Distribution of 137Cs in Latvian Pine Wood

Full text: Significant changes in the environmental radioactivity were brought about by the Chernobyl nuclear accident. Due to the favourable meteorological conditions Latvia did not suffered a lot from the radioactive fallout. Forests effectively accumulate the pollution. The best it can be seen in the coniferous forests. We established that the linear dependence exists between the amount of needles in the litter and the amount of the 137Cs. The concentration of it in foliage trees forest litter is significantly smaller. The average speed of migration of 137Cs is characterised by 0.2 cm/year in the soil, but in the litter of coniferous forests it is even lesser. To do such investigation it is especially important in such countries as Latvia where the radioactive pollution is comparatively small. We choose for study the forest litter from pine forests. Such choice is due to the fact that pine trees occupy 50% of Latvian forests. Samples were collected from 34 forests throughout Latvia in 112 constant observation points. In recent time radioactive pollution is defined by the long-lived radionuclide 137Cs. The measurements were carried out by using high performance gamma-spectrometry. The content of 137Cs radioactivity in litter of pine forest was 60-970 Bq/kg. The increased radioactivity was observed on the coast of the Baltic Sea in Kurzeme (the western part of Latvia) mainly near the Lithuania border. We have established that the radioactive pollution of 137Cs in Latvia has mosaic-like structure. (author)