730
“
ae
Ann. Acad. Scient. Fennice
A. IT.
102
‘
4
Table 1
187Cs in Finnish Milk in 1959
No.
1.
2.
3.
4,
5.
6.
7.
8.
9.
Sample
Farm
Apukka,
Vik
Malminkartano
Halola
Jokioinen
Anttila
Kreuksela
Myttaala
Toivonniemi
Latitude
Date (1959)
66°N
60°N
Aug. 29
—y—
60°N
63°N
61°N
60°N
65°N
61°N
69°N
Aug.
Sept.
Aug.
Aug.
Sept.
Aug.
Sept.
31
1
30
31
2
29
6
Milkash
Cs
8.83
13.3
82
122
g
14.5
12.7
14.0
13.7
13.0
13.2
12.0
ppc
94
59
63
64
140
48
500
yyet’Cs! pycCs/
ek
1 milk
60
43
48
23
220
260
37
21
21
25
51
19
18
12
11
13
28
10
height spectrum taken from grass sample number 9. The determination
of 7Cs is complicated by the relatively high amount of radioactive zirkonium + niobium in the sample. Because the ™’Cs and Zr + ®Nb
peaks are fairly well separated, it is possible to estimate the relative amount
of Zr + Nb in the spectrum.
This is done by taking only that part from the photopeak whichis far
enough from the photopeak of 8’Cs. After an estimation of the relative
amount of Zr -+ %Nb in the spectrum, a correction for pulses due to
them in the #’Cs-channels in addition to the background- and “K-pulses,
becomes possible. A more reliable but also more tedious way to distinguish
the two peaks from each other would be the »try and correct» method.
The results are given in Table 2. Our results show that contamination
by Cs of milk produced in South Finland is of the same order as that of
milk of other countries with similar climatic conditions (2,5—8). Samples
from North Finland (nos. 7, 1, 9, lats. 65°—69°N) show higher contamination, comparable, for instance, with the values from Wales (9). The cause
of this is not known, but it is not due to higher rainfall (see ref. 1) as in
the case of Wales. A more detailed study of the conditions in Lapland
will be needed.
The ratio ®’Cs/*Sr (Table 2) has been calculated on the basis of the
present results and those of Paakkola eé al. (1). Similarly, for the 2 nothernmost samples (1 and 9) this ratio is about 3 times as high as the average of
the other samples. No correlation is visible between the values of this ratio
in grass and in milk. The discrimimation factor grass-milk to 8’Cg is also
presented in Table 2. The mean forit is 0.28.