Conclusions on model intercomparison studies

6. MODELLING

6.3. Model intercomparison studies

6.3.4. Conclusions on model intercomparison studies

The Fruits WG has provided a unique opportunity to test the performance of existing and newly developed models for predicting radioactivity in fruits. The results of the study show that even for this simple and well defined scenario the differences in model predictions may be quite large. In this exercise, the differences between models were as high as five orders of magnitude for short term predictions following the acute radionuclide deposition. For the long term consequences and for the continuous deposition scenario, the differences between models were about two orders of magnitude.

Predicted levels of radionuclide concentrations in three types of fruit selected for this study were found to be very similar. The difference between apple, strawberries and blackcurrant contamination predicted by one model is far less than the difference in prediction of contamination for a single plant species given by different models. The large difference between model predictions reveals the current uncertainty in predicting future radionuclide concentrations in fruits once contamination occurs. The parameter uncertainty associated with a selected model is likely to be much lower than model uncertainty.

In conclusion, the results of model–model intercomparisons clearly indicate the need for further development of existing models for the fate and transport of radionuclides in fruit ecosystems. This will not only result in reducing model uncertainty but will also provide a knowledge base with which other pollutants, such as heavy metals and organic chemicals, as well as nutrients could be modelled.

Text cont. on page 71.

FIG. 8. Predicted concentration of ¹³⁷Cs in fruit for an acute source term.

01-Jul-91 01-Jul-92 01-Jul-93 01-Jul-94 01-Jul-95 01-Jul-96 01-Jul-97 01-Jul-98 01-Jul-99 01-Jul-00 Deposition date: May

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00

Deposition date: May

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00

Deposition date: July Apples

Concentration of 137Cs in Fruit (Bq kg-1)

1.0E-03

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Deposition date: October

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

FIG. 9. Predicted ¹³⁷Cs in plant and soil for an acute source term.

01-Jul-91 01-Jul-92 01-Jul-93 01-Jul-94 01-Jul-95 01-Jul-96 01-Jul-97 01-Jul-98 01-Jul-99 01-Jul-00 Deposition date: May

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Deposition date: May

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00

Deposition date: May

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

Concentration of ⁹⁰Sr in Fruit (Bq kg^-1)

01-Jul-91 01-Jul-92 01-Jul-93 01-Jul-94 01-Jul-95 01-Jul-96 01-Jul-97 01-Jul-98 01-Jul-99 01-Jul-00 Years after deposition

Deposition date: May Strawberries

Concentration of Sr-90 in Plant (Bq m^-2)

1.0E-04

01-Jul-91 01-Jul-92 01-Jul-93 01-Jul-94 01-Jul-95 01-Jul-96 01-Jul-97 01-Jul-98 01-Jul-99 01-Jul-00 Years after deposition

Deposition date: May Strawberries

FIG. 10. Predicted ⁹⁰Sr in strawberry fruit, plant and soil for an acute source term.

Concentration of ¹²⁹I in fruit (Bq kg^-1)

01-Jul-91 01-Jul-92 01-Jul-93 01-Jul-94 01-Jul-95 01-Jul-96 01-Jul-97 01-Jul-98 01-Jul-99 01-Jul-00 Years after deposition

Deposition date: May Strawberries

FIG. 11. Predicted ¹²⁹I in strawberry fruit, plant and soil for an acute source term.

Concentration of Sr-90 in fruit (Bq kg^-1)

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

Concentration of Sr-90 in tree (Bq m^-2)

1.0E-02

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

Concentration of Sr-90 in soil (Bq m^-2)

1.0E-02

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

FIG. 12. Predicted ⁹⁰Sr in apple fruit, tree and soil for an acute source term.

Concentration of I-129 in fruit (Bq kg^-1)

1.0E-03

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

Concentration of I-129 in tree (Bq m^-2)

1.0E-03

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

Concentration of I-129 in soil (Bq m^-2)

1.0E-02

01-Oct-91 01-Oct-92 01-Oct-93 01-Oct-94 01-Oct-95 01-Oct-96 01-Oct-97 01-Oct-98 01-Oct-99 01-Oct-00 Years after deposition

Deposition date: May Apples

FIG. 13. Predicted ¹²⁹I in apple fruit, tree and soil for an acute source term.

Concentration of Sr-90 in fruit (Bq kg^-1)

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

Concentration of Sr-90 in plant (Bq m^-2)

1.0E-02

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

Concentration of Sr-90 in soil (Bq m^-2)

1.0E-02

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

FIG. 14. Predicted ⁹⁰Sr in blackcurrant fruit, plant and soil for an acute source term.

Concentration of I-129 in fruit (Bq kg^-1)

1.0E-03

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

Concentration of I-129 in Plant (Bq m^-2)

1.0E-03

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

Concentration of I-129 in soil (Bq m^-2)

1.0E-03

15-Jul-91 15-Jul-92 15-Jul-93 15-Jul-94 15-Jul-95 15-Jul-96 15-Jul-97 15-Jul-98 15-Jul-99 15-Jul-00 Years after deposition

Deposition date: March Blackcurrant

FIG 15. Predicted ¹²⁹I in blackcurrant fruit, plant and soil for an acute source term.

FIG. 16. Predicted ¹³⁷Cs in fruit, plant and soil for a continuous source term.

Activity concentration of Cs-137 in plant (Bq m^-2)

1.0E+00

Concentration of Cs-137 in soil (Bq m^-2)

1.0E+00

Activity concentration of Cs-137 in Fruit (Bq kg^-1f.w)

1.0E+00

FIG. 17. Predicted ⁹⁰Sr and ¹²⁹I in fruit for a continuous source term.

Concentration of I-129 in Fruit (Bq kg^-1f.w)

1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

FRUTI-CROM SPADE DOSDIM

Strawberries Concentration of Sr-90 in Fruit (Bq kg^-1f.w)

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

Strawberries

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

Blackcurrant

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

Blackcurrant

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

Years after deposition Apples

1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03

1 2 3 4 5 6 7 8 9 10

Years after start date

6.4. MODEL VALIDATION STUDIES

Dans le document Modelling the Transfer of Radionuclides to Fruit | IAEA (Page 69-77)