Dataset: Radium isotope measurements from bottom waters in the South Atlantic Bight from 2015-2020 (SAB BMA project)

Final no updates expectedDOI: 10.26008/1912/bco-dmo.882140.1Version 1 (2022-10-24)Dataset Type:Cruise Results

Principal Investigator: James L. Pinckney (University of South Carolina at Columbia)

Scientist, Contact: Willard S. Moore (University of South Carolina at Columbia)

BCO-DMO Data Manager: Sawyer Newman (Woods Hole Oceanographic Institution)


Project: Groundwater sources of "new" N for benthic microalgal production in the South Atlantic bight (SAB BMA)


Abstract

These are measurements of radium isotopes collected from bottom waters in the South Atlantic Bight during 2015-2020. These data were used to verify an episode of submarine groundwater discharge that occurred in August 2019.

Methods & Sampling

Bottom water samples were obtained by lowering a submersible pump to near the seafloor and filling two 26-liter carboys. Subsamples for salinity were usually taken from each sample and measured with a YSI conductivity meter to confirm the CTD measurement. Radium samples were filtered through a column of Mn-fiber to quantitatively remove Ra [Moore, 1976]. The Mn-fiber was returned to the lab, where short-lived radium isotopes (223Ra, half-life = 11.4 days, and 224Ra, half-life = 3.66 days) were measured using a delayed-coincidence counting system [Moore and Arnold, 1996]. After the short-lived measurements were complete, Ra and Mn were stripped from the Mn-fiber and radium was coprecipitated with BaSO4 and transferred to a small tube. 226Ra and 228Ra were measured by gamma spectrometry after 222Rn had equilibrated with 226Ra [Moore et al., 1985]. The RaDeCC systems were calibrated for 224Ra with a NIST standard solution of 232Th adsorbed to Mn-fiber and for 223Ra by the technique of Moore and Cai [2013]. The gamma detector was calibrated with NIST standard solutions for 226Ra and 228Ra in a BaSO4 matrix [Moore, 1984].

Samples were taken from R/V Trinity, owned by a private charter company called Charleston SCUBA. This company is no longer in operation. 


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Related Publications

Results

George, C., Moore, W. S., White, S. M., Smoak, E., Joye, S. B., Leier, A., & Wilson, A. M. (2020). A New Mechanism for Submarine Groundwater Discharge From Continental Shelves. Water Resources Research, 56(11). Portico. https://doi.org/10.1029/2019wr026866
Results

Moore, W. S., Vincent, J., Pickney, J. L., & Wilson, A. M. (2022). Predicted Episode of Submarine Groundwater Discharge Onto the South Carolina, USA, Continental Shelf and Its Effect on Dissolved Oxygen. Geophysical Research Letters, 49(24). Portico. https://doi.org/10.1029/2022gl100438
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. (1984). Radium isotope measurements using germanium detectors. Nuclear Instruments and Methods in Physics Research, 223(2-3), 407–411. doi:10.1016/0167-5087(84)90683-5
Methods

Moore, W. S. (2008). Fifteen years experience in measuring 224Ra and 223Ra by delayed-coincidence counting. Marine Chemistry, 109(3-4), 188–197. doi:10.1016/j.marchem.2007.06.015