Transfer of 137

Cs and 60

Co from irrigation water to a soil-tomato plant system

C. Sabbarese1,*

, L. Stellato1, M.F. Cotrufo

1, A. D'Onofrio

1,

A. Ermice1, F. Terrasi

1, S. Alfieri

2

(1)

Dipartimento di Scienze Ambientali, Seconda Università di Napoli, via Vivaldi, 81100

Caserta, Italy (2)

Centrale Nucleare Garigliano, Sogin, Sessa Aurunca (Caserta), Italy * Corresponding author. E-mail: sabbares@na.infn.it

Abstract

An experiment has been performed at the Nuclear Power Plant of Garigliano (Caserta, Italy),

aiming to the measurement of transfer factors of 137

Cs and 60

Co radionuclides from the irrigation

water to a soil-plant system, with particular attention to the influence on such transfers of the

irrigation technique (ground or aerial). Tomato plants were irrigated weekly with water

contaminated with 137

Cs and 60

Co (about 375 Bq/m2 week), using both irrigation techniques. After

13 weeks fruits, leaves, stems, roots and soil were sampled, and radionuclide concentrations were

measured by high-resolution spectroscopy. It was found that the activity allocated to the plant

organs is significantly dependent upon the irrigation technique, amounting to 2.1% and 1.6% for

aerial treatment and 0.4% and 0.3% for the ground treatment, for 137

Cs and 60

Co respectively. The

activity absorbed by plants is allocated mainly in leaves (>55%), while less then 10% is stored in

the fruits, for both irrigation techniques. Transfer factors (soil-plant and irrigation water-plant) of

tomato plants and of weeds have been determined for 137

Cs and 60

Co, as well as for natural 40

K in

the soil.

Keywords: Radionuclide transfer factor; Foliar and ground sorption; tomato

1. Introduction

Assessment of internal doses to humans from ingestion of radionuclides present in

agricultural products requires detailed information on the main processes determining the route of

radionuclides in the environment (Russel, 1966; Peterson, 1983; IAEA, 1995). A large amount of

data is available but, generally, they do not reflect natural conditions, and the mechanisms of

translocation and mobility of radionuclides within the soil-plant system are still not understood

(Fresquez et al., 1998; Krouglov et al., 1997; Howard et al., 1995; Strand et al., 1994; Konshin,

1992; Frissel, 1992; Alexakhin & Korneev, 1992; Desmet et al., 1990).

The knowledge of the contributions of direct contamination of plant fruits and of the process

of root to fruit transfer can improve the understanding of exposure through ingestion and of the

mechanisms determining sorption and translocation. Agricultural soil can be contaminated because

of radioactive fallout in atmosphere or because of irrigation which uses contaminated water. Plants

growing on that soil absorb radionuclides by roots and/or by leaves. Radionuclides absorbed are

transferred to the plant organs and their quantities are determined on the basis of the kind of

contamination source and of biological and environmental processes. Plant physiology, soil

characteristics, nuclide and plant kind are important parameters which influence sorption (Howard

et al.,1995; Strand et al.,1994; Konshin,1992).

Few studies have been designed considering real agricultural conditions and very few

simulate a contaminated rain which daily falls on the plants or on soil surface only. In the present

research, both kinds of contaminations have been studied in experimental conditions very close to

the real-life situation. Transfer factors have been calculated considering the weekly increase of

contamination in soil and the increase of plant mass.

2. Materials and methods

An experimental field, 25x30 m long, was arranged in the soil area of the Nuclear Power

Plant of Garigliano (Caserta, Italy) to perform the experiment. The field was on anthropogenic soil

characterized by morphological heterogeneity and spatial discontinuity, suggesting variability in its

properties. After adequate soil preparation and fertilization, the field was divided in 30 plots as

displayed in Fig. 1. Tomato plants were cultivated in the same conditions in 24 plots, 2x2 m2: 12

(named P) were contaminated using a low radioactivity water solution containing 137

Cs and 60

Co,

while the other 12 plots (named B) were not contaminated and used as blank reference. The

remaining 6 plots were also contaminated but not cultivated (named S) to obtain a control of

uncultivated soil. The 12 P-plots were divided in two groups of 6 plots named P1 and P2, and, at the

same way, B1 and B2 for B plots. The indices 1 and 2 indicate irrigation at rain and at foot

respectively. Hence, five different groups of plots with different cultivation kinds were performed:

B1: irrigation at rain using uncontaminated water;

B2: irrigation at foot using uncontaminated water;

P1: irrigation at rain using contaminated water,

P2: irrigation at foot using contaminated water,

S: irrigation of nude soil using contaminated water.

Each plot was irrigated weekly using 80 l of water with or without contamination as before

explained. Water due to natural rain, eventually present during the week, was measured and

subtracted from 80 l; hence, in each week supplemented water quantity was variable but the

contamination quantity was the same.

The contamination solution was obtained from two radioactive sources produced by

Amersham International containing 2 MBq of 137

Cs and 60

Co respectively. Contaminant solution

used for irrigation was homemade in acid environment and on April 7h, 1998 contained (0.31

0.02) kBq/ml of 137

Cs and (0.30 0.02) kBq/ml of 60

Co. Weekly, 5 ml of such solution were used

for irrigation of each plot. At the end of cultivation, 13 weeks long, each plot received (19.9 1.7)

kBq of 137

Cs and (19.5 1.7) kBq of 60

Co, and the entire experimental field received about 700

kBq (19 Ci). It is worth to emphasise that such activity represents 0.00019% of dumping liquids of

the Nuclear Power Plant of Garigliano; hence, the environmental impact was practically zero.

After 13 weeks of cultivation, tomatoes, leaves, stems, roots and soil of the entire

experimental field were collected, separated per plot, disposed in containers and exposed to the sun

for two days. Tomatoes were separated in ripe and unripe and were analysed separately; as no

significant difference was found between the two categories, we have analysed the data without

distinction between ripe and unripe. Each part of the plants was placed in oven at 60°C for 36 h and,

then, at 105 °C for 12 h to obtain a satisfactory sample dehydration. Samples removed from oven

were pulverized to obtain a homogeneous matrix, which was weighted and placed in a 350 cc

Marinelli beaker. Root samples were placed in 80 cc volume cylindrical containers because of the

small amounts available. Also weed growled in the plots was collected and analysed using the same

procedure of tomato plants.

Soil samples were collected in 30x30 cm2 cores, 20 cm deep from six contaminated plots

(S1, S2, P11, P15, P23, P24). Four samples of 5 cm long sections of soil cores of each plot were

considered. They were placed in oven at 60°C for 36 h and 12 h at 105 °C, were sieved at 2 mm and

placed in 2.8 l Marinelli beaker. Moreover, in the P15 plot six soil cores were collected at different

positions to study the variability of radionuclide concentration.

Soil density was also determined in six plots, which were representative of the entire

experimental field. Samples were extracted by using 270 cc volume metallic cylinders, which are

opened at two bases. Soil captured by cylinders was oven-heated and its mass was determined to

calculate dry bulk density.

High-resolution -spectrometry was used to measure radionuclide activities of the vegetable

and soil samples. Two germanium hyperpure detectors (1.9 keV resolution and 30% efficiency)

properly shielded were used with standard electronics: spectra were analysed, displayed and stored

using a computer.

Total efficiencies for each detection geometry were experimentally determined by using the

same matrix contaminated in a uniform way by a polinuclides source produced by Amersham

International. Radionuclide specific activities were obtained from a quantitative analysis of -ray

spectra using the lines at 661.6 keV (137

Cs), 1173.2 keV and 1332.5 keV (60

Co). Analysis results

yield specific activity of each detected radionuclide referred to dry mass.

As potassium and caesium elements have similar chemical characteristics, and potassium

radionuclide (40

K ) is naturally present in the soil, we analysed also the 40

K peak (1460.5 keV)

present in -ray spectra and we calculated its specific activity too.

3. Results and discussion

Data analysis was performed by dividing data per plant organs: tomatoes, leaves, stems, and

roots. Then, we compared results obtained on the same organ of the six plots of the same treatment.

Table I shows 137

Cs, 60

Co and 40

K specific activities of the plant organs of all plots. The variations

of these values measured on the same organ and for the same treatment show variations in the six

repetitions larger than the respective experimental errors. For this reason, sample standard

deviations in each group were taken as representative of the variability of experimental conditions.

In Fig. 2 mean values and standard errors of measured specific activities are reported for the plant

organs of two treatments.

Specific activities of uncontaminated plant organs are negligible with respect the

corresponding contaminated ones, while differences of 137

Cs and 60

Co results between two

irrigation techniques are statistically significant at 95% confidence level, as indicated by the student

t-test. It is evident from the results that the procedure of irrigation influences strongly the sorption

of radionuclides: the aerial irrigation (P1-plots) furnishes a quantity of radionuclides higher than the

ground irrigation (P2-plots). The 40

K values are not different between the two irrigation techniques

as expected. In the Table II the ratios between P1 and P2 specific activities for each plant organ and

each radionuclide are reported.

The relative distribution of mean specific activities among plant organs has been displayed

in Fig. 3. No significant difference appears between two irrigation techniques; in effect, percentage

values are about the same for P1 and P2. This fact indicates that plants not distinguish between the

two ways of sorption and they distribute the absorbed quantity of radioactivity in the same way. 40

K

distributions in the plant organs are similar in the P1, P2, B1 and B2 plots, but they are very

different from the distributions of artificial radionuclides. Tomatoes contain about 60% of 40

K of

plant, stems and roots contain a percentage about equal for 137

Cs and 60

Co ones. In conclusion, 40

K

is especially allocated in fruits and 137

Cs and 60

Co are allocated especially in leaves, independently

of treatment, as shown by Smolders & Merckx (1993) for hydroponic cultivation.

To obtain data of direct human interest, we have calculated also specific activities referred to

fresh mass of tomato. Such mean specific activities of fresh mass are (3.0 0.5)Bq/kg and

(0.4 0.1) Bq/kg for 137

Cs, (1.1 0.2) Bq/kg and (0.2 0.1) Bq/kg for 60

Co for P1 and P2

treatments, respectively and (75 6) Bq/kg for 40

K.

Weed growled during the cultivation in the plots was also collected and analysed. Mean

specific activities of 137

Cs and 60

Co measured in weed samples show no differences within the

measurement errors for the two treatments, as expected, due to the small weed height above ground

(Table I).

To calculate transfer factors from soil to plants, specific activities of 137

Cs, 60

Co and 40

K in

the upper 20 cm of soil have been measured. Mean specific activities are (22 2) Bq/kg, (21 2)

Bq/kg and (1080 96) Bq/kg for 137

Cs, 60

Co and 40

K, respectively. About 80% of the activity

present in the soil is detained in the upper 5 cm. The aerial variability of radionuclide distributions

is characterised by a standard deviation of about 20%.

Using the mean density of analysed soils of six plots (1.15 0.08) g/cm3, total activities

detained in the upper 20 cm of each plot of (5.1 0.9) kBq/m2, (4.8 0.8) kBq/m

2 and (250 66)

kBq/m2 for

137Cs,

60Co and

40K are in agreement with total activity given to the plot through water

(5.0 0.9 kBq/m2 of

137Cs, 4.9 0.9 kBq/m

2 of

60Co). The resulting transfer factors, calculated as

ratios of the plant specific activity to the soil aerial activity at the end of the experiment (i.e. 13

weeks) are reported in Table III for P2 treatment. In order to compare the two kinds of treatment,

the transfer factors from irrigation water to plant was also calculated for P1 and P2 plots and are

reported in Table II, where are also reported transfer factors from irrigation water to weed.

Coming back to soil-plant transfer, one may note from Table III that 137

Cs has a transfer

factor large by a factor about 2 with respect to 40

K. The average 137

Cs to 40

K specific activity ratio

in the soil is 0.029. On the other hand, if one considers the individual transfers to different plant

organs, one can see from the data in Table IV that the 137

Cs to 40

K discrimination is strongly

dependent on the compartment considered.

4. Correction of the transfer factor.

The transfer factors obtained above have been calculated assuming that the total amount of

radionuclides was present in soil from the beginning of cultivation without considering its weekly

increase due to the contaminated irrigation water. Hence, the transfer factors reported in the Table

III are not comparable with those measured in conventional experiments performed in soils fully

contaminated before plantation. In order to correlate the two approaches we consider the differential

equation which describes the increase of the activity in the tomato plants as a function of the

activity in the soil (Somlders & Merckx, 1993). If we neglect the decrease of activity due to the

radioactive decay and we assume an exponential behavior of plant growth (constant value of

relative growth rate, RGR), the variation of the specific activity in the plant, C, is

)1()()( tCRGRtUdt

dC

where U (t), expressed in Bq/kg/d, is the increase of radionuclide activity at constant mass per mass

unit and RGR is the relative growth rate of plant per mass unit expressed in d-1

. If U(t) and RGR

are considered constants, the solution of the equation (1) is

where U/RGR is the asymptotic value of the specific activity absorbed from the plant and it is equal

to F*Cs, where F is the soil-plant transfer factor and Cs is the specific activity of radionuclide in the

soil. Hence,

In our experiment Cs(t) is linearly increasing with time and it can be expressed as

tktCs

)( , with **)( ttCk s and t* the time at the end of the experiment.

The solution of eqn. (1), in this case, is

where

The transfer factor F (eq. (4)) has to be compared with the transfer factor Fc calculated

neglecting the time dependence of soil contamination, i.e. normalizing the specific activity at time

t*, C(t

*), to the total activity supplied to the soil during time t

*, Cs (t

*):

)()()(

)(*

*

**

**

tf

tRGRF

tftC

tRGRtCF c

s

In our cultivation, we calculated C(t*) from the average specific activities of the six plots of

the same treatment at the end of cultivation (t = 92 d, RGR = 0,051 d-1

and k = 54 Bq/g/m2 for

)2(1)( RGRteRGR

UtC

)3(sCRGRFU

)4()()(

)(*

*

tftRGR

tCFtC s

tRGRetf tRGR 1)(

137Cs and k = 53 Bq/g m

2 for

60Co). To correct the transfer factors calculated above, the following

expression

)( ** tftRGRFF c

can be used.

The soil-tomato plant and soil-weed transfer factors calculated with this formula are 0.014

Bq/g m2 and 0.011 for

137Cs and

60Co, respectively. This correction increases values of about 27%;

accounting for the fact that the entire quantity of radionuclides was not available to plants from the

beginning of the cultivation. If one takes into account that uptake efficiency is in fact decreasing

with plant growth (Sabbarese et al., 2000), the correction factor can be expected to be larger.

5. Conclusions

The experiment presented, regarding tomato plant cultivation in an agricultural soil with

irrigation water containing 137

Cs and 60

Co, allowed to conclude that tomato plants absorb less than 2

% of the activity available in the soil. This quantity is about 6 times higher if contaminated

irrigation was aerial with consequent foliar absorption. In effect, the ground irrigation reduces by

about 80% the absorption of radionuclides from plant. Relative distributions of radionuclide in the

organs of tomato plants are not different for the two treatments. In both treatments, more than 90%

of the entire activity of plant was absorbed by steams and leaves, and the remaining activity is

distributed between fruit and root. Otherwise, the 40

K activity distribution is very different from the

artificial radionuclides. Transfer factors are also calculated for tomato plants and for weed with

respect to irrigation water and to soil contamination for 137

Cs, 60

Co and 40

K.

Acknowledgements

The authors are grateful to technical operators of the Nuclear Power Plant of Garigliano

which participated to the experiment, and they thank, in particular, Mr. G. Fiore for its continuous

attention for cultivation.

References

Alexakhin, R.M., N.A. Korneev (1992). Agricoltural Radioecology (in Russian). Ecology

Publishers, Moscow.

Desmet, G., P. Nassimbeni, M. Belli (1990). Transfer of radionuclides in natural and semi-

natural environments. Elsevier Applied Science, London and New York.

Fresquez P.R., D.R. Armstrong, M.A. Mullen, L.jr. Naranjo (1998). The uptake of radionuclides

by beans, squash, and corn growing in contaminated alluvial soils at Los Alamos National

Laboratory. Journal of Environmental Science and Health, B33, 99-122.

Frissel M.J. (1992). Thirty years soil-to-plant transfer of Cs-137 and Sr-90. A comparison of

‘old’ data, IUR data and Russian, White Russian and Ukranian data. In: Proc. Int. Symp.

Radioecology. Chemical speciation-Hot Particles. CEC, IUR, SCR, Brussels, Belgium.

Howard, B.J., K. Hove, P. Strand, V. Pronevich (1995). Aggregated transfer coefficients: A

simple approach to modelling transfer of radionuclides to food products from semi-natural

ecosystems. In: IAEA-SM 339/149, Vienna 8-12 May 1995. IAEA, Austria, 247-258.

International Atomic Energy Agency (1995). The interception, initial and post deposition

retention by vegetation of dry- and wet-deposited radionuclides. Pröhl G., Hoffman F.O. (ed.),

IAEA, Vienna.

Konshin, O.V. (1992). Transfer of 137

Cs from soil to grass: Analysis of possible sources of

uncertainity. Health Physics., 63, 307-315.

Krouglov, S.V., A.S. Filipas, R.M. Alexakhin. N.P. Arkhipov (1997). Long-term study on the

transfer of 137

Cs and 90

Sr from Chernobyl-contaminated soils to grain crops. Journal of

Environmental Radioactivity, 34, 3, 267-286.

Peterson H. T. Jr. (1983). Terrestrial and aquatic food chain pathways. In: Till J.E., Meyer H.R.

(ed.), Radiological Assessment: A Textbook on Environmental Dose Analysis. U.S. Nuclear

Regulatory Commission, Washington, D.C., Document No. NUREG/CR-3332, 5-1 to 5-156.

Russel R.S. (1966). Radioactivity and Human Diet. Pergamon Press, Oxford.

Sabbarese C., L. Stellato, M.F. Cotrufo, A. D’Onofrio, A. Ermice, C. Lubritto, F. Terrasi, S.

Alfieri, G. Migliore (2000). Dependance of radionuclide transfer factor on plant growth stage.

Submitted to Environmental Modelling and Software.

Scotti I.A., S. Silva, F. Carini (1993). Removal foliar radiocaesium by sprinkling. J.

Environmental Radioactivity, 20 (1): 63-68.

Smolders E., R. Merckx, (1993). Some principles behind the selection of crops to minimize

radionuclide uptake from soil. The Science of the Total Environment, 137: 135-146.

Strand, P., P.J. Howard, L. Skuterud, V. Averin (1994). Fluxes of radionuclides in rural

communities in Russia, Ukraine and Belarus. Transfer of radionuclides to animals, their

comparative importance under different agricultural ecosystems and appropriate countermeasures.

ECP9 Annual report to the EC, DGXII.F-6, Nov.93-Dec-94.

Figure and Table Captions

Figure 1. Experimental field scheme, with indications of the five treatments.

Figure 2. Mean specific activities divided for radionuclide and for plant organ are reported for each

treatment.

Figure 3. Percentage distribution of mean specific activities among plant organ for each analysed

radionuclide.

Table I. Specific activities of 137

Cs, 60

Co and 40

K, expressed in Bq/Kg, measured in all vegetable

samples of the present experiment.

Table II. Ratios between the specific activities of three radionuclides studied in two cultivation

treatments (P1 and P2).

Table III. Transfer factors calculated in the described experiment.

Table IV. Ratios of 137

Cs to 40

K specific activities in plant organs are reported with respect the

correspondent average ratio in the soil.

P1 P2 B1 B2

137Cs 60Co 40K 137Cs 60Co 40K 137Cs 60Co 40K 137Cs 60Co 40K

T

O

M

A

T

O

82 2 36 1 1524 41 5.6 0.2 4.7 0.3 1466 41 1.6 0.2 < 0.1 1857 47 0.7 0.2 < 0.1 1310 34

63 1 27 1 1314 40 8.2 0.2 4.6 0.4 1560 49 0.9 0.2 < 0.1 1404 37 0.5 0.2 < 0.1 1219 32

65 1 19 1 1411 49 6.6 0.2 1.4 0.2 1518 42 0.9 0.2 < 0.1 1555 41 0.3 0.1 < 0.1 1114 29

47 1 16 1 1272 39 9.8 0.2 4.5 0.4 1513 43 0.5 0.2 < 0.1 1104 29 0.6 0.2 < 0.1 1288 34

57 1 17 1 1646 45 5.4 0.2 2.6 0.2 1497 42 0.7 0.2 0.8 0.2 1428 37 0.2 0.1 < 0.1 1397 36

46 1 14 1 1450 42 9.4 0.3 2.2 0.2 1460 42 0.9 0.2 0.8 0.1 1303 35 < 0.1 < 0.1 1303 34

S

T

E

M

343 9 266 7 1034 38 48 12 31 8 1215 39 2.1 0.3 < 0.1 1381 39 0.5 0.3 < 0.1 1140 31

438 11 283 7 1147 31 38 2 24 1 1137 40 1.7 0.3 < 0.1 957 29 0.5 0.3 < 0.1 1108 30

224 6 161 5 951 35 62 1 38 1 1435 44 1.3 0.3 < 0.1 938 27 < 0.1 < 0.1 1062 29

350 9 201 5 934 28 55 1 38 1 799 23 < 0.01 < 0.1 989 29 < 0.1 < 0.1 927 38

246 7 164 5 746 30 33 1 25 1 969 33 1.3 0.3 < 0.1 1027 29 < 0.1 < 0.1 786 22

373 10 228 6 1057 31 93 3 52 2 742 26 < 0.01 < 0.1 807 25 < 0.1 < 0.1 776 22

L

E

A

V

E

1269 31 1136 27 695 26 121 3 101 3 726 25 2.4 0.2 < 0.1 747 20 4.3 0.3 4.9 0.3 697 21

1040 25 851 20 710 25 227 6 167 5 847 28 1.7 0.2 0.8 0.1 675 19 2.6 0.3 < 0.1 713 22

750 18 670 17 688 24 174 5 138 4 1006 33 2.1 0.3 < 0.1 647 19 2.5 0.3 < 0.1 730 22

840 20 624 15 596 22 131 4 104 3 486 22 1.1 0.3 1.0 .2 653 19 1.9 0.3 < 0.1 645 19

841 20 661 16 620 23 149 4 114 3 498 22 2.1 0.2 < 0.1 658 19 1.8 0.3 < 0.1 532 17

759 18 585 14 653 23 339 9 240 7 456 20 1.4 0.3 < 0.1 464 16 1.7 0.3 < 0.1 535 17

R

O

O

T

95 8 139 10 1296 99 46 4 76 6 886 77 < 0.2 < 0.2 < 0.2 < 0.2 < 0.2 751 69

56 5 101 8 1294 100 21 2 40 3 1525 116 < 0.2 < 0.2 1298 121 < 0.2 < 0.2 1321 101

90 7 150 11 1434 110 23 3 43 4 1335 103 < 0.2 < 0.2 1351 104 < 0.2 < 0.2 1492 113

76 6 115 9 1255 96 13 3 36 3 1177 91 < 0.2 < 0.2 469 61 < 0.2 < 0.2 1266 97

27 3 50 4 302 54 31 3 67 5 1466 112 < 0.2 < 0.2 787 73 < 0.2 < 0.2 1336 102

63 6 117 9 785 73 34 4 75 6 1001 79 < 0.2 < 0.2 1304 100 < 0.2 < 0.2 1354 104

W

E

E

D

552 481 86324 432 422 90135 0.30.2 < 0.2 340 11 < 0.2 < 0.2 751 69

742 692 121232 432 341 87429 0.60.5 0.30.2 918 27 < 0.2 < 0.2 1321 101

312 291 85994 312 251 49323 1.70.3 < 0.2 1003 28 < 0.2 < 0.2 1492 113

344 331 101135 422 492 97032 < 0.2 < 0.2 705 21 < 0.2 < 0.2 1266 97

381 391 90425 181 191 97533 < 0.2 < 0.2 821 24 < 0.2 < 0.2 1232 94

171 161 84731 492 612 86030 < 0.2 < 0.2 536 21 < 0.2 < 0.2 1354 104

Table I

PLANT ORGANS 137

Cs 60

Co 40

K

TOMATOES 8.0 1.1 6.5 1.5 0.96 0.04

STEMS 6.0 1.1 6.2 1.0 0.93 0.11

LEAVES 4.8 0.9 5.3 1.0 0.99 0.14

ROOTS 2.4 0.6 2.0 0.4 0.86 0.16

Table II

TRANSFER FACTOR CULTIVATION

TREATMENT

137Cs

60Co

40K

Soil – Tomato Plant

(Bq/kg/Bq/m2)

P2 0.011 0.002 0.009 0.002 0.005 0.001

Soil –Weed (Bq/kg/Bq/m2) P1, P2, S 0.007 0.001 0.007 0.001 0.004 0.001

Irrigation Water – Tomato

Plant (Bq/kg/Bq/l)

P1 15 2 11 2 -

P2 3.0 0.7 2.2 0.6 -

Irrigation Water –Weed

(Bq/kg/Bq/l) P1, P2, S 1.9 0.2 1.7 0.2 -

Table III

P2 PLANT ORGANS (137

Cs/40

K)plant/(137

Cs/40

K)soil

TOMATOES 0.17

STEMS 1.81

LEAVES 9.83

ROOTS 0.79

WEED 1.54

Table IV

1 2 3 4 5 6

B1: irrigation at rain usinguncontaminated water

B2: irrigation at foot usinguncontaminated water

P1: irrigation at rain usingcontaminated water

P2: irrigation at foot usingcontaminated water

S: irrigation of nude soil atrain using contaminatedwater

P1 TREATMENT

1

10

100

1000

10000

TOMATOES STEMS LEAVES ROOTS

SP

EC

IFIC

AC

TIV

ITY

(B

q/k

g) Cs-137 Co-60 K-40

P2 TREATMENT

1

10

100

1000

10000

TOMATOES STEMS LEAVES ROOTS

SP

EC

IFIC

AC

TIV

ITY

(B

q/k

g) Cs-137 Co-60 K-40

B1 TREATMENT

0,1

1

10

100

1000

10000

TOMATOES STEMS LEAVES ROOTS

SP

EC

IFIC

A

CT

IVIT

Y (B

q/k

g) Cs-137 Co-60 K-40

B2 TREATMENT

0,1

1

10

100

1000

10000

TOMATOES STEMS LEAVES ROOTS

SP

EC

IFIC

A

CT

IVIT

Y (B

q/k

g) Cs-137 Co-60 K-40

0%

20%

40%

60%

80%

100%

P1 Cs-137 P2 Cs-137 P1 Co-60 P2 Co-60 P1 K-40 P2 K-40 B1 K-40 B2 K-40

Perc

en

tag

e d

istr

ibu

tio

n o

f sp

ecif

ic a

cti

vit

yTomato Stem Leave Root