Measurements of the two relatively long-lived radium (Ra) isotopes have been widely applied in oceanography. In coastal and open ocean settings, 226Ra and 228Ra are used to provide important information on processes such as diffusion, horizontal and vertical mixing, water-mass and particulate residence time etc.
The isotopic measurement of Ra has traditionally relied on decay counting techniques with large volume seawater samples. Comparing to the decay counting techniques, the use of Nu Plasma instrument for 226Ra analysis has a few advantages: it reduces the sample size requirement, the measurement time is shorter with improved precision, thanks to the higher instrument sensitivity, fast analysis speed and superior analytical performance of the full size discrete dynode multipliers. The Nu Plasma instrument will allow studies of 228Ra in the ocean interior where concentrations are low, and extend the application range of this isotope to understand mixing and trace element fluxes in the oceans.
In this study, 228Ra/226Ra with external reproducibility of 2% (2SD) have been achieved on Nu Plasma HR instrument on Geotraces seawater samples.
Data source: Hsieh and Henderson, J. Anal. At. Spectrom., 2011, 26, 1338