RADIOACTIVITY ALONG THE 80TH MERIDIAN . GUAYAQUIL 10% Poof —_— | LIMA ! , _— + 5; ACTIVITY, PC/SCM OF AIR 3 3 3 ° 4 \ L 4 I T : oe py SANTIAGO M/ 1073 - . a {oNtot Magee PUERTO MONTH -.—_ —-+ 10 | CHACALTAYA 1072 | 10-4 SS — . 1 104 + Cal + 107+ + { jo 0 + 1072| 487 PUNTA ARENAS 10-3 - , 1957 1958 | 17 | oe r PN | | 1959 | 1960 1961 1962 Fig. 6——Concentrations of ?Sr in the air at selected sites in the southern hemis phere. SOURCES OF AIRBORNE RADIOACTIVITY DURING 1962 The radiochemical analyses of bimonthly composited samples of airborne fission products collected during 1962 have permitted a reasonable identification of the source of the debris in the ground-level air at various sites along the 80th meridian, Therelative amounts of *8sr, *y, “4ce, and “Sr have been employed to determine both an av- erage shot date and the percentage contribution of the youngest component in the mixture, as described elsewhere.’? Assumptions were made that all fresh debris in the northern hemisphere originated from U.S.S.R. tests of 1961—1962 and that all in the southern hemisphere

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