Dataset: GP15 Dissolved Radium-226 and Radium-228 Leg 2

Name: Water column dissolved radium-226 and radium-228 from Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018
Published: 2023-10-02
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.825947.3

Spatial Extent: N:18.907 E:-151.986 S:-20 W:-155.258

Temporal Extent: 2018-10-25 - 2018-11-23

Project:

Collaborative Research: US GEOTRACES PMT: Sources and Rates of Trace Element and Isotope Cycling Derived from the Radium Quartet (PMT Radium Isotopes)

US GEOTRACES Pacific Meridional Transect (GP15) (U.S. GEOTRACES PMT)

Program:

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

Principal Investigator:

Matthew A. Charette (Woods Hole Oceanographic Institution, WHOI)

Co-Principal Investigator:

Willard S. Moore (University of South Carolina)

Contact:

Matthew A. Charette (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

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

Version:

Version Date:

2023-10-02

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Abstract:

Water column dissolved radium-226 and radium-228 from Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018. In this dataset version (v3), the radium-226 data have been updated from the previous version of the dataset.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2023-10-02	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.825947.3	2023-10-02
2021-12-28	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.825947.2	2021-12-29
2020-10-01	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.825947.1	2021-01-14

Methods & Sampling

At sea, Radium-226 samples were collected following the GEOTRACES cookbook. Samples were collected from a 30-liter (L) Niskin mounted directly above a McLane large volume in situ pump WTS-LV (>1000 meters) or on a CTD Rosette (<1000 meters). These samples (10-25 L) were gravity-filtered through 15 grams (g) of manganese oxide impregnated acrylic fiber at approximately 0.5 liters per minute (L/min). The filtrate was collected inside of a graduated rigid sided container and the volume was recorded. A mass was also obtained by using a hand-held digital balance.

The Mn fibers from the Niskin bottles were rinsed with deionized water back at Woods Hole Oceanographic Institution (WHOI), partially dried, and sealed within a fiber holder after being flushed with helium equivalent to 30 column volumes. Samples were stored for a minimum of 12 days and analyzed for 226Ra via 222Rn ingrowth using alpha scintillation counting (Key et al., 1979). Samples were counted for 1-20 hours depending on the activity on the fiber, which resulted in counting uncertainties of ~2% dependent upon 226Ra content on the fiber and sample volume.

Radium-228 was collected on manganese-coated cartridges filtered at depth using an adapted McLane in situ pump (WTS-LV). The pumps were programmed to filter 1500-2000L of seawater per deployment. The cartridges were rinsed with radium-free fresh water and excess moisture was removed using compressed air. Samples were analyzed multiple times using a delayed coincidence counter (RaDeCC) for determination of radium-228 via thorium-228 ingrowth. At selected stations, samples were ashed in a muffle furnace at 820 degrees Celsius for 24 hours and the fiber ash was transferred to polystyrene vials, sealed with epoxy (to prevent 222Rn loss), and counted on high purity, well-type germanium detectors to measure 228Ra, using the lines of 228Ac (338 keV, 911 keV, and 969 keV).

In addition to the water column samples, large volume surface samples were collected by pumping from a depth of 2 meters through a single Mn-cartridge accompanied by a 15-25-liter sample that was passed through a 15 g Mn-fiber column to retain radium-226.

Data Processing Description

Data Processing:
The data were corrected for decay from the time of sampling. Data is originally calculated in disintegrations per minute per liter (dpm/L) and is converted to milli-Becquerels per kilogram (mBq/kg) using the standard ocean rho = 1.0235 kg/L and 1 dpm = 16.667 mBq.

Quality Flags:
Data were flagged using the SeaDataNet quality flag scheme. Two additional flags, 'B' and 'C' (defined below), were also assigned to this dataset. For more information on SeaDataNet flags, see: https://www.geotraces.org/geotraces-quality-flag-policy/ and https://www.seadatanet.org/Standards/Data-Quality-Control.

Quality flag definitions:
0 = No quality control;
1 = Good value;
2 = Probably good value;
3 = Probably bad value;
4 = Bad value;
5 = Changed value;
6 = Value below detection;
7 = Value in excess;
8 = Interpolated value;
9 = Missing value;
A = Value phenomenon uncertain;
B = Value obtained from Radium/Barium ratio;
C = Value measured through gamma spectroscopy.

BCO-DMO Processing

*Version 1:*
version 1 date: 2020-10-01
- renamed fields to comply with BCO-DMO naming conventions;
- added date/time columns in ISO 8601 format;
- replaced "N/A" with "nd" to indicate "no data".

*Version 2:*
version 2 date: 2021-12-28 (v2)
- - same as version 1, plus made the following corrections to the Event_ID column:
- changed event number for Sample 14731 from 6882 to 6879;
- changed event number for Samples 14883-14890 from 6828 to 6898;
- changed event number for Sample 33 from 6943 to 6942.

*Version 3:*
version 3 date: 2022-09-29
- imported two Excel files, "BCODMO GP15 Charette 226Radium leg2.xlsx" and "BCODMO GP15 Charette 228Radium leg2.xlsx", into the BCO-DMO system;
- joined the two files, using Event_ID and Sample_ID as they key, to create a single dataset;
- renamed the 'Flag' field for Ra228 to follow GEOTRACES naming conventions;
- renamed the Ra-228 fields using the parameter names assigned by the GEOTRACES DOoR portal;
- saved the final file as "825947_v3_gp15_ra226_ra228_leg2.csv"
- note that in the final csv file, missing data are blank/empty.

Data Files

File
825947_v3_gp15_ra226_ra228_leg2.csv (Comma Separated Values (.csv), 29.72 KB) MD5:b20ff80eaa1cf8d7fe68b016218ee0a5 Primary data file for dataset ID 825947, version 3.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1736277

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
RR1815	GP15 GP15 Leg 2 33RR20180918 PMT US GEOTRACES PMT	2018-10-24	R/V Roger Revelle	Gregory A. Cutter (Chief Scientist) Karen L. Casciotti (Co-Chief Scientist) Phoebe J. Lam (Co-Chief Scientist)	data info

Instruments

McLane Large Volume Pumping System WTS-LV

Supplied Name:

Supplied Description:

Radium-228 was collected on manganese-coated cartridges filtered at depth using an adapted McLane in situ pump (WTS-LV).

Instrument Type

Generic Name: McLane Large Volume Pumping System WTS-LV

Acronym: WTS-LV

Generic Description:

The WTS-LV is a Water Transfer System (WTS) Large Volume (LV) pumping instrument designed and manufactured by McLane Research Labs (Falmouth, MA, USA). It is a large-volume, single-event sampler that collects suspended and dissolved particulate samples in situ.

Ambient water is drawn through a modular filter holder onto a 142-millimeter (mm) membrane without passing through the pump. The standard two-tier filter holder provides prefiltering and size fractioning. Collection targets include chlorophyll maximum, particulate trace metals, and phytoplankton. It features different flow rates and filter porosity to support a range of specimen collection. Sampling can be programmed to start at a scheduled time or begin with a countdown delay. It also features a dynamic pump speed algorithm that adjusts flow to protect the sample as material accumulates on the filter. Several pump options range from 0.5 to 30 liters per minute, with a max volume of 2,500 to 36,000 liters depending on the pump and battery pack used. The standard model is depth rated to 5,500 meters, with a deeper 7,000-meter option available. The operating temperature is -4 to 35 degrees Celsius.

The WTS-LV is available in four different configurations: Standard, Upright, Bore Hole, and Dual Filter Sampler. The high-capacity upright WTS-LV model provides three times the battery life of the standard model. The Bore-Hole WTS-LV is designed to fit through a narrow opening such as a 30-centimeter borehole. The dual filter WTS-LV features two vertical intake 142 mm filter holders to allow simultaneous filtering using two different porosities.

Niskin bottle

Supplied Name: 30L Niskin

Supplied Description:

Radium-226 samples were collected from a 30L Niskin mounted directly above McLane large volume in situ pump WTS-LV (>1000 m) or on a CTD Rosette (<1000 m).

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.

Radium Delayed Coincidence Counter

Supplied Name: Radium Delayed Coincidence (RaDeCC) counter

Supplied Description:

Samples were analyzed using Radium Delayed Coincidence (RaDeCC) counters and high-purity, well-type germanium detectors.

Instrument Type

Generic Name: Radium Delayed Coincidence Counter

Acronym: RaDeCC

Generic Description:

The RaDeCC is an alpha scintillation counter that distinguishes decay events of short-lived radium daughter products based on their contrasting half-lives. This system was pioneered by Giffin et al. (1963) and adapted for radium measurements by Moore and Arnold (1996).

References:
Giffin, C., A. Kaufman, W.S. Broecker (1963). Delayed coincidence counter for the assay of actinon and thoron. J. Geophys. Res., 68, pp. 1749-1757.
Moore, W.S., R. Arnold (1996). Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. J. Geophys. Res., 101 (1996), pp. 1321-1329.
Charette, Matthew A.; Dulaiova, Henrieta; Gonneea, Meagan E.; Henderson, Paul B.; Moore, Willard S.; Scholten, Jan C.; Pham, M. K. (2012). GEOTRACES radium isotopes interlaboratory comparison experiment. Limnology and Oceanography - Methods, vol 10, pg 451.

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
Station_ID	GEOTRACES station number	unitless	station
Start_Date_UTC	Sample collection start date Format: %m-%d-%y	unitless	date
Start_Time_UTC	Sample collection start time (UTC) Format: %H:%M	unitless	time
Start_ISO_DateTime_UTC	Sampling start date and time (UTC) in ISO 8601 format Format: %Y-%m-%dT%H:%MZ	unitless	ISO_DateTime_UTC
End_Date_UTC	Sample collection end date Format: %m-%d-%y	unitless	date
End_Time_UTC	Sample collection end time (UTC) Format: %H:%M	unitless	time
End_ISO_DateTime_UTC	Sampling end date and time (UTC) in ISO 8601 format Format: %Y-%m-%dT%H:%MZ	unitless	ISO_DateTime_UTC
Start_Latitude	Sample collection start Latitude; negative values = South	decimal degrees	lat
Start_Longitude	Sample collection start Longitude; negative values = West	decimal degrees	lon
End_Latitude	Sample collection end Latitude; negative values = South	decimal degrees	lat
End_Longitude	Sample collection end Longitude; negative values = West	decimal degrees	lon
Event_ID	GEOTRACES event number	unitless	event
Sample_ID	GEOTRACES sample number	unitless	sample
Sample_Depth	Depth of sample collection	meters (m)	depth
Ra_226_D_CONC_BOTTLE_zkto8n	Dissolved Radium-226 activity	milliBecquerels per kilogram (mBq/kg)	Ra226
SD1_Ra_226_D_CONC_BOTTLE_zkto8n	One standard deviation of Ra_226_D_CONC_BOTTLE_zkto8n	milliBecquerels per kilogram (mBq/kg)	Ra226
Flag_Ra_226_D_CONC_BOTTLE_zkto8n	Quality flag for Ra_226_D_CONC_BOTTLE_zkto8n; refer to 'Data Processing' section of metadata for flag definitions	unitless	q_flag
Ra_228_D_CONC_PUMP_eokmy1	Dissolved Radium-228 activity	milliBecquerels per kilogram (mBq/kg)	Ra228
SD1_Ra_228_D_CONC_PUMP_eokmy1	One standard deviation of Ra_228_D_CONC_PUMP_eokmy1	milliBecquerels per kilogram (mBq/kg)	Ra228
Flag_Ra_228_D_CONC_PUMP_eokmy1	Quality flag for Ra_228_D_CONC_PUMP_eokmy1; refer to 'Data Processing' section of metadata for flag definitions	unitless	q_flag

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Dataset: GP15 Dissolved Radium-226 and Radium-228 Leg 2