Radium isotope (223Ra, 224Ra, and 226Ra) measurements from CTD and underway water samples collected on R/V Endeavor cruise EN640 from June-July 2019 (NCEI Accession 0278365)

This dataset contains physical data collected on R/V Endeavor during cruise EN640 in the Caribbean Sea and North Atlantic Ocean from 2019-06-14 to 2019-07-08. These data include depth and salinity calculated from CTD primary sensors. The instruments used to collect these data include Niskin bottle, Pump - Surface Underway Ship Intake, Radium Delayed Coincidence Counter, and Sea-Bird SeaCAT Thermosalinograph SBE 21. These data were collected by Richard N. Peterson of Coastal Carolina University, Joseph Montoya of Georgia Institute of Technology, and Ajit Subramaniam of Lamont-Doherty Earth Observatory as part of the "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)" project. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2021-09-07.

The following is the text of the dataset description provided by BCO-DMO:

EN640 Radium

Dataset Description:
Acquisition Description:
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 Thermosalinograph. 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.