reprinted from NUCLEONICS | June 1954, Volume 14, No. 6, Pages 78-84 Copyright 1956, McGraw-Hill Pub. Co., Inc. 330 West 42nd St., New York 36, New York RaD, RaE, and Po in the Atmosphere By P. KING,* L. 8. LOCKHART, Jr.,* R. A. BAUS,* R. L. PATTERSON, Jr.,* H. FRIEDMAN,{ and I. H. BLIFFORD, TABLE 1—Rainwater Collections Made at Washington, D. C.* Pb fraction Jr.t Naval Research Laboratory Washington, D. C. Date collected Volume collected G-activily a-activity B-activity a-activity Jan, 12-30 Mar. 31-Apr. 24 May 3--12 340 220 260 1,400 850 2,140 6 8 10 12,000 14,600 14,200 710 600 490 (1950) At the time this research was undertaken, a survey of the literature revealed many references concerning the amounts of the short-lived RaB and ThB in the atmosphere, but no information on the quantities of the longerlived RaD, Rak, and Po.f{ This Bi fraction (gal) (dpm) (dpm) (dpm) (dpm) * Activity not corrected for decay, absorption, or backscattering. dearth of information prompted us to install facilities at several naval bases in different parts of the world to collect: natural radioactive products from the atmosphere for subsequent analysis at Washington, D. C. These collections were made by either, or sometimes by both, of two methods. Thefirst method used highcapacity air filter units with filter paper as the collecting medium. The second involved the collection of large volumes of rainwater (100-600 gal) andthe con- TABLE 2—Distribution of RaE(Bi?!") Activity Among Rainwater Fractions Collected at Washington, D. C. B-activity (dpm/gal) Date collected (1950) June 29 centration of the activity with aluminum hydroxide floc, Asa result of the chemical methods used, the radioactivity from up to 1,000 gallons of rainwater or 108-107ft of air could be con- July 9 earrier. July 20 centrated readily on 50-100 mg of Counting of the separated July 15-16 G-activity gave a reasonably accurate measurement of the concentration of the long-lived products in the atmosphere. Qualitative estimates of the Po alpha activity were made. Rain-Water Collection Volume Fainfall collected {in.) (gal) Aug. 19 Aug. 23 Sept. 11 1.5 1.4 4.8 (cont.} 1.35 (2-hr rain) Rain was collected on 500-1,000-ft? surfaces made of aluminum sheeting and was conveyed by aluminum gutters and pipes to aluminum collecting tanks. For someof the colleetions made at the Naval Research Laboratory, automatic controls diverted portions of the rain into three different tanks so as to compare the activities collected during different parts of the rain. In many of the collections more rain * High Polymers Branch, Chemistry Div. + Electron Opties Branch, Optics Div. t Recently some information on the longer-lived activities in air has been reported (7, 2). Sept. 21 Oct. 8-9 Oct. 23 Nov. 20 0.86 0.54 1.86 0.55 30 60 150 30 60 225 40 55 300 40 60 300 40 60 275 40 60 275 40 115 275 40 60 275 40 60 275 40 60 275 40 60 150 Insoluble residue f-activity (qm) (dpm) * 12.5 2.9 1.4 0.8 0.8 2.4 7.0 2.1 0.9 7.6 1.7 1.7 25.0 3.6 3.0 4.9 1.4 2.0 5.3 3.0 2.0 12.5 2.1 2.1 7.6 3.5 2.5 4.0 6.2 3.0 5.3 13.7 2.8 1,930 1,740 3,200 1,200 160 450 2,360 1,230 3,080 2,300 2,160 3,240 1,700 1,080 2,180 2,760 1,760 10,640 250 790 2,640 1,330 1,740 8,250 1,280 950 2,260 2,000 1,890 3,400 2,220 1,640 1,580 Average Tank A 64 40 59 57 43 69 6 33 32 50 56 46 Tank B 29 3 22 36 18 29 7 29 16 32 27 22 Tank C Total collection 29 21 2 10 11 8 39 10 30 8 12 11 15 6 17 19 13 40 9 30 12 20 22 20 * Activity of BisO; fraction corrected to time of Pb-Bi separation. C4,