Preliminary studies on the spatial distribution of artificial ¹³⁷Cs and natural gamma radionuclides in the region of the Ojców National Park, Poland

Abstract

The aim of the research is to obtain preliminary information about the spatial distribution of gamma radionuclides in the soils taken from the Ojców National Park with emphasis on the behaviour of artifi cial radionuclides, with 137 Cs as a representative. The natural radionuclides 40 K, 226 Ra (uranium series), and 228 Th (thorium series), which are considered as background radiation, were also determined. In total, 18 soil samples were collected during the summer periods in 2015-2017, while the sampling points were selected with respect to differences in rainfall and local topography gradient. The method was based on gamma-ray spectrometry performed on high-purity germanium (HPGe) gamma detector (relative effi ciency 34%). 137 Cs was mostly deposited in the top soil layers, with activity in the range of 27.9÷586.6 Bq·kg -1 . We found strong positive correlation of the 137 Cs activity with the soil organic matter content, and at the same time, its dependence on the rainfall amount. Consequently, the soil types and local climate can control the spatial distribution of 137 Cs on a small spatial scale. The quantity of natural radionuclides was highly similar in all samples with the following mean values: 38.0 Bq·kg -1 for 228 Th, 33.1 Bq·kg -1 for 226 Ra, and 479.9 Bq·kg -1 for 40 K.

A Geological Context in Radiation Risk Assessment to the Public

“…Naturally occurring radionuclides of terrestrial origin are present in almost all environmental media. There are many different radioisotopes, but in practical terms only a few have sufficient abundance and radiological importance [ 1 , 2 ]. Most research on naturally occurring radionuclides in soils has focused on primordial 40 K, 238 U, 232 Th and 226 Ra from uranium series [ 3 , 4 , 5 ].…”