Effect of Exchangeable and Nonexchangeable Potassium in Soil on Cesium Uptake by Quercus serrata Seedlings

Abstract

AbstractIn general, potassium in soil greatly reduces radiocesium uptake by plants. Using four extraction methods, we investigated forms of potassium retained in soils from Quercus serrata (Konara oak) forests in nine regions across Japan to investigate the effect of potassium on the transfer factor of cesium in oaks. Of the potassium extracted with ammonium acetate (exchangeable K), hydrogen peroxide (H2O2-K), boiling nitric acid (HNO3-K), and tetraphenyl boric acid (TPB-K), HNO3-K, which is considered to be an indicator of nonexchangeable K content, showed the highest correlation with the transfer factor of cesium in Konara oak. H2O2-K showed the second highest correlation coefficient with cesium concentration in Konara oak. On the other hand, no significant correlation was found for exchangeable K with ammonium acetate solution, which is used to determine cesium uptake characteristics of crops. In addition, large variations were observed for all four forms of K. To determine characteristics of cesium uptake and transfer to trees, it is necessary to consider various forms of K, including nonexchangeable K.