PRECIPITATION VS. ®’Cs IN MILK IN NORWAY | 700 |- a ~, qe 4k 600 }- ~_ — 500 a — — ] I ° * w x, 400 |= 7 ee 7 T . a °e ° . ° oe 0 . 6 . * = — ~ ® = — oo ou = ° | ~ | l 2000 ZONE } 3000 0 | l 1000 2000 4 4 ° s , e : e .. = ba ° 1000 7 . : . . - * . . Oh 4 ° ° e FO . * - ° 4 e 2 ° ee ° ae? ¥. 4 0 s e . .. oe “‘_ . 100 = T . *f n 300 [oe T > 4 a. z 200 e . es 7 7 Joe 871 . ° 7 ° e. oe a e 3000 0 ZONE 2 PRECIPITATION, MM l | 1000 2000 3000 ZONE 3 Fig. 7—Cesium-137 in milk in the spring of 1963 us. the precipitation in 1962, In Norway the grass that is to be cut for hay is usually grown during May, June, and July. Besides finding the correlation between the yearly precipitation and the '*’Cs concentration in milk, it was of in- terest to correlate the amount of precipitation in this period with the 137¢s concentration in the milk the next spring. Statistical analyses Showed no such correlation in any of the three zones, However, in zones 2 and 3 there is a statistically significant correlation between the yearly precipitation and the concentration of '’Cs in milk the following spring. This correlation is valid for zone 2 for all three years and for zone 3 for precipitation in 1962 and 1963 and milk in the springs of 1963 and 1964,,. respectively. In zone 1 no such correlation was found. The coefficients of correlation are shown in Table 2, Several of these amount to statistically significant correlations, but only those which are consecutive (underlined in the table) were used. In Fig. 9, with respect to zone 2, and in Fig. 10, with respect to zone 3, the correlations between precipitation and 1370s are drawn as lines of regression together with their curves of 95% confidence. (In every calculation we tried equations of both first and secor. . degree, but the S00

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