Journal of Geochemical Exploration | 2019
The 232Th distribution in modern sediments near radioactive lovchorrite mine, the Khibiny Mountains, Kola Peninsula
Abstract
Abstract The 232Th migration in environment is linked to transportation of thorium-bearing mineral particles. In cold climatic conditions of alpine tundra, leaching of 232Th is the least typical process. The spread of 232Th in environment is associated with the transport of thorium-bearing mineral particles. The total content of the 232Th and its distribution between different grain-size fractions, bulk samples of modern sediments from a lovchorrite mine in the Hackman Canyon, in the southern part of Khibiny Mountains (Kola Peninsula, Russia) in 2015–2017 were determined using gamma-ray spectrometry. The most active samples were sequentially extracted and processed via alpha-spectrometry to identify physicochemical forms of radionuclides. It was recognized that 232Th concentrates in fine grain-size fractions of sediments and easily be washed out by temporal or constant water currents. As it was explored during sequential extraction procedure, the genesis of this phenomenon is likely not to be related to leaching and sorption of radionuclides. Hypothetically, uneven redistribution of 232Th emerges during weathering of radioactive rocks. Metamictic thorium-rich accessories with crystal lattice damaged by own radiation destroyed more intensively than more resistant rock-forming minerals. Hence, fine grainsized fractions become enrich with radioactive particles.