title: The grain storage of wet-deposited caesium and strontium by spring wheat - A modelling study based on a field experiment.
abstract: The aims of this study were to extend the Tracey model in order to quantify and to analyse spring wheat's grain storage dynamics of wet-deposited radionuclides. Tracey, a dynamic model of trace element cycling in terrestrial ecosystems, was extended with descriptions of wet-deposition, interception, foliar uptake and radioactive decay. Radionuclide fluxes were set proportional to corresponding water or carbon fluxes, simulated with CoupModel. The extended Tracey was calibrated against experimental data, where134Cs and85Sr were deposited on spring wheat at six growth stages in 2010 and 2011. Sensitivities of grain storage to wheat's and radionuclide properties were assessed, using the Eikos software, by 1000 Monte Carlo simulations for each of the 48 scenarios (combination of 2 radionuclides, 1 foliar uptake, 2 root uptake approaches, 6 deposition treatments and 2years). Simulations were accepted if simulated grain storage values were within 95% confidence intervals (CI) of measurements. We found that 15% of134Cs and85Sr simulations for 2011, and 6% of the 2010 simulations met the CI-criterion. Foliar uptake accounted for 99% and 90% of total plant uptake of134Cs and85Sr, respectively. Mean simulated grain storage at harvest increased with lateness of deposition, as the stored proportion of radionuclide deposited was 0.02% when deposition was before flowering, 2% between flowering and ripening, and 5% (2010) or 10% (2011, late harvest) after ripening, respectively. Similarly, the property that governed grain storage depended on the growth stage at time of deposition; stem and leaf fixation rates (deposition before flowering), grain fixation rates (between flowering and ripening) and grains' interception capacity (after ripening). We conclude that grains' interception capacities can be used to predict grain storage of radionuclides deposited in the riskiest period, i.e. close to harvest.
authors.affiliation: Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-75007 Uppsala, Sweden. Electronic address: annemieke.gardenas@slu.se.
authors.forename: Annemieke I
authors.initials: AI
authors.lastname: Gärdenäs
authors.affiliation: Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-75007 Uppsala, Sweden.
authors.forename: S Linnea
authors.initials: SL
authors.lastname: Berglund
authors.affiliation: Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-75007 Uppsala, Sweden.
authors.forename: Stefan B
authors.initials: SB
authors.lastname: Bengtsson
authors.affiliation: Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-75007 Uppsala, Sweden.
authors.forename: Klas
authors.initials: K
authors.lastname: Rosén
mesh_terms: D002586:Cesium; D002588:Cesium Radioisotopes / Q000032:analysis*; D008962:Models, Theoretical; D011848:Radioactive Pollutants / Q000032:analysis*; D013324:Strontium; D013326:Strontium Radioisotopes / Q000032:analysis*; D014908:Triticum / Q000737:chemistry*
chemical_list: D002588:Cesium Radioisotopes; D011848:Radioactive Pollutants; D013326:Strontium Radioisotopes; D002586:Cesium; D013324:Strontium
keywords: Crops; Dynamic model Tracey; Foliar uptake; Interception; Radioactivity