Short-Lived Radium-Isotope (Radium-223 and -224) Specific Activity for Samples Collected Between November 2022 and March 2024 Along the West Florida Shelf (Indian Rocks Beach, Nature Coast, and Venice Headland)

In 2021, a collaborative scientific investigation (National Science Foundation Grant Award OCE-2148989, Project 880516) was stated for the purpose of quantifying shelf inventories and boundary fluxes of dissolved organic nitrogen and dissolved iron to the West Florida Shelf (WFS) to assess their role in supporting the oligotrophic WFS ecosystem. To assess the spatial and temporal variability in submarine groundwater as a boundary source to the shelf, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center designed a marine well network (three transects of wells across different coastal regions) and conducted five sampling events over a 16-month period. For each trip, samples were collected from shallow (less than 10 meters water depth), offshore groundwater wells and coincidental surface water stations. Samples were collected from the different water types for the determination of naturally occurring, short-lived isotopes of radium (Ra): Ra-223 (half-life, t1/2 = 11.4 days) and Ra-224 (t1/2 = 3.63 days). Identifiers for the transects and subsequent samples are two to three letter acronyms based on coastal communities or geographic features: Nature Coast near Hudson (FL); Indian Rocks Beach near Indian Rocks Beach (FL), and Venice Headland near Venice (FL). Radium-223 and Radium-224 were absorbed onto manganese (di)oxide impregnated fibers (referred to as Mn-fibers from hereon) following exposure to seawater and the fiber was retained as the sample. Radium-223 and Radium-224 activity determined from the Mn-fibers were measured on a set of Radium Delayed Coincidence Counters (RaDeCC) as outlined in Moore and Arnold (1996). Data included in this data release correspond to USGS Field Activity Number 2022-340-FA, with associated events spanning over one year (November 2022 to March 2024) and are distinguished by alternative FANs (altFANs) of 22WFS05, 23WFS01, 23WFS02, 23WFS03, 23WFS04, 24WFS01. Samples were acquired in November 2022, January-February 2023, May-June 2023, September 2023, December 2023, and February-March 2024, respectively.

Moore, W.S., and Arnold, R., 1996, Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter: Journal of Geophysical Research, v. 101, no. C1, p. 1321-1329, https://doi.org/10.1029/95JC03139.