Natural radioactivity levels (K, Th, U and Rn) in the Cecita Lake area (Sila Massif, Calabria, Southern Italy): An attempt to discover correlations with soil features on a statistical base

Abstract

Soils can exhibit a complex range of physical, mineralogical, and chemical features depending on many interrelated factors such as parental rock composition and mineralogy, climate, topography, vegetation amounts and types, water infiltration versus runoff, soil moisture, organic matter, presence and types of anthropogenic contaminants, and many others. Radioactivity as measured on these complex systems is consequently perturbed by several mixed effects. In order to find out a possible (potential) relationship among soil properties and experimental data attributable to radioactivities of K, Th, U and Rn a detailed investigation has been performed in the Cecita Lake basin (Sila Grande, Calabria, Southern Italy). Most of the soil types outcropping in the Cecita Lake surroundings belong to the Entisol and Inceptisol orders [USDA (United States Department of Agriculture), 2006. Keys to Soil Taxonomy. 10th edit., USDA, Soil Survey Staff, Natural Resources Conservation Service, Washington D.C., 333 pp.], representing relatively young, poorly to moderately differentiated soils, showing features strongly dependent on the nature of the parent rock and the climatic conditions. Disintegrations contributed by K, Th, U and Rn measured respectively in % (K), ppm (U and Th) and kBq/m 3 (Rn), have been related to 13 a priori known soil unit groups with well-defined general features and spatial position. The data have been analysed by using graphical and numerical statistical procedures able to manage compositional data in a correct sample space. The paper summarises the results of this research and highlights the conclusions drawn from these investigations, particularly concerning i) the modelling of the high U variability, a behaviour that tends to homogenise the differences potentially attributable to soil features, with the exception of situations where uranium could be enriched due to adsorption onto iron oxi-hydroxides and/or clay minerals or concentrated in argillic horizons due to illuviation; ii) the discovering of the discriminative effect of the K/Th ratio values, particularly for soil groups where Th behaviour, as other tetravalent actinides, is strongly affected by the presence of mineral colloids or where the presence of clays affects the trapping of K; iii) the clustering of the a priori known soil groups in four new sets characterised by internal similarities for Rn values for which the morphology appears to be the most important discriminative effect.

Edaphic factors affecting the vertical distribution of radionuclides in the different soil types of Belgrade, Serbia

“…8 Buccianti et al (2009) and Belivermis et al (2010) confirmed the influence of particle size on radionuclide specific activities in soil. 9,10 Nevertheless, there is a scarcity of information on the behaviour of radionuclides in the soils of Serbia. 11,12 In this study the depth distribution of the natural radionuclides, 40 K, 226 Ra and 232 Th, and Chernobyl-derived 137 Cs, was studied in profiles representing typical soil types of the Belgrade area.…”

“…11,12 In this study the depth distribution of the natural radionuclides, 40 K, 226 Ra and 232 Th, and Chernobyl-derived 137 Cs, was studied in profiles representing typical soil types of the Belgrade area. 13 Although a substantial body of knowledge already exists in this area, in the majority of studies correlations between natural or anthropogenic radionuclides and a limited number of soil parameters, mainly particle size, [6][7][8][9][10][14][15][16][17][18][19][20][21][22] pH, organic matter content, 6,10,[16][17][18][20][21][22] carbonate content 6,7,16 or selected stable elements, 7,20,21 have been investigated. To assess the pedogenic effect on the distribution of radionuclides, the relationships between radionuclide specific activities and a number of soil properties (particle size distribution, pH, organic matter content, carbonate content, cation exchange capacity, bulk density, particle density, saturated hydraulic conductivity and specific electrical conductivity) were analysed.…”

Assessment of Natural Radionuclide Distribution Pattern and Radiological Risk from Rocks in Precambrian Oban Massif, Southeastern Nigeria

“…However, locations with low U/Th indicate that processes responsible for U-enrichment are higher than that of [44]. Furthermore, it is also possible that weathering and other soil-forming processes might have caused the depletion of U from the rocks in some locations, leading to their uneven spatial distribution [49].…”

Is compositional data analysis a way to see beyond the illusion?

“…Furthermore they can well describe processes of element partition, or groups of elements, when they present coherent (similar) behaviour in geochemistry (Buccianti, 2011a;Buccianti, 2011b). The identification of easily interpretable balances may also be useful to reveal natural laws governing proportions in several field of earth (Buccianti and Esposito, 2004;Nisi et al, 2008;Buccianti et al, 2009) and ecological sciences (Bertocchi et al, 2008;Tricarico et al, 2008). Although the sequential binary partition can be performed following rigorous mathematical steps (Egozcue et al, 2003, Hron et al, 2010, here in the case studies analysed, the choice of the balances starts from a geochemical hypothesis.…”