Table II.
Isotope
The Naturally Occurring Radioisotopes in Sea Water
Total activity
Per cent
Radioactivity
in ocean in
of total
in sea water
megacuries!
activity
97.1
(MP C)y,4)
d/m/1
uc/ec??
pc/ee
736
3x1077
*
K40
460, 000
Rb 87
8, 400
1.77
13
6xi079
1073
238
3, 800
80
6
3xi07°9
2x1074
Ra226
1, 100
23
2
1079
1077
5x107!0
ci4
270
057
1
235
110
023
I
12
003
1
"
03
8
002
i
"
2xi075
H3
Th*32
Total
473, 700
100.0
758
gx1073
$x1074
3xi077
1)
Revelle (1957)
2)
Disintegrations per minute per liter based upon calculated
value for K40
3)
Microcuries per cubic centimeter
4)
Maximum permissible concentration for water consumed by man
(Handbook 89, 1959)
*
No value given, hazard negligible