Dataset: Particulate Th-234 Activities
Deployment: KM1910

Particulate Th-234 Activities

View Data: For data, See Dataset Metadata Page: https://osprey.bco-dmo.org/dataset/854150

Principal Investigator:

Matthew J. Church (University of Montana)

Co-Principal Investigator:

Sara Ferrón (University of Hawaiʻi at Mānoa, HIGP)

Erica Goetze (University of Hawaiʻi at Mānoa, HIGP)

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)

Project:

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

Version:

Deployment Synonyms:

EAGER, Chief Sci cruise, 2019 Chief Scientist Training Cruise

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Description

Methods & Sampling

Dataset acquisition description

In-situ particulate material was collected using McLane pumps. All thorium data were decay-corrected back to mid-pumping times. See Pike et al., 2005 and Clevenger et al., 2021 for detailed methods and counting techniques.

>51 micrometer (µm) Th-234 (LSF, large particulate Thorium): The entire 142 millimeter (mm) mesh screen was rinsed onto a 25 mm silver filter and dried in a low temperature oven before beta counting. The mean volume pumped through the 142 mm mesh screens was ~640 liters (L).

1-51 micrometer (µm) Th-234 (SSF, small particulate Thorium): Whole 142 mm QMAs, located below the mesh screen in the filter head housing, were dried in a low temperature oven. A 25 mm subsample was taken from this 142 mm filter for beta counting for Th-234.

Data Processing Description

Dataset Processing Description

Data were flagged with quality indicators: 1 = Good Value; 2 = Probably Good Value.

Empty fields marked ‘nd’ denote that there were pump or filterhead issues that resulted in a compromised sample or no sample at this depth for either the QMA or screen or both. Data were originally calculated in dpm per L and were converted to mBq per kiligram (kg) using the standard ocean rho = 1.025 kg/L and 1 dpm = 16.667 mBq.

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.

More information about this dataset deployment

Funding

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

Instruments

McLane Pump

Supplied Name:

Supplied Description:

McLane pumps sample large volumes of seawater at depth. They are attached to a wire and lowered to different depths in the ocean. As the water is pumped through the filter, particles suspended in the ocean are collected on the filters. The pumps are then retrieved, and the contents of the filters are analyzed in a lab.

Instrument Type

Generic Name: McLane Pump

Generic Description:

McLane pumps sample large volumes of seawater at depth. They are attached to a wire and lowered to different depths in the ocean. As the water is pumped through the filter, particles suspended in the ocean are collected on the filters. The pumps are then retrieved and the contents of the filters are analyzed in a lab.

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%.

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
Pump_Event_ID	Pump casts were indicated with a P, followed by the cast number (1 to 5)	Unitless	deployno
Depth	Depth below water surface (zero = water surface and all values are reported as positive)	Meters	depth
Latitude	Latitude North	Decimal degrees	lat
Longitude	Longitude East	Decimal degrees	lon
Date_Pump_On_HAST	Date and Time in Hawaiian-Aleutian Standard Time (GMT-10) when large volume pumps were programmed to turn on; format: MM/DD/YYYY hh:mm	Unitless	date
Date_Pump_Off_HAST	Date and Time in Hawaiian-Aleutian Standard Time (GMT-10) when large volume pumps were programmed to turn off; format: format: MM/DD/YYYY hh:mm	Unitless	date
Pump_On_ISO_DateTime_UTC	Date and Time in UTC when large volume pumps were programmed to turn on in ISO8601 format: YYYY-MM-DDThh:mmZ	Unitless	ISO_DateTime_UTC
Pump_Off_ISO_DateTime_UTC	Date and time in UTC when large volume pumps were programmed to turn off in ISO8601 format: YYYY-MM-DDThh:mmZ	Unitless	ISO_DateTime_UTC
Filtered_Volume	Volume of water passing through the filterhead.	Liters	volume
Th234_LSF	>51 µm Thorium-234 (large particle activity)	mBq/kg	Th234
LSF_Err	Error of Th234_LSF. Error is propagated from the counting uncertainty and uncertainties associated with sample processing.	mBq/kg	no_bcodmo_term
LSF_QF	Quality flag for Th234_LSF	Unitless	no_bcodmo_term
Th234_SSF	1-51 µm Thorium-234 (small particle activity)	mBq/kg	Th234
SSF_Err	Error of Th234_SSF. Error is propagated from the counting uncertainty and uncertainties associated with sample processing.	mBq/kg	no_bcodmo_term
SSF_QF	Quality flag for Th234_SSF	Unitless	no_bcodmo_term

Database

Contribute Data

Dataset: Particulate Th-234 Activities
Deployment: KM1910

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Particulate Th-234 ActivitiesDeployment: KM1910

Dataset acquisition description

Dataset Processing Description

Dataset: Particulate Th-234 Activities
Deployment: KM1910