ee A study of total 8 activity and radiostrontium in rain water was undertaken at the Health and ul we William R. Collins, Jr., and Naomi A. Hallden Health and Safety Laboratory Sytill Sk, cet eleetna Fmt A STUDY OF FALLOUT IN RAINFALL COLLECTIONS FROM MARCH THROUGH JULY 1956" Safety Laboratory (HASL) during the Spring of 1956. At that time a survey of atmospheric aerosols and the elemental constituents of rainfall was being conducted by the Cloud Physics Section of the Air Force Cambridge Research Center. The samplesfrom the network of stations were analyzed by a contractor, Skinner and Sherman, of Boston, Mass. HASL re- ceived a part of the total month’s sample from eachsite, if there was sufficient sample for 1 1.1 PROCEDURES Collection The rain collection devices consisted of 1-liter polyethylene bottles equipped with wide- mouthed funnels that presented a surface area of 0.56 sq ft to the atmosphere. The whole 1.2 Analysis When each sample was received at HASL, the volume was measured and the solution acidified.? Then the sample was evaporated to a small volume, transferred to a glass planchet, and dried for beta counting. This residue was fused with sodium carbonate and the strontium separated with fuming nitric acid. The sample was then stored to allow the Sr*® to equilibrate with its yttrium daughter. At this stage the yttrium was separated andprecipitated as the oxalate for beta counting. The Sr*® was determined from the counting rate of Y°°, and the Sr® was determined by oe ba leee ee assembly was enclosed in a wooden container designed to be opened manually during rain and closed at other times. Figure 1 is a diagram of this apparatus as it was usedin thefield.! 1.3 Reporting The Sr’® and total 6B activity are reported in units of millicuries per square mile per month. These values were calculated from the original counting data (disintegrations per minute per aliquot) using the formula, *Issued as USAEC Report NYO-4889., 339 2 det ee «a aby, counting total strontium and subtracting the Sr*° result. * Sampling covered the period from March through July 1956 for 61 stations within the continental United States, Bermuda, Newfoundland, and the Azores. The original purpose of the study at HASL was to correlate the amount of fallout in rainfall with the estimate of total fallout from gummed film measurements. tn itis altel Hes ange both laboratories to run analyses.