e t ee eae te mes re wy a? mm * pa f mh oa Bote : r y BPRSre s te ete rere (Ga TARPS ic a adihe 2 : v ee a reteNr the Be le See be a Be -ll- Island BELLE Figure 4 shows the decline for island soil as well as the only two observations for beach sand at Belle. The slope for island soil of -1.06 (Table 1) corresponded closely with that of survey meter readings. From an initial level on the first day of 13 millicuries per kilogram, the island soil declined fairly regularly for a period of two years. The dip at 130-200 days is reflected in the decline curves for land hermit crab but is not appsrent in the data for green leaves of plants on Belle. Figure 5 shows the decay of OAYS te AFTER 100 may 14, 1954 Fig. 4 samples of island soil from Belle (plate 7542) and from Edna (plate 9170), and of intertidal beach sand from Henry (plate 9711A). A slope of -1.2 is in- Soll decay cluded for comparison. the basis for computation of the decay correction factors for converting values back to date of collection. The same s The Belle island soil decay curve is for plate number 7542 which served as Radioactivity factors were used for all types of material except rats collected post- Nectar at Eniwetok Atoll. The dashed, early portion of the curve is not a ; . . 76 +e Days offer May 6 AT~e straight line because it was originally Fig. 5 For comparison, Figure 6 shows the decay of the sample of lagoon bottom sand. TOT extrapolated on semi-log paper. TT Mike soll decay test residues Superimposed upon the Nectar test effect. —1-1-F curve of Figure 2 is striking. It was practically uninfluenced by residues from previous detonations. The more pronounced flexures in the curve for Belle island soil, &3 well as its generally more gradual slope are the result of the influence of the Mike b Tr 1952(Donaldson 1953:25), and for 20-1000 days its similarity to the theoretical Radiaactiylty calculation of decay correction factors for the collections following the Mike test in 7& dredged November 7, 1952 off Tilda (northwest of Vera). This decay was used for ~ ‘, Dayt after Movember 1 t45E Fig. 6 a _} mee