## 1 Introduction  
As the radiocontaminated soil from the Chernobyl nuclear power plant accident in 1986 is concerned, [PERSON] and co-workers [1] proposed countermeasures such as the removal of contaminated surface soil, spraying contaminated canopies with detergents or cleaning agents, defoliation and removal of fallen leaves, as well as plowing after clear felling and prior to planting. Zeolite was found to reduce the uptake of \({}^{134}\)Cs in peat soil by a winter wheat under well controlled laboratory conditions [2]. Zeolite also decreased the transfer factors of \({}^{137}\)Cs and \({}^{85}\)Sr from sandy podzol soil to spinach [3]. Concerning the soil for crop production, ammonium-ferric-hexacyano-ferrate (II) is believed to be able to reduce the transfer of radiocesium to plants. Application of K- and Ca-containing fertilizers is also thought to be effective in depressing the uptake by plants of radiocesium and radiostrontium. Other methods, such as phytoremediation [4], were also proposed. The effect of soil properties on the deposition of radionuclides was studied. The capability of different soil minerals in reducing \({}^{134}\)Cs uptake by ryegrass from peat soil is in the following order: zeolite > heavy clay > bentonite > biotite > apatite [5]. However, results from post- and pre-Chernobyl studies have often been inconclusive, probably due to the wide range of soils under investigation as well as to the rates and forms of treatments [6]. [PERSON] and co-workers studied the ion exchangeability of a single solution of CsCl or SrCl\({}_{2}\).2H\({}_{2}\)O with Bulgarian zeolitized tuffs and indicated the high selectivity over a wide range of concentrations of Cs\({}^{+}\) and Sr\({}^{2+}\)[7]. They also examined the kinetics of the ion exchangeability of both Cs\({}^{+}\) and Sr\({}^{2+}\) in the same solution and found that the equilibrium ion-exchange data (qmax (mg/g)) were 122.7 and 21.50 for Cs\({}^{+}\) and Sr\({}^{2+}\), respectively [8]. However, they did not mention what inorganic ions in Bulgarian zeolitized tuffs did exchange ions with Cs\({}^{+}\) and Sr\({}^{2+}\) in solution. [PERSON] and co-workers [9] employed two cation exchange resins, namely calcium polystyrene sulfonate and sodium polystyrene sulfonate, to adsorb \({}^{137}\)Cs in water, Japanese pharmacopoeia 1 st fluid (pH 1.2) and 2 nd fluid (pH 6.8). They found that both resins adsorbed \({}^{137}\)Cs and that the adsorption rate decreases with increasing pH of the solution. They also found that in a potassium solution up to 20 mmol-L\({}^{-1}\) the adsorption of \({}^{137}\)Cs by the sodium polystyrene sulfonate resin was slightly decreased from 99% to 79% but that of the calcium polystyrene sulfonate resin greatly decreased from 93% to 30%. In light of the above results, phytoremediation using sunflower and application of zeolite as a radioadsorbent were undertaken as remediation strategies to decontaminate paddy soils after the Fukushima Daiichi nuclear power plant accident in March 2011. However, these trials did not yield any encouraging result. Thus, the official strategy was to use potassium-containing fertilizers, such as potassium chloride or potassium silicate [10]. In a different approach to the abovementioned treatments of contaminated paddy soil, a paper sludge carbon (PSC) made by a pulp and paper mill was used to adsorb \({}^{137}\)Cs in an aqueous solution and its uptake kinetics already reported [11]. The objectives of this work are (1) to examine the effect of PSC on the activity concentrations of \({}^{134}\)Cs and \({}^{137}\)Cs in rice harvested in 2011 from a radiocontaminated paddy field in the Iitate village, Fukushima; (2) to investigate the effect of radiocesium in soil on the components of the PSC; and (3) to propose a possible mechanism for the adsorption of radiocesium by PSC. It is worth mentioning that the Iitate village along with Minami-soma, Namie, Futaba, Okuma, and Tomioka were the heavily contaminated areas in Fukushima.