Dataset: Water column Th-234 activities

Name: Water column Th-234 activities from 4-liter water samples at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) site in the Northeast Atlantic Ocean during RRS Discovery cruise DY077 in April of 2017
Published: 2019-05-02
Keywords: Neutrally-Buoyant Sediment Trap, carbon pumps, biological carbon pump, Porcupine Abyssal Plain, oceans

Cite This Dataset

DOI:10.1575/1912/bco-dmo.765859.1

Spatial Extent: N:48.7487 E:-16.2624 S:48.7487 W:-16.78

Temporal Extent: 2017-04-19 - 2017-04-28

Project:

Collaborative Research: Are all traps created equal? A multi-method assessment of the collection and detection of sinking particles in the ocean (Are Traps Equal)

Principal Investigator:

Kenneth O. Buesseler (Woods Hole Oceanographic Institution, WHOI)

Co-Principal Investigator:

Margaret L. Estapa (Skidmore College)

BCO-DMO Data Manager:

Amber D. York (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2019-05-02

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Water column Th-234 activities from 4-liter water samples at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) site in the Northeast Atlantic Ocean during RRS Discovery cruise DY077 in April of 2017

Abstract:

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2019-05-02	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.1575/1912/bco-dmo.765859.1	2019-06-26

Description

Water column Th-234 activities from water samples at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) site in the Northeast Atlantic Ocean during RRS Discovery cruise DY077 in April of 2017.

Related datasets collected during the same cruise:
In-situ pump: https://www.bco-dmo.org/dataset/765850
Sediment trap fluxes: https://www.bco-dmo.org/dataset/765835

Methods & Sampling

Samples were collected during two deployment cycles (termed “deployment 1” and “deployment 2”) occupied during the RRS Discovery cruise DY077 to the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) Site in April 2017. In each of the cycles, we conducted particle flux sampling method intercomparisons between fluxes derived from upper water column deficits of 234Th vs. its parent isotope 238U, two types of neutrally buoyant sediment traps (NBST and PELAGRA), and a surface tethered array of sediment traps (STT).
234Th profiles were sampled at the beginning and end of each deployment, triangulated 10 km apart around the drifting trap location (Figure 1). A total of 161 234Th samples were collected (Table 1). A 4-L sample was collected from CTD casts, a stable Th yield monitor was added and the pH was adjusted to promote the formation of a Mn precipitate that scavenges Th. This was then filtered onto a 25-mm diameter quartz filter (Buesseler et al., 2009). The quartz filter was dried and mounted, then beta counted on board and again 6 months post-cruise to determine the amount of interfering beta activity and detector background that was not associated with 234Th in the sample.

Porcupine Abyssal Plain Sustained Observatory (PAP-SO) site in the Northeast Atlantic Ocean (49°N, 16.5°W)

Data Processing Description

Integrated 234Th fluxes were calculated as in Buesseler et al. (2009) using a 1-D steady state model.

BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* blank values in this dataset are displayed as "nd" for "no data." nd is the default missing data identifier in the BCO-DMO system.
* added ISO_DateTime_UTC column from date and time columns

Data Files

File
Th234.csv (Comma Separated Values (.csv), 13.53 KB) MD5:cc3391d064df5bdc3442b4cb4c5cd361 Primary data file for dataset ID 765859

Supplemental Files

File
Figure 1. Locations of platforms filename: Fig1.png (Portable Network Graphics (.png), 945.63 KB) MD5:dc3d6d1d9c796de9027e51149381b31b Figure 1. Locations of platforms during deployment 1 (19-21 Apr) and deployment 2 (24-27 Apr).
Table 1. Locations and depth ranges filename: Table1.csv (Comma Separated Values (.csv), 830 bytes) MD5:3f7b594b18cae18c7c300bf9d6f827e0 Locations and depth ranges sampled for 234Th flux determinations.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1659995
NSF Division of Ocean Sciences	OCE-1660012

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
DY077		2017-04-14	RRS Discovery	Dr Richard Lampitt (Chief Scientist) Margaret L. Estapa (Contact)	data info

Instruments

CTD - profiler

Supplied Name: CTD Seabird 911plus

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.

Niskin bottle

Supplied Name:

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.

Riso Laboratory Anti-coincidence Beta Counters

Supplied Name: 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
deployment	deployment cycle during cruise DY077	unitless	deploy
station	station occupied during cruise DY077	unitless	station
cast	CTD cast number	unitless	platform
bottle	rosette bottle number	unitless	bottle
depth	depth of water sample collection	meters (m)	depth
lat	latitude of CTD cast	decimal degrees (DD)	lat
lon	longitude of CTD cast	decimal degrees (DD)	lon
date	date of CTD cast (GMT) in ISO 8601 format yyyy-mm-dd	unitless	date_utc
time	time of CTD cast (GMT) in ISO 8601 format hh:mm:ss	unitless	time_utc
ISO_DateTime_UTC	date time (UTC) in ISO 8601 format yyyy-mm-ddTHH:MMZ	unitless	ISO_DateTime_UTC
U238_tot	total uranium-238 activity calculated from CTD salinity as per Owens et al. 2011	disintegration per minute per liter (dpm/L)	U238
U238_tot_err	total uranium-238 uncertainty, derived from the uncertainty in the relationship in Owens et al. 2011	disintegration per minute per liter (dpm/L)	U238
Th234_tot	total uranium-238 activity determined from 4-liter water samples	disintegration per minute per liter (dpm/L)	Th234
Th234_tot_err	total uranium-238 uncertainty, derived from counting statistics and error propagation for mass/volume measurements and ICP-MS recovery analysis	disintegration per minute per liter (dpm/L)	Th234