STRONTIUM-90 ON THE EARTH’S SURFACE, IU
200 TTT
TTT
<x
365
TTP
—~
180
_—
x
=
160
oO
-~
x
x*
140
=
X *o8
=
°
x
80
o
Of
x
Op x
rn toe
_
x
x
oO
x
—
© 6
60
4
x
x
o
oO
—
x
e
oO
G
.
x
oO
2 100
YQ
s
wo
x xx
°
= 120
*
0?
—
oO
°
x
°
49
°°
x
o
Oo
°o
o
oO
20
°
°
8
0
{ |
90°N 60°N
{|
|
30°N
|
°
090
3
o
l
0°
|
oO
Jo
—
5
dS
|
30°S
_
9
jf
jf
60°S 90°S
LATITUDE
Fig. 6— Latitudinal distribution of 9Sr in soil in 1963 and early 1964.
(Crosses indicate samples collected in the United States.)
related error is believed to be small. There are unresolved differ-
ences between extraction of the *Sr from the soil sample by the HCl
technique and by fusion; this could result in as much as a 10% underestimate of the total deposition. It has also been suggested that fallout
over the oceans might be considerably higher than that over the land,
but a comparison of soils from sites having a maritime exposure with
soils from sites having a continental exposure indicated no systematic
differences either in the total amount deposited or in the amount of
Sr deposited per inch of rainfall.
DEPOSITION IN THE CONTINENTAL UNITED STATES
The greatest density of soil-sampling sites is located in the
‘continental United States and southern Canada, permitting a more detailed study of variability from site to site. The results of the 1963 to
1964 soil survey
are shown in Fig.
7.
As can be seen, the general
pattern of deposition is influenced by the precipitation pattern; for
example, the dry southwestern states have the lowest Sy fallout.
However, there are two obvious exceptions. One is the maximum found
in the vicinity of the Great Salt Lake. The deposition at Salt Lake City,