904
GUSTAFSON, BRAR, AND MUNIAK
air into that due to various test series as illustrated in Fig. 6. The
contribution of pre-1961 tests has been removed by taking the aver-
ages of the "Cs observed in like months in 1960 and 1961 and subtracting them from the 1962 values. In 1963 the pre-1961 '2’Cs levels
were reduced by 10%, and reduction by another 10% was used for 1964.
co
Lo
rrTTrrrrrr yy rr rrr rr rir pr rrr Tee
SOVIET HIGH ALTITUDE, 1961 -—-— SOVIET LOW ALTITUDE, 1961
--—-—-— SOVIET, 1962
/
107! —
—
“ry
T
=
UO
w
7
~
&
Y
s
f
/
O°
os
i
\
=z
\
\
/
Ay
\.
I
\
i
/
fy
1
7
\
_
7
fo\
\
t
\
\
—
.
_
western U.S., 1962
=f
f
ON
7
\
\
fu
4
=
f
|
Ee
5
Lo
4
=
Lo
1073
_
4
Ll
Lipbhppettpyrtpyptrtriprtttsros)
Jan. — Dec.
Jan. ~ Dec.
Jan.— Dec.
1962
1943
1964
Fig. 6—Partition of 1°’Cs in surface air at Argonne, Ill.
An initial “Mn/'*"Cs activity ratio of 40 to1 was used to obtain the 1961
high-altitude component in 1962-1963, and during 1963-—1964 a ratio
of 20 to 1 was used. The amountof debris from the Operation Dominic I
series was estimated by a comparison with the observations of 1®!w/
87Cs made in air collected during 1958—1960. The Soviet 1963 contri-
bution was derived from the bestfit ofthe ®Zr/!°"Cs ratio curve, which
indicated a mean time of production of Oct. 15, 1962, during the interval
January to July 1963 and of Nov. 15, 1962, during the remainder of
1963 and into 1964. This attempt at partitioning may be somewhatin
error, particularly regarding the high-altitude 1961 component in
1963-1964, as well as the evaluation of Dominic ] debris. During the
spring of 1962, less than 10% of the total "Cs present in surface air
was of pre-1961 origin, and in 1963 and 1964 this source accounted for