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.
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