Dataset: GT10-11 - Th234_Total_and_U238
Deployment: KN204-01

Water-column total Thorium-234 and Uranium-238.

Principal Investigator:

Kenneth O. Buesseler (Woods Hole Oceanographic Institution, WHOI)

Contact:

Stephanie Owens (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

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

Project:

U.S. GEOTRACES North Atlantic Transect (GA03) (U.S. GEOTRACES NAT)

Current State:

Final no updates expected

Version:

31 Dec 2012

Deployment Synonyms:

GA03, GT11, KN204-01A, KN204-01B, USGT-NAT-2011, USGNAZT, GNAT, 316N20111106, KN204-1

Version Date:

2013-03-05

Data URL:

https://www.bco-dmo.org/dataset-deployment/455694/data

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Description

Water-column total Th-234 with 4 L method and U-238 from U-salinity relationship from the 2010 and 2011 U.S. GEOTRACES cruises.

Methods & Sampling

Dataset acquisition description

Uranium-238
Value and uncertainty from equation derived in Owens et al. (2011)
U-238 (dpm/L) = (Salinity * 0.0786) - 0.315
Salinity was measured onboard the ship by the Scripps Ocean Data Facility.

Thorium-234
Determined by the widely-adopted 4 L method. Shallow (< 1000 m) samples were collected from the SIO ODF Rosette and deep samples (>1000 m) were collected from Niskin bottles hung above in situ pumps. Data are decay corrected to the mid-point time between when bottles 1 and 12 were fired for shallow casts and when the messenger was dropped for deep cast. All surface samples were collected using a deck-mounted pump (denoted as bottle 13). All data have been recovery-corrected using the Th-230/Th-229 recovery method (see references below) to account for any loss of sample material during processing. All samples were analyzed using RISO Laboratory Anti-coincidence Beta Counters, using a helium/1% butane mixture. Overall method efficiency was determined by minimizing the percent difference between mean U-238 and Th-234 values for samples from >1000 m to > 1000 m from the bottom (44.5 % for KN 199-4 and 46.4 % for KN 204-01a and KN 204-01b).

Data Processing Description

Dataset Processing Description

Data were flagged with quality indicators: 1 = Good; 2 = Questionable; 3 = Bad.

BCO-DMO made the following modifications:
- Parameter names have been modified to conform with BCO-DMO naming conventions.
- cruise_part was separated from the official cruise ID for cruise KN204-01.
- Added Cast_ISO_DateTime_UTC from the original cast dates and times.

Additional GEOTRACES Processing:
After the data were submitted to the International Data Management Office, BODC, the office noticed that important identifying information was missing in many datasets. With the agreement of BODC and the US GEOTRACES lead PIs, 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: station_GEOTRC, cast_GEOTRC (bottle and pump data only), event_GEOTRC, sample_GEOTRC, sample_bottle_GEOTRC (bottle data only), bottle_GEOTRC (bottle data only), depth_GEOTRC_CTD (bottle data only), depth_GEOTRC_CTD_rounded (bottle data only), BTL_ISO_DateTime_UTC (bottle data only), and GeoFish_id (GeoFish data only). 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_GT10, GT-C_Bottle_GT11, ODF_Bottle_GT10, and ODF_Bottle_GT11 datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the Event_Log_GT10 and Event_Log_GT11 datasets. McLane pump cast numbers missing in event logs were taken from the Particulate Th-234 dataset submitted by Ken Buesseler.

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.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-0925158	NSF Division of Ocean Sciences

Instruments

Niskin bottle

Supplied Description:

Shallow samples for Th-234 were taken using the SIO ODF Rosette (12 30-Liter Niskin bottles). Deep samples were taken using Niskin bottles hung above in situ pumps.

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.

Riso Laboratory Anti-coincidence Beta Counters

Supplied Description:

Th-234 samples were analyzed using a Riso Anti-coinicidence Beta Counter using a helium/1% butane mixture.

Instrument Type

Generic Name: Riso Laboratory Anti-coincidence Beta Counters

Acronym: Riso Beta Counter

Generic Description:

Low-level beta detectors manufactured by Riso (now Nutech) in Denmark. These instruments accept samples that can be mounted on a 25mm filter holder. These detectors have very low backgrounds, 0.17 counts per minute, and can have counting efficiencies as high as 55%.

Typically used in laboratory analyses. Designed to measure low levels of beta particle emission. The systems work on the principle of anticoincidence.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
cruise_id	Official cruise identifier e.g. KN199-04 = R/V Knorr cruise number 199-04.	text	cruise_id
cruise_part	Part of cruise. For KN204-01: A = 11/6/2011 to 11/18/2011 (Woods Hole to Bermuda) B = 11/19/2011 to 12/11/2011 (Bermuda to Praia, Cabo Verde)	text	cruise_part
station_GEOTRC	GEOTRACES station number; ranges from 1 through 12 for KN199-04 and 1 through 24 for KN204-01. Stations 7 and 9 were skipped on KN204-01. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'Station', this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	unitless	station
lat	Latitude. Positive = North.	decimal degrees	lat
lon	Longitude. Negative = West.	decimal degrees	lon
event	GEOTRACES event number; provided in original data submission.	unitless	event
cast_GEOTRC	Cast identifier, numbered consecutively within a station. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'Cast', this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	unitless	cast
month_gmt	2-digit month of year (GMT). in the format mm (01 to 12)	unitless	month_gmt
day_gmt	2-digit day of month (GMT). in the format dd (01 to 31)	unitless	day_gmt
year	4-digit year. in the format YYYY	unitless	year
time_gmt	Time (GMT); 24-hour clock. in the format HHMM	unitless	time_gmt
bottle	Bottle number; provided in original data submission.	unitless	bottle
sample_GEOTRC	Unique identifying number for US GEOTRACES samples; ranges from 5033 to 6078 for KN199-04 and from 6112 to 8148 for KN204-01. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'Geotraces #', this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	unitless	sample
depth_n	Nominal sample depth.	meters	depth_n
depth	Actual sample depth; provided in original data submission.	meters	depth
U238	Total Uranium-238 concentration. Includes dissolved + particulate (though particulate fraction is very small).	dpm/Liter	radioactive_isotope_conc
U238_unc	U238 uncertainty. Derived from the uncertainty in the relationship in Owens et al. (2011).	dpm/Liter	no_bcodmo_term
Th234_tot	Thorium-234 concentration.	dpm/Liter	radioactive_isotope_conc
Th_234_tot_unc	Th234 uncertainty. Derived from counting statistics.	dpm/Liter	no_bcodmo_term
q_flag	Quality flag: 1 = Good 2 = Questionable 3 = Bad	unitless	q_flag
depth_GEOTRC_CTD	Observation/sample depth in meters, calculated from CTD pressure. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
event_GEOTRC	Unique identifying number for US GEOTRACES sampling events; ranges from 2001 to 2225 for KN199-04 events and from 3001 to 3282 for KN204-01 events. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	event
sample_bottle_GEOTRC	Unique identification numbers given to samples taken from bottles; ranges from 1 to 24; often used synonymously with bottle number. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	bot_Nis
bottle_GEOTRC	Alphanumeric characters identifying bottle type (e.g., NIS representing Niskin and GF representing GOFLO) and position on a CTD rosette. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	bottle
Cast_ISO_DateTime_UTC	Cast date/time (UTC) formatted to ISO8601 standard. T indicates start of time string; Z indicates UTC. Calculated from original date and time fields.	yyyy-MM-dd'T'HH:mm:ss.SS'Z'	ISO_DateTime_UTC
BTL_ISO_DateTime_UTC	Date and time (UTC) variable recorded at the bottle sampling time in ISO compliant format. Values were added from the intermediate US GEOTRACES master file (see Processing Description). This standard is based on ISO 8601:2004(E) and takes on the following form: 2009-08-30T14:05:00[.xx]Z (UTC time)	unitless	ISO_DateTime_UTC

Database

Contribute Data

Dataset: GT10-11 - Th234_Total_and_U238
Deployment: KN204-01

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GT10-11 - Th234_Total_and_U238Deployment: KN204-01

Dataset acquisition description

Dataset Processing Description

Dataset: GT10-11 - Th234_Total_and_U238
Deployment: KN204-01