http://lod.bco-dmo.org/id/dataset/812511
eng; USA
utf8
dataset
Highest level of data collection, from a common set of sensors or instrumentation, usually within the same research project
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
2020-05-21
ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data
ISO 19115-2:2009(E)
Water column total and particulate Thorium-234 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
2021-05-05
publication
2021-05-05
revision
Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)
2020-11-30
publication
https://doi.org/10.26008/1912/bco-dmo.812511.1
Kenneth O. Buesseler
Woods Hole Oceanographic Institution
principalInvestigator
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
publisher
Cite this dataset as: Buesseler, K. O. (2021) Water column total and particulate Thorium-234 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 2) Version Date 2021-05-05 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.812511.2 [access date]
Water column total and particulate Thorium-234 Dataset Description: Methods and Sampling: <p><strong>Total water-column Thorium-234</strong><br />
234Th was determined by the widely-adopted 4 L method (now reduced to a 2 L method, see Pike et al. 2005). (Buesseler et al., 2001), which has been utilized previously for other GEOTRACES efforts (e.g. Owens et al., 2015). An exact 1 mL aliquot of 230Th (50.03 dpm g⁻¹) was used as the yield monitor and added during initial acidification of the samples. QMAs were used to collect the precipitate from the 2 L process and immediately dried. Once dried, they were mounted onto plastic 25 mm discs, covered with a mylar layer and 2 layers of aluminum foil, and immediately beta counted at sea. The filters were counted again 5 to 6 months later to quantify the background radioactivity due to the beta decay of long-lived natural radionuclides that are also precipitated. The mean value of the at-sea counts (decay-corrected to the time of collection) minus the background value for each filter is reported as the 234Th activity (mBq kg⁻¹). Activities for 234Th are generally reported in dpm L-1, but have been converted here using a standard density of 1.025 kg L⁻¹ and 1 dpm = 16.667 mBq. Data are decay corrected to the mid-point time between when the first and last bottles were fired for shallow casts, when the messenger was dropped for deep casts, and the time of collection for fish tow samples. Generally, shallow water column (&lt; 1000 m) samples were collected from the ODF Rosette and deep samples (&gt;1000 m) were collected from Niskin bottles hung above in-situ pumps. All fish samples (namely intermediate surface and surface samples) were collected directly from the clean fish tow (denoted as either arriving or intermediate fish, depth 3 m). All data have been recovery-corrected using the 230Th /229Th recovery method (see References) to account for any loss of sample material during processing. All samples were analyzed using Risø Laboratory Anti-Coincidence Beta Counters, using a helium/1% butane mixture.</p>
<p>In order to calculate flux, Th-234 disequilibrium from its parent U-238 must be calculated. U-238 can be calculated via the equation described in Owens et al. (2011): U-238 (dpm/L) = (Salinity * 0.0786) – 0.315</p>
<p>Salinity was measured on board the ship by the Scripps Ocean Data Facility (ODF).</p>
<p><strong>Particulate Thorium-234</strong><br />
Particulate material was collected using in situ McLane pumps (16-24 depths per station, see also PMT data from Lam group). All samples were analyzed using Risø Laboratory Anti-coincidence Beta Counters, using a helium/1% butane mixture. All Th-234 are measured 3 times for at least 12 hours or to &lt;5% error. All data were decay corrected back to mid-pumping times.</p>
<p><strong>&gt;51 µm Th-234 (LPT, large particulate Thorium)</strong><br />
Mesh screens were provided by the Lam group. A whole or partial (3/4) mesh screen was rinsed onto a 25 mm silver filter for beta counting. The mean volume pumped through the whole Supor mesh screens was 406 L.</p>
<p><strong>1-51 µm Th-234 (SPT, small particulate Thorium)</strong><br />
Whole QMAs, located below a mesh screen in the filter head housing, were provided by the Lam group and oven-dried upon recovery. A 25 mm subsample was taken from this whole filter for beta counting for Th-234. The mean effective volume for the 25 mm QMA subsample was 41 L (1042 L for entire QMA).</p>
Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-1735445 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=1735445
completed
Kenneth O. Buesseler
Woods Hole Oceanographic Institution
508-289-2309
266 Woods Hole Road MS #25
Woods Hole
MA
02543
USA
kbuesseler@whoi.edu
pointOfContact
asNeeded
Dataset Version: 2
Unknown
Station_ID
Start_Date_UTC
Start_Time_UTC
Start_ISO_DateTime_UTC
End_Date_UTC
End_Time_UTC
End_ISO_DateTime_UTC
Start_Latitude
Start_Longitude
End_Latitude
End_Longitude
Event_ID
Sample_ID
Sample_Depth
Niskin_Bottle
Th_234_SPT_CONC_PUMP_kcfgxs
SD1_Th_234_SPT_CONC_PUMP_kcfgxs
Flag_Th_234_SPT_CONC_PUMP_kcfgxs
Th_234_LPT_CONC_PUMP_ndfccj
SD1_Th_234_LPT_CONC_PUMP_ndfccj
Flag_Th_234_LPT_CONC_PUMP_ndfccj
Th_234_T_CONC_BOTTLE_o9yxf7
SD1_Th_234_T_CONC_BOTTLE_o9yxf7
Flag_Th_234_T_CONC_BOTTLE_o9yxf7
theme
None, User defined
station
date
time of day
ISO_DateTime_UTC
latitude
longitude
event
sample identification
depth
bottle
thorium-234 activity
quality flag
featureType
BCO-DMO Standard Parameters
McLane Pump
Niskin bottle
Riso Laboratory Anti-coincidence Beta Counter
instrument
BCO-DMO Standard Instruments
RR1814
service
Deployment Activity
Seattle, WA to Hilo, HI
place
Locations
otherRestrictions
otherRestrictions
Access Constraints: none. Use Constraints: Please follow guidelines at: http://www.bco-dmo.org/terms-use Distribution liability: Under no circumstances shall BCO-DMO be liable for any direct, incidental, special, consequential, indirect, or punitive damages that result from the use of, or the inability to use, the materials in this data submission. If you are dissatisfied with any materials in this data submission your sole and exclusive remedy is to discontinue use.
U.S. GEOTRACES
http://www.geotraces.org/
U.S. GEOTRACES
GEOTRACES is a SCOR sponsored program; and funding for program infrastructure development is provided by the U.S. National Science Foundation.
GEOTRACES gained momentum following a special symposium, S02: Biogeochemical cycling of trace elements and isotopes in the ocean and applications to constrain contemporary marine processes (GEOSECS II), at a 2003 Goldschmidt meeting convened in Japan. The GEOSECS II acronym referred to the Geochemical Ocean Section Studies To determine full water column distributions of selected trace elements and isotopes, including their concentration, chemical speciation, and physical form, along a sufficient number of sections in each ocean basin to establish the principal relationships between these distributions and with more traditional hydrographic parameters;
* To evaluate the sources, sinks, and internal cycling of these species and thereby characterize more completely the physical, chemical and biological processes regulating their distributions, and the sensitivity of these processes to global change; and
* To understand the processes that control the concentrations of geochemical species used for proxies of the past environment, both in the water column and in the substrates that reflect the water column.
GEOTRACES will be global in scope, consisting of ocean sections complemented by regional process studies. Sections and process studies will combine fieldwork, laboratory experiments and modelling. Beyond realizing the scientific objectives identified above, a natural outcome of this work will be to build a community of marine scientists who understand the processes regulating trace element cycles sufficiently well to exploit this knowledge reliably in future interdisciplinary studies.
Expand "Projects" below for information about and data resulting from individual US GEOTRACES research projects.
U.S. GEOTRACES
largerWorkCitation
program
US GEOTRACES Pacific Meridional Transect (GP15)
http://www.geotraces.org/
US GEOTRACES Pacific Meridional Transect (GP15)
<p>A 60-day research cruise took place in 2018 along a transect form Alaska to Tahiti at 152° W. A description of the project titled "<em>Collaborative Research: Management and implementation of the US GEOTRACES Pacific Meridional Transect</em>", funded by NSF, is below. Further project information is available on the <a href="https://www.geotraces.org/" target="_blank">US GEOTRACES website</a> and on the <a href="https://geotraces-gp15.com/" target="_blank">cruise blog</a>. A detailed <a href="https://datadocs.bco-dmo.org/docs/geotraces/GEOTRACES_PMT/casciotti/data_docs/GP15_Cruise_Report_with_ODF_Report.pdf" target="_blank">cruise report is also available</a> as a PDF.</p>
<p><em>Description from NSF award abstract:</em><br />
GEOTRACES is a global effort in the field of Chemical Oceanography in which the United States plays a major role. The goal of the GEOTRACES program is to understand the distributions of many elements and their isotopes in the ocean. Until quite recently, these elements could not be measured at a global scale. Understanding the distributions of these elements and isotopes will increase the understanding of processes that shape their distributions and also the processes that depend on these elements. For example, many "trace elements" (elements that are present in very low amounts) are also important for life, and their presence or absence can play a vital role in the population of marine ecosystems. This project will launch the next major U.S. GEOTRACES expedition in the Pacific Ocean between Alaska and Tahiti. The award made here would support all of the major infrastructure for this expedition, including the research vessel, the sampling equipment, and some of the core oceanographic measurements. This project will also support the personnel needed to lead the expedition and collect the samples.</p>
<p>This project would support the essential sampling operations and infrastructure for the U.S. GEOTRACES Pacific Meridional Transect along 152° W to support a large variety of individual science projects on trace element and isotope (TEI) biogeochemistry that will follow. Thus, the major objectives of this management proposal are: (1) plan and coordinate a 60 day research cruise in 2018; (2) obtain representative samples for a wide variety of TEIs using a conventional CTD/rosette, GEOTRACES Trace Element Sampling Systems, and in situ pumps; (3) acquire conventional CTD hydrographic data along with discrete samples for salinity, dissolved oxygen, algal pigments, and dissolved nutrients at micro- and nanomolar levels; (4) ensure that proper QA/QC protocols are followed and reported, as well as fulfilling all GEOTRACES intercalibration protocols; (5) prepare and deliver all hydrographic data to the GEOTRACES Data Assembly Centre (via the US BCO-DMO data center); and (6) coordinate all cruise communications between investigators, including preparation of a hydrographic report/publication. This project would also provide baseline measurements of TEIs in the Clarion-Clipperton fracture zone (~7.5°N-17°N, ~155°W-115°W) where large-scale deep sea mining is planned. Environmental impact assessments are underway in partnership with the mining industry, but the effect of mining activities on TEIs in the water column is one that could be uniquely assessed by the GEOTRACES community. In support of efforts to communicate the science to a wide audience the investigators will recruit an early career freelance science journalist with interests in marine science and oceanography to participate on the cruise and do public outreach, photography and/or videography, and social media from the ship, as well as to submit articles about the research to national media. The project would also support several graduate students.</p>
U.S. GEOTRACES PMT
largerWorkCitation
project
Quantifying Upper Ocean Export and Remineralization of Bioactive and Particle Reactive Trace Elements along the US GEOTRACES Tahiti to Alaska Transect
https://osprey.bco-dmo.org/project/811478
Quantifying Upper Ocean Export and Remineralization of Bioactive and Particle Reactive Trace Elements along the US GEOTRACES Tahiti to Alaska Transect
<p><em>NSF Award Abstract:</em><br />
The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. A core approach of GEOTRACES involves coordinated expeditions that measure multiple trace elements and isotopes (TEIs) across key gradients in the ocean, such as changes in productivity, redox/oxygen, boundary scavenging intensity, and hydrothermal activity. However, trace elemental distributions are not enough to meet the GEOTRACES goal to "identify processes and quantify fluxes that control the distribution of TEIs in the ocean and to establish the sensitivity of these changing distributions to environmental conditions." To measure rates of processes requires the use of other measurements, such as naturally occurring radioactive isotopes. This project involves the measurement of two isotopes of the element thorium on a U.S. GEOTRACES expedition in the Pacific Ocean, from Alaska to Tahiti. Thorium has a tendency to become associated with particles in the oceans, and therefore it can be used to measure the sinking of other elements out of the ocean surface. Thorium isotopes with short half-lives can be used to track processes that occur on faster timescales (weeks or seasons), such as those related to biology in the surface waters of the ocean, while isotopes with longer half-lives are useful for studying processes that occur on longer time scales like that of ocean circulation. This project would use measurements of thorium-234 and thorium-228, with half-lives of 24.1 days and 1.9 years, respectively, to estimate sinking rates of thorium and other elements in the upper ocean.</p>
<p>The proposal is broken down into four main activities: 1) Use short-lived Th-234 to estimate particle export and remineralization rates; 2) use ratios of Th-234 to major biogenic phases (e.g., carbon, nitrogen, biogenic silica) and trace elements (e.g. iron, manganese, etc.) to derive flux profiles of other major and trace elements; 3) extend the export and remineralization rates in time/depth using Th-228; 4) examine how changes in #1-3 are related to expected gradients in particle concentration and type, plankton community shifts, net community production, aerosol inputs/dust, physical forcing (e.g. upwelling), hydrothermal plumes, and other features along this GEOTRACES transect. Profiles of total Th-234:U-238 provide quantitative estimates of Th-234 flux vs. depth, which along with parallel size-fractionated particulate profiles of Th-234 and TEIs allow us to empirically calculate the vertical profile of net particle export for any TEI. With high resolution vertical and spatial sampling, the application of Th-234 can be extended below the zone of net removal in the surface ocean to include quantification of particle export and remineralization in the upper several hundred meters. Based upon prior studies, the Th-234 flux model will need to be adjusted for physical transport, especially upwelling across the equator. Selected Th-228 profiles can extend these flux and remineralization estimates even further with depth and over longer time scales. The project will support a Ph.D. student.</p>
PMT Upper Ocean Trace Elements
largerWorkCitation
project
eng; USA
oceans
Seattle, WA to Hilo, HI
-156.96
-152
19.68
56.06
2018-09-24
2018-10-21
From projects that focused on the following 2 locations: 1. Pacific Meridional Transect along 152W (GP15) 2. GEOTRACES Pacific Meridional Transect (Alaska to Tahiti along 151 W)
0
BCO-DMO catalogue of parameters from Water column total and particulate Thorium-234 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
http://lod.bco-dmo.org/id/dataset-parameter/812557.rdf
Name: Station_ID
Units: unitless
Description: <p>GEOTRACES station number.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812558.rdf
Name: Start_Date_UTC
Units: unitless
Description: <p>Event start date (UTC); format: dd/mm/yyyy</p>
http://lod.bco-dmo.org/id/dataset-parameter/812559.rdf
Name: Start_Time_UTC
Units: unitless
Description: <p>Event start time (UTC); format: HH:MM</p>
http://lod.bco-dmo.org/id/dataset-parameter/812560.rdf
Name: Start_ISO_DateTime_UTC
Units: unitless
Description: <p>Event start date and time (UTC) formatted to ISO8601 standard: yyyy-mm-ddTHH:MMZ</p>
http://lod.bco-dmo.org/id/dataset-parameter/812561.rdf
Name: End_Date_UTC
Units: unitless
Description: <p>Event end date UTC). For CTD casts, this is not provided. Format: dd/mm/yyyy</p>
http://lod.bco-dmo.org/id/dataset-parameter/812562.rdf
Name: End_Time_UTC
Units: unitless
Description: <p>Event end time (UTC). For CTD casts, this is not provided. Format: HH:MM</p>
http://lod.bco-dmo.org/id/dataset-parameter/812563.rdf
Name: End_ISO_DateTime_UTC
Units: unitless
Description: <p>Event end date and time (UTC) formatted to ISO8601 standard: yyyy-mm-ddTHH:MMZ</p>
http://lod.bco-dmo.org/id/dataset-parameter/812564.rdf
Name: Start_Latitude
Units: degrees North
Description: <p>Latitude. Negative = South.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812565.rdf
Name: Start_Longitude
Units: degrees East
Description: <p>Longitude. Negative = West.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812566.rdf
Name: End_Latitude
Units: degrees North
Description: <p>Latitude. Negative = South.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812567.rdf
Name: End_Longitude
Units: degrees East
Description: <p>Longitude. Negative = West.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812568.rdf
Name: Event_ID
Units: unitless
Description: <p>GEOTRACES event number.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812569.rdf
Name: Sample_ID
Units: unitless
Description: <p>Unique identifying number for US GEOTRACES samples.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812570.rdf
Name: Sample_Depth
Units: meters (m)
Description: <p>Actual sample depth from CTD rosette readout.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812571.rdf
Name: Niskin_Bottle
Units: None
Description: <p>Niskin bottle number from the CTD rosette for Th-234 total sample collection.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812572.rdf
Name: Th_234_SPT_CONC_PUMP_kcfgxs
Units: mBq/kg
Description: <p>Total Th-234 concentration collected from Niskin bottles on the CTD rosette.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812573.rdf
Name: SD1_Th_234_SPT_CONC_PUMP_kcfgxs
Units: mBq/kg
Description: <p>Th-234 uncertainty. Derived from counting statistics and error propagation for mass/volume measurements and ICP-MS recovery analysis.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812574.rdf
Name: Flag_Th_234_SPT_CONC_PUMP_kcfgxs
Units: unitless
Description: <p>Data were flagged with quality indicators: 1 = Good Value; 2 = Probably Good Value (SeaDataNet flag system).</p>
http://lod.bco-dmo.org/id/dataset-parameter/812575.rdf
Name: Th_234_LPT_CONC_PUMP_ndfccj
Units: mBq/kg
Description: <p>Particulate Thorium-234 from QMA filters. Particle size of 1 to 51 um. Data were decay corrected back to mid-pump times.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812576.rdf
Name: SD1_Th_234_LPT_CONC_PUMP_ndfccj
Units: mBq/kg
Description: <p>Th_234_SPT_CONC_PUMP uncertainty.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812577.rdf
Name: Flag_Th_234_LPT_CONC_PUMP_ndfccj
Units: unitless
Description: <p>Data were flagged with quality indicators: 1 = Good Value; 2 = Probably Good Value (SeaDataNet flag system). Empty fields denote that there were pump or filterhead issues that resulted in a compromised sample or no sample at this depth for either the QMA or screen or both.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812578.rdf
Name: Th_234_T_CONC_BOTTLE_o9yxf7
Units: mBq/kg
Description: <p>Particulate Thorium-234 from mesh screens, filtered onto silver filters. Particle size greater than 51 um. Data were decay corrected back to mid-pump times.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812579.rdf
Name: SD1_Th_234_T_CONC_BOTTLE_o9yxf7
Units: mBq/kg
Description: <p>Th_234_LPT_CONC_PUMP uncertainty.</p>
http://lod.bco-dmo.org/id/dataset-parameter/812580.rdf
Name: Flag_Th_234_T_CONC_BOTTLE_o9yxf7
Units: unitless
Description: <p>Data were flagged with quality indicators: 1 = Good Value; 2 = Probably Good Value (SeaDataNet flag system). Empty fields denote that there were pump or filterhead issues that resulted in a compromised sample or no sample at this depth for either the QMA or screen or both.</p>
GB/NERC/BODC > British Oceanographic Data Centre, Natural Environment Research Council, United Kingdom
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
80673
https://darchive.mblwhoilibrary.org/bitstream/1912/27045/1/dataset-812511_gp15-water-column-total-and-particulate-th-234-leg-1__v2.tsv
download
271950
https://darchive.mblwhoilibrary.org/server/api/core/bitstreams/c2482313-8255-55bc-8ffd-b41759b2dc25/content
download
https://doi.org/10.26008/1912/bco-dmo.812511.1
download
onLine
dataset
<p><strong>Total water-column Thorium-234</strong><br />
234Th was determined by the widely-adopted 4 L method (now reduced to a 2 L method, see Pike et al. 2005). (Buesseler et al., 2001), which has been utilized previously for other GEOTRACES efforts (e.g. Owens et al., 2015). An exact 1 mL aliquot of 230Th (50.03 dpm g⁻¹) was used as the yield monitor and added during initial acidification of the samples. QMAs were used to collect the precipitate from the 2 L process and immediately dried. Once dried, they were mounted onto plastic 25 mm discs, covered with a mylar layer and 2 layers of aluminum foil, and immediately beta counted at sea. The filters were counted again 5 to 6 months later to quantify the background radioactivity due to the beta decay of long-lived natural radionuclides that are also precipitated. The mean value of the at-sea counts (decay-corrected to the time of collection) minus the background value for each filter is reported as the 234Th activity (mBq kg⁻¹). Activities for 234Th are generally reported in dpm L-1, but have been converted here using a standard density of 1.025 kg L⁻¹ and 1 dpm = 16.667 mBq. Data are decay corrected to the mid-point time between when the first and last bottles were fired for shallow casts, when the messenger was dropped for deep casts, and the time of collection for fish tow samples. Generally, shallow water column (&lt; 1000 m) samples were collected from the ODF Rosette and deep samples (&gt;1000 m) were collected from Niskin bottles hung above in-situ pumps. All fish samples (namely intermediate surface and surface samples) were collected directly from the clean fish tow (denoted as either arriving or intermediate fish, depth 3 m). All data have been recovery-corrected using the 230Th /229Th recovery method (see References) to account for any loss of sample material during processing. All samples were analyzed using Risø Laboratory Anti-Coincidence Beta Counters, using a helium/1% butane mixture.</p>
<p>In order to calculate flux, Th-234 disequilibrium from its parent U-238 must be calculated. U-238 can be calculated via the equation described in Owens et al. (2011): U-238 (dpm/L) = (Salinity * 0.0786) – 0.315</p>
<p>Salinity was measured on board the ship by the Scripps Ocean Data Facility (ODF).</p>
<p><strong>Particulate Thorium-234</strong><br />
Particulate material was collected using in situ McLane pumps (16-24 depths per station, see also PMT data from Lam group). All samples were analyzed using Risø Laboratory Anti-coincidence Beta Counters, using a helium/1% butane mixture. All Th-234 are measured 3 times for at least 12 hours or to &lt;5% error. All data were decay corrected back to mid-pumping times.</p>
<p><strong>&gt;51 µm Th-234 (LPT, large particulate Thorium)</strong><br />
Mesh screens were provided by the Lam group. A whole or partial (3/4) mesh screen was rinsed onto a 25 mm silver filter for beta counting. The mean volume pumped through the whole Supor mesh screens was 406 L.</p>
<p><strong>1-51 µm Th-234 (SPT, small particulate Thorium)</strong><br />
Whole QMAs, located below a mesh screen in the filter head housing, were provided by the Lam group and oven-dried upon recovery. A 25 mm subsample was taken from this whole filter for beta counting for Th-234. The mean effective volume for the 25 mm QMA subsample was 41 L (1042 L for entire QMA).</p>
Specified by the Principal Investigator(s)
<p>Data are decay corrected to the mid-point time between when the first and last bottles were fired for shallow casts, when the messenger was dropped for deep casts, and the time of collection for underway (fish tow) samples. Overall method efficiency was determined by minimizing the percent difference between mean 238U and 234Th values for samples from &gt;1000 m to &gt;500 m from the bottom (44.18 %). Stations that were included to determine method efficiency were chosen to not include samples with potential coastal or hydrothermal influences.</p>
<p><strong>Problem Report:</strong> Data were flagged with quality indicators: 1 = Good Value; 2 = Probably Good Value; Data is originally calculated in dpm/L and is converted to mBq/kg using the standard ocean rho = 1.0235 kg/L and 1 dpm = 16.667 mBq. If pumps failed during deployment, the data is either not included or marked with 'nd' for 'no data'.</p>
<p><strong>Quality Flags:</strong> Data flags are according to the SeaDataNet scheme (<a href="https://www.geotraces.org/geotraces-quality-flag-policy/" target="_blank">https://www.geotraces.org/geotraces-quality-flag-policy/</a>).</p>
<p><strong>BCO-DMO Processing:</strong><br />
- renamed fields;<br />
- added ISO8601 date/time fields;<br />
- Version history:<br />
- 2021-05-05 (v2; current) - replaced entire dataset with version 2, which includes corrections to event numbers and quality flags.<br />
- 2020-11-18 (v1) - version 1 processed and&nbsp;published.</p>
Specified by the Principal Investigator(s)
asNeeded
7.x-1.1
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
PI Supplied Instrument Name: Instrument Name: McLane Pump Instrument Short Name:McLane Pump Instrument Description: McLane pumps sample large volumes of seawater at depth. They are attached to a wire and lowered to different depths in the ocean. As the water is pumped through the filter, particles suspended in the ocean are collected on the filters. The pumps are then retrieved and the contents of the filters are analyzed in a lab.
PI Supplied Instrument Name: PI Supplied Instrument Description:Shallow samples for 234Th were taken using the ODF Rosette and deep samples were taken using niskin bottles hung above in-situ pumps. Instrument Name: Niskin bottle Instrument Short Name:Niskin bottle Instrument 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. Community Standard Description: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/
PI Supplied Instrument Name: PI Supplied Instrument Description:Efficiency Calibrations: The detectors are intercalibrated with each other and across the transect using high-energy U standards.
Limits of Detection: Limits of detection are not reported because they are not applicable to the 234Th beta counting method. A 'non-detect' for 234Th or a case where there is no 234Th present (initially or after 6 months of decay) will still result in a measurable amount of background radioactivity due to the beta decay of long-lived natural radionuclides that are also present. These background values are utilized and therefore, they are not reported as non-detections of 234Th. Instrument Name: Riso Laboratory Anti-coincidence Beta Counter Instrument Short Name:Riso Beta Counter Instrument 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%.
Typically used in laboratory analyses. Designed to measure low levels of beta particle emission. The systems work on the principle of anticoincidence.
Cruise: RR1814
RR1814
R/V Roger Revelle
Community Standard Description
International Council for the Exploration of the Sea
R/V Roger Revelle
vessel
RR1814
Gregory A. Cutter
Old Dominion University
https://datadocs.bco-dmo.org/docs/geotraces/GEOTRACES_PMT/casciotti/data_docs/GP15_Cruise_Report_with_ODF_Report.pdf
Report describing RR1814
R/V Roger Revelle
Community Standard Description
International Council for the Exploration of the Sea
R/V Roger Revelle
vessel