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Tomato and squash plants were grown in greenhouse pot cultures using soil from Rongelap Atoll, which received fallout contamination in 1954. The treahents involved variand CS-137 contents of foliar sanples of several woody species collected on !longelap Island are also Lncluded. In the most higher than those of t%helower leaves, but one species consistently showed higher K but lower CS-13? in the upper foli~~e. Law K status of the soil and differences in mobility within the plant may explain these patterns. BEST COPY AVAILABLE lcontribution from the Universi~y of Washington under Contract No. AT(45-1)54D, with the United States Atomic 2Department of Botany, Laboratory of Radiation Biology,
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‘fnedata reported here concern the upuka of C3-137 by plants from soils of Rongdap Atoll, Marshall Ialands, with a.~cial refecerice to fertilization of the soil wit-h s, 2, culture tests ush~ Rongelap top soil, as well as foliar analyses of native vegetation gzowing ma the atoll. Rongelap Atoll was contaminated by radioacclve fallout on March 1, 1954. ,~e principal radimuclide found in plan: tissues in 1958 anG cium carbonate fragments dsrived fmm corals and foraminifara, into which is incorporated about 9% orgaiiic rnattar. In the rather coarse unsievad field soil the pH is 3.O; the CatiGn exchange capacity ia attrLbu&ble antirely to the organic fraction and is about 8 meq per LOO gm; among the axchange*le cations thera am about 80% Ca, 15% W, 4% N&, and O.?>gK: the soil is coarse, very friable, and highly porous.
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portions of soil which were placed into 6-inch plast.h uniform seedlings were transferred to the pots, and ‘d by gaxmna ray with distilled water as needed. Plait.,3I about 30 days, and the tissue oven-dzi~ C9-137 content of the dry material was d{ spectroscopy using a three-inch thallium foliage, and were cofa~site samples from several plan: vicinity of a collecting point. The tissu~ was over and analyzed in the same manner as the greenhouse sam; the fertilizer treutxaents and tho CS-137 in disintegr,
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minute per gm dry tissm wara: unfertilized control, 490: results are particularly interesting because all fertilizer additions depressed the uptake of cesium. mere ~as m~k~ zesponse in yield to the nitrogen and the potassium fertilization, but not enough for dilution to account for the differences in CS-137 contents. The absence of rackxxksium in the P-K tramtment was lssociated with an unusually high K lavel in the plant Lissue. Follow$ng this preliminary experiment with tomato, a further gzeeahause trial was mad= with squash, variety Hubbard. Squaah was used because iT.is oxw Of the few harbaceous plants and the plants grew well except for some chlorosis which was not entirely corrected by the application of 1.5 mg Fe per pot TM plants were divided into upper leaf, fractions at harvest. 3ince the rasults the same for the different fractions and Table 1 presents the yields and K and Cs lower leaf, and stem analysea on the basis of the entire shoot. The results of this experiment wera in general similar co those with the tomato, although there was
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from cha N0P4K2 treatment contained CS-137. In all cases the fertiJ.izer amendments caused a sharp reduction in the CS-137 content expressed on a d/m/gm dry basis, although this eff~~- could not be associated w$t.h a particular The depressive effect of fertilization on also evident whm the total CS-137 in the cesium uptake is not explain the dilution by a greater amount of dry yield can reduced casium content . In the different PrLevels were very high. eap@cially Ca ranged from 690 to 980 meq per in the lower leaves, in whick 100 gm of dry tissue. Jumlvses of Laaf Tissue Collected on RonqelaR Atol~ Foliage samples have bean collected in the field, primarily from woody plants, which dominate the atoll environment. In mast cases Jeparate samples were taken of the upper and the
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and CS-137 in three of the cormaon species are given in ‘&e lower part of Table I. Potassium contents of the upper foliage have consistently proved to be much higher than :Aose in the lower foliage. On the other hand, Ca and Mg Levds hav~ been consistently higher in the lower than in the upper leavss l In the case of CS-X37, the pattern is consistent in the samples of a particular species, but there am differfia~d was tested. Two 1/S0 acre plots in a coconut grove on ibogelap Island w~ra txeatk with a broadcast applicatiori of dominant ground vegetation, a grass (&pPturw w.) was samplad in March 19S9 from the fertilized and control areas. Average values for the content of K(meq per 100 dry gm) ati CS-~37
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of the K fertilization on C3-137 was although Lhe possibility of seasonal prasaed the uptake of CS-137 in all cases in the greenhouse The results of the p+a~cultures Go not distinguish mante on Cs-137 content of the plants, 3ince no treatments inThere was an in~ication in the tomato but ‘this was not confirmed by the tests using squash. A POSsible explanation for this difference iie3 ‘in the fact. that
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creased absorption of CS-137 with K fertilizatim of mil which was low in K. The Rongelutp soils are Low in K as evi~enced by SOL1 analysas and by leaves of the plants the wary low lwds of X in the alder Data from additional field samples af a greater number of plant gpecies is being accumulated at presant with the hope of establishing wra clearly the differences beLween species in this respect and the significance of ~ha sharp differences betwean the older and younger leaves. Ron@ap soil have been shown t.obe greatest Immediately
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IysAmoter studies in glacial till and coral atoll assay of fertility of California soils. Hilgardia 24:1-3.