137Cs determination

Cristaldi, M., E. D Arcangelo, L.A. Ieradi, D. Mascanzoni, T. Mattei, and I.V.A. Castelli. 1990. 137Cs determination and mutagenicity tests in wild Mus musculus domesticus before and after the Chernobyl accident. Environ. Pollut. 64 1-9. 

The results for the ICP-MS determination of "Tc in soil were compared with those for 137Cs [39]. The "Tc/137Cs ratio in soil was 3.9xlO-3 to 3.8 x 10 2 which is considerably larger than that expected theoretically. 

The age-determination results by using 210Pb and 137Cs for the sedimentary columns of the alluvia beds along the trunk stream and main tributaries of the Anhui section of Yangtze River show that the variations of the contents of Cd and other heavy metals were basically corresponding closely to major historical events, say the establishment of PRC, the exercise of the policy of reformation and opening and the course of extensive industrialization, etc. 

The difference in efficiency between the large planar 18-cm.3 Ge(Li) detector and the small round 8-cm.3 Ge(Li) detector depends essentially on their cross-sections since they have approximately the same depletion depths. This is apparent in comparing the peaks from 10 pCi of 137Cs generated by the large and small detectors (Figure 9). The geometry of the aluminum can was determined to be less efficient by approximately a factor of 10 than a disc-mounted point source. 

The equation in this form states that in the samples analyzed the distribution of any radionuclide, A, can be expressed as a linear combination of the distribution of two species, a refractory and 137Cs. Therefore, we need to determine only refractory distribution, 137Cs distribution, and mass distribution with particle size and the distribution of all other isotopic species for which aA values are known and can be calculated. The refractory species used is 155Eu. It has a half-life of 1.811 years and two easily resolved gamma photopeaks so that its abundance as well as that of 137Cs can be determined readily by gamma spectrometry. 

The lower size limit of crystalline population is 0.31 /. This is based on experimental determination that 137Cs atoms/Mg = 2400 X 109 for fractions consisting of all particles less than 1.2/ in diameter. This value coupled with the equation 137Cs/Mg = 1170 X 109/ implies that is 0.49/. However, if 1/2 (1/2 + 1/Dmin) = 1/.49, Dmin is equal to 0.31/. ... 

We now wish to determine i and fa so that the ratio of 137Cs to 155Eu for the whole population is equal to the ratio in which they were formed. Based on the r137 values of Table I, and the atom ratios observed for residual portions of the filter samples, we find ... 

Various ancillary measurements from accompanying cores were needed to calculate accumulation rates and describe phase associations of Hg. 21wPb and 137Cs profiles in sediments were used to determine sedimentation rates from which historical interpretations could be made. 

Delaune, R.D., Patrick, W.H., and Buresh, R.J. (1978) Sedimentation rates determined by 137Cs dating in a rapidly accreting salt marsh. Nature 275, 532-533. 

From the data of Table 3.7 and the mineral composition of the rocks (Tables 3.4 and 3.6), the distribution coefficients of the minerals (kcfi)) can be determined by Equation 3.9. The distribution coefficients for the different groups of minerals and the calculated relative sorbed quantity of 137Cs ion (x., and the differences between the experimental and calculated values (AxCs) are shown in Tables 3.7 and 3.8. 

As seen in Table 3.7, the differences between the experimental and calculated values (<0.07) are within the deviation of the determination of the mineral composition and relative sorbed quantities of 137Cs ion (5%-10% ). So, the linear model fairly well describes the relation between the mineral composition and sorbed quantity of cesium ions on different rocks. 

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