Dataset: Particulate Thorium-234 Flux

Name: Particulate Th-234 collected with surface-tethered sediment traps at Station ALOHA as part of the EAGER chief scientist training cruise (KM1910) in the subtropical North Pacific gyre in June 2019
Published: 2021-07-20
Keywords: particulate thorium, thorium activity, thorium flux, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.854241.1

Spatial Extent: N:23.13 E:-157.785 S:22.1 W:-158.44

Temporal Extent: 2019-06-16 - 2019-06-23

Project:

EAGER Collaborative Research: Early career chief scientist training for biological and chemical oceanographers (Chief Sci KM1910)

Principal Investigator:

Matthew J. Church (University of Montana)

Co-Principal Investigator:

Sara Ferrón (University of Hawaiʻi at Mānoa, SOEST)

Erica Goetze (University of Hawaiʻi at Mānoa, SOEST)

Angelicque E. White (University of Hawai'i, UH)

Scientist:

Erin E. Black (Columbia University)

Student:

Jennifer Kenyon (Woods Hole Oceanographic Institution, WHOI)

Contact:

Erin E. Black (Columbia University)

Jennifer Kenyon (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Taylor Heyl (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

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

Version:

Version Date:

2021-07-20

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Particulate Th-234 collected with surface-tethered sediment traps at Station ALOHA as part of the EAGER chief scientist training cruise (KM1910) in the subtropical North Pacific gyre in June 2019

Abstract:

This dataset includes particulate Th-234 collected with surface-tethered sediment traps at Station ALOHA as part of the EAGER chief scientist training cruise (KM1910) in the subtropical North Pacific gyre in June 2019.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2021-07-20	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.854241.1	2021-07-20

Methods & Sampling

Particle flux measurements from the Chief Scientist Training cruise generally followed the methods of the Hawaii Ocean Time-Series (HOT). Measurements were made at 75 meters, 150 meters, and 300 meters using multiple cylindrical particle interceptor traps deployed on a free-floating array for approximately 3 days twice during cruise KM1910 at station ALOHA. Sediment trap design and collection methods are described in Winn et al. (1991). Sediment trap tubes were split, with roughly 50% of the split going to Th-234 particulate analysis.

All thorium-234 data were decay corrected back to mid-deployment times. The subsampled trap material was gradually poured into 25 millimeter (mm) filter funnels containing 25 mm QMA or GFF filters (most were QMA and efficiency differences were taken into account). Once all the trap subsample liquid was filtered, the 25 mm filter was dried at low temperature for a few hours (<60 degrees Celsius). Samples were mounted and prepared for beta counting according to the techniques noted in Pike et al., 2005 and Clevenger et al., 2021.

Data Processing Description

Data were flagged with quality indicators: 1 = Good Value.

Data flags are according to the SeaDataNet scheme (https://www.geotraces.org/geotraces-quality-flag-policy/).

BCO-DMO processing description:
- Adjusted field/parameter names to comply with BCO-DMO naming conventions;
- Added a conventional header with dataset name, PI names, version date;
- Converted dates to ISO8601 format: YYYY-MM-DDThh:mmZ;
- Converted longitude values from positive degrees West to negative degrees East;
- Rounded fields as requested by data submitter.

Data Files

File
Th-234_traps.csv (Comma Separated Values (.csv), 2.62 KB) MD5:69fec28e290dd980110158542f8c9b95 Primary data file for dataset ID 854241

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1911831
NSF Division of Ocean Sciences	OCE-1911990

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
KM1910	EAGER Chief Sci cruise 2019 Chief Scientist Training Cruise	2019-06-15	R/V Kilo Moana	Matthew J. Church (Chief Scientist) Erica Goetze (Co-Chief Scientist) Angelicque E. White (Co-Chief Scientist)	data info

Instruments

Riso Laboratory Anti-coincidence Beta Counters

Supplied Name:

Supplied Description:

Low-level beta detectors manufactured by Risø (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%. Efficiency Calibrations: The detectors are intercalibrated with each other and across the transect using low-energy U standards. Limits of Detection: Limits of detection are not reported because they are not applicable to the 234Th beta counting method. A ‘non-detect’ for 234Th or a case where there is no 234Th present (initially or after 6 months of decay) will still result in a measurable amount of background radioactivity due to the beta decay of long lived natural radionuclides that are also present. These background values are utilized and therefore, they are not reported as a non-detections of 234Th.

See: https://cafethorium.whoi.edu/services/ and https://www.nutech.dtu.dk/english/products-and-services/radiation-instruments/gm_multicounter

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%.

Sediment Trap

Supplied Name:

Supplied Description:

Sediment trap array (spar buoy, radiotransmitter, strobe light, floats, trap supports, collector tubes)

Instrument Type

Generic Name: Sediment Trap

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/33/

Generic Description:

Sediment traps are specially designed containers deployed in the water column for periods of time to collect particles from the water column falling toward the sea floor. In general a sediment trap has a jar at the bottom to collect the sample and a broad funnel-shaped opening at the top with baffles to keep out very large objects and help prevent the funnel from clogging. This designation is used when the specific type of sediment trap was not specified by the contributing investigator.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Trap_Event_ID	Sediment trap deployments were indicated with a T, followed by the deployment number (1 or 2)	Unitless	deployno
Depth	Depth of trap below water surface (zero = water surface and all values are reported as positive)	Meters	depth
Tube_ID	Each letter represents trap material from a different tube at a given depth	Unitless	sample
Start_Date_HAST	Date and time (Hawaii-Aleutian Standard Time, GMT-10) of deployment start; format: MM/DD/YYYY hh:mm	Unitless	date
End_Date_HAST	Date and time (Hawaii-Aleutian Standard Time, GMT-10) of deployment end; format: MM/DD/YYYY hh:mm	Unitless	date
Start_ISO_DateTime_UTC	Date and time (UTC) of deployment start in ISO8601 format: YYYY-MM-DDThh:mmZ Format: %Y-%m-%dT%H:%MZ	Unitless	ISO_DateTime_UTC
End_ISO_DateTime_UTC	Date and time (UTC) of deployment end in ISO8601 format: YYYY-MM-DDThh:mmZ Format: %Y-%m-%dT%H:%MZ	Unitless	ISO_DateTime_UTC
Latitude_In	Latitude at time of trap deployment in degrees North	Decimal degrees	lat
Longitude_In	Longitude at time of trap deployment in degrees East	Decimal degrees	lon
Latitude_Out	Latitude at time of trap recovery in degrees North	Decimal degrees	lat
Longitude_Out	Longitude at time of trap recovery in degrees East	Decimal degrees	lon
Volume	Volume of the water sample from the trap tube that was analyzed for thorium-234	Liters	volume
Fraction_Trap_Material_Coll	The G, H, I tubes were subsampled. Approximately 1/2 was used for the thorium-234 measurements. The absolute fraction of the total tube volume (i.e. the total sample collected) is indicated here.	Decimal fraction	samp_fraction
Th234_Flux	Sinking flux of 234Th calculated from sediment trap samples	Decays per minute (dpm) per square meter per day (dpm m-2 d-1)	Th234
Th234_Flux_SD	Standard deviation of Th234_Flux	Decays per minute (dpm) per square meter per day (dpm m-2 d-1)	std_dev
Th234_Flux_QF	Quality flag for Th234_Flux (1 = good data)	Unitless	q_flag

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Database

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Dataset: Particulate Thorium-234 Flux