CHAPTERIi Gross Activity A. Land Plants Thehighinitial activity of the “edible plants’’ (Graph 2) was probably due to surface contami- nation caused by the direct fallout. The rise in activity after a year after the fallout occurred may be due to (a) sampling and counting variances, (b) the ability of some plants to concentrate Cs’ (see Section Radiochemical Analysis), (c) the increased availability of the radioactive fallout material to the plants, or (d) a combination of these factors. Initially the ac- Graphs 2 and 3 indicate the general levels of activity of edible plants (pandanus, papaya, breadfruit, arrowroot), and coconut meat and milk at Rongelap Atoll together with their decline of activity with time.’ ? Tables 1 and 2 show. the analyses made by NRDLfor their first survey in February 1955.? Table 3 is based on the February 1956 survey.‘ tivity in the coconut milk and meat was less than other edible plants, but the rate of decline of activity has been less than for other edible land plants due principally to the higher percentage uptake of this longer-lived Cs"’. Tables 4, 5 and 6 show the analyses by ee HASL-:& Table i—Summary of Gross Beta Activity in Miscellaneous Plant Samples* AVERAGE ACTIVITY (gc/g x 105 5 > Punt MaTeRu. IsLanD Likiep Utirfk Grass. ..--.----..-------..5. xn Coconut leaf... .-..---..----}--....-- 400 W000 Rongelap| Busch 3000 i [eee fe Coconnt frond stem.......-.-}-..---..]--2 22.222 e fee Coconut shell. Coconut husk......-..---..o Coconat sprout. LT? L6 Bprouted coconut roots... -..)-....-2 fe. Besevols leaf. Scaevols trunk section ......}-.....-Arrowroot stam. Arrowroot leaf... .- - 8300 78 eee] eee eee ee 53 W f.---.22.]--2- 2-22 72 fee |- - -.]- - - -] -. eee eee Kabelle Lukuen 1900 1900 fee en eee 20 2.0 L1 j. Bananas 46 [o f 140 |-.........]....-----.]--------]------ ene 150 7 Ho H10 |..2..2--.. 740 ee eee een] 35 fee fe ek = Wot weight. © As determined on basis U:O: standards and empirical) scattering and absorption corrections. *Collections made about February 1, 1955. Data reported as of March 1, 1055. Lomuilal) Bikar {Eniwetak 2100 8, 000 5600 180 mo 670 fie] fee eee 120 }..-----... apennneee ene feee nnn eee 61 |..-----. ween eee] ee eee Gejen M7 |..---..... 19 j.---2 22 |---| eee ee ee fee Pumpkin. Limes_.-.....--Taro Vines... Eniaetok| Labaredj| 100 fe 200 &4@ fol fe eee 67 2 oO eee] eee [ene een ee ee fee eee ee fee fe [ae eee |e eee nee om mo 5