.
Bu 1058 ane ee
ow
12
Orisin of ost in PMN milk.
A nw
4%
=
—
4
-
<
AS snown in figure 1, there are ten veriods with I
reaver than 30 oci/1 in the
L321
concentrations
PMN from April 1963 through December 19658.
The
Jonuary through March 1963 is a continuation of the elevated values
Bfu
Cc
Ne
—]
Ne
WS
Ne
Ww
Ne
kK
Pin
Ne
i.
Oo
fu
o
KH
wo
te
ck
ry
@
Oo
a)
re
w
oy cht
in fig. 1) followed six of
the eight atmospheric tests conducted at Lop Nor in weatern China (40°N,
90°Z).
These six nuclear tests were reported to have total yields ranging
from less than 20 kilotons to a few hundred kilotons equivalent TNT (3).
Nuclear explosions near the ground with yields in this range inject radioactivity mainly into the troposphere, the active weather layer of the |
atmosphere (4).
The movements of the leading edges of these six nuclear
cloucs appear in Figures 2 through 7.
The behavior of the clouds from the
:
Mey 1955 and Mey 1966 tests has already been discussed by Machta (5) in
conection
,
With preferential thunderstorm scavenging in the mid-western
United States.
Two other atmospheric nuclear detonations were reported
each having @ total yield of about 3 megatons of equivalent TNT (6).
Fallout
Sy
or all bomb produced radioisotopes from the first megaton test of 17 June 1967
was virtually non-existent.in ground Level air or rainwater for months after
+.
‘This may be due to the fact that an explosion with the yield of
-
the event.
eee
about 3 megatons will inject most of its radioactivity into the stratosphere.
The second megaton test took place on 27 December 1968 so that its fallout,
if axy, would not cccur in the pericd covered by this study.
Tnixrteen atmospheric nuclear tests have been conducted by the Republic
“4
of France in the South Pacific near Muraroa (22°S, 140°W), (7, 8).
Unfortunately, the sparsity of weather deta over the equatorial oceans
eee ee
prevents the construction of reliable meteorological trajectories of the
aa ae
Icdine-13l1 concentrations in excess of 30 pci/1
occurred during period 10 following tests in the South Pacific.
Hot
clouds from these tests.
One milk
sample, 32 pCi/l, in the Canal Zone in the lest week of August 1968
probably cerived its ys from these tests.
was Yound
ther short-lived radioactivity
in air during the same period av stations in South America and
the tropics, which fits a pattern expected of a South Pacific source (9).
.