MEASUREMENTS OF AIRBORNE RADIONUCLIDES 215 (7 RAINOUT 7 fe J 70 : Zz ps o 6 : 5 2 ” 4 ok - a _ = 4 By 2 ee nn Fe al Yoomy Fk — NPNE FE | 20 10 7 | Mn 8C5 By i — yo LU # ee a 2NIa ra m7 bE 2 an 30 fe Ee sd 40 4 & 4 a o Ss 4 80 z 7 oz 90 = — PSSA} DRY FALLOUT 100 EE a Ni 7h IR, RADIONUCLIDE oN i B 7 : : WAch, nN We, Mee Fig, 13—Percent of radionuclide found in solution in fallout trays. rather short period of time and was then filtered, whereas the dry fallout was collected over a period of several days in the water-filled trays prior to filtration. The rather high solubilities of these radio- nuclides facilitate studies of their oxidation states. Measurements designed to determine the radionuclide oxidation states and other chemical properties are presently being conducted. PHYSICAL AND CHEMICAL CHARACTERISTICS OF 434) IN FALLOUT During the nuclear test series of 1962, measurements were made to determine both the physical and the chemical form of ‘J in fallout.’ The physical form of ''I whether gaseous or particulate was deter- mined by filtering air through a filter of 5 pore size for particle removal and then passing it through an activated charcoal trap for removal of gaseous !*4], The fraction of 81 associated with particulate