[M-AG38] 福島原発事故により放出された放射性核種の環境動態

[MAG38-P11] USLEモデルに基づく放射性セシウム分布および移行量の広域評価

*中村 典子¹、恩田 裕一¹、近藤 昭彦²、脇山 義史¹ (1.筑波大学　アイソトープ環境動態研究センター、2.千葉大学 環境リモートセンシング研究センター)

キーワード：東日本大震災, 福島原発事故, セシウム１３７, USLE, 土壌侵食, 放射性物質移行

The radioactive contaminations which flowed out from the Fukushima nuclear power plant first due to the Great East Japan Earthquake are still contained great amounts in the soil around the nuclear power plant, and it causes serious concern over the health of inhabitants. In this study, for the prediction of the migration dynamics of radioactive caesium deposited on the soil around the nuclear power plant, the time-spatial variation of deposition and washoff ratio of ¹³⁷Cs up to the present was calculated based on the soil erosion rate obtained from the USLE and the initial ¹³⁷Cs inventory obtained by the airborne monitoring. The parameters needed for calculation of USLE were determined from the observation results obtained from the study sites established in the Fukushima prefecture. The estimation results from the calculation were compared with the measurements of ¹³⁷Cs washoff ratio obtained from the rivers around the nuclear power plant. As the result, calculated ¹³⁷Cs washoff rate was approximately underestimate than the measured rate however was consistent qualitatively. And in the view of landuse, in the catchment of Abukuma river, the ratio of washoff from the paddy was large in the early period from the accident, however, as time goes on, the ratio of washoff from the paddy has decreased and the ratio of other landuses has increased.