Radium isotope (223Ra, 224Ra, and 226Ra) measurements from CTD and underway water samples collected on R/V Endeavor cruise EN640 from June-July 2019

Website: https://www.bco-dmo.org/dataset/846802
Data Type: Cruise Results
Version: 1
Version Date: 2021-03-24

Project
» Collaborative Research: Impact of the Amazon River Plume on Nitrogen Availability and Planktonic Food Web Dynamics in the Western Tropical North Atlantic (Amazon River Plume Nitrogen)
ContributorsAffiliationRole
Peterson, Richard N.Coastal Carolina UniversityPrincipal Investigator, Contact
Montoya, JosephGeorgia Institute of Technology (GA Tech)Co-Principal Investigator
Subramaniam, AjitLamont-Doherty Earth Observatory (LDEO)Co-Principal Investigator
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
This dataset includes radium isotope (223Ra, 224Ra, and 226Ra) measurements from CTD and underway water samples collected on R/V Endeavor cruise EN640 from June-July 2019.


Coverage

Spatial Extent: N:16.0182 E:-50.3937 S:4.87673 W:-60.0198
Temporal Extent: 2019-06-14 - 2019-07-08

Methods & Sampling

Water samples for radium isotope analysis were collected from both the ship's clean underway intake system ('U' designator in data) and niskin bottles attached to the CTD rosette ('C' designator in data). Salinity data were derived from the ship's clean underway intake system with SBE 21 SEACAT Thermosaliograph. Water samples were filtered through 47 mm GFF filters (unless otherwise noted), then passed slowly through 25 g (dry) acrylic fibers impregnated with MnO2 (Moore, 1976). Fibers were then washed 10x with Ra-free freshwater to remove salts and dried to a mass between 35 and 57 g for optimal humidity levels (Sun and Torgersen, 1998). Fibers were then immediately counted on a Radium Delayed Coincidence Counter (RaDeCC; Moore and Arnold, 1996) for total Ra-224 and Ra-223. Roughly 3 weeks later, fibers were counted again for supported Ra-224. Thus, excess ('XS') Ra-224 is the difference between total and supported Ra-224 measurements. Ra-226 activities were then measured on a radon emanation line as per Peterson et al. (2009).

Minimum detectable activities (dpm/100L) are calculated based on Currie (1968). Any measured values lower than the minimum detectable activity is labeled 'BD' in the dataset.


Data Processing Description

Data processing was performed in Microsoft Excel (2016).

BCO-DMO Processing:
- modified field names to conform with BCO-DMO naming conventions;
- converted date/time field to ISO8601 format.


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Data Files

File
radium_2019.csv
(Comma Separated Values (.csv), 49.47 KB)
MD5:162ad4efd40481941181b0b71be3b3d7
Primary data file for dataset ID 846802

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Related Publications

Currie, L. A. (1968). Limits for qualitative detection and quantitative determination. Application to radiochemistry. Analytical Chemistry, 40(3), 586–593. doi:10.1021/ac60259a007
Methods
Moore, W. S. (1976). Sampling 228Ra in the deep ocean. Deep Sea Research and Oceanographic Abstracts, 23(7), 647–651. doi:10.1016/0011-7471(76)90007-3
Methods
Moore, W. S., & Arnold, R. (1996). Measurement of 223Ra and224Ra in coastal waters using a delayed coincidence counter. Journal of Geophysical Research: Oceans, 101(C1), 1321–1329. doi:10.1029/95jc03139 https://doi.org/10.1029/95JC03139
Methods
Peterson, R. N., Burnett, W. C., Dimova, N., & Santos, I. R. (2009). Comparison of measurement methods for radium-226 on manganese-fiber. Limnology and Oceanography: Methods, 7(2), 196–205. doi:10.4319/lom.2009.7.196
Methods
Sun, Y., & Torgersen, T. (1998). The effects of water content and Mn-fiber surface conditions on measurement by emanation. Marine Chemistry, 62(3-4), 299–306. doi:10.1016/s0304-4203(98)00019-x https://doi.org/10.1016/S0304-4203(98)00019-X
Methods

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Parameters

ParameterDescriptionUnits
U_or_C

Underway (surface) or CTD sample designator

unitless
Station

Station number

unitless
Cast

Cast number at each station

unitless
Date_Local

Local date (EST) sample collected

mm/dd/yy
Time_Local

Local time (EST) sample collected

0:00
ISO_DateTime_UTC

Date and time (GMT/UTC) sample collected formatted to ISO8601 standard

YYYY-MM-DDThh:mmZ
Latitude

Sampling latitude

decimal degrees North
Longitude

Sampling longitude

decimal degrees East
Depth

Water depth of sample collection

meters (m)
Salinity

Salinity of ship’s seawater intake system

unitless
Sample_Volume

Water sample volume

liters (L)
Ra223_Activity

Radium-223 activity

dpm/100L
Ra223_Unc

1-sigma analytical uncertainty for Ra223

dpm/100L
XS_Ra224_Activity

Excess radium-224 activity

dpm/100L
XS_Ra224_Unc

1-sigma analytical uncertainty for Ra224

dpm/100L
Ra226_Activity

Radium-226 activity

dpm/100L
Ra226_Unc

1-sigma analytical uncertainty for Ra226

dpm/100L


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Instruments

Dataset-specific Instrument Name
niskin bottles
Generic Instrument Name
Niskin bottle
Generic 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.

Dataset-specific Instrument Name
ship's clean underway
Generic Instrument Name
Pump - Surface Underway Ship Intake
Generic Instrument Description
The 'Pump-underway ship intake' system indicates that samples are from the ship's clean water intake pump. This is essentially a surface water sample from a source of uncontaminated near-surface (commonly 3 to 7 m) seawater that can be pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the underway supply that may also be referred to as the non-toxic supply. Ideally the data contributor has specified the depth in the ship's hull at which the pump is mounted.

Dataset-specific Instrument Name
Radium Delayed Coincidence Counter
Generic Instrument Name
Radium Delayed Coincidence Counter
Dataset-specific Description
Radium isotopes (224Ra and 223Ra) were analyzed with a Radium Delayed Coincidence Counter (Moore and Arnold, 1996). This system was calibrated to standard MnO2 prepared from NIST-traceable solutions of Th-232 and Ac-227 (with daughters in equilibrium).
Generic Instrument Description
The RaDeCC is an alpha scintillation counter that distinguishes decay events of short-lived radium daughter products based on their contrasting half-lives. This system was pioneered by Giffin et al. (1963) and adapted for radium measurements by Moore and Arnold (1996). References: Giffin, C., A. Kaufman, W.S. Broecker (1963). Delayed coincidence counter for the assay of actinon and thoron. J. Geophys. Res., 68, pp. 1749-1757. Moore, W.S., R. Arnold (1996). Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. J. Geophys. Res., 101 (1996), pp. 1321-1329. Charette, Matthew A.; Dulaiova, Henrieta; Gonneea, Meagan E.; Henderson, Paul B.; Moore, Willard S.; Scholten, Jan C.; Pham, M. K. (2012). GEOTRACES radium isotopes interlaboratory comparison experiment. Limnology and Oceanography - Methods, vol 10, pg 451.

Dataset-specific Instrument Name
SBE 21 SEACAT Thermosaliograph
Generic Instrument Name
Sea-Bird SeaCAT Thermosalinograph SBE 21
Generic Instrument Description
A platinum-electrode conductivity sensor and a thermistor mounted in a corrosion-resistant plastic and titanium housing designed to be continuously plumbed into a vessel's pumped seawater supply. The instrument may be interfaced to a remote SBE 38 temperature sensor mounted either on the hull or in the seawater inlet. Data are both stored in internal memory and output to a serial port for external logging.  Conductivity is measured in the range 0-7 S/m with an accuracy of 0.001 S/m and a resolution  of 0.0001 S/m. Housing temperature is measured in the range -5-35C with an accuracy of 0.01 C and a resolution  of 0.001 C. Remote temperature is measured in the range -5-35C  with an accuracy of 0.001 C and a resolution  of 0.0003 C. More information at http://www.seabird.com/products/spec_sheets/21data.htm.


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Deployments

EN640

Website
Platform
R/V Endeavor
Start Date
2019-06-13
End Date
2019-07-08
Description
See more information from the Rolling Deck to Repository (R2R): https://www.rvdata.us/search/cruise/EN640


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Project Information

Collaborative Research: Impact of the Amazon River Plume on Nitrogen Availability and Planktonic Food Web Dynamics in the Western Tropical North Atlantic (Amazon River Plume Nitrogen)

Coverage: Amazon River plume


NSF Award Abstract:
This is a focused program of field research in waters of the Western Tropical North Atlantic influenced by the Amazon River Plume during the high river flow season. The Amazon Plume region supports diverse plankton communities in a dynamic system driven by nutrients supplied by transport from the river proper as well as nutrients entrained from offshore waters by physical mixing and upwelling. This creates strong interactions among physical, chemical, and biological processes across a range of spatial and temporal scales. The field program will link direct measurements of environmental properties with focused experimental studies of nutrient supply and nutrient limitation of phytoplankton, as well as the transfer of phytoplankton nitrogen to the zooplankton food web. The Amazon Plume exhibits a close juxtaposition of distinct communities during the high-flow season, making it an ideal site for evaluating how nutrient availability, nutrient supply, and habitat longevity interact to drive offshore ecosystem dynamics and function. This project will include German collaborators and will seamlessly integrate education and research efforts. The investigators and their institutions have a strong commitment to undergraduate and graduate education and to increasing the diversity of the ocean science community through active recruiting and training efforts. The team has a strong track record of involving both undergraduate and graduate students in their field and lab research. The two research cruises planned will provide opportunities for students and technicians to interact with an interdisciplinary and international research team.

The ultimate objectives of this project are to understand the processes and interactions that promote distinct communities of nitrogen-fixing organisms (diazotrophs) and other phytoplankton around the Amazon Plume and to explore the impacts of these diazotroph-rich communities on zooplankton biomass and production. The research team includes scientists with expertise in nutrient and stable isotope biogeochemistry, remote sensing as well as specialists in characterizing water mass origin and history using naturally occurring radium isotopes. This combination of approaches will provide a unique opportunity to address fundamental questions related to plankton community structure, primary production, and links to secondary production in pelagic ecosystems. The project will address the following key questions focused on fundamental issues in plankton ecology resulting from previous research in this region:

A. What mechanisms promote the preferential delivery of bioavailable phosphorus and the resulting strong nitrogen limitation associated with the northern reaches of the Amazon Plume during the high flow season?

B. What factors lead to the clear niche separation between diazotrophs within and around the Amazon Plume and how are the distinct diazotroph communities influenced by hydrographic and biogeochemical controls associated with the Amazon River Plume and offshore upwelling processes?

C. How does the nitrogen fixed by the different types of diazotrophs contribute to secondary production, and how efficiently does diazotroph nitrogen move through the food web?



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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