Retention of 137Cs in forest floor at three temperate coniferous forest stands in the Czech Republic diversely affected by fallout after the Chernobyl disaster in 1986

Distribution of the 137Cs activity concentrations, soil pH, content of organic matter and composition of mineral portion in humus were investigated in forest soils variably loaded by Chernobyl-derived fallout. Maximum in the 137Cs activity concentrations were found in the uppermost organic soil horizons. In forest humus the 137Cs activity concentrations was negatively related to pH and the content of organic matter. No significant content of clay minerals was detected in humus. Slow vertical migration (0.04–0.06 cm year−1) and effective half-life of 137Cs in humus about 20 years was found. The initial surface 137Cs activities in 1986 were estimated.