Dataset: Dissolved Thorium Isotopes PE17-24
Deployment: PE17-24

Dissolved thorium-230 and thorium-232 from the deep Northern Gulf of Mexico

Principal Investigator:

Christopher T. Hayes (University of Southern Mississippi, USM)

BCO-DMO Data Manager:

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

Project:

Collaborative Research: U.S. GEOTRACES Pacific Meridional Transect: Thorium-232, Thorium-230 and Protactinium-231 as tracers of trace element supply and removal (PMT Thorium Isotopes)

Data URL:

https://www.bco-dmo.org/dataset-deployment/819634/data

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Description

Dissolved thorium-230 and thorium-232 from the deep Northern Gulf of Mexico collected on R/V Pelican cruise PE17-24 during June 2017.

Note: These data were collected through auxiliary activities in coordination with the GEOTRACES PMT project funded by NSF OCE-1737023.

Methods & Sampling

Dataset acquisition description

Sampling occurred according the GEOTRACES cookbook recommendations for radionuclides (https://www.geotraces.org/methods-cookbook/). Water was filtered from standard Niskin bottles through a 0.45 micron Acropak capsule filter and teflon line tygon tubing. Water was acidified to 0.024 M HCl using optima acid once the samples were returned to the lab about 2-3 days after collection. Water samples were left to sit acidified for at least 3 months prior to analysis to avoid adsorption loss.

Analysis of the thorium isotopes was by isotope dilution inductively-coupled plasma mass spectrometry as described by Hayes et al. (2017). Briefly, thorium-229 was added to acidified 4-liter water samples and allowed to equilibrate overnight. About 10 mg of Fe from an iron chloride solution was added and pH was raised with optima ammonium hydroxide to 8-9 and iron (oxy)hydroxide precipitate was allowed to settle for 2 days. Overlaying seawater was decanted and the iron precipitate was isolated using a series of centrifugation steps. The precipitate was digested with HNO3, HF and H2O2, then thorium was purified using anion exchange resin AG1-X8. Final solutions were dried down and taken up in 2% HNO3 for analysis on ICP-MS.

Data Processing Description

Dataset Processing Description

Data processing: Thorium-230 and thorium-232 concentrations were determined using measured 232/229 and 230/229 ratios and a gravimetrically-calibrated Th-229 spike. Corrections for mass bias and tail-corrections were estimated using U-238/235 and U-234/235 ratios, respectively, using a uranium standard CRM-112a.

Quality flags: Data were flagged using the SeaDataNet quality flag scheme. For more information on SeaDataNet flags, see: https://www.geotraces.org/geotraces-quality-flag-policy/ and https://www.seadatanet.org/Standards/Data-Quality-Control

SeaDataNet 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.

BCO-DMO Processing:
- modified parameter names;
- added ISO8601 date/time fields;
- rounded Th_230_D_CONC_BOTTLE columns.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1737023	NSF Division of Ocean Sciences

Instruments

Inductively Coupled Plasma Mass Spectrometer

Supplied Name: Inductively-coupled plasma mass spectrometry

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.

Niskin bottle

Supplied Name: Niskin bottles

Supplied Description:

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.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Sample_Depth	Sample depth	meters (m)	depth
Start_ISO_DateTime_UTC	Start date and time (UTC) formatted to ISO8601 standard: YYYY-MM-DDThh:mmZ	unitless	ISO_DateTime_UTC
Start_Latitude	Start latitude	decimal degrees North	lat
Start_Longitude	Start longitude	decimal degrees East	lon
Th_230_D_CONC_BOTTLE_xdopme	Concentration (or activity) of dissolved 230Th	microBecquerels per kilogram (uBq/kg)	trace_metal_conc
Th_232_D_CONC_BOTTLE_bf1qqr	Concentration (or activity) of dissolved 232Th	picomoles per kilogram (pmol/kg)	trace_metal_conc
End_ISO_DateTime_UTC	End date and time (UTC) formatted to ISO8601 standard: YYYY-MM-DDThh:mmZ	unitless	ISO_DateTime_UTC
End_Date_UTC	End date; format: DD/MM/YYYY	unitless	date
End_Latitude	End latitude	decimal degrees North	lat
End_Longitude	End longitude	decimal degrees East	lon
End_Time_UTC	End time (UTC); format: hh:mm	unitless	time
Event_ID	Event identifer	unitless	event
SD1_Th_230_D_CONC_BOTTLE_xdopme	One standard deviation of Th_230_D_CONC_BOTTLE_xdopme	microBecquerels per kilogram (uBq/kg)	trace_metal_conc
SD1_Th_232_D_CONC_BOTTLE_bf1qqr	One standard deviation of Th_232_D_CONC_BOTTLE_bf1qqr	picomoles per kilogram (pmol/kg)	trace_metal_conc
Flag_Th_230_D_CONC_BOTTLE_xdopme	Quality flag for Th_230_D_CONC_BOTTLE_xdopme	unitless	q_flag
Flag_Th_232_D_CONC_BOTTLE_bf1qqr	Quality flag for Th_232_D_CONC_BOTTLE_bf1qqr	unitless	q_flag
Sample_ID	Sample identifier	unitless	sample
Start_Date_UTC	Start date; format: DD/MM/YYYY	unitless	date
Start_Time_UTC	Start time (UTC); format: hh:mm	unitless	time
Station_ID	Station identifier	unitless	station

Database

Contribute Data

Dataset: Dissolved Thorium Isotopes PE17-24
Deployment: PE17-24

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Dissolved Thorium Isotopes PE17-24Deployment: PE17-24

Dataset acquisition description

Dataset Processing Description

Dataset: Dissolved Thorium Isotopes PE17-24
Deployment: PE17-24