Dataset: Total Th

Name: Total Th data from samples collected on 5 cruises at Station ALOHA off Hawaii and Station M off California from 2019 to 2020
Published: 2024-03-20
Keywords: particle export, thorium-234, Carbon flux, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.923028.1

Spatial Extent: N:35.14 E:-123 S:22.65 W:-157.9

Temporal Extent: 2019-04 - 2020-08

Project:

Collaborative Research: Assessing the relative importance of small vs large particles as sources of nutrition to abyssal communities (Abyssal food web)

Principal Investigator:

Jeffrey C. Drazen (University of Hawaii at Manoa, SOEST)

Co-Principal Investigator:

Claudia R. Benitez-Nelson (University of South Carolina)

BCO-DMO Data Manager:

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

Version:

Version Date:

2024-03-20

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Total Th data from samples collected on 5 cruises at Station ALOHA off Hawaii and Station M off California from 2019 to 2020

Abstract:

The abyssal plains of the oceans cover roughly half of the earth's surface, host enormous reservoirs of biodiversity and mineral resources, and play important roles in nutrient regeneration and carbon sequestration. The most important process controlling the structure and function of these ecosystems is the quantity and quality of food (mostly sinking organic particles) that reaches the deep-sea floor. The goals of this research were to evaluate the relative importance of small and large particles that sink to the deep-sea using the naturally occurring short-lived radionuclide, 234Th. Particulate and dissolved samples were collected throughout the water column (12-17 depths) during 5 cruises in the productive waters off of California (Station M, May and October 2019) within the nutrient-poor central Pacific, north of Hawaii (Station ALOHA, July 2019 and January and July 2020). Total water column (2 L) and particulate 234Th activities collected using in situ pumps (53 um, 1 um, and 0.3 um) have been measured in all of the samples collected from the 5 cruises: April 2019, July 2019, October 2019, January 2020, and July 2020. This dataset includes the Total Th measurements. Particulate Th is available in a separate, related dataset.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2024-03-20	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.923028.1	2024-04-02

Methods & Sampling

Total 234-Thorium (Th) sampling and analyses are similar to those described in Buesseler et al. (2020). Briefly, 2 liters (L) of seawater was collected from 5 - 2500 meters (m) depth. Samples were acidified to pH ~1 and a 230Th yield tracer added. After samples were allowed to equilibrate for 6-8 hours, the pH was adjusted to ~8-9, and reagents were added to form a Mn-oxide precipitate that scavenges Th. Samples were allowed to stand for ~8 hours; after which the precipitate was filtered onto a 25-millimeter (mm) quartz microfiber filter (QMA) and dried at 60 degrees Celsius (˚C) before counting on a low level RISO beta counter using a helium/1%butane gas mixture. Samples were recounted after six months to account for any residual background activity stemming from other naturally occurring radionuclides that co-precipitate with the Mn-oxide. 230Th sample recoveries were measured using ICP-MS after acid digestion and spiking with 229Th according to the methods described in Pike et al. (2005) and Umhau et al. (2019) to account for any loss of sample material during processing.

Data Processing Description

All data are decay corrected to the mid-point of sample collection. Calibration was confirmed using deep waters (> 1000 m) with overall efficiencies determined via minimizing the difference between 238U (determined from salinity) and 234Th at depth. U-238 (not reported) was calculated using the equation described in Owens et al. (2011): U-238 (dpm/L) = (Salinity * 0.0786) – 0.315

BCO-DMO Processing

- Imported original file "Total Th Data BCO-DMO.csv" into the BCO-DMO system.
- Converted the "Date" column to YYYY-MM format.
- Renamed fields to comply with BCO-DMO naming conventions.
- Saved the final file as "923028_v1_total_th.csv"

Data Files

File
923028_v1_total_th.csv (Comma Separated Values (.csv), 5.13 KB) MD5:cbd33e3bf6d05f4f14e2019f267b77f8 Primary data file for dataset ID 923028, version 1

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1829519

Deployments

Deployment	Start Date	Platform	Investigator
AT42-10	2019-04-28	R/V Atlantis	Jeffrey C. Drazen (Chief Scientist)	data info
KM1914	2019-07-18	R/V Kilo Moana	Jeffrey C. Drazen (Chief Scientist)	data info
KM2002	2020-01-17	R/V Kilo Moana	Jeffrey C. Drazen (Chief Scientist)	data info
KM2008	2020-07-24	R/V Kilo Moana	Jeffrey C. Drazen (Chief Scientist)	data info
Pulse 72	2019-10-16	R/V Western Flyer	Kenneth Smith (Chief Scientist)	data info

Instruments

CTD - profiler

Supplied Name: Standard CTD Rosette

Supplied Description:

Instrument Type

Generic Name: CTD - profiler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/130/

Generic Description:

The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.

This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934.

Inductively Coupled Plasma Mass Spectrometer

Supplied Name: ICP-MS

Supplied Description:

Instrument Type

Generic Name: Inductively Coupled Plasma Mass Spectrometer

Acronym: ICP Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB15/

Generic Description:

An ICP Mass Spec is an instrument that passes nebulized samples into an inductively-coupled gas plasma (8-10000 K) where they are atomized and ionized. Ions of specific mass-to-charge ratios are quantified in a quadrupole mass spectrometer.

McLane Large Volume Pumping System WTS-LV

Supplied Name: McLane WTS-LV Pump

Supplied Description:

McLane WTS-LV Pump fitted with three stage mini-MLVFS filter holders and bubbler to remove air pockets

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.

Riso Laboratory Anti-coincidence Beta Counters

Supplied Name: low level RISO Beta Counter

Supplied Description:

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%.

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise_ID	Station ID number	unitless	cruise_id
Station	Station M or ALOHA	unitless	station
lat	Station latitude, south is negative	decimal degrees	lat
lon	Station longitude, west is negative	decimal degrees	lon
Date	Year and month Format: %Y-%m	unitless	date
Depth	Depth in water column	meters (m)	depth
Th234	Total 234Th	disintegrations per minute per liter (dpm/L)	Th234
Th234_err	+/- error based on counting statistics and efficiency correction	disintegrations per minute per liter (dpm/L)	Th234

Database

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Dataset: Total Th