Organic cesium carrier(s) in lichen

Most of the radiocesium was extracted from the lichen Cetraria islandica in aqueous medium (91.5%) without significant destruction of the lichen itsel f. Fractional precipitation with ethanol demonstrated that essential biomac romolecules were contaminated slightly with cesium. Using thin-layer and co lumn chromatography at least three cesium-containing compounds were found i n the residual solution. Two of them absorbed light at 270 nm. Further anal ysis of the main peak demonstrated instability resulting in newly formed co mpounds with smaller molecular masses. From this it was concluded that a si gnificant amount of radiocesium in lichen is associated with organic molecu les which tend to decompose upon isolation. (C) 1999 Elsevier Science B.V. All rights reserved.