Comparison of measurement methods for radium‐226 on manganese‐fiber

Abstract

Acrylic fibers impregnated with MnO 2 (Mn-fiber) have become a valuable tool for concentrating dissolved radium for oceanographic applications. With four naturally-occurring radium isotopes ( Rn. We present a proven, air-tight cartridge design that allows one to use these measurement techniques. We then review the procedures for three radon-based nondestructive measurement techniques for 226 Ra on Mn-fiber (via RAD7, RaDeCC, and Rn emanation line systems) and perform an intercomparison among them, using the standard technique of γ-spectrometry as a reference. We find that all methods statistically agree in terms of measured activity. The Rn emanation line and the RaDeCC systems (both based on Lucas cell counting) provide the lowest measurement uncertainties and minimum detectable activities (MDAs) for a given counting time. The RAD7 technique, on the other hand, offers the advantage of being an automated system, thus requiring minimal user interaction. The standard γ-spectrometry technique, while more time-consuming and sample destructive, has the advantage of providing a simultaneous measurement for 228 Ra.

Evaluation of groundwater discharge into small lakes based on the temporal distribution of radon‐222

“…To assess the 226 Ra content in lake waters, we collected 63-liter samples (three 21-liter 'cubitaners') from different parts of the lakes and extracted the radium isotopes onto Mn-impregnated acrylic fiber. Radium is later evaluated in the laboratory by a radon emanation technique (Peterson et al 2009). The diffusive flux of 222 Rn through the sediment-water interface was calculated using a depth-independent relationship described in Martens et al (1980).…”

The <sup>226</sup>Ra-Ba relationship in the North Atlantic during GEOTRACES-GA01

“…The copper trap was heated to allow the 222 Rn to be transferred to an evacuated "Lucas cells" via a stream of He. The "Lucas cells" are airtight chambers with inner walls coated with silver-activated zinc sulfide that emits photons when struck 25 by alpha decay particles (Key et al, 1979 ;Lucas, 1957 ;Peterson et al, 2009). The cells were held 3 hours to reach the secular equilibrium of all 222 Rn decay chain daughters.…”

“…The Mn Fiber samples were placed into gas-tight PVC cartridges (Peterson et al, 2009) that were flushed with helium (He) for 20 5 min at 250 mL min -1 . The cartridges were sealed and held for approximately 2 weeks (minimum of 5 days) to allow for 222 Rn ingrowth from 226 Ra decay.…”

Quantification of Groundwater-Derived Nutrients Into Beach Ridge Drainage Using Radon Mass Balance Model

“…The measurement of Rn radium followed method as described in [16,27]. In general, the radium samples were first preconcentrated by passing the water samples through the manganese oxide impregnated fiber inside a PVC cartridge (Figure 3).…”