The activity concentration of post-Chernobyl 137Cs in the area of the Opole Anomaly (southern Poland)

Abstract

During the years 2007 and 2010, the activity concentration of 137Cs accumulated in soil, mosses Pleurozium schreberi and lichens Hypogymnia physodes was measured. The studies covered the areas of the so-called Opole Anomaly. In consequence of the Chernobyl nuclear power plant breakdown in 1986, relatively large amounts of this radionuclide were deposited in this area. In some areas of the Anomaly, over 100 times higher surface activity of 137Cs was detected, compared to the lowest values registered in Poland. Currently, 137Cs is still present in woodlands and wastelands. As at 2 April 2013, the surface activity concentration of 137Cs in soil on the tested area was from 0.34 to 67.5 kBq m−2. In comparison, the surface activity concentration of 137Cs as at 1 June 1986, soon after deposition, was from 2.08 to over 125 kBq m−2. The maximum specific activity concentrations of 137Cs in mosses and lichens sampled for testing in 2010 were respectively 1234 and 959 Bq kg−1. It was also proven that the changes in activity concentration of 137Cs in the area of the Anomaly are mainly the consequence of the radioactive decay of this radionuclide.