Influence of acid rain components on radiocesium-137 desorption from Cetraria islandica (L.) Ach. lichen

Desorption of 137Cs from Cetraria islandica (L.) Ach. lichen was performed by five consecutive desorptions with five identical solution volumes. Solutions of H2SO4, HNO3 and their mixtures, with pH 4.61, 5.15 and 5.75 were used for desorption. The desorbed amount of 137Cs (average value, all solutions used) from lichen, for a given pH value was 49.2% for pH 4.61; 47.0% for pH 5.15 and 47.6% for pH 5.75. The obtained values of the desorbed amount of 137Cs from lichen are in accordance with the data obtained in earlier work, when 46.2 % 137Cs was desorbed from lichen for pH 3.75, and 47.2% was desorbed for pH 2.87. A higher percentage of 59.8%, obtained for pH 2.00 indicates increased activity of H+ ions. The amount of desorbed 137Cs from lichen using solutions corresponding to acid rain cannot be lower than the stated values as they contain other substances besides the acid solutions used in this work.