plastic 700 liter holding tanks and then passed through iron-oxide impregnated Acrylic fiber filters (adsorbs Be-7). The efficiency of the fiber for extraction of Be from seawater was determined by adding stable Be atomic absorption standards to a drum containing seawater, pumping the water through an iron fiber cartridge, and at every 100 L measuring the Be content of the cartridge effluent. Based on several trials, it was found that for sample volumes in the range 400-700L, extraction efficiencies are respectively, 82 +/- 3% to 76 +/- 2%.

All fibers were returned to the lab where they were dried, ashed, and pressed into pellets, which in turn were placed over a low background germanium gamma detector. 7Be has a readily identifiable peak at 478keV. The detector is calibrated for these samples by adding a commercially prepared mixed solution of known gamma activities to an ashed fiber and counting it in the pellet geometry.

Please refer to:
Kadko, D. and D. Olson (1996) Be-7 as a tracer of surface water subduction and mixed layer history. Deep Sea Res. 43, 89-116. doi:10.1016/0967-0637(96)00011-8

Data Processing Description

BCO-DMO Processing:
- modified parameter names to conform with BCO-DMO and GEOTRACES naming conventions;
- added cruise_id column;
- replaced "bd" with "BDL" (below detection limit);
- removed PI-provided lat, lon, and date. Same as values in EPZT master data file.

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
Be7_joined.csv (Comma Separated Values (.csv), 6.12 KB) MD5:eef9d8ec2a99227998cd77a8bd3dd988 Primary data file for dataset ID 665158

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1451120

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

None available yet

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
GEOTRC_EVENTNO	GEOTRACES event number	unitless	event
ISO_DATETIME_UTC_START_EVENT	Date and time, formatted to the ISO 8601 standard, at the start of the sampling event, according to the event log.	YYYY-MM-DDTHH:MM:SS[.xx]Z	ISO_DateTime_UTC
EVENT_LAT	Latitude at the start of the event; north is positive.	decimal degrees	lat
EVENT_LON	Longitude at the start of the event; east is positive.	decimal degrees	lon
GEOTRC_SAMPNO	Unique GEOTRACES sample number	unitless	sample
depth	Sample depth	meters (m)	depth
Be_7_CONC	Be-7 measured in disintegrations per minute (this is equivalent to 1 Becquerel/60) per cubic meter	disintegrations per minute (dpm) / per cubic meter (dpm/m^3)	trace_metal_conc
Be_7_CONC_ERR	Error (+/-) associated with Be_7_CONC	disintegrations per minute (dpm) / per cubic meter (dpm/m^3)	trace_metal_conc

Status message

Database

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Dataset: GP16 Beryllium-7