PRECIPITATION VS. '3’Cs IN MILK IN NORWAY
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curves turned out to be so similar that only equations of first degree
were used.)
DISCUSSION
The prevailing winds in Norway blow from west to east. At some
distance from the coast, mountains force masses of moist air upward
where the temperature is lower, causing moisture to condense and fall
as rain or snow. This condition favors an increase in radioactive fallout. Figure 11 shows the total yearly precipitation in Norway averaged
over a 30-year period. In zone 1 a greater part of the precipitation
falls in summer as rain. A considerable part of the remaining precipitation that falls in this zone comes down as snow, bringing fallout with
it. Part of this snow melts and together with its content of radioactive
particles flows away while the earth is still frozen without contaminating the soil. In this way someof the radioactive particles are carried to the rivers and therefore do not contribute to the contamination
of milk. In zone 2 most of the precipitation falls in winter as rain, In
the counties Aust-Agder (8), Vest-Agder (9), and the southern part of
Rogaland (10), the precipitation is more evenly distributed over
summer and winter. In zone 3 by far the greater part of the dairies
and also the districts where the milk is collected are situated along
the coast. Here, too, most of the precipitation falls in winter, but a
greater percentage than that in zone 2 falls as snow instead of rain.
The precipitation continually decreases northward, In the interior of
Finnmark (18) the climate is rather dry. Here most of the precipitation
falls in summer as rain. The precipitation in zone 2 and partly in
zone 3 is greater than that in zone 1 and therefore presumably washes
out larger amounts of fallout from the atmosphere.
SUMMARY
The prevailing winds in Norway blow from west to east. Along the
west coast the peculiar topographical conditions favor a greater precipitation and thus a greater deposition of radioactive fallout than in
the eastern part of the country. The precipitation in several districts
in Norway was estimated for three consecutive years (1961, 1962, and
1963), and the concentration of '"Cs in milk from about 90% of the
dairies in Norway was measured during the following spring of each
year. Along the coast a statistically significant correlation between
the precipitation one year and the amount of '%"Cs in the milk the
following spring was demonstrated for three consecutive years. In the
eastern part of Norway, no such systematic correlation was found,