137Cs in the meat of wild boars: a comparison of the impacts of Chernobyl and Fukushima

The impact of Chernobyl on the 137Cs activities found in wild boars in Europe, even in remote locations from the NPP, has been much greater than the impact of Fukushima on boars in Japan. Although there is great variability within the 137Cs concentrations throughout the wild boar populations, some boars in southern Germany in recent years exhibit higher activity concentrations (up to 10,000 Bq/kg and higher) than the highest 137Cs levels found in boars in the governmental food monitoring campaign (7900 Bq/kg) in Fukushima prefecture in Japan. The levels of radiocesium in boar appear to be more persistent than would be indicated by the constantly decreasing 137Cs inventory observed in the soil which points to a food source that is highly retentive to 137Cs contamination or to other radioecological anomalies that are not yet fully understood.

Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5)

We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium (134Cs and 137Cs) up to 800 Bq kg-1 as well as 90Sr up to 5.6 Bq kg-1. This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg-1 radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit). Analysis of the Unit 5 reactor coolant (finding only 3H and even low 129I) leads to the conclusion that the purification techniques for reactor coolant employed at Fukushima Daiichi are very effective.

Effective and ecological half-lives of 90Sr and 137Cs observed in wheat and rice in Japan

Published pre-Fukushima food monitoring data from 1963 to 1995 were used to study the long-term presence of 137Cs and 90Sr in rice and wheat. Effective half-lives (T eff) were calculated for rice (137Cs: 5.6 years; 90Sr: 6.7 years) and wheat (137Cs: 3.5 years; 90Sr: 6.2 years), respectively. In rice, 137Cs exhibits a longer T eff because putrefaction processes will lead to the formation of NH4 + ions that are efficient ion exchangers for mineral-adsorbed cesium ions, hence making it more readily available to the plant. Knowledge on the long-term behavior of radiocesium and radiostrontium will be important for Japanese food-safety campaigns after the Fukushima nuclear accident.