RELATIVE Sr CONCENTRATIONS IN SURFACE AIR MONTHLY CONCENTRATIONS OF Sr/ AVERAGE ANNUAL CONCENTRATIONS OF ™Sr SEPTEMBER AND OCTOBER eT oL_p ot MARCH AND APRIL 2b ib ol {1 | _ No _ poy Lo 2e Te 0 60°N | ~UCUdLE LL | l 40°N | | 20°N | | 0 i 20°S | | 40°S — | 60°S LATITUDE Fig. 7—Relative 9Sr concentrations in tropospheric air along the 80th meridian (1962 and 1963 averages). The shaded areas represent excess concentrations. 625

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