25.63 + 029 ——~
29.57 + 0.26 ——-~
20.44 + 066 ——.
34.72 + 0.346 ——
24.24 + 0.45 ———-
ul
pyc Sr9YG Ca
0
|
|
MsJASONDIJFMAMJ J ASONODISFMAMIJIJVASOND|Y FMAM J
1955
1956
1957
1958
Fig. 11— Monthly Sr®® levels in Mandan, N. Dak., powdered milk,
1955
1956
1957
Fig. 12— Monthly Sr®° levels in Columbus, Wisc., powdered milk.
a9