Specific Activity
0.11 pCi/ug Th
Table 11
Natural Levels of Th-232
Estimated Mean
Earth's Crust
Range
Area
Reference
1.2 pci/g
3
0.2 pCi/g
2
Rocks
sedimentary
Igneous
-~ 217
Ocean Water
3 pci/g
<0.002 pci/1
1 pci/g
1 - 15 pCi/g
2
O.0001 = 0.001
A
2
4