Mn-Fibers for ²²⁶Ra and ²²⁸Ra by gamma detection

This method specifies the minimum requirements and laboratory methods for measuring ²²⁶Ra and ²²⁸Ra in seawater samples using gamma-spectrometry via leaching Mn-fiber.

Water samples are collected in acid-cleaned containers and pretreated on board, by passing through a 1 mm cartridge filter followed by a MnO₂-impregnated acrylic fiber (Mn-fiber) column to extract dissolved radium (see Rama and Moore, 1996). Post processing will take place at the home laboratory by leaching the Mn-fiber and co-precipitating radium with BaSO₄. Ra isotopes emissions are finally measured by gamma spectrometry (see Moore, 1984). Isotope ingrowth and decay corrections are applied to calculate ²²⁶Ra and ²²⁸Ra activities.