2015 Fiscal Year Research-status Report
Development and application of the flux approach for modelling of the long-term radiocesium cycling in Fukushima forests
| Project/Area Number |
15K00563
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| Research Institution | Fukushima University |
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Principal Investigator |
Yoschenko Vasyl 福島大学, 環境放射能研究所, 特任教授 (40745569)
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | Fukushima accident / radiocesium / forest ecosystems / radiocesium fluxes |
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| Outline of Annual Research Achievements |
The final goal of the project is creation of the model for prediction of the long-term redistribution of radiocesium in Fukushima forests. During 2015 we developed the conceptual model of radiocesium cycling in the forest ecosystems and determine in the experiments the values of its input parameters.
We have performed the infiltration tests at the experimental site Yamakiya to obtain the values of the saturated permeability coefficients, and modelled the experimental dependence of the moisture contents at various depths on the matrix potentials using the physically based theoretical dependence. It enabled calculation of the annual infiltration rates through the root-inhabited soil layer, which is one of the most important parameters for description of the radiocesium vertical migration in the soil profile. Also, we have started the measurements of the distribution coefficients of radiocesium in the soil samples, and have completed these measurements for the throughfall and stemflow samples. Completion of the measurements for soil will allow to model the radiocesium migration.
Based on the results of the radiocesium activity measurements in the samples of biomass, litter, throughfall and stemflow, we determined the present distribution of radiocesium in the studied ecosystem and its main fluxes that will determine its long-term dynamics. Moreover, we performed the new sampling of soil, litter and biomass at the studied site in the end of 2015 and demonstrated the changes of the distribution of radiocesium with time, and extent our study to the new sites in Tsushima.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The results expected for the FY 2015 have been achieved. As it was mentioned above, as compared to the initial plan we added the new experimental site in order to characterize variability of the studied parameters; however, the measurements for this site are in progress now. Also, we discussed with the Ukrainian institution the possibility to obtain the dataset for the model validation and reached the principal agreement. The obtained results were published in the scientific journals and widely presented at the international conferences.
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| Strategy for Future Research Activity |
TThe main efforts in FY2016 will be spent for the further development and parameterization of the model of radiocesium cycling in the forests. The experimental results for the Yamakiya forest site will be thoroughly analyzed for identification of uncertainties and possible data gaps.
We will repeat assessment of the annual moisture flow through the root layer of soil based on the data for April 2015-April 2016 in order to address its variability, and will characterize the radiocesium chemical forms in the soil profile. We will continue the litterbag experiment aimed to characterize the rates of the radiocesium leaching from the litter. Soil and biomass will be sampled and the soil moisture flux monitoring will be started at several other forest sites in the Fukushima prefecture.
Also, the sub-contract will be signed with the Ukrainian institution for obtaining the model validation dataset. We anticipate that the first model test exercises for the Ukrainian site(s) will be done by the end of FY2016.
It is also anticipated that in the end of FY2016 the main results showing the radiocesium redistribution at the Yamakiya forest site in FY2014-2015 will be submitted for publication in the international scientific journal(s). Also, the wider set of results will be presented at the international and domestic conferences.
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