DECOMPOSITION IN 2 PINE FORESTS - THE MOBILIZATION OF CS-137 AND K FROM FOREST LITTER

Decomposition rates of pine litter and cotton were measured in the lit ter (AoL) and fermentation (AoF) horizons of two forests in Ireland (P inus contorta) and the Ukraine (Pinus sylvestris). The extent of decom position was similar in spite of seasonal climatic differences between the two sites. The amounts of Cs-137,, and K in litter bags were dete rmined at different stages of decomposition. During the first 2-4 mont hs of decomposition, the K content of litter bags decreased by up to 8 0%; maximum weight loss in this time was 18%. At both sites decomposit ion of the litter was accompanied by an increase in Cs-137 content of the litter bags. It is suggested that the increase in Cs-137 content i s due to importation of Cs-137 by invading decomposer fungi. Fungus-me diated translocation of Cs-137 to, fresh litter is proposed to explain the persistence of Chernobyl radiocaesium in the upper horizons of fo rest soils. (C) 1997 Elsevier Science Ltd.