RELATIVE Sr CONCENTRATIONS IN SURFACE AIR 619 higher latitudes. This makes it difficult to delineate arrival time as a function of latitude. The peaks seem to occur in the months of April, May, and June, as in previous years, with no particular trend along the meridian, The high Sr concentrations in air for 1963 are in agreement with the high levels of “Sr deposition,” but it is interesting to note that the peak in fallout deposition in the northern hemisphere seemsto have occurred a month or two later than the peak observed in the groundlevel air.? Figure 3 is a copy of NRL’s Sr concentration graph for the 80th meridian sites in the southern hemisphere with HASL’s 1963 data added. As in the north, the Sr air concentrations were generally higher than in previous years; however, they were not as sharply defined as those in the northern hemisphere. No generalized seasonal peak is shown in 107? 1 GUAYAQUIL 3 or '0 -4 tw LIMA 95- ACTIVITY, PC/SCM OF AIR 4 nA| | | | | i 1073 { 1074 PUERTO MONTT ormaPo 4 + | ad)Ae" one + | ongPp 1 | PUNTA ARENAS Pop, 1957 1958 Qo. + Cono---04 | 1073 1074 ot Nmappoeees SANTIAGO 1073 A,ol 4 | woes L 10-4 os " + + | ANTOFAGASTA | pomp + CHACALTAYA 1o73 F 1074 | | a 10" 3 1074 Pp | spe oe eee et T + | 4 | ~~ 4 . 1959 1960 1961 1962 1963 Fig. 3—Concentrations of 9Sr in the air at selected sites in the southern hemisphere along the 80th meridian (west). 1957-1962, NRL data; 1963, HASL data.

Select target paragraph3