MiniMizing the ContaMination of agriCultural environMent toward food Safety - with priMary foCuS on the fukuShiMa nuClear diSaSter

Radioactive materials released during the accident at the Fukushima Daiichi nuclear power station affected farmlands in Fukushima and its neighboring prefectures, contaminating soil and agricultural products. Soon after the accident, high concentrations of radionuclides were detected in cultivated green leafy vegetables and fresh raw milk, caused by the direct deposition of radioactive materials. Shipment of crops from affected areas was restricted. After the early phase of direct contamination, the potential contamination of rice through uptake of radioactive cesium through plant roots from contaminated soil became a concern. Based on the monitoring data since 1959, rice planting was restricted in fields where contamination levels were higher than 5,000 Bq/kg soil. The transfer of radioactive cesium from soil to crops is affected not only by its concentration in soil but also by soil type and soil management practices such as fertilizer application and tillage. In order to estimate the actual contamination conditions for farmland soil, a map showing the concentration distribution of radioactive cesium in farmland soil was created. A long-term problem is soil contamination by radioactive cesium, particularly by 137Cs with a half-life of 30 years. Farming in highly contaminated areas requires active decontamination practices. Depending on the soil conditions, the application of potassium fertilizers and the addition of adsorbents are effective for inhibiting any further uptake of radioactive cesium by plants. While 2011 was an extremely difficult year for agriculture, 2012 will be a year of large-scale recovery; although there is no doubt that a lot of efforts are necessary, which will continue for many years to come.