Vertical and lateral distribution of fallout 137 Cs and soil properties along representative toposequences of central Rif, Morocco

Abstract

The purpose of this study is to understand and quantify the relationships between current Cs inventories and the soil properties and the physiographic characteristics. A total of 36 cores were taken in seven transects with different slopes, lithology and land use. The analysis focused on theCs mass activity as well as inventories and its relationship with soil properties as grain size and organic matter. The mass activity of Cs and the inventories varied between 3.6 and 63.7 Bq kg and between 521.7 and 3304.4 Bq m, respectively. At uncultivated soils, high concentrations of Cs are located in the top 10 cm and decreased exponentially in depth. Cultivated soils record disturbed and heterogeneousCs profiles with values of mass activity and inventories up to 38.7 Bq kg and 2510.8 Bq m, respectively. The Cs inventories were significantly higher in uncultivated soils (mean: 2086.9 Bq m) compared to cultivated soils (mean: 1397.1 Bq m). The Cs mass activity showed a significant positive correlation with organic matter, silt and clay, but it was negatively correlated with sand and pH respectively. High levels ofCs were found at altitudes between 500 m and 640 m a.s.l, and at slopes from 8° to 11°, as well as in dense scrub land and Fersialitic soils. A principal component analysis showed that more than 86.7% of the variance in Cs mass activity was explained by the organic matter content and the land use. The results of this study provide insights into the effects of soil properties and physiographic factors on the behaviour ofCs in soils of Mediterranean environments of North Africa and strengthen the reliability of this radioisotope as an erosion tracer.

Vertical distribution and radiological risk assessment of 137Cs and natural radionuclides in soil samples

“…According to the literature, the soil organic matter contains chains of carbon atoms, containing polar and/or ionized surface functional groups, like OH – and COOH – , and generally, radionuclides strongly adsorbed to these functional groups and form stable complexes 19 . The strong correlation was not found between particle size and carbonate content of soil with 137 Cs radioactivity, which is consistent with the previous studies 4,15,35,36 . Concerning the moisture content, the positive correlation was obtained with 226 Ra activity concentrations with R 2 = 0.44 (see Supplementary Materials), which agreed with the study of 32 .…”

“…Figure 1 shows that the organic matter is very low for all soil samples mainly due to low vegetation cover; it varies from 0.08% to 0.68%. Because of the high cationic exchange capacity of the organic matter, the results of low organic matter may lead to assumption that adsorption in soil samples may be controlled mainly by an ion exchange mechanism with the clay minerals 15 . Organic matter is of great importance because it tends to form soluble or insoluble complexes with radionuclides, which may then transport throughout the profile or retain within the soil 22 .…”

“…At low pH value, more 137 Cs is detected. Physical soil actions caused by runoff can also affect the final distribution of 137 Cs 14,15 .…”

Estimating soil redistribution patterns with 137Cs measurements in a Mediterranean mountain catchment affected by land abandonment

“…Studies using the 137 Cs technique have confirmed its potential over the medium term (∼50 years) for estimating soil redistribution rates (Alewell, Meusburger, Juretzko, Mabit, & Ketterer, ; Gaspar, Navas, Walling, Machín, & Gómez Arozamena, ; Mabit, Bernard, Makhlouf, & Laverdière, ; Navas & Walling, ; Sadiki, Faleh, Navas, & Bouhlassa, ) and for validating spatially distributed catchment erosion and sediment yield models (Collins, Walling, Sichingabula, & Leeks, ; Du & Walling, ; Mabit, Bernard, & Laverdiere, ; Mesrar et al, ; Quijano, Beguería, Gaspar, & Navas, ).…”

Establishing correlations among pore structure, surface roughness, compressive strength, and fracture toughness of ceramic water filters local to Rajasthan, India

“…Higher the content of alumina in the clay, better is the refractoriness of the clay [41]. The content of alumina inversely affects the mechanical strength of ceramics [42].…”