Variation of Cs-137 deposition in soil and lakes in the north-east region of Poland

The aim of this work is to assess the current deposits of Cs-137 in soil and in lakes in the Poland's north-eastern lake district (12-14 years after Chernobyl accident) a dozen or so years after the Chernobyl disaster. Caesium content in soil and sediment was determined by gamma spectrometry (in 79 soil samples and 136 sediment samples). The soil samples were collected in summer 1998-2000. The sediment from 29 lakes were sampled in May 2000. The highest surface activity was found in soil with the arithmetic mean (AM) 3.13 kBq m-2 and median (M) 2.37 kBq m-2. For lakes, the respective values were 1.89 kBq m-2 and 1.5 kBq m-2. In the case of the soil samples collected from forests, fields, lake shores and arable lands, the mean values of caesium deposition were: 4.37, 2.56, 3.42 and 1.52 kBq m-2, respectively. The mean surface activity of sedimentary samples (AM) from oligotrophic, mesotrophic and eutrophics lakes was found to have different values, viz. 1.48, 2.23 and 1.86 kBq m-2, respectively.