5 ABSTRACT This repcrt · summarizes the results of the r adiological surveys and assay of soils and plants collected during the Biol ogical Field Surveys of 1949 and 1950 from the areas contaminated by t he Fall-out from the ' First Atomic Bo b Detonation in New ii exico -- The r e sults of these in- vestigations Y be summarized as follows i -L The radiological surveys of the Chupadera 1' esa twenty to · thirty-five __Idles from ground-zero show the continued presence of measur· a b le a mounts c t _radioactive fission product contamination relatively ' small changes in elevation have no detectable effect evident at this late date on distribution of Fall-out and there is little evidence of lateral migration of ontarainants during the last t wo years in the areas surveyed _ 2 In he Fenced Area the area for more than 50 mro 24 hours _ gar ima radiation has decreased from 1400 feet to approximately 700 feet in J I di eter in four years 3 Whd erosion is more effective than water erosion Some wind- - drift material collected adjacent to the Fenced Area assayed as much as • 0 12 dis sec f Jil of silt and clay It was demonstrated that vegetation o _i s ___ ·- _ the most important influence in decreasing the removal of wind- borne ma J ·· 1 - s · terial 4 Wat er-borne silt deposits within the Crater were always several · tIDes less rad oactive than the underlying soil or sand 5 Powdered Trinitite 11 is only sparingly soluble in water and lute alkali s olutions and only slightly more soluble indilute acids -· _ - - - - - - - ' - - - '- ' - - - - ' -'-- '--'--'-' f - r i J ___ ' -b f • ibf 6 There is scme indicaticn from t he 1950 data t r a t downward mi- gration of fission product contaminant s in t he s oil is taking place on the Chupadera Mesao There is as of 1950 an average of approximatel y one micrccurie of fission product activity per square foot one inch deep or 600 dis sec gra of soil in Area 21 twenty-eight miles from ground-zero - - 7 Pre iminary laboratory studies on the clay fraction from Area 21 indicate that · cs1 37 is fixed almost quantitatively while s r90 fJO are fixed to a much ··l esser degree o 8 Normal background activity differs -between plant species a d genera for a col l on grass Bouteloua gracilis the natural beta-garr ma background activity ranges from 0 5 to 0 44 dis sec gm of dried plant material - - 9 Tne ratio of soil to plant beta-gan ma radioactivity of residual fission prcducts in Area 21 reveals that in 1949 the activity of a gram of · dried plant material was 1950 t his value was 10 3o85%of the radioactivity in a gram of soil In 5 59% T ne uptake of residual beta-gamma radioactivity by Russian ' thistle Salsola pestifer in the Fenced Area has app rently reached an eq tj libri mn based on comparative assays of samples collected in 1948 and 1950 ·•· • --- - ---• · -- - liq Preliminary greenhouse da ta presented from research in pro- - gress indicate that the identity a c d chemical form of thP isotopes dif· ferences in soil co position and its chem is try cl atic factors and in• 4 • - ·· _ - - ·herent differences in plant species are all m portant f a ctors in determining the behavior of the fission _products in the overall biological cycle ' - - '-' - _ -- - - - 7 T HE 19h9 A t'JD 1950 J DIOLOGIC AL SOIL Sli RVEY OF FISSION PRODUCT CONT AlUNATIOX A -W SOME SOIL- LANT INTERR LATIONSHIPS OF ARE AS IN 1EW i-IBXICO AFFECTED BY THE FIRST A'ro IC BC ' B DETONATION INTRODUCTION This report is concerned with additional radiological observations and some consideration of the soil-plant_interrelationships due to the residual radioactivity of the Fall-cut from the First Atomic Bomb Detonation July 1945 in New Hexicoo The 1949 and 1950 Biological Surveys were in part- concer c -ed v ith the determination of the fourth and fifth year dis- tribution of remaining fission products in soils and plants and the interrelationships between these two_systems with respect to biological cycling The several equilibrium or Threshold values for fission products and alpha emtters distributed as Fall-out from detonation in soils lants o anirr als have not been establishedo These values are essential - t the es tablishm ent of _a basis for the evaluation of chronic and acute ra io1ogical hazards to ma and other biological systemso Annual bio- · logical ·surveys and correlated controlled laboratory research have been designed and are in progress to determine the mechanisms by which the long -_ - y·- • a id medium half-life fission products and the important alpha emitters are ··' absorbed and metabolized by important crops and animals In order to further define the residual fission product activity S ·three areas were selected Area 21 Ratliff Area and the ieir Area for the 1949 Survey These were S€lected on the basis of the highest•beta- gamma activities found ' during the 1948 Survey t See Detailed Map Fig 3 - - - 1 '· -·- -- i- - · ·- - J' • e c i I tllt bt l C' 8 Report UCLA-32 _ Area 21 a 'ld the Weir P rea were a gain selected for the 1950 Soil and R diological Survey In se ecting these areas described in detail below the several objectives were 1 rain and the radioactivity 2o To determine the relationship betw een the elevation of the ter- To establish additional pemanent l ocations for future soil and l biological su -veys 3o To est2 blish a representative area for erosional studies 4 To recheck previous permai ent soil sampling locations J In each of the an '1ual field surveys conducted so far soil profile studies have been made in typical locations These studies have been made each year rith the following objectives in mind L The pro file soil samples were collected and radi ologically as ayed for beta- gam na and alpha activity to determine the verti- cal distribution of radioactivity 2 To ccn firm -the surface mr hr values obtained wi th the survey L'1strm 1ents • · 3 To obtain data -on the overall decrease of radioactivity due to t e interplay of such factors as erosion is otopic decay hori- 2ontal and vertical diffusion of the fission products in soil and the effect of temperature and rainfall l The 19h8 Radiolce ical and Biological Survey of Areas in New Meri co Affected by the First Atomic Bomb Detonation Report UCLA -32 See map inside _be ck cover The reader is referred to this report by the authors for data and reference points at which tLme the Crater Area and the do 'TI- «ind Fall-out were measireaa d the reference transect and permanent markers were established 9 One phase of the annual field surveys by this group has been the deter i L ation of the uptake of residual radioactivity by plants For this purpose plant specL ens have been collected each year from the following ·areas --· 1 The Fenc d Area the area of primary Fall-out o 2 The Chupadera Mesa the area of secondary Fall-out 3 Various locations outside the known area of contamination as established in 1948 See Report UCLA- 32 75 and 78 T'ne collection and assay of plant material and soil adhering to roots has been done as an attempt to establish the soil-plant relation hip with respect to fission products Collections outside the area of contamination have been made in an attempt to establish _the naturally occurring ' 0 oackgrou '1d 11 value for each species of plant sampled · G£NERAL DESGRI TION OF LOCALITIES Th --ee of the four areas previously entioned were studied in detail during the Radiological and Soil Survey The location 't opography gen- eral soil description and vegetation for each of these three areas is -presented _ _ - ··· -- Area 21 t · · 28 miles roughly northeast of Zero is situated just east of the Primary Transect Reference Line see Figo 1 p lb on Lateral - _ 31 Right on the · Chupadera tesa - - -- · - The major part of this LS square mile area consists of ridges and valleys lying in a general north-south direction with drainage generally to the southwest supplying several stock tanks on the Coker Rancho The soils of the ridges and· thP-ir slopes are coarse sandy loams often with hiEh gravel content and surface rock several locations in this area long continued er osion has exposed the In - ­ · ¾ -K f 11 1 _ •' I M IL E 11 partially decomposed limestone-gypsum substratum which now appears as large hills or ridgeso The soils of the valleys are usually loa s of fairly hi gh silt- content and are calcareous · In general the ridges and their slopes in Area 21 are densely populated with juniper ar d pinon pine __ The valleys have vegetation con- · sisting ainly of grasses and scattered junipero The northeastern sec- I - tion approximately one-fourth of the area is a broad open plainslop ng gently tli·o to four per cent to the east The soil and vegetation here are siJni1a to t ose of the valleys described above Ratlif£ Area This region is located about one mile east of the Prima 'Transect Reference Line on Lateral 17 Right 22 iles north of Zero s ee Fig 1 p 10 on the ·thupadera lfosa It consists mainly of alluvial Ia s and terraces forming the southwestern slope of the mesao The so ils are generally coarse sandy loams vd th considerable gravel A ridge rising 6iJO feet ibove the floor of the canyon forms the eastern boundary The soils of this ridge are in general coarse sandy loams or loamy szz1d s larg'2ly co· ered r i th rock particularly on the eastern slope The vegetation of the Ratliff Area is grass with scattered juniper • througnout with the exception of the ridge where juniper and pinon pine · - i-form · the main cover on the west and north slopes o · · The very rocky eastern ' _sJ ope somewhat less than half of the total area is abost barren with _ only-a few yucca and scattered grass tufts · In each of three years ·soil profiles were taken at two locations in these areas one in the l Ratliff nHo t Canyon t ie other AE-1 at the section corner one-half mi l e north of Nalda Headquarters and four miles east of Old Bingham Additional profiles were taken in t he valley of Area 21 av-id at the Earvey Gate location I I 15 inch abcve t he £round The scil profile sample s collecte d fer b5ta-Garr a rac i 0a c ivi Y assay in the laboratory were prcce5sf d in the sa e r ar ner as t he 19L8 sa r ples with one exception all soil fractiona t1 ng sie in£' wc s done fer fifteen minutes on a Ro- Tap sieve shak r JI J l Qf the- lab oratory data have bee 1 corrected f or ir- stru_- ie -it and s o l backgrou d naturally occurri '1g racl ioactivi ty and self-at sor1- tion • Average s o il bac°£ground was deterndnen to be G 7 dis s P c g- n l Ad- ditional data accunulated and r epeated determinations in s ubseque nt years· has sub stantiated the v2 lidi ty and constancy of this average value A self-absorption factor of 1 5 apyroxi TJate was determined using the 1950 surface sa r ples fr on Ez rvey Gate as well as on s oi samr les from the Feri ced f rea This value has been used througboL t en the sc il assays RADIOLOGIC L RESULTS MID 03 SE VJ TIO 'S Chu pad era •esa The fie ld data and infor E tion collected fro n tr e twc 3-reas rea 21 and Ratliff Ar ea i n 1949 are r resented i n ' 'ables I nd II and f i gs 3· and h On ly one pcint · - as found in the t- rn a rea s which had an ave rage reading greater than 0 3 mr hr beta- ga l ila activity An average 'eading is the arithmetical ean of all mr itr values taken at any one lo cation - Several l ocations h ad i ndi v i du2 l r e adi '1GS b t ce 0 3 '• and O• 6 a- hr • - No significant difference s were fou 1d cm the ridges and tlv adja- cent valleys in beta- gamma r adioactivity In general U- e higher 1 he lS -48 ciologic2 l a - d Biologtcal Survey CJ Areas in Ne·u l exi co P ff 'ct ed by the r irst Ator jc o r ib Det or a tior f eport UCU - 32 p 21 I - l ' 1 _i i _ • _ _ _ _ __ 23 activities were found i n r r2 ss tufts which had 2 ccu r ulate d dust silt and sc T d or ar ce r the ju 1i Jer trees on decaying orgar ic n 2 tte r dead needles Th' l ower ac ti vi ties occur red on hC'a vi ly eroded r ock and soil especially that found on the r idg s The wcod-rat nests investi- I g ted were only ti 'lo to thre e ti 11es more than r ackground In a ddition to the two areas surveyed in Getail nine othe r locatio 1s en the i esa v hioh has been measured in parative purposes in 1949 1 45 were checked for corn- These data are presented in Table III Table III CO A ATIVE AVERAGE MR HR • RSADINGS TA KEN · I l 8 AND 19h9 ON THE Cf- JPADERA ESA AT SEVERAL LOCA IONS kr hr - beta-Gam na J ocat on Harvey Gate E G Lateral 20 Miles frO i Coke ♦ House norttieast al o - g State Highway o o 15'4 1949 0 26 0 17 Oo09 o 14 ul 00008 l o0 O GC9 2 0 C Oli2 J O o oos h o 0 080 0 290 0 029 5 o 0 160 0 113 0 220 0 0 1 6 0 0 CO4 0 014 T -r o otter locations the Vihite Store and ·the Ratliff 1 Hot11 Canyon Areas on the Chupadera Ue sa have been checked eriodically since the -'C· bomb detona ticn i Il 19h5 These data are o f L-npor-tance since they g ive an est mation c f -the overall rate of c hange of activity resulting fro 1 decay of fission products erosion effects translocation and other influences These data are presente in Table·rv I ' u -· t r Table IV BETA- GAM1 A ACTIVITY fl R HR TAKEN AT TNO LOCATIONS PERIODICALLY SINCE I1i MEDIATELY FOllOWING THE INITIAL FALL-OUT hr Mr Date of Time Elapsed _ White Reading·' - - - - -Since Zero Hour - - ----------- -S t o re •- Julys Dec Aug Aug Aug _ 5 to 8 19h5 1945 · 1947 hours 3 336 hours l8 36o hours 27 000 hours 35 7 J hours l9h8 1949 2500 0 5 Beta -Gc iEna Ratliff 1 Hott' Canyon · 6000 2 2 1 3 o 6h 0 06 C 07 These values were r eported by t he 1-os Alamos Group The Crater Region - Fenced and Unfenced Areas The portion of Tri nity i 'lll ediatel y outside the enced Area and that i nside the fence includi ng the Crater -were resurveyed for bet a- gam ' ' a and gamma radi ation as in 1948 The or hr- 'eadings of beta- gamma radioactivity obtair1ed in 19hR 19h9 and 1950 along the radials outside of the Fenced Area are sum llarized in Table ·v · Table VI summarizes t he r eadings of gamma radiation obt a inedin 19h7 191 8 1949 and 19S0 along the four principal r a dials _ri thin the Fe - riced Area ti'·' - During the 1950 Survey mr hr readings were also obtained along --' 1 _ the --other eight 30° radials within the Fenced Area marized by the _Figs • 5 and 11 These data are s um- - isodose 11 map s of the Crater and the Fenced Area shown in 6• Radioaut o graphs were obtained in the Fenced Area in 19h9 and 1950 with film packs twenty square inches i n area supported one inch above the s' ll face Y r hr · r ·e adings obtained YTi th these fil rns by densi tow eter t ichniques are su mmarized in Table VII -' _ The high and low readings $-- _ - _t -- 0- --- - - · ' • r - • _ •Q i l _ • • 25 - · -• fr- ''' - Table V BETA-G PJtMA RADIOACTIVITY EXPRESSED AS l rn H 'L ALONG SIX RADIALS OUTSIDE OF FENCED AREA 2 154 1950 Distance Direction in Miles from Zero from Fence 1948 o o 0 77 Oo26 0 067 00031 0 040 0 034 59° E of N '· _ Ool 0 2 0 3 0 4 o 5 66° E of s 11° E of s o 6 0 7 o 8 OoO 0 oJ 0 2 0 3 Bkgd 0 020 0 012 7 qf s c co4 o s OoOC4 Bkgd 0 061 0 012 o co6 0 002 0 032 0 010 0 010 0 010 0 007 OoOl O c 6 0 7 Oo32 0 13 C 002 0 002 Bkgd Bkgd o o o 6 C 7 0 8 0 9 1 0 0 0 0 1 Oo2 0 3 0 1 2 C 26 o h 0 '5 o 6 --- 0 080 Bkgd Bkgd 0 37 00013 Bkgd O C03 c · 003 Bkgrl c 47 0 19 0 027 - Bkgd Bkgd L _ Jli g -- ·· - --- 0 021 Bkgd Bkgd o coB Go008 o co6 0 008 C 010 0 008 o c 08 0 J 3 0 2 2 0 049 o 51 0 Cu9 0 032 00032 c 016 0 010 0 004 o co4 0 19 0 0049 0 042 o co4 0 006 o s ' i of N 0 026 Bkgd Bkgd _o oC OS 0 1 0 2 0 3 0 4 4 ° 0 012 0 010 o oc8 0 1 0 2 0 3 0 4 o s 87° 0 27 0 0007 O OC3 00013 Bkgd 0 004 0 010 o o 1950 0 37 0 21 0 70 o h3 Oo07 O OL6 0 012 0 012 0 012 0 027 0 008 0 012 0 016 0 0 0 1 0 2 0 3 o 4 o 4 38° w of s Mr _hr • Beta and Ga·una 1949 -- - - _ _i t - • I _ -- - · -· i · - ·· ·_ - - - - 28 _ N 2 5 _ -I Jl 0 ALL RESUL 1S N M'R H 1 RADIATION READINGS TAKEN I INCH ABOVE SURFACE WITH 2 6 3A- V iCTOREEN SURV EY ME TERS AUGUS T 1950 FIG 5 0 100 ____- - - - d SCALE 100' MAP OF GAMMA RADIATION IN THE GRATER IS ODO SE - ·• - · - f9' - - $i 200 - IS ODO S E LINES IN _ - ------·_ --· ___ __ - - -· _ · ' ___ ·- · · ·- _ Q 5_ · ·- _·- __· --1 · ·-- · ___ -· · -·· -· 1 -·· - - -·_- · _ - · - - ' _ -· I ·-- · · ' · -· - -· ·- -·· · -· y -·_ -· _ ---· --·· · -_ _ - -- ·_ - - - - _ -· · MR HR ··- - ·- __ · · •·· ••••· ·- - I -··- - - _ir - · I ·1 · ·-1 •••__J_ · · · I _ · ·' ' ··t · -· I ·I · -- j ✓t ✓ · ' · - - - · --· ' · AMOUNT OF TRIN ITITE V ·_ -- -· TAKEN INCH ABOVE SURFACE WIT 263A-V CTOREEN SUR VEY METERS _ __ AUGUST 1950 LIGHT 1- _··- __·· _ ·- 1 MEO I UM ¢ -- - - _ ·_ _ ·· 1 HEAVY i 0 100 ZOO l OC 0 0 SCO 600 700 600 900 10 0 0 It t 3 11o Ct ° - -- - -- -cd- -_ '- -- -- SCALE F·IG 6 · I 400 1 ISODOSE MAP OF GAMMA RADIATION IN THE FE NCED AREA - I · i c J - r _ Jl recorded are gi ven to indicate the variations that are pos s i ble on t he ground surface due to the variable pattern of the present disposition of Trinitite -- • Weir Area The beta-ga'E a ac t ivity survey measurements that were ta ken north · south east and west of each reference point established in Au st 1949 were repeated durL g 1950 A few random r eadings were taken during the first__week in July 1950 and two complete surveys of the area -were made about three weeks apart during- la te July and August 1950 A heavy rain clcudburst and several windstorms occurred between these last two surveys in 1950 •irr Table VIII Representative data for the two years are presented · Table IX shows the average mr hr readings around eaqh stake as det1 rmined August 22 19h9 and August 22 1950 These av·e rage rea dL gs are plotted in Fig 2 inside back cover The four radioactivity readings taken ar ound each stake were quite variabie in m2 ny instances This variation can be ascribed in part to the · particulate nature of the radioactive material and in part to the variation in distribution ·and density of the original F'all--0ut The particu- ' late nat ure of rcdioactive material on the surface of the soil in this 1 area is clearly illustrated by typical radioautograpbs r eproduced in Fig 1 o The high readings were invariably observed over loose sand and in many ' ·o cases small 11 glass beads were visible in those spcts The differences betieen readings at_ the various stakes in 15'l9 and 1950 and between the - • -· - l 9 5 0 point out the shifting of e radioactive contai ina__tion from · its orig inal point of deposition by the effects of the • erosional ··f ictors wind and runoff in the areao _ __ _ ' J 36 19h9 surface readings in the ce tral s ct or both in the chan- The nel botto lis c ' ld on the steep heavily eroded headla nds were extremely l ow This suggested that the c cntamination was possicly bP ing removed from the area by the action of Yia ter i'i'ind Eros ion in the Vteir Area and Crater Re ion i'ihen the Neir Area w s first visited on July e 1950 the ma L 1 drainage channel and the Weir proper nad 9_een filled with wind- blown sa 1d to a depth of six inches in eleven months this n aterial Surface activity read L 1gs were uniformly quite low over Soil profiles designated i'ir and WrI were cut through the drift material eighteen inches up from and thirty- s ix inches dovm from the eir jn the channel Analysis o f the depth increnents Table XI do not · show a uniforn distribution of radioactivity tr roughout this deposit This observation indicates that vnnd is of great importance in the lateral mi gration of radioactive contasnination frr this area Table XI BETA-G AJD A RADIOACTIVITY OF F IlJD-BLOWN DEPOSITS rn WEIR CIDJ 'NEL PROFILES Wr AJ'JD II' 1950 Dis sec '5-i•• of Soil or Sand Depth ·--- - i i 1 lches WI W n o o - Co5 o s loO 1 0 1 5 o 6 0 3 0 3 1 5 2 0 2 5 3 0 3 5 u O h 5 s o 5o5 6 o 7 0 0 3 Bkgd Oo8 2 0 o 6 2 S 3 0 3 5 0 3 G 4 0 1 0 2 0 3 0 7 0 7 Bkgd 7 0 7 Oo6 o 6 i O h 5 s o j 5 5 0 1 Bkgd Bkgd Bkgd 6 0 7 0 - 8 o - · 1 h -· 38 Fig 8' timber11 l4n x 14 x 24 1 l ong lying several h dred feet out from the Fenced Area along T-2 70 showing the wind- blown material deposited Note the sa 'ldblast effects wliich removed the soi'ter wood • A 1 The two sets of data presented above suggest that appreciable am ur ·ts o f radioactive material are being carried from the Crater by wind The absen c·e of any other concentrations of contaminants outside of the Fenced Area as a result of the wind erosion suggests that the wind- borne ·material ordinarily is redeposited over a wide area and is thereby diluted to the e xtent tha t it is not detectable with survey instruments Water Erosion or Runoff in the Weir Area and Crater Region Rain showers of suffici ent ir1 tensity have not fallen on the feir Area at any time when observations could be made on the volume of runoff quently there have been no samples of runoff water coll cted Cons e However a flash flood resulting from a r ain of ·cloudburst proportions f alling on -- - -- - WEIR AR EA - -- -··---···-··- • FLOOD NO WEST PLAYA _ _ SKET CH MAP OF CRATER AREA S_HOWING REGIONS AfFECTEO BY CLOUDBURST AND FLOOD - - A 1JGUS T 1 1950 I - -- --- - -----✓- - ✓ I MILE -- t h1tltri i -- · ••• ·' ' • I ff ' f-j · • • •· '_ · •· fr '·' ' ' 1 ' ·•·1 ' • f ' I • •l i · · T11blo XVII 1 ' ' ' • ·1· ' ·· it· •' ·- -•- •i i··1 - i - ·'i FI• l · __1 •1• - 1 · i v-t·- · INDICATION OF DOWNWARD MOVl MT N'l' Ofi' Reaults are given as disintegro tiona per second per gram o f soil Location --Depth in Inches o o o 5 1 0 t t ' t h '•Jlf 'J t' § I 'fjy 1 ' • yt' -i 1 • i i i J t 11 ¥ 1 tJ•'i I' fi Pt· • 0 o - ' - I - 1 0 2 0 3 0 - H -' - J 13 Jt b i l O - 5 o 6 o 70 - Ji 1 0 5-itl O 1 5 ➔ 1 0 2 o 3 ♦0 h o - 950 19 9 1950 19h9__ li 5 5 1 1 i 2 6 o 191-1-9 1950 19h9 6 1 LO 2 8 3 1 --- Bkgd Bkgd o 6 --- o 6 --- 3 9 --- 8 • r' Bkgd Bkgd B1 gd Dkgd o h Bkgd 5 o Bkgcl Bkgd Bkgd 7 Harvey Ga t _ _ 21-C 21-·B 21-A J o 1 6 ----- Bkgd 1 0 Bkgd Bkgd Bkgd Bkgd ALL INCRE MENTS BELOW o 4 Bkgcl 5 7 o 4 Bkgd Bkgd THIS LEVEL Bkgd -- i Lateral 20 AE-2 ' 1950 1949 195Q__ 1950 9 4 --- 2 4 3 6 --- 2 2 Bkgd --- 7 2 --Bkgd 1 8 Bkgd Bkgd · Dkgd · Bkgd WERE BACKGROUND o h 5 4 Blq d Bkgd fjf · 'I l ·· ·ri I I' 4 8 o 1 t 3 9 3 0 Bkgd Bkgd Bkgd Bkgd Bk d 0 i l3kgd Bkgd '' ' ' '' -' ' j ' i rH l ' ' 6 0 7 o fl 0 10 o - 12 o 13 0 - 15 o 14 0 · - 17 0 1 1 0 - 20 0 20 0 - _22 0 ti J · Bkgd H P Bkgd H P Bkgd H P iHf H P Bkgd H P Bkgd H P - -1H l·· rni i i r tjii ' f j • l j h' rl'· The half inch increments were collected so that a study could be made of the dilution factors when compare d t o the one inch increments · -l - H H P Hard Pan in this area is the characteristic layer of partially lime -cemented clay accumulation tha t occurs at various depths ¼1tr1-1 - 'f -- · t _ - ' ' s •I ' BI TA A m GAMMA H ADIOAC'l'IVI1'Y OF' ·rinf PH li'IJ J s- cOLLECTED IN AH EA 21 HARVEY GA'l'g-2 LA1'ERAL 20 AND AE-2 IN 19h9 AND 19 ' ' ' • ' i '- l 1 _l s - V1 J C0 Sl F I D1 N T I A L Soil Profile Studies within the Fenced Ar ea Six soil profiles -were taken each yea ' frc•m wi tt in tbe Fenced i r ea alo 1 g the line T- 90 - T- 270 wl ich bisects the Crater in a southeast-nort 'lwest direction Jo profil_e s_ were located ·200 tion Thes e and 1000 feet fro l Zero in either direc- Table XVIII presents representative data a comfariscn of beta- ga nnr a activity with- respect to depth obta ined from the 19h7 19h8 and 19h9 profiles a t - 50 7 6oo feet and T-270 6co feet A alysis of the 1950 Fenced A ea profiles have not been completed at this tLme The data are consistent iu dicating the a bsence of any factors other than isotopic· decay ac-t i '11 g to reduce the radioactivity below the first i nch be This is to eA-pectrcrl sin e the normal ar nual rainfall in the area is slight and conseque tfy 1fttle leaching by water can take place In 9_5n two soil profiles were taken within the Crater proper 75 feet nortfuea t of Zero and assayed ioF c ctivity 25 feet west of Zero O ly the former has been The data shown in Table XIX show a very signi fi- cant a nount K beta- gamma activity present down to at least two feet bel ow the surface _ Since - be radioactivity in the lower levels of the soil profiles within cmd a 200 feet from Zero can be attributed in part at least to neutron induc ition the soil profile collected in 1947 135 feet from Zero under thse c Sph lt road was partially rerun to determine the approximate half-life 0 fro n whi ch 2n t h-e neutron induced activity Table XX presents these data approxi r ate half-life of 740 days was calculated C 0 N F I D E N T I A I I i - · r- ◄ - - f j l ' ' ' - · i-- - • · t 7 z -- - - Soil Clays and their Fixation Capacities Since the chemical com- iLriations of the rc dioactive fission prcducts cont inatjng the Chupadera Kesa are not knovm by this laboratory at this time it is im ossible to co pletely evalu-a te the iHfluence of soil clays upon the observed di stri- bution of radi activity Ho·Never preliminary investigations involvLrig the fixation of soluble isotopes on clays in acid suspensio 1 pH ---- h-5 indicate that many factors are involved The ost apparent factor is the different degree of fixation characteristic of each specific isotope I Fixation of comparable concentra- tions of Cs 1 37 nd sr90 f O at levels far below the fixation capacities of the several clays test-ed r eveals that Cs1 3 7 is fixed almost quantitatively in so Z e ca ses whlle sr90 fJO is r-ot At most concentrations Cs 1 37 is fixed rs co' pletely and in no case less comple tely than sr90 Investig ti s oJ the effects of clay type on fixa tion were limited to tte - 20 i c n f ract ic-r of several n orrr al soils coomercial kaolin and a Utah bent0n i t Kz 1i 7te and n nunori llonite the primary mineral c on- stftuents c f kaolin -c nd bentonite res _ ectivelY are n on ally found in soils in varyi g _prc- --o-r t icns they repre sent t he high mon tmori1loni te · and low kaclin ite ertreoes b1 fixation capacities of the major soil -clays Benton ite adsorbs both csl37 and sr90 fJO more completely than does kaolin while tne adsorpti on of either isotope by the soil clays t ested is generally as gr at as or in excess of that of bentonite As an __example of a Chupa de -a rtesa soil the - 20 micron fraction of the four to fh-e inch depth incre - en t o f Pr ofile 21B was used This eoil was found to exceed bentoni te in the adsorption ·cf cs 1 37 but is except_ional jn having a l o er fixation capacity for sr90 190 r l • Greate r adsorpti on by the natural s oil clays can probably be ascr ibed in l a r ge part to the pr es er ce of organic matter and the ar ount of hydrated iron which is a ns ent in bentonite In general the degree of fixation of a given isotope b J a soil re fleets an equilibrium of that isotope between tha solid clay and liquid soil solntion phases The particular equilibriun esto blished is a function of type concentration and state of oxidation of isotope type of clay mineral par-t t _ a 1-e s ize distribution nature and amount of na turally ·-· adsorbed cations n a t-fu £ and _amount of or ganic matter etc Consequently a qomplete u der st ih mg of the role of tne fixa t ion capacity of the Chupa dera esa soi ls rith r egard to the distr ibution of radioactivity in - that -r egion -d epe _p cn the evaluation of these numerous factcrs This · is under investi g t5 cn in this laboratory and 11 be r eported at a later date · PLANT OBSERVATIONS AND RESULTS Backgrour rli S c r ples Whenever possible samples of the grass Boutelcua gracil is the predominant r rass sJkcies in the contaminated ' area especially on the Chupadera Mesa were collec ted grass sr ecies - or 1950 was of whidn at least Poa interior The o 1ly othe r five samples were c ollected in either 19h9 Typical data sho ing beta- gam a radioactivities · -·the · tops a n d l 'cJ idl stubs 11 of - gracilis a lon g with the uncorrecte d P-- - soi radioactivit 5 es a presented in Tables XXI and XXII A partial sum- mary of ether b s ck dl data including Salsola pestifer Russian thistle - wb ich is at preserrt -tl e p r edominant plant species in the Fenced Area is p esented in Table XJ111 59 Other plant s2 Illpl e s c·btained on the Chupadera v esa in 191 9 and 1950 consisted c f twenty sam les of juniper bark from various locations and ten saz1ples of yucca leaves collected in Area 21 -· activity of the ju r i r bark was ·1- • h 64 The mean beta- gamma radio- dis sec gm of dried mat ria l · 'E is is about £arty-five t 1mes the aver age backeround va lue 0 11 dis sec gm for- ti d s material The high values obtained with the -juniper · bar k are nost el y attributable to particles of radioactive material her ing to the rwgh surface 9f the bark These r ay wel l have been de- posited o r-'- ·t Jhe bark during the Fall-out fr om the r adioactive cloud The yim- c --ca ·samples had a mean activity of o· 30 dis sec gm dried material cra paired to 0 30 dis sec gm for the background salclpl es Yucca · bei-'1g a d ·e ep r cooted plant has not taken u p any of the soil activity which is r estri d to the upper '·two inches of soil Pl t uts f r oe the Crater Region At pr esent the only pl ant gr owing within the Fenced Area in suffici ent m1r 1oers to per 1i i t systema Lie sampling is t' -le ussian thist l e Sal sola pest_i f · r J Sa 11pl es of this pl t were coi - lected in 19 8 a nd 1950 along the four pr incipal radials within the Fenced Area Only a °1rel'l of the Eb 8 samples were assayed at that t i me but the cooplete l9 series as assayed i 1950 along with the 1950 sampl e s complete dztc n-e presented in Table X'JY is difficnlt The Direct comparison of t he data c 'll e to the isotopic decay occurring du ri ' 1g · the two years be- tween samp1 n g and the· r adiological a ssays of t he 1948 samples ' cases where sec rp l es wer e collected and a s sayed in The few 19h8 serve to point out ·' that the pla '1t s growi n g i i the Cr ater Region in 1950 were as radioactive as - -he sarr a s 1-€cies in 191 i 8 even though the soil activity has decreased · lllc rkedly in hat --' tir ie • The decrea se i n activity bet · een 1948 and 1950 in ll tr e plant s a - -le s cc ll e cted i n 1 48 d ow that the r adiois otopes taken up by the plant 1ad Discussion c a l apparent a verage half-life 0f a be ' lt JC0-40O days See 75 ·Root soil sar iples were not obtained with tbese pla ts hence ·no · exact evc luation -of--the ratio of soil- plant radioactivity is possible Some indication of ·the soil activity at the various sampling -locations can be obtained Iron the or hr data obtained adjacent to these radials Table VI and from the soil profile data Tables XVIII and XIX Labo ratc r7 and Greenhouse Studies on Soil-Plant Interrelationships - The data preseu ed herei come from a desert area where only nat ve or _naturally occu -r-ring vegetation was sparsely available Interpretation of the foregoin oil-p ant duta in ter ns of soil- plan t interrelationships in agricultural areas requires supple entary datao Greenhous e experiment s are currently in progress on the upta 1 e of sol uble radioisot opes from various soils by s eve ral eccno ru cally important crops to bridge the gap Five cro s barley beans carrots lettuce and radish are being grown on a California soil Sorrento In addition barley is being grown on three other Ca li fornia soil s · Aiken Yolo and Hanford and on a mixed I de s ert soil Mojave and Karrc typee typical of the Trinity Region in New Jiexico collected near Deming New Mexico the 4 The soils were sieved to remove 150 micron fractiono The soluble isotopes sr90 £ixed on this fL e f raction and tbe sails reconstituted iJO and cs137 were All soil etivi ties are bet- een 94 and 108 dis sec gm of reconstituted soil The con- trols are the sane soils with no conta'lllination In addition tc the soluble isotope being used in the present studies barley and radish are being grown in soil to which powdered T-rinitite has- beer added _to give activities of about 100 il'i s sec gm of ------· 62 e c s tuted scil In one set of pots the Trinitite is t horoughly mixed t i t ne total quantity of soil and i another set it is spread over the s - face of the potted soil f ormi IJ g a layer one half jnch deep _ Tables XXVI a d XXVII present some of the data obtained to date o Es cially notenort y is the wide variation in uptake- of the two isotopes c 10 the lack of uptake of radioactive r iaterial fr vm t he Trinitite which sumacly contaL s ooth cs1 37 and sr90 y90 as fission products of the - ew iierico oomb Test but in i n s ol uble form Table XXVI AMOU1-i1' OF UPTAKE BY l3A 1i IBY OF Sr90 y90 AND csl37 FRCM SEVF RU cmI'TAlHNA TED SOIL TYPES IN Aiken Soil Tv7Je • tt WEEKS ll ixed Hanford Desert Sorrento Dis Zsec 7gm Plant Dr- z Material · Yolo aves Control CesituJ Strontium 2o43 J 2 7 l cLC lo96 8 47 208 0 0 93 2 60 102 o 2 41 2 88 ll 13 o Stems - --Control Cesium Strontiu ' 1 3 86 3 82 13700 2 56 4oOO 1 56 2 JO 85 7 2 99 3 85 Soil Ac tivi t z c 5 137 sr9C £0 1C2o0 l o8 0 119 o 111 0 Dis l sec gn of Reconstituted Soil l Ou O 97 0 99 0 94 0 97 0 95 o l 46 2 018 72 o2 2 5 2 60 62 1 107 0 97 c 64 DISCUSSICX Radiolo ical Survey 'fi1e radiological survey data gathered from tl- e Chupade ra 1 esaJ particularly that from Area 21 and the Ratliff Area in 19u9 and Area 21 in 1950 show that measurable amounts of radioactive fis- sion produc contarnin tion resulti g from the First Atomic Bomb Detonation on July 16 l9h5 still are present throughout the hu dreds of square miles previously describe d Report UCLA-32 The detailed surveys of Area 21 and I the Ratliff Area show that relatively small changes in elevation 300 feet or less had no detectable effect evident at this late date on the distri- · bution of t e Fall-out The highest mr hr readings were observed in cl 1ffips of g -ass en fallen and partially decayed pinon and juniper needles or whereve r acc-u1mllations of organic matter occur There is little evi- de ce of lateral migration of the contamina ts in these areas except from the barren -cck- -r slopes which gave the lowest readings As previously in- dicated ·t h average re adings i D these two areas were generally beloTI mr r-J' O J I rec ividual readings ranged f r om O 006 to Oo5 mr hr with most of the 1 7 divid al l ocations reading about 0 2 mr hr ' In he Crater Region surface mr hr r eadings outside the Fenced Area are decreasing year by year a Dd the area showing measurable amounts of radioactive contar ination is decreasing in extent l l · _ · Only along the li e • of drift read i n6s of lliore than twice the instrument background en- a _-e c ou tered outside of the Fenced Area Within the Fenced Area the r adio- activity s decreas g year by year vrith a ·resulta t r eduction of the area i constituting a direct radiation hazardo 50 As of August 1 1950 the area for mr 24 r rs gar $ 8 radiation has shrunken to a diame ter of a pproxi ately 700 feet Over a i- eriod of four years thi s diameter has decreased 700 r feet i e from approximately 11 00 fe et tc the pr·e sen t 7CD feet I • • - · ' I • C ON F I DE N T I A L Erosional Factors in the Crater Region 65 The i'leir Area v hich is loca_ted about two miles north northeast of the site of detonation was originally selected and laid out for the purpose of studyi g the effect of ·the ·erosional agents w d and water in removal of fission product contaminants fr·om the -·areas of original Fall-out fil i le the data accumulated from this area to date consist primarily of surface mr hr readings they indicate that several factors enter into the overall erosional picture --- - The relatively high surface radioactivity r eadings in the northern sector of the Weir Area which is comparatively densely covered with shallow rooted plants points cut the gYeat effect that plant cover has in reducing erosion The southern sector is only sparsely covered by deep r ooted plants which offer little resistance to the late·ral migration of the radioactive c cntarrdnation and surface activi ty readings are consequentl 1 lower in t i h is sector In i 949 the drainage cha nnels in the Weir Area showed very low -m r hr o readi 'lgs _ both in the channel bottoms and on the steep heavily eroded This is evidence that water runoff is effect ively removing headlandso some pf the co otamination from the area of Fall-out · During the eleven months in e -vening between August 1949 and July 1950 wi 'ld- bl ovm soil filled the main channel to a depth of six incheso - Depth increments of - _profiles cut through·this material indicate erratic distribution of r adi o ctivity throughout the deposit Table XI p 36 of When the large amount terial' i nvolved is taken into account the total activity represented by this deposit is great - 1 - Wind Erosion F'urther opportunity to study the effect of wind as an erosional factor in the Crater Region was found in wind-blown soil ·accu ulatioris several inches deep at the Crater Fence and adjacent to a CONFI D ENTIAL 67 Tr e drift rr aterial collected a long the timber and I-beams northv est of the Fenced _ rea is knov n t o · have o ccumulated during the early i art of 1950 as the bea i s were placed there during January or February of that - • year • This is based on information furnished by ¥ r D hlacDonald co- mrner of the land on which the detonation took place Beta-gamma radio- activity in this ind- bloYm n aterial ranged from ho2 to 603 dis sec gm This material not being in the Fall-out area must have corae from within the Fenced Area a d is conclusive evidence that radioactive material is being tra rispcrted from the Fenced Area b wind This is quite feasible since no vegetatio 1 was growi Tlg in the Fenced Area July 7 and hence accelerated wind erosion was possible fer at least three months See Fig 17 i Fig 17 Grater July 7 19S0 sho' '1 ing no growing vegetation JP· t ·' ' ' 66 _arger timber and a steel I-beam located 300-500 feet northwest of the enced Area along T-270 • 1 The depth increments of profile samples collected in the drift i aterial along the fence showed a significant amount of beta-gam ma radio -- - t6tivi ty throughout w th some increr ents showing as much as 12 dis sec of silt and claya · Such a level of activity could only have originated o 'rom well within the Fenced Area fo estimate is possible of the exact ime at which this aterial was deposited but signi1ica t accumulations rere first observed in 19h8 It has no doubt been accunul ating at vary- Ilg rates during the years since the detonation especially after the 19h8 rop of thistle the first significant plant cover since July 1945 ac- umulated at the fence In many locations accumulations of wind-blown lants reached the cp of the fence See Fig 16 - Fig 16 Thistle accumulation at the Crater Fence-south sj de ' · - · -- 68 CO N FID ENT IAL 2 Hater Erosion er Hu no ff The first rain of t he 1950 s ea son fell on J' lly 6t o · From observations ma de in -the Fie l d two days later it was clear that this rain did not result in any appreciable runoff frorc the Crater Region There was no evidence of runoff from that area having oc- O curred between t e time of this observation and July 26 hen the survey proper was startedo Several light showers fell on the area during the following days none of which resulted in runoff The heavy rain of --- Aug- st l 1950 a ong the west face of the Oscuro ountains resulted in a flash flood covering the area from Lateral 2 soutlrRard and including the Crater See Fig 9 The data obtained on samples of water silt and sand collected dur- ··· ing the flocd from and adjacent· to an arroyo draining the area between Laterals land 2 Table XIII indicate that radioactive material is carrie-d b runoff water fro n the areas of lesser contamination The most active material on a comparative we i ght basis were the dissotved solids which probably include S n all amounts of non-filterable clay particles of_ sub-micron sizeo The -water-borne silt and freshly deposited silt rrere of le ' a ctivity as 'i as the ttnormal'' soil of the area ' See footnote p 42 o After the flood had receded and the ground had dried out several sa -ples of freSI' ly deposited silt and the underlying sandy s oil were col-lecta d in and around the Fenced Area Silt deposit within the Crater it- _- self ·although showi -r tg beta-gamma radioactivities as high as 22o5 diso sec • gm were lways several times less acti e than the underlying soil or sa d Silt and soil sa ples collected on the east side of the Fenced Area Observations made by K H Larson during a three-day reconnaissance preJ nary to the Biological Survey of August 1950 CON FI n· E NT I A L V at the point of major breakthrough of water entering the Crater sho ed backgr-0cmd activity Comparable samples collected at the point of najor breakthrough on the west side of the Fenced Area had beta-gamrn a activities · ·_ · o ' -·3 d-i s · sec - gm 1 2 To supplement the infcmation to be gained frore the ' Vater-borne - samples collect d a survey was made of several small washes north and · '-- Y est ·cyf _the Fenced Area and of a large arroyo originating 1 5 of tbe fence to which the bulk of the observed runoff funnels miles west See Fi g 18 No evidence was found of measurable concentrations of radioactive _ material in any of these drainage channels or on the playa on which the -- ·- entire drainage of the area terr ri nates l · Comparison cf ·m_ _d and tlater Erosion Comparison of the two sets of data on erosional i 2 ctors in the Cr2 ter Region indicates that wind has been the more important erosional factor in spreading the contamination c · from - the area originally affected by the detonation The much higher ac- -- tivity associated with· the wind-blom1 drift materials compared to silt I • 1· ' - de osits at the perimeter of the Fenced Area is in itself conclusive evi1 dence of the greater effect of ind The conclusion is further strength- · ened by other observations in the field and by laboratory studies on the _ ' ' ' ·' -- olubility of Trini ti te - - J · · - · - According to information furnished by Mr Do li acDonald the mon ths of Y ay and Ju '1e j 1950 were particularly dry and windy with almost daily severe desert storms affecting the entire valley in which the detonation 1 The large arroyo which originates L S miles from the west side o f the Fenced Area started four years ago according to Er J _ MacDonald At the present r ate of recession this arroyo could conceivably come to have its origin somewhere within the Fenced Area in a fe years It is not lUlcommon for deeper arroyos to form during one ·rain due to excessive runoff - _ - _ · - _- - - - f ' t 'I _ · __ J Nl _ - C' -- ' -- -- - - ---- - 9 fft#Jt - p_ 1 - ·- -ri - ' - • '' ·f • ' t ·- $- ·j • 7· -v J t % · '¾_ i • - c - - ' 70 Evid ence for tl is was apparent in the N L d-tlc· 1 soil deposits in the f eir rea along the I-bean1s northwest of tr e Crater and in fTesh wind-blown deposits a l ong the varic us Fenced Area 11 black-tcpn rcc ds around the ✓ Durir g the five weeks of the 1950 Field Survey seven dust storms ' ' ere observed 'li th wi 11ds of fro n 35-55 these stor ns ca e fro the satie direction niles an ho1 r I✓ No two of Dust clouds were observed rising f r mrr fifty to several hu dred feet above the floor of the·valley See Report CLA-108 p 11 I ✓ Fig 18 1 5 miles This also illustrates a A wide and deep arroyo near its origin est of the Fenced Area tleep rooted plant The r L d drifted material sampled although repres nting a large total ar iount of activity by no means gives a complete measure of the total activity being carried by this medium from the area T he wind-blown material deposited in the vicinity of the Fenced Area consists mainly of - __ r- - -- l C O NF I D E N T I A L the coarser fra tion 71 No estimate is possible as to how much activity is carried away with extremely fine particles to be distributed over an inde- termir ate but extensive area r L ability to detect concentration of wind- -r_ • 1 - borne ontaminants by the usual survey or l aboratory procedures away from - - the Crater Region is due merely to the dilution attributable to the wide - - · ·a sea ttering - ·-However j -- - ·it has been demonstrated that even on the cake st - days air- borne -dus in the Crater Region contains significant amounts of ' · alpha emitters presumably plutonium See Report UCLA - 108 pp 11-28 • - · · · -' Future detection of plutonium activity may well beccime the best measure of the extent of conta n ination now that suitable procedures have been developed 1or its assayo In contrast to the great frequency of dust storms in the Crater _R egicn f _lash floods are a very rare occurrence In the four years that the area has been under observation by this group only two flash floods ha e been observed one in 19h7 and the other in 1950 The surveys have all been conducted during the season of greatest rainfall in the region the month of August t' There are several fortunate local conditions preventing the spread ·- I of material from t r e Crater Area by water All drainage from the region - is to a pl a ya approximately four miles west of the Fenced Area -t· Any con- i -tamination carried from the Crater Region by water would be • ·- 0 found in that _ ' relatively small areao Complete absence of detectable amounts of radio- f active materials in this area clearly indicates that no significant amount of contamination has been spread from the Crater Region by t is erosional a gent This is not surprising· in view of the virtually compl ete insolu- bility of Trinitite in water or weak alkali It is very unlikely that any particulate material would be carried directly from the Fenced Area to the CONFIDENTIAL -4£-a ·• - C ' ' l lt I' - -- •- _ 1 _ t- - ' · ' J $ -_- - - · l 72 playa v hen one considers that tbe duration of t hese floods is a matt er of inutes and t at the load of sus ended material carried by the water is in the process cf being deposited as the floods fan out In acdition there bas never been an observed cloudburst directly over the Fenced Area and consequently no £loads have originated in thz Area Soils An lysis of the depth increments of ·the s oil profiles col- lected on the ·chupadera Mesa show that the radioactive contamination is still concentrated in the upper one to two inches of soil However there ·is so e indication fron the ·1950 data that downward igra tion of the radi·-- 02 ctive fissicrl pr oducts y be taking place For example the depth in- crement fr cm one to two i Tl ches at Stations 21-B 21-C and Harvey Gate showed ckgro' l d activities in 1949 and l c0 0 4 and 1 8 dis se c gm of soil r espectiTely in 1950 This is the first indication of any such down- ·ward rr igra ion of fission product activityo Further investieati on is re- ·' quired to def 7 tely establish whether this is actually taking place or if these v-alu es e an artifact If borne out by f' lture s tudies this can mean that the contaminants which are considered to have been insoluble up -1 o this tme are becoming more _r eadily soluble due to weathering and thus probab y are becoming more available to forage plants growing in the areao It is cnly t - ro _gh future surveys of the Chupadera llesa and correlated · -· laboratory stuc ies that the ultimate answers to the many problems involved -·· 'f ' · The existing levels of beta-ga '11I la radioactivity in the surface inch -'• l of soil on the C upadera· rtesa ranging from 1 to 9 o4 dis se·c f JII o of soil ·-__ · F tnay not at first appear to carry much significance However if one as- sum es that the density of the soils of that area is 2065 the col llllonly ac·- cepted figure and calculate s the activity per square foot of a spil layer -· 73 one inch deep the acti vi ty on a per gra n basis is iagriifie d app cxirr a te ly This eans that an actiYity of 6 dis sec gn 6 250 ti meso 0 cc res onds f b f · to 37 SOO dis seco or approximately one microcurie per square foot As yet no evidence has ap eared to indicate any dovmward migration of the radioa ctiye materials in the Crater Area l Profile depth increomts -· show decreasing - activity from year to year at all levels here activity is • · _ pre sent · Event lly this picture will change as weather ing of the Trini tite progresses further and the resultant material becomes more solubleo t- The small ·SJReU lt of a ual rainfall in the area could then bring about - ome· leaching action 5 e C A On the basis of pre ent knowl edge it appea rs that nee - ·· - V eral decades might be required before this occurs The f o re oing discussion has been based on the assu 'T ption tli a t the radioactive contaminants hav remained on or near the surface of the soil purely by vi rtu e of being soluble in water It is conceivable that even now - the bulk o f the f'is sicn product contamination on t he Chupadera 1Jesa is in a soluble form a d that it rer aj_ns near the surface as a result of being stror gly adsorbed r fixed on the clay particles in the soil lirain ry laboratory studies on the fixation of cs 1 37 Pre - and sr90 y90 indi cate ihat these t o isotopes are independently f ixed by different clays and in di f ferent mounts -j csl37 is a1Jnost quantitatively fixed by the · clay fraction o the soil from Area 21 while 3r90 y90 are fixed to a much lesse - degree by the same clay This makes it possible to predict --t hat in that particular area soluble cs1 3 7 would remain at or v e ry near the surface of this type of soil whereas sr90 1-BO would be expected to gra t -downward by __ t he leaching a -c tion of water in the present soil- plant laboratory studies o This has been observed sr90 y90 is leached from the pot when excessively watered while cs 1 37 is not ' •• _ The -i_inpor _tant 5'h-oi 7h implication of thi s is t hat certaill radioisotopes on or very near the surface are not readily available Lo plants whereas they can be taken up and assimilated when present at the depth of the major portion of th root svstem of the plants especially so if weakly adsor-bed on the clay present ill the soils Scil-plarit Relationships and their Fission Product Equilibrium The backg ound st es of plant samples from New exico areas out ide of f the known area of contamination conducted to date ha e indica te i a relatively Yiide range cf natural radioactivity within a plant · species Report UCLA-7 _· See Even greater variation among species has been observedo The Boutel oua gracilis s2ll ples collected in 1949 had beta- gamma activities rangir g from OG05 t o c 44 ·d is seco rzm of dried plant material rhe root soils from the two extremes had activities of Oo35 and Oo64 dis o sec gJ ll • cf E oil Si - d lar v2riations ·t ere encountered in 1950 In general compar- able variation s were observed in the other control species sampl ed Agree- ment bet qeen naturu ally occurring soil a '1d plant radioactivity has been pear based en the in o r- tion ·obtained so far development of better sampling 1 tec bniques is per r a ps -tl e ar s-Ner to this pr oblem It -is imposs ble at this time to assign any definite reliable value for normal background r4dioactivity to _any plant species studied to date Further study of the subject ay enabl e r easonabl e limits to be fixed for a given plant s pecies bePn cbservedo Dei'inite differences between species aI1d genera have Grasses in general have much l ower activities than for example Salsola pesti er or various shrubso The lack of agreement between plant and soil beta-ga r m a background radioactivities indicate factors other tha '1 speci e differences play a t1ajor ro'le in determining the radioactivity of pla t s growing in any particular areao betz -5arr a radioactivities cf fission r r0duct origin of the ean 2c-utel u2 gracilis s a m1 les collected in Area 21 in 1949 and 1950 were C h88 and 0 332 dis sec f JP- or 2 8 and ·L 8 times the mean background values for the species respectively averaged 12 67 Root scil samples for the two yea1·s a n _ S 9h dis sec gm or 18 1 and r 8 5 times average soil background • · Comparison of the ratio of soil· to plant radioactiyi ty reveals tr at in 3 85% of the 1949 the activity of a gram of dried plant aterial was a tivity in a gram of soil In 1950 this- value was 5 59% Ttis indicates that the remaining soil activity is afparently becoming noye available to the plants growing in the area I The fact that any ac- tiv i ty whaisoever -is being taken up by the pla 11 t is a significant observation The relatiYely greater uptake observed in 1950t compared to 19h9 pcints out that as a potential biological hazard the remaining of fission pr duct c ont a-- ---iTJ aticn of t he ChU padera Besa is relatively greater now t han iI the pas _The need for further investigation of the Chupadera Mesa in the matter of soil-plant relationships is indicated since only by field observation end corz-elated laboratory research can the equilibrium values be established in this or any other contaminated area - Salsola pesti fer Russia ri thistle growing within the Fenced Area in 1950 vms as radioactive as was the same species in that area in 19h8 based on the fel'I st -ictly compa rable assays This is an indication that l 'the thistle upta e is at equilibrium with the remaining fission product contamination i the Crater Region Table XXV p 60 Further the esti- n ated half-life in this ylant material is 300'-L oo days whereas the esti - mated half-li± 'e in certain soil -sanples from this area is approxi roa tely 700 days· shi ps The difference may be accotL ted for by the soil-plant r elation- Wi thi °'l 600 fe et of ground ero which is the pre·s ent approximate - - ·- · z 1ft l 76 detectable lL -nt of neutron induced radioact vity t he r e is t he dded pos sible corrplicat1ng fac tor that the total amoant of a va ila l e r adioisotope s neut on ind ced is great enough so that availability of fission p r odu cts is no longer the factor limiting uptake I From the li I ' i ted data arailable at this t ime on the uptake by pla11ts of radioactive fission products from X r-finely powdered Trinitite Table XXVII p - ·t ·that-'2DY 6J it is highly improbable of the activity in t h e plants growing in the Crater ccmes directly ·l'•_·srom the macroscopic fragments of this material ' ·· '-- It would appear that in order for Tr b itite to be com an available source of radioactive material ' for plants the particles would have to be L11 the sub-micron size range The pr-e1i t rina ry greenhouse data presented in this report s erve to point out· sc Tre -of' the rr a riy factors influencing fission product uptake by t pla Tlts rith potenti a1 subsequent transfer to animal s and man Although - incomplete tbese data indicate that the identity and chemical form of the isot opes$ d i2f erences in soil composition and its chemstry climatic · factors and i liherent dif ferences in plant species all play important roles in the overall picture It is apµrent Sron the data presented that no hazard from external · •--------------------------------------------- --- _ -__t _tal body ex pcsure to penetrating ionizing radiation gamma rays exists - any place out side of the Fenced Area Although this has been pointed out _________________________ - · _ many times previously we c2n not assume at this time that no hazard exists i outside ·the Fenced Area from the -widespread fission product contamination t ·· - - - - - - - - -_ _ _ ___ ___ __ _ _ __ T_h e problem outside of the Fenced Area is entirely different for there are many FOtential long ter JlSidious hazards from the present low l evel con- 1tamination which is the focal point of these studies ginning to accunu late from these a -ri ards exist Evidence is be hat such haz- See Reports UCLA- 108 and 111 · _ 77 Continued study cf Trinity Alai--riogcrdo Area in New Mexico especi lly the Ctu-padera 1' esa in conjunction v j_ th continued laboratory and greenho- J se studies on soil-plant relationships could furnish much valuabl e infor tio on what may be expected to result foll owing a detonati on anywhere in the UnitE id States Only from actual fie l d stuclies and correl ated laboratory research can e hope to gather and correlate information which takes into account all of the major factors which will determine in time the equilibriu n reached with respect to radioactive fission products in e total bioloeical system As our knowledge of this equilibrium in- c eases so must our ability to predict the pr esence or absence of potential long term hazards to nan become rossible and logical Sffi fl 1 ARY Ai JD CONCLUSIONS This rer-0rt presents a greatly compressed SUY ary of additional r a diological observations and some c onsideration of the soil-plant interrelationship s due to the residual radioactivity of the Fall-out from the First AtoT ic Bomb Detonation of July 1945 in Nevr llex ico The l9h9 and ' 1950 Biological Su eyswere in part concerned with the determination of I i the fo rth and fifth year distribution of remaining fission products in soils and plants md their relationships with respect to biological · ·_ cyclir g Radiological Survey The radiological survey data from the Chupa- _ dera 1'' esa twenty to thirty- fi v-e miles from ground- zero in 19L 9 and 1950 product con tamiD ation thrcughout the hur dred s of square miles delineated Relatively S1J all change s in leva tion 300 feet or less have no 0 detectabl effect evident at this late date on the distribution of the - ' • - - ' - - ' • -t • -- · show_ the continued presence of -r easurable a lounts of radioactive fission L'1 19u8 ' · 78 Fc ll-o' l t an ts T ere is little evic er ce cf lateral i l 3Tc tion of the contarnin- tl1e areus slli--veyed h r this r-1etbod except fr om t ·e barr en r ocky i II slo' es '1 the Crater Region surface ·rnr hr readings outside the Fenced -4rea are decreasing year by year Rithin the Fenced ·J rea the radioac- tivity is c ecre asin 6 with a r e sultant reduction of the area constituting a direct external total body radiation hazard As of August 1950 the area for more tr r- 50 mr_ 2h hcurs gamma radiation has decreased in diameter fr om a proximately 1h00 feet to the present 700 feet in four years Brcs onal Factors in the Crater Region l r i nrl Erosion The depth increments of pr ofile samples c ol- lected in drift material a l ong the Crater Fence show a significant a mount of bet-a -'g radioactivity throu hout with sone i ricrements showine as n uch 2 12 dis sec gm o of silt and clayo These leve ls of r adioactivity could only baTe originated from vrithin the Fenced Areaa No es ti -nate i s possible oi t he -ate of accur ulation of wind-borne material however sig ni fican t a o n ts -were first observed in 1948 especially after thf l t year 1 s cr p of t nstle accunul ated at the fence Betc -ga -nm a radioactivity nas found 3CO to 400 feet outside the r Fenced i _-r-ec in seven to ten nches of Ylind- blovm material known to have acc ulatec rithin the fir st seven months of 1950 Vegetation is the most imFortant influence in decreasing the remcval of wind- borne materiala This is particularly evident in the Ifeir Area a repeatedly studied area tHo r iles north northeast of the Fenced Areaa hater Erosion or R off Data obtai led from samples of water silt ar d sa ld collected during a flash f l oc l 11 from the area be twe en ' Late sals 1 2 -- i 2 Left indicate that radicactive material is ra sport€-d by -2 ter rur c f fron areas cf lesser c ontamination Silt deposits · 7ithj_n the C c-2 ter although showing beta- ga m n a activities as high as 22 S dis sec gmo were alvrays several times less radioactive than the underlying s oil or sa i a Tliis observation is in accord with the well-known physical lm' S governing erosion and sedimentation and the characteristic pattern of flooding of t 1----- e Fer ced Area thus far o served 0 Su rveys ere made of several washe s and a large arroyo north and west of the Fenced Area No evidence was found of me asurable concentra- tions cf r dio ctive aterial by the field survey It ethods employed in any of the draina5 e channels or on the west playa ' Apparently the dilution factors caused by the large amour ts of ·non-contamir ated soil transported by tI'-e several floods and rrdxed with Fall-out material have con tar ·- 1a tion t he terr iinal d eposi ts Studies 01 the solubility of Trinitite indicate that even finely powdersd 'Iri nitite is cnly spar ngly soluble i '1 water and dilute alkali sol tions a d c ly slig tly more soluble in dilute ac ds This factor of ns6lucility· c- 1 pled ti th the initial deposition of Trinitite· as particulate material OY r a great part of the area conta inated must be taken 7 into CO siceration as a partial eA1 lanaticn of the lag of several years _ before ission pr o'ducts or alpha em i tters a ppear in the biological systems · ·· Com-oarisor of ind and Water Erosion Data on erosional factors in the Crater Region indicate that wind has been iliore important than water in spreading contamin2 ticn This is due tc the continued effoct of wind dur- ing the i ong dry periods of more than ten months of the year in this semiarid area Vegetation protects the surface from the wind effect however this is of kpcrtance only duri 1g the term ined by t ce max ir tu _ growth peri d -whj er is de- ar o- 1n t and d- 1ration of rainf JlL ind- born e deposits containing a large total amount of radioactivity do ot afford a complete measure of the total actiYity eing carried by this medium The velocity of the wind varies from time to time ·a d -the particle size carried is dependent to a great extent upon the vel city r There are of course other controlling factors too such as surface -phenomena oisture content etc Gentle 7ii '1 ds wo· 1ld tend to carry only fine - aterial thus acting as another leaching out process of a specia 7 i zed nature No accounting can be JT ade of wind conditions for a ' - great part of the year so that many assu r iptions must be ·d rawn from the I l L 1 itedi obse·rvation period which may or may not be cr aracteristic of the I ' rest of' the year Soils bl There is some indication from the 1950 data that downward 1 migration of radioactive fission products in the soil is taking place on the Chupadera l' esa _ an average of approximately one microcurie per square foot one inch deep 6 o dis sec gm of soil - - I As yet no evidence has ap- pea red to indicate any dovmward migration of the radioactive naterials in the Crater Area The predoininance of large particles and chunks coupled with thE' general insolubility cif the Trinitite are probabl r important fac-_ tors in the delay of downward migration The importance of considering individual isotopes with respect to fixatiom and vertical migration is emphasized by preliminary laboratory ' studies on clay fixation Cs 1 37 is almost quantitative ly fixed by the clay ' · -- - ·· - s Ji -1 I' The existing levels of beta-ga i llna radioac tivi ty in the surface inch of soil from Area 21 on the Mesa range from 1 0 to 9 4 dis sec g□ o or t-0 i fTJlf'f 7j'fjf t-- ti 81 r · d t o a muc h fr-action of the soil from Area 21 while sr90 ·_r90 are lX lesser degree by t e ca n9 clay S il- -·l2 1t Relationships and their Fission Product EquiEbriu It is not ros sible at ' tis tiffie to assign a rel i a' le value for norr al background radioactivity t o any plant srecies studied to date - · ferences be t ' ee 1 _species and genera have been coserved However dif- The nor al back- ground activity ir a-grass samples Eouteloua gr acilis c cllectgd cutside oi ccntamination r anged from o c5 tc O li4 dis sec on • _ of dried pla aterial The soil associated with the gr ass roots had the known area ba kgrc1 md acuvf ties rangfag f r ' ll O 35 to O 6 i dis sec fJno of oil he r2 0 cf soil to plant beta-gamma radioactivity of residual ' ' ·fjssion p r-ucuc'ts in Area 21 reveals that in l9h9 the activity of a gra l - cf dried ill zn t material was 3 e5% cf the rad i oa ctivi ty in a gra n cf soil 7hus tte resinual soil contamination is a J parentl y be' twe -ty-ei £1 t • o JE ncre available to the i rasses growirg in Area 21 1rr 1 ' e S from r ou 1c - zerc 'l'Le pctee ir-i ality of an incr- a8i'1g biolo ical hazard is pointed to _ by this aL r T o l j ncrease in fission prcduct uptake by grass Ho sound pre- dictJ o i c - eYen an csti r ate cf the equilibril w ich must eventually be reacl1ed en It he 1' e sa c2I1 be made fron the facts · availarle at present The re is am indication that the uptake of remai '1ir g beta- ga Ti la '· r adioacti i t- b7 E assiar thistle Salsola pest if Gr in the Fenced Area has r eache f -2t eq r_ilibrim1 s mall nUir hc r o 5 s-- mples collected from the fenced Area in 1948 and 1950 'I'he estir ia- E d 2 1 f-life in this pla 1t a tP rial is 3C0- 40G days whereas the estimated h alf-1-'ife in certair scil an ples in this a rea is apr roximately 7CD J udg L --i 6 fro ' the li iteci lator s tory c ata available at this time on the upta' l by plants of fis s icn prcducts fro - finely powdered Trini ti t e it is i m prc ba ble that any of the radioactivity i ri the plants growi 6ir1 the Crater five years after the detonation comes directly from the macroscopic fragme ts of this material It may be several years yet before fission p oducts- become available to plants in the Crater Area r - liminary greenhouse data presented from research in progress indicate that the i dentity a 'l d chemical form of the isotopes differences in soil -zomposition a d its chemistry climatic factors and inherent dif- ference--15 in plant species are all important factors in determini rig the behavior- of the fission products in the overall biological cycle It is apparent rom the data presented that no hazard from external total body ex posure to i onizing gar ma radiation exists any place_o tside the Fenced Area Al thcugt tr1is -- as been pointed out many times previously we can not assume at this time that no other radiological hazard exists thereo It is abundantly clear that the entire area is in a state of f lux with respect to distri bution and biological availability of radioactive fission products and ur fissioned raaterial Evidence is accumulating from - the a ual Biological Su rve ' s and correlated laboratory studies that many years raay pass before a bi-o logical equilibrium with respect to residual co tamination is r eached Only when we are in a position to predict with some degree of certainty Yrhat this equilibrium will be can we assess the abserr c e1 presence or mar nitude of the biological hazardo --- - __Hkr t