Radiocesium in Ponds in the Near Zone of Fukushima Dai-ichi NPP

The article presents the results of studying radiocesium concentration and distribution between dissolved and particulate forms in ponds in the near zone of Fukushima Dai-ichi NPP NPP after the 2011 accident. The total concentration of Cs-137 in pond water and its variations are shown to be largely governed by the concentration of particulate matter being as high as 68 Bq/L, compared with 5 Bq/L in solution. The values of the distribution coefficient K-d in the ponds are similar to those in rivers and in large flow-through lakes in the accidentally polluted zone at Fukushima Dai-ichi NPP. The contributions of the main competing ions K+ and NH4+ to radiocesium desorption from solid particles into solution were similar for the ponds; however, their relative effect on dissolved radiocesium concentration varied over time because of variations in ammonium concentration.