ABSTRACT
To understand the long-term behavior of radiocesium in the biological processes of a forest ecosystem, its concentration in Japanese epigeic earthworms (Megascolecidae), litter, and soil, and the ambient dose equivalent rates, were investigated after the Fukushima Dai-ichi Nuclear Power Plant accident. The metabolism of radiocesium in the earthworms was also investigated in the laboratory, and its biological half-life (Tb) was estimated. The concentration of 137Cs in the habitat soil and litter changed from 2014 to 2016, with levels in the litter going from 44.9 Bq/g dw (in 2014) to 45.3 Bq/g dw (2015) and 10.7 Bq/g dw (2016); in soil, these values were 9.79 Bq/g dw, 7.14 Bq/g dw and 18.0 Bq/g dw, respectively. By contrast, no significant changes were observed in the concentrations in the earthworms, which were 4.87 Bq/g fw, 5.30 Bq/g fw and 4.67 Bq/g fw in 2014, 2015, and 2016, respectively. The ambient dose equivalent rates at the sampling site declined significantly over these three years, going from 2.15 µSv/h to 1.68 µSv/h and 1.35 µSv/h, mostly corresponding to physical decay of radiocesium. The majority (95%) of the 137Cs in the earthworms, observed via autoradiography, was concentrated primarily in the intestine. The clearance of 137Cs from the earthworms was described by dual exponential functions: the half-life in the rapid loss due to gut clearance was 0.10 days and a second slower loss due to physiological clearance was 27.4 days.
Subject(s)
Cesium Radioisotopes/metabolism , Oligochaeta/metabolism , Soil Pollutants, Radioactive/metabolism , Animals , Cesium Radioisotopes/analysis , Fukushima Nuclear Accident , Half-Life , Japan , Radiation Monitoring , Radioactivity , Soil Pollutants, Radioactive/analysisABSTRACT
A 48-year-old woman with a 15-year history of a painful nodule in the para-Achilles tendon area was evaluated by clinical examination, magnetic resonance imaging and ultrasonography, then treated by simple surgical excision of the nodule. Pathology revealed a glomus tumor, which is extremely rare in the para-Achilles tendon area. This is the first report of a glomus tumor in this location.
