scholarly journals Investigation of the dependence of the activity concentration of natural and artificial radionuclides on particle size in surface soil

2019 ◽  
Vol 24 ◽  
pp. 217
Author(s):  
I. K. Mitsios ◽  
D. J. Karangelos ◽  
M. J. Anagnostakis
Keyword(s):  
Particle Size ◽  
Activity Concentration ◽  
Surface Soil ◽  
Soil Samples ◽  
Size Fractionation ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Activity Concentrations ◽  
Particle Size Fractionation ◽  
Natural And Artificial Radionuclides

Surface soil radioactivity is being studied at NED-NTUA since almost thirty years. The last few years this research has expanded to the study of soil particle size fractionation of radionuclides. The purpose of the present work was to study the tendency of many radionuclides to accumulate in the smaller particle size fractions. To this end, soil samples were collected from an area in the NTUA Campus where 241Am contamination, due to a failed 241Am-tipped lightning rod, had been previously detected. The samples were separated into size fractions using a sieving machine and analyzed by gamma spectrometry to determine 210Pb, 241Am, 234Th, 228Ra, 228Th, 226Ra, 7Be, 137Cs and 40K. The activity concentrations of these nuclides were found to significantly differ among the size fractions examined.

scholarly journals Spatial variability of particle size fractions of an Oxisol cultivated with conilon coffee

Revista CERES ◽  
2012 ◽  
Vol 59 (6) ◽  
pp. 867-872 ◽  
Author(s):  
Julião Soares de Souza Lima ◽  
Rone Batista de Oliveira ◽  
Samuel de Assis Silva
Keyword(s):  
Particle Size ◽  
Spatial Variability ◽  
Clay Fraction ◽  
Soil Samples ◽  
Landscape Configuration ◽  
Sand Fraction ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Average Value ◽  
Significant Difference

Information on the spatial distribution of particle size fractions is essential for use planning and management of soils. The aim of this work to was to study the spatial variability of particle size fractions of a Typic Hapludox cultivated with conilon coffee. The soil samples were collected at depths of 0-0.20 and 0.20-0.40 m in the coffee canopy projection, totaling 109 georeferentiated points. At the depth of 0.2-0.4 m the clay fraction showed average value significantly higher, while the sand fraction showed was higher in the depth of 0-0.20 m. The silt showed no significant difference between the two depths. The particle size fractions showed medium and high spatial variability. The levels of total sand and clay have positive and negative correlation, respectively, with the altitude of the sampling points, indicating the influence of landscape configuration.

scholarly journals Natural radioactivity in the soil of Thoulakhom district in Vientiane province, Laos

2019 ◽  
Vol 2 (4) ◽  
pp. 119-125
Author(s):  
Sonexay Xayheungsy ◽  
Khiem Hong Le
Keyword(s):  
Activity Concentration ◽  
Democratic Republic ◽  
Surface Soil ◽  
Natural Radionuclides ◽  
Soil Samples ◽  
Radiation Hazard ◽  
Gamma Spectrometer ◽  
Mean Values ◽  
Activity Concentrations ◽  
The Mean

Results of the first investigation of the activity concentration of the surface soil samples collected at various locations of Thoulakhom district of Vientiane province of Laos People's Democratic Republic (PDR) are presented in this work. The activity concentration of the natural radionuclides 226Ra, 232Th and 40K in the soil samples were determined by gamma spectrometer using a highenergy resolution semiconductor detector HPGe. The activity concentrations of the natural radionuclides were in the range from 11.28 to 31.46 with the mean of 21.76 Bq.kg-1 for 226Ra, from 7.13 to 44.47 with the mean of 21.85 Bq.kg-1 for 232Th and from 8.96 to 581.52 with the mean of 112.89 Bq.kg-1 for 40K. These mean values of the activity concentration were lower than the average worldwide ones, which were 33, 45 and 420 Bq.kg-1 for 226Ra, 232Th, and 40K, respectively. The results indicate dthat the radiation hazard from natural 226Ra, 232Th, and 40K radionuclides in all investigated soil samples taken from area under investigation in this work was not significant.

Pouvoir fixateur vis-à-vis des ions phosphate de sols tropicaux à argile 1:1

1992 ◽  
Vol 72 (2) ◽  
pp. 135-143 ◽  
Author(s):  
E. Frossard ◽  
M. Brossard ◽  
C. Feller ◽  
J. Rouiller
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Mineralogical Composition ◽  
Clay Soils ◽  
Exchange Method ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Particle Size Fractionation ◽  
Low Activity

This study was aimed to clarify the influence of secondary mineral constituents (iron and aluminium oxides, kaolinite) and organic matter on the determination of the phosphate-fixing capacity (PFIX) of well-drained low-activity clay soils. This study was done on soil samples (0–2 mm) and on their particle size fractions. The phosphate-fixing capacity, estimated by an isotopic exchange method, was highly related to the total iron content of the soils. The phosphate-fixing capacity of the particle size fractions was related to their mineralogical composition, and to the organisation of their constituents. H2O2 strongly increased the phosphate-fixing capacity of the soils and of their particle size fractions. Two hypotheses were proposed to explain this. Either H2O2 caused the formation in vitro of amorphous constituents with a high phosphate fixing capacity; or the destruction of organic matter by H2O2 caused the apparition of new surfaces previously masked by organo-mineral aggregation and/or caused the apparition on surfaces of fixation sites previously occupied by organic compounds. Key words: Phosphate-fixing capacity, low-activity clay soils, particle size fractionation, mineralogy, organic matter, H2O2 effect

Digital soil mapping of compositional particle-size fractions using proximal and remotely sensed ancillary data

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. WB201-WB211 ◽  
Author(s):  
S. Buchanan ◽  
J. Triantafilis ◽  
I. O. A. Odeh ◽  
R. Subansinghe
Keyword(s):  
Particle Size ◽  
High Resolution ◽  
Soil Mapping ◽  
Additive Models ◽  
Digital Soil Mapping ◽  
Unbiased Estimation ◽  
Ancillary Data ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Log Ratio

The soil particle-size fractions (PSFs) are one of the most important attributes to influence soil physical (e.g., soil hydraulic properties) and chemical (e.g., cation exchange) processes. There is an increasing need, therefore, for high-resolution digital prediction of PSFs to improve our ability to manage agricultural land. Consequently, use of ancillary data to make cheaper high-resolution predictions of soil properties is becoming popular. This approach is known as “digital soil mapping.” However, most commonly employed techniques (e.g., multiple linear regression or MLR) do not consider the special requirements of a regionalized composition, namely PSF; (1) should be nonnegative (2) should sum to a constant at each location, and (3) estimation should be constrained to produce an unbiased estimation, to avoid false interpretation. Previous studies have shown that the use of the additive log-ratio transformation (ALR) is an appropriate technique to meet the requirements of a composition. In this study, we investigated the use of ancillary data (i.e., electromagnetic (EM), gamma-ray spectrometry, Landsat TM, and a digital elevation model to predict soil PSF using MLR and generalized additive models (GAM) in a standard form and with an ALR transformation applied to the optimal method (GAM-ALR). The results show that the use of ancillary data improved prediction precision by around 30% for clay, 30% for sand, and 7% for silt for all techniques (MLR, GAM, and GAM-ALR) when compared to ordinary kriging. However, the ALR technique had the advantage of adhering to the special requirements of a composition, with all predicted values nonnegative and PSFs summing to unity at each prediction point and giving more accurate textural prediction.

CHARACTERIZATION OF PARTICLE SIZE FRACTIONS OF PEAT. AN INTEGRATED BIOLOGICAL, CHEMICAL, AND SPECTROSCOPIC APPROACH

Soil Science ◽  
1992 ◽  
Vol 153 (5) ◽  
pp. 382-396 ◽  
Author(s):  
B O NORDEN ◽  
ELISABET BOHLIN ◽  
MATS NILSSON ◽  
ÅSA ALBANO ◽  
CHRISTINA RÖCKNER
Keyword(s):  
Particle Size ◽  
Size Fractions ◽  
Particle Size Fractions

ANALYSIS OF AIRBORNE PARTICULATE MATTER COLLECTED AFTER AN ERUPTION EPISODE OF THE POPOCATÉPETL VOLCANO

2003 ◽  
Vol 13 (03n04) ◽  
pp. 133-139 ◽  
Author(s):  
F. ALDAPE ◽  
J. FLORES M.
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Mexico City ◽  
Airborne Particulate Matter ◽  
Airborne Particulate ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Two Samples ◽  
Popocatépetl Volcano ◽  
Popocatepetl Volcano

Samples of airborne particulate matter were collected in four sites along an east-west line from the Popocatépetl volcano after the eruption episode of June 30, 1997. The Popocatépetl volcano, with variable activity since it was known, is currently under low but continuous activity prolonged for almost one decade, with occasional moderate eruption episodes producing mainly fumes, ashes and volcanic dusts. The main objective of this study is to determine whether or not some elements have increased their presence in the atmosphere as a result of the volcanic activity, and also if some others, not usually found in urban aerosols, have appeared because of the same reason. In addition, the information obtained will be a source of scientific data for health risk assessment of the population exposed to volcanic emanations. The sample collection was performed on alternate days from July 10 to August 13 1997 in Puebla and Atlixco in Puebla State. Tlalpan within Mexico City, and Salazar in the State of Mexico. Two samples a day were taken in two periods: 7-19 h and 19-7 h. The samplers separated particles into two particle size fractions. PM25 and PM15. Elemental concentrations were determined by PIXE and the results obtained showed increased concentrations of mainly Ti and Fe in all sampling sites, thus indicating a long range transportation of volcanic dusts in both particle size fractions. Concentrations of Ti were found clearly above the average values of urban areas such as Mexico City, and although this element can be considered of low toxicity, the biological, metabolic and toxic effects on human beings are still under investigation.

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