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- 444 - - -b JRE VOL. 241 FEBRUARY 16 197
<br /> LETTERS TO NATURE
<br /> PHYSICAL SCIENCES The sites in Table 1 were grouped into ten degree latitude
<br /> _ bands and the deposition values averaged. We plotted these
<br /> - averages against the sine of the latitude and made straight line
<br /> Global Inventory and Distribution extrapolations to zero at the poles. The average activities per
<br /> of Fallout Plutonium sq°~ ~ m each ten degree latitude band are given in Table 2
<br /> The error term associated with the average for each ten degree
<br /> PLUlntvttrvt isotopes, Pu-239,240 and Pu-238 in particular, latitude band is simply the standard deviation when two or
<br /> have been injected into the stratosphere as a result of atmo- more sites are located in the same band. R'here only one site
<br /> spheric nuclear weapons tests, and have reached the grotmd is represented or the value was derived by extrapolation, as
<br /> as particulate fallout. An accidental stratospheric injection of average error for other bands in the hemisphere was applied.
<br /> Pu-238 in 1964 resulted in almost athree-fold increase in the The distribution pattern for weapons' plutonium shows
<br /> global fallout of this isotope, and we now desaibe the accumu- heaviest deposition in the Northern Hemisphere temperate
<br /> laced fallout and geographical distribution from this unexpected latitudes and a minimum in the equatorial region. There is a
<br /> release as well as from weapons testing.
<br /> On April 21, 1964, a Transit navigational satellik was
<br /> . ~ Crunched from Vandenbuig Air Force Base in Califor7»a The Tabb 7 Pu laotopes in Soil Collected 1970-77
<br /> payload included a Systems for Nuclear Auxiliary Power-
<br /> generator, SNAP-9A, coetaining 17 kCi or about 1 kg of
<br /> - - Ptt-2381•x. Because the rocket failed to boost the satellik into a~ "
<br /> orbital Sight, the payload re-entered the atmosphere in the ra...,r ,a« lea ~ i'~.ie' «-,af.aN r«o«.-"wo
<br /> Southern Hemispheres''.
<br /> r«rra .«a.ae.<.
<br /> Subsegt7ent st2tospheric checks'-6 indicated that the
<br /> - :.el.•a fuel. ,a.a o. as o.e« (0. rani
<br /> gehaator cmnpkkly burned up during rG<n[ry apd tamed o<+ r.+... a1«.. ».a u o.ao o.elo w.oai
<br /> W M1a[W.. al«Y. N.a Ta O.lf 0.030 O. de
<br /> _ mto small particles at an altitude of about 50 km*. Conxntra. :<.x.m y!t°lt M.1 M 1.! 0.0% 0.01t
<br /> lions of the SNAP Pu-238 in the stratosphere were meativrabk al's » o.» o.m: o.mx
<br /> +en•f +°v° N.a lsa a.1 o. o,a o. as
<br /> 8t the and Of 1970 when it was estimated that less than a kCi etlrar °n• ,a l.s a. ma o. e1o
<br /> rcmelned above 12 km'. Attem is to measure the ° r1°' N•a w >_a o.o« 0.ou
<br /> p ground oe.n reaar ».a » l.a o. m+ o. oo+
<br /> -depos/tlOn Ink OII a COntiaUOUS basis nSing a global fBIIOUt @ rOS'+'• eic"'• n.a N 1-+ o.exa o.mr
<br /> a..rey rice N.1 n a.s o. as, o. ml
<br /> network were 1nISUC02ast•Ula. We finelly used soil sampling l0 ,~,r x
<br /> R. ru4 is:e us o. toiaNO u:oa
<br /> obtain integrated fallout samples, having previously demon- oa elee•. N.f N 1., o. Nl o. m.
<br />
<br /> ~ strafed that soil at properly selected sites serves as a good w 1al~Lm• a. sa.s 1as i:i o:o s o:us
<br /> indiCatO[ of cumUlatlve fallOUl+. aaee~r. alt. s1.e N l.a o.o« e.ou
<br /> r r sixr, s. r. N.s 9o a.s o.aax o. ols
<br /> The SSraLOSpherlC IllvenLOrlCS Clearly IndlCBfed that by sale ,m eiey 0c. ae,+ ao a.a o. Na o.on
<br /> oN os°c• ppn. ,s.a la -1.5 O.Na o.ov
<br /> mId-1970, 95°fo Of the SNAP Pu-238 Was deposited On the w alee•aa«, m. ».x n :.a o.oN o.0v
<br /> resccecl a«..° »s » l.s o.ma o. all
<br /> Earth's Surface. IL was Important t0 find OU[ hOW It Was au sw«, m. ».x N l.x 0.e» 0.0»
<br /> distributed and to record the gro7md deposit. Knowledge of 0° oueafe• e.°- as.a ua x.a e.oN o, a>
<br /> x«« sarw ssa i.s e,0aa 0.01.
<br /> - the fate of this debris is pertinent to studies of nuclear explosions 0° nun. x. x as o. n o1a o, m1
<br /> M!1•t« Lb[. ll.a N La 0.0» 0.011
<br /> a the upper atmosphere and the use of nuclear power sources x100•,111., - s » o.» o. oa. 0.oa
<br /> oar. aro, rase., eta. v.s xa: t.o °,oN e. ms
<br /> 171 spaCC. r w1•es• s•r. M.x a o.w o.ou o. ms
<br /> L7 October 1970 tmtil January 1971, 65 sites around the ~(voN«.•e.a. war 10pe•1°"LLa io:i b'!a o:ia o: owoa o: ~i
<br /> world were sampled by HASL personnel and scientists from a„era• .eaee. 1a o.» o. wa i0. non
<br /> other wuatries; soils were collected from undisttubed areas. s°+e«• e«a•o•..•
<br /> Each sample consisted of ten 8.9 ctn diameter cores taken to
<br /> x«r• 1+vee• t.a N a.u o.ou °.oss
<br /> 30 cat depth, representing a surface area of 622 sq. cm. The le«u rl« 1.5 n. e.u e. olo o. m,
<br /> measured Pu-238 included that from weapons testing plus r.~ lo."M°'aa. 1 i:i ii oo°:esa o°: o~ox o: o~oa
<br /> the SNAP-9A contribution. The Pu-239,240 was assumed t0 u.l a o.» o. oea o. ol!
<br /> ac.as.u. nave. 1a.a 1« o.° o. m, o. ma
<br /> be entirely derived from weapons testing. rw.ra.c. srwl• u.l lm ~o.u o.oN o. ms
<br /> «m«t. e.aa.e°y v., n e.la o.aN o. ox:
<br /> ]n order to meassue the total Pu-238 with a counting error a•.er.1a. Are..au. a.: 11+ o.1a o.oa o. oft
<br /> (G) of less than OI CQUSI to t 10% 1,000 g aliquots of soil °a,,,,°1,°° ~
<br /> .,o,,,, ;o;; 1;; o:;; ms a: e,i
<br /> ' - -wee required. M acid kaCh771g prOOedUrelO USCd t0 Y«al w N ae.a° _ n.! 1« a. a1 e. ass o-1«
<br /> w«u aer« sa «a• n,a e.N e.01a 0.a»
<br /> accommodak this large size sample was found to be equally •..o.aa. aaa« asraes• ,a., as o. nos o-mx
<br /> b A[[le• Mtsb x1,0 ,f 0.» O.OM 0.051
<br /> efficimN' to complete dissolution. r«.as« ra.l~es e..ae.e ».o ° o. as o.oN
<br /> - The soil data arc given in Table 1. The weapons Pu-238 „'°,v
<br /> is. r~«ea.~ ii:i 1101 au o:oio o:oNl
<br /> ' -contnbution was obtained by multiplying the Pu-239,240 a«•a.w ».s x o.» o.oos +•°a'
<br /> e. atra« ae•11•eueem ,0 e.K o.0a
<br /> -vetoes by 0.024 (the average weapons Pu-238 to Pu-239,240 a..c..w .,a..r ».o lu o.a o.eu o.oso
<br /> atati0 -found for six ao0s Collected before fallout from the ""°sa° o'!°O' e1r u.e » o.« o. o1a a:o»
<br /> r wa.ea x. a.alw af.a ' 1» e.» o. olo o.aet
<br /> 3NAP-9A). These sotlt were sleeted to cover a range Of aN1•ar ».a a o.» o.ao.
<br /> -le•ti•11• «mer• sa.a tm o.u e.ou
<br /> ladtudea from 71° N t0 33° S and the standard deviation Of natl. ...1« rea al.f 1N e. se e. nos °.0s,
<br /> thu''pvtrage ratio was 12° The SNAP•9A Pu-238 is '°`1'1" a1.s u a.x o.ooa °a'
<br /> f /o• r ra.ea orgawu u.s a« e.s, o.ma o. ale
<br /> -[hGn %~ply fhC d$ellnCG betWxn the total IDeasurtd Pn-238 r wa°a o, eress«r u.a s, o. r. e. oo, o. °+s
<br /> and thrweapoas Pu-238. °*s' .°ea_a.... u.s as te.vt te.ooN re. man
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