Se A kei Eeda ae 2lateddtdha
Jes
40
The measurements of *!°Pb, 71"Po, and stable lead
were made on four trees 100 to 120 years old, cut in
1966 on the grounds of Argonne National Laboratory,
which is in a rural-suburban area about 25 miles southwest of the Chicago Loop. These were a hickory (Carya
cordyformis), a black oak (Quercus velutina) and two
white oaks (Quercus alba). A cross section of each
trunk 12 to 18 inches in diameter and 18 inches thick
was cut about 6 feet above the ground. A fifth tree, a
30-year-old elm from a nearby suburban street, was
also examined for stable lead.
TABLE 15.
#°Pb anp ”§Ra CoNncENTRATIONS IN BLACK Oak
Sampl
number Age of Mean
years years
_ and
cirection
4.0
Li
18
1-10
E
1-10{
N
14-18
258
a8
58
23-25
32-35
42-46]
ie
9S
10S
vores
83-84
88-90]
45
6S
E
N’
52-56
53-57
52-58
0.0880 + 0.0061
0.0081 + 0.0022
0.0722 + 0.0067
16.0
0.03851 + 0.0054
0.0097 + 0.0035
-& 0-046
0.0244
0.0189 + 0.0038
0.0185 + 0.0039
0.0008 + 0.0031
5.5 | 0.0746 + 0.0065
24.0
33.5
44.0
54.0
55.0
55.0
washed and used in the wood several times befor
samples were taken. Only this particular bit was
The drillings were dried 8 hr at 110° C, weighed
wet ashed in nitric and perchloric acids. (The sai.
in which only stable lead was measured weredry :
at 500° C.). The solutions were converted to 0.6 N
and the 2!°Po daughter of the 72°Pb was plated o1
silver disk by heating 6 to Shr at 95° C, after
the ?!°Po was alpha counted. The solutions were
stored 4 months or more to allow the *°Po to gro
after which they were replated and
counted.
amounts of both 72°Po and 7!°Pb present were c¢:
lated from the Bateman equations for radioa
growth and decay.”Stable lead was estimate:
the spectrophotometric dithizone extraction metho
Theerrors of measurement for stable lead were a
5% (standard deviation) and for 7#°Pb and 7!°Pc
errors based on counting statistics at the 90% lev:
confidence are given in the data.
to 17. G
in Tables d142Pg
The results are presented
|
he 240Ph
t
o in|
an
are the concentrations of t le *
0.0311 + 0.0045
0.0180 + 0.0037
O pape + peas
of pCi/g dry wood, the ratios of these values In :
group of rings and the respective ages of these rin¢
the trees. Some values of 7°*Ra concentration are
0.0111 + 0.0028
tions (N, 8, E, W, and ENE)of the radii along w!
ne
83.5
89.0
pods : 0 oolg
0.0078 + 0.0023
0.0070 + 0.0022
given. Because of the large errors in the 72°Po dc
minations in the black oak, only the amPb conceli
tions are given in Table 15. The directional represe
91.5
0.0049 0.0018
samples were taken are relative and not necessarily
.
.
.
.
actual directions in the living tree.
90-94
92.0
118
96-99
97.5
88-95
228Ra,
pCi/g dry
5.5
BE
N’
20Pb,
pCi/g dry
The wood from 2 to 5 adjacent rings was ren
by a power drill, the bit of which had been care
0.0184 + 0.0032
’
TABLE 16.
Samplepumper Ageorang
1s
Ww
N
28
38
48
5S
638
Ww
N
7s
8S
98
10S
us
128
Ww
N
17
1-7
2-9
14-18
20-97
33-37
43-48
52-56
52-57
51-35
59-ti4
69-73
79-83
85-87
89-93
96-98
94-97
93-06
Meanag
4.0
4.0
5.5
16
24.5
35.0
45.5
54.0
54.5
53.0
61.5
71.0
81.0
86.0
91.0
97.0
95.5
94.5
7°Pb, 2°Po anp #6Ra CONCENTRATIONS IN WHITE Oak I
spb, pCi/g dry
0.108
0.089
0.085
0.055
0.040
0.030
0.037
0.028
0.029
0.023
0.028
0.026
0.014
0.016
0.013
0.017
0.013
0.023
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
0.008
0.008
0.008
0.006
0.005
0.004
0.004
0.004
0.005
0.004
0.004
0.004
0.003
0.004
0.003
0.004
0.003
0.004
20Po, pCi/g dry
0.112
0.127
0.010
0.088
0.102
0.069
0.022
0.038
0.009
+
+
+
+
+
+
+
+
+
0.078
0.079
0.075
0.054
0.049
0.040
0.042
0.087
0.048
Ratio °Po/29Pb
26Ra, pCi/g dr
0.72
0.89
0.88
1.00
1.26
1.37
1.13
1.36
1.67
0.0142 + 0.00
1.03
1.42
0.11
1.61
2.52
2.31
0.59
1,22
0.33
4
+
+
+
+
4
4
+
4
0.022 + 0.038
0.76 © 1.35
0.016 + 0.033
0.012 + 0.03
0.024 + 0.035
1.17 4 2.39
0.72 42.14
1.83 + 2.71
0.020 + 0.0381
0.012 + 0.041
1.53 + 2.48
0.52 4 1.80
Mean
1.18 + 0.70 (8.D.)
0.0107
0.0249
0.0176
0.0172
+
+
+
+
0.00.
0.000.00:
0.00: