ee tes erepemegeaed UNCLASSIFIED Studies of Factors Involved in tha Biological Urtake of Radiostrontiim Identification of the properties of soil which influence the ke of radiostrontium by biological systems is a prerequisite to undersfanding the significance of the deposition ef radiogtromtivm in soil. Dependence of Sr89°90 Yotake on Soil Calcium The Beltsville Experiment Station has demonstrated that ir laboratery soils containing Sr99, the uptake of this isotope by Pow Peas plant radioe is dependent on the exchangeable calcium in the soil in which is grown, They have demonstrated that this is likewise true for barium and the Health and Safety Laboratory has demonstrated a lation= ship between radium uptake and exchangeable calcium in soil. If, as the Beltsville experiment suggests, the radicetrontim ccntent of plants is dependent not alone on the amount of radiostrontiu a the soil, but on exchangeable calcium as well, a correlation should st between exchangeable calcium and the ratio of sp89~90 in livest amok bone to S799-90 sn soil from which their food 1s derived. To test this hypothesis, soils from five pastures in various par s of the United States were analyzed for radiostrontium and exchange ble ealeium. Three lembs and two oalves that had spent their entir lifes tims in these pastures were sacrificed and samples of ge eton Figure 6 is a presentation of our data in the form sr ia > in soil versus the reciprocal of exchangeable caloium. These < ta take the form which would be predictable fram the Beltsville experiz nts where a linear regression with a slope af 529 wae obtained. Because the few data, a curve through the points in this figure is not she Howe ever, a least squares fit of the data gives a slope of 760 which is in fair agreement with the Beltsville data sonsidering the few observations we have and the possible differences between field and laboratogy conditions. pe yset8s90 In @der to emphasize the importance of the exchangeable calci Parameter in the relationship between bone end soil radiostrontium, Figure 9 presents bone radiostrontium versus soil rediostrontium. Presented are not eo orderly as in comparison with Figure 8. Thejdata thus Dependence of Ba Uptake on Soil Calcium If a similar dependence on exchangeable calcium could bp demonstrated for mtural radium, we would bave « weful tool for evaimting the significance of radiostrontium deposition in soile. The rahge of Wrld wide Ra in soil is mown to a first approximation and sani determined if need be. The relationship of this deposition to human bone has been tmder study for some tine. Our knowledge « bilo radium equilibrium oould be used to estimate the ultimte Pediostronti um. be better dium in the geote of wile sae 00131986 027 [057056