Dataset: Total Th
Deployment: KM2002

Total Th

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/923028

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)

Project:

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

Version:

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Description

Methods & Sampling

Dataset acquisition description

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

Dataset 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

More information about this dataset deployment

Funding

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

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

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	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

Contribute Data

Dataset: Total Th
Deployment: KM2002

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Total ThDeployment: KM2002

Dataset acquisition description

Dataset Processing Description

Dataset: Total Th
Deployment: KM2002