title: Measurement of 224Ra and 225Ra activities in natural waters using a radon-in-air monitor.
abstract: We report a simple new technique for measuring low-level radium isotopes (224Ra and 226Ra) in natural waters. The radium present in natural waters is first preconcentrated onto MnO2-coated acrylic fiber (Mn fiber) in a column mode. The radon produced from the adsorbed radium is then circulated through a closed air-loop connected to a commercial radon-in-air monitor. The monitor counts alpha decays of radon daughters (polonium isotopes) which are electrostatically collected onto a silicon semiconductor detector. Count data are collected in energy-specific windows, which eliminate interference and maintain very low backgrounds. Radium-224 is measured immediately after sampling via 220Rn (216Po), and 226Ra is measured via 222Rn 218Po) after a few days of ingrowth of 222Rn. This technique is rapid, simple, and accurate for measurements of low-level 224Ra and 226Ra activities without requiring any wet chemistry. Rapid measurements of short-lived 222Rn and 224Ra, along with long-lived 226Ra, may thus be made in natural waters using a single portable system for environmental monitoring of radioactivity as well as tracing of various geochemical and geophysical processes. The technique could be especially useful for the on-site rapid determination of 224Ra which has recently been found to occur at elevated activities in some groundwater wells.
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Korea.
authors.forename: G
authors.initials: G
authors.lastname: Kim
authors.forename: W C
authors.initials: WC
authors.lastname: Burnett
authors.forename: H
authors.initials: H
authors.lastname: Dulaiova
authors.forename: P W
authors.initials: PW
authors.lastname: Swarzenski
authors.forename: W S
authors.initials: WS
authors.lastname: Moore
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D011883:Radium / Q000032:analysis*; D012680:Sensitivity and Specificity; D013910:Thorium; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D014881:Water Supply
chemical_list: D014875:Water Pollutants, Radioactive; C026062:thorium X; D013910:Thorium; D011883:Radium